Breaktru Forum

eCigarette Forum => Modding => Topic started by: Breaktru on May 14, 2013, 06:34:49 PM

Title: Low Battery Indicator
Post by: Breaktru on May 14, 2013, 06:34:49 PM
I used the schematic from Electronics-DIY.com and revised it for one LED and for two 3.7 cells. Will indicate at 6.0v.
Use 1% resistors. 1/8 watts is fine. The components can be wired tightly together as shown in the Elect. DIY photo except there will be one LED not two and one more resistor.
See the attached photo (only viewable to logged on members).

I have it also revised it for a single 3.7v cell and low voltage indicates at 3.0v but need to tweak it for a brighter LED illumination.
It's not as easy as I thought. Changing the resistor for the LED will also effect the Adjustable precision shunt regulator (TL431) from turning on. The Ref pin requires 2.5v to turn on.

The attached schematics show an ON-Semi diode. Pin numbers vary on manufacture so check your manufactures datasheet.
See --> DETAILS (http://breaktru.com/smf/index.php/topic,804.msg10499.html#msg10499)

**I am happy to share info with all that drop by this forum. So dropping a mention when you post your mod elsewhere would be a decent gesture.
Show your support by signing up as a member and please participate by posting**
Title: Re: Low Battery Indicator
Post by: Breaktru on May 15, 2013, 12:51:12 PM
Okay, I've got this circuit revised for a single 3.7v cell note the resistor changes. All resistors are 1% tolerance.
Title: Re: Low Battery Indicator
Post by: Tameron on May 16, 2013, 09:17:36 AM
Very good  :thankyou:
This looks small enough to squeeze in to any small mod project  :yes"
Title: Re: Low Battery Indicator
Post by: FlameOut on May 16, 2013, 09:39:03 AM
I'm going to build two. One for my 3.7v mod and one for my 7.4v mod.
Question. Is the TL431 the same as the LT431?
Title: Re: Low Battery Indicator
Post by: Breaktru on May 16, 2013, 10:29:25 AM
I'm going to build two. One for my 3.7v mod and one for my 7.4v mod.
Question. Is the TL431 the same as the LT431?


The pins and Ref voltage are the same but the Minimum cathode current for regulation and the Off-state cathode current is different.
Even the TL431 has different models w/ different specs. I used part # TL431BCLPGOS (http://www.digikey.com/product-search/en?WT.z_header=search_go&lang=en&site=us&keywords=TL431BCLPGOS-ND&x=11&y=13) and a standard Red LED which has a typical Forward voltage of 2v and 20ma.
Title: Re: Low Battery Indicator
Post by: Breaktru on May 16, 2013, 11:43:57 AM
I would like to point out that the resistor tolerance will play a role for a particular low voltage LED on when low as well as the TL431 on/off state. That's why I mentioned to use a 1% tolerance.
Also LED colors have different specs. Even the Red standard VS the Bright Red LED and Super Bright Red LED. Using a different LED will effect the functionality of the circuit. The circuits are revised for the standard Red LED.
Title: Re: Low Battery Indicator
Post by: kortt on May 17, 2013, 10:46:17 PM
Nice! Been looking for something like this.  Thanks!  :thankyou:
Title: Re: Low Battery Indicator
Post by: marlow57 on May 22, 2013, 10:58:00 AM
I can use something like this. It's perfect. I'll see if my hubby can put one into my box mod
Title: Re: Low Battery Indicator
Post by: Breaktru on May 22, 2013, 01:56:01 PM
I installed the Low Battery Indicator circuit in my .44++ mini mod.
Works great. Low battery indication comes on at 3.03 volts.
What I like about it is you know prior to the above said voltage because you see a very dim, hardly noticeable light. When it reaches the 3.03v, the LED is very noticeable.
See the attached photos (logged on members only)
Title: Re: Low Battery Indicator
Post by: jumper on June 15, 2013, 08:58:58 AM
This is a great idea. Very useful and not just cosmetic. I look forward to when I can put this on one of my mods. Love the feature. Great work!
Title: Re: Low Battery Indicator
Post by: been there on October 12, 2013, 07:19:30 PM
Hi,I'm new to the forum sort of been a member for a while but don't post much and this is where I get a great deal of info from but I have a question what kind of resistors should I use for this I mean like carbon,metal ceramic  ,thanks
Title: Re: Low Battery Indicator
Post by: Breaktru on October 12, 2013, 07:31:08 PM
Hey Florida Vaper,
Any type will do. You can use a low wattage like 1/8 watt.
There are two circuits. Make sure you get the resistors for the battery voltage that you are using.
Title: Re: Low Battery Indicator
Post by: been there on October 13, 2013, 03:15:13 AM
thanks Breaktru for a quick reply .    
Title: Re: Low Battery Indicator
Post by: kortt on December 17, 2013, 06:01:40 PM
Breaktru, what specs are important for the shunt regulator to work correctly?  Where I want to shop only has the exact model number you listed in min order of 4000 units.  I found another one that looks similar to me but not sure of what specs to match up for it to work properly.
This is what I found:
http://canada.newark.com/on-semiconductor/tl431bilprag/ic-prog-shunt-v-ref-2-495v-0-4/dp/04R7864
Would that work?
Title: Re: Low Battery Indicator
Post by: Breaktru on December 17, 2013, 08:14:17 PM
I found a vendor from Canada on eBay --> TL431 (http://www.ebay.com/itm/Lot-of-5-Texas-Adjustable-Precision-Shunt-Regulator-2-5-36V-TL431AILP-TL431-/120851418606?pt=LH_DefaultDomain_2&hash=item1c234e4dee)

The diode is a "programmable shunt regulator diode"
The Reference Input Voltage should be (Typical): 2.495v
Cathode Current: 100ma Max
Title: Re: Low Battery Indicator
Post by: kortt on December 18, 2013, 12:07:03 PM
Nice, thanks Dave!  :thankyou:
Title: Re: Low Battery Indicator
Post by: kortt on December 23, 2013, 03:40:51 PM
Quick question about the pins on the TL431.  Are the pins as shown in the schematic as follows?
1 = anode
2 = ref
3 = cathode
Thanks :P
Title: Re: Low Battery Indicator
Post by: Breaktru on December 23, 2013, 04:36:00 PM
Quick question about the pins on the TL431.  Are the pins as shown in the schematic as follows?
1 = anode
2 = ref
3 = cathode
Thanks :P

NO

My schematic shows an ON-Semiconductor diode TL431BCLPGOS (http://www.digikey.com/product-detail/en/TL431BCLPG/TL431BCLPGOS-ND/921689).

ON-Semi TL431BCLPGOS:
1 = Ref
2= Anode
3 = Cathode

If you bought the eBay one then its a Texas Instrument TL431AILP (http://download.siliconexpert.com/pdfs/2013/10/27/23/55/47/678/txn_/auto/522tl432b.pdf)


The Texas Instrument TL431AILP is the same pin reference as above.
Title: Re: Low Battery Indicator
Post by: kortt on December 23, 2013, 04:56:17 PM
Yeah, I bought from the ebay link you provided.  I need a keeper lol, never occurred to me to compare the datasheets of the two different parts until you said that.
Thanks again Dave!   ;bow;
Title: Re: Low Battery Indicator
Post by: kortt on January 10, 2014, 12:59:42 PM
I put this little image together to help me with the 1 cell circuit that Breaktru so kindly provided.  I find having a visual representation of a circuit helps me keep things sorted and for me I can refer to it along with the schematic when I build.  Hopefully this might help someone else out as well.  I've asked Breaktru to look at it to make sure I didn't make any mistakes.  (Thanks dude!)
(http://i1308.photobucket.com/albums/s603/korttwulfe/kortt-LVI-1cell_zps9803df59.jpg) (http://s1308.photobucket.com/user/korttwulfe/media/kortt-LVI-1cell_zps9803df59.jpg.html)
Title: Re: Low Battery Indicator
Post by: Breaktru on January 10, 2014, 01:37:39 PM
Nice going Greg  :rockin smiley: That should make it easy for those that are not schematic literate  :laughing:
Title: Re: Low Battery Indicator
Post by: Visus on January 10, 2014, 05:51:23 PM
Woot
Kindergarten picture book electronics work best for visus  :thumbsup:

Title: Re: Low Battery Indicator
Post by: rrtwister on January 10, 2014, 07:48:47 PM
Good job interpreting the schematic into a diagram Kortt  :thumbsup:
Title: Re: Low Battery Indicator
Post by: ADozer on January 15, 2014, 04:17:53 PM
Awesome! I've been working on one of these myself, but this is super elegant :)
Title: Re: Low Battery Indicator
Post by: pako75 on February 04, 2014, 02:00:25 PM
Hello guys,
I was searching for a circuit to monitor the battery voltage....
i've read this post i't's excellent, but i was searching for circuit that could do something like

green - full ...... green/red - medium ....... red - low

maybe with a bicolor red/green led...

Someone has any idea???

Thank you to all
Title: Re: Low Battery Indicator
Post by: columbusbk on February 04, 2014, 03:16:18 PM
Hello guys,
I was searching for a circuit to monitor the battery voltage....
i've read this post i't's excellent, but i was searching for circuit that could do something like

green - full ...... green/red - medium ....... red - low

maybe with a bicolor red/green led...

Someone has any idea???

Thank you to all

I wonder if this can be modified for our needs?
Monsoon 8 (http://www.sparkbright.co.uk/products/product_monsoon8.html)
Title: Re: Low Battery Indicator
Post by: Breaktru on February 04, 2014, 08:14:03 PM
Hello guys,
I was searching for a circuit to monitor the battery voltage....
i've read this post i't's excellent, but i was searching for circuit that could do something like

green - full ...... green/red - medium ....... red - low

maybe with a bicolor red/green led...

Someone has any idea???

Thank you to all

Hi Pako,
I have something in mind that I can add to the existing circuit but I would like to test it out before posting the schematic. I need some time to get the parts first.
Title: Re: Low Battery Indicator
Post by: pako75 on February 05, 2014, 12:19:31 PM
I found this on the Bay.... but i don't know whic IC uses....

http://www.ebay.com/itm/200709081697 (http://www.ebay.com/itm/200709081697)
Title: Re: Low Battery Indicator
Post by: CraigHB on February 05, 2014, 02:47:59 PM
Power consumption says 5mA which is current not power, but if it's 5mA and not 5mW, that's a bit high to leave on a battery full time.  Probably okay for removable cells, but not for permanently mounted cells.  If you were to leave your device lying around for a couple months, it would over-discharge the battery.
Title: Re: Low Battery Indicator
Post by: pako75 on February 05, 2014, 03:41:11 PM
Power consumption says 5mA which is current not power, but if it's 5mA and not 5mW, that's a bit high to leave on a battery full time.  Probably okay for removable cells, but not for permanently mounted cells.  If you were to leave your device lying around for a couple months, it would over-discharge the battery.

you could power it everytime you push the atom button.... perhaps in an angel eye style button....
(http://thumbs4.ebaystatic.com/d/l225/m/mKw501l0TB3mQiEzF54hA8A.jpg)
Title: Re: Low Battery Indicator
Post by: CraigHB on February 05, 2014, 05:23:39 PM
Yeah, that would solve the problem of the battery drain, but I have an indicator like that and don't often notice it (LED illuminates red when the trigger is pressed with the battery below 10% charge).  Most of the time I don't realize the battery is discharged until the mod flags a low battery and stops working.  Still it's better than nothing, but you really need a cut-out of some kind.  You could Tie that LED output to a MOSFET to switch battery power.
Title: Re: Low Battery Indicator
Post by: pako75 on February 06, 2014, 01:38:34 PM
You could Tie that LED output to a MOSFET to switch battery power.

I really don't how to do this...  :no: :no:
Title: Re: Low Battery Indicator
Post by: pako75 on February 23, 2014, 04:35:27 AM
Hy guys,

I was thinking.....   with this revisited schematic could be possible to light the red led on the charging board????
Could be an idea to use a bicolor led to indicate both charging status and low battery.....
What do you think?
Title: Re: Low Battery Indicator
Post by: aflex on February 26, 2014, 12:00:29 AM
There are two circuits. They are making a combination of parallel and series. On looking at these circuits we can realize that at least 1% tolerance and low wattage like 1 to 6 watt is require. It may vary with time.
Title: Re: Low Battery Indicator
Post by: Breaktru on February 26, 2014, 06:29:45 AM
There are two circuits. They are making a combination of parallel and series. On looking at these circuits we can realize that at least 1% tolerance and low wattage like 1 to 6 watt is require. It may vary with time.

Not sure what you mean. ???
Title: Re: Low Battery Indicator
Post by: pako75 on February 26, 2014, 05:01:36 PM
I found it!
That's what i was looking for...

Do you think this will work???
Title: Re: Low Battery Indicator
Post by: Breaktru on February 26, 2014, 07:27:54 PM
Yes it will work.
Looks like that the green LED will light at 3.5v or above and go out when the voltage is 3.4v or below. The red LED will light at 3.4v and below.
Title: Re: Low Battery Indicator
Post by: pako75 on February 27, 2014, 01:48:36 PM
Tried today..... doesn't work!  :wallbash:

At 4.2V the red led is enough bright, at 3.5V very low red light...
Green led lights (very low) at 3.1V....
transistor BC547C


Title: Re: Low Battery Indicator
Post by: Breaktru on February 27, 2014, 04:30:42 PM
Are you certain of the pins and the position of the transistor when reading the pin numbers:
Looking at it with the pins facing down and the flat side toward you,
from left to right........
1. Collector 2. Base 3. Emitter
Title: Re: Low Battery Indicator
Post by: pako75 on February 27, 2014, 05:18:43 PM
Tomorrow i'll check this, but i'm pretty sure i wired it correctly
I've controlled the datasheet before start wiring....
Title: Re: Low Battery Indicator
Post by: ChainVaper on February 27, 2014, 08:56:14 PM
I just noticed something.
The schematic shows a BC547 and you used a BC547C transistor.
Don't know if that has anything to do with it  :Thinking:
Title: Re: Low Battery Indicator
Post by: vaperkarma on April 23, 2014, 12:45:25 PM
I just built one using the TL431. Thanks breaktru. It works great  :thumbsup:
Title: Re: Low Battery Indicator
Post by: blkbd on May 07, 2014, 03:52:52 AM
I found it!
That's what i was looking for...

Do you think this will work???

Hello to all, New member and noob to circuitry but looking to build my first mod and is there schematic yet for a dual battery set up? Or is the schematic posted by Breaktru the same and uses a red and green led as it was not specified?
Title: Re: Low Battery Indicator
Post by: Visus on May 08, 2014, 09:11:30 PM
Hi blkbd I saw your post on ecf too.

Breaks 1st diagram will work for you on the okr with 8.4v  you will have to figure a different resistor if its not a standard led.  That will be cool, his circuit is designed to light when the voltage reaches ~6v its off until then.. 

Off post:
Heres a really cool indicator for a single cell
https://www.fasttech.com/product/1225203
Title: Re: Low Battery Indicator
Post by: blkbd on May 09, 2014, 04:27:31 AM
Why 2 LED's? Sorry I can do basic wiring and soldering but all these LED's and resistors make my head swim.
Title: Re: Low Battery Indicator
Post by: Visus on May 09, 2014, 11:33:36 AM
Why 2 LED's? Sorry I can do basic wiring and soldering but all these LED's and resistors make my head swim.

He wired them in series-- he says, the posted diagram is for a single 2v 20ma led,  he obviously used a different method of achieving same results but with two instead of one.

Re-read his first post.

Pako then later finds a diagram at another site that shows full battery  green led emit and discharged showing red led emit but he never got it to work properly since his last post..  Noone else has tried that diagram or has posted about trying it.  Breaks diagram works as posted @~6v..

This may be to advanced for ya but its really not difficult at all, its a very simplistic design just make sure you buy the right parts.

Title: Re: Low Battery Indicator
Post by: blkbd on May 09, 2014, 05:52:49 PM
Thank you for your patience, :thumbsup: I did read it but got to fixated on the diagram and pic trying to understand it. The Kortt diagram is the kind that I can follow. I don't see any spec's on what LED to use with Breahtru's diagram? But would guess this one http://www.radioshack.com/product/index.jsp?productId=2062554&znt_campaign=Category_CMS&znt_source=CAT&znt_medium=RSCOM&znt_content=CT2032233
 Thank you for your time.  :beer-toast:
Title: Re: Low Battery Indicator
Post by: Breaktru on May 09, 2014, 07:08:08 PM
A standard Red LED has a typical Forward voltage of 2v and 20ma. The link to your RS LED is 2.25v, 28ma. You would have to tweak the resistors to work with that LED. Or find a typical Red LED like THIS (http://www.digikey.com/product-search/en?pv37=1&pv319=25&pv543=29&pv16=2&pv69=80&pv69=690&FV=fff40008%2Cfff801b9&mnonly=0&newproducts=0&ColumnSort=0&page=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25)
Title: Re: Low Battery Indicator
Post by: blkbd on May 09, 2014, 07:53:25 PM
Thanks for that info, Looks like I have some sketching to do and a weekend project.
Title: Re: Low Battery Indicator
Post by: Jasen on May 10, 2014, 04:08:57 PM
Finding someone that stocks those resistors in a through hole configuration is proving to be challenge, Digikey, mouser are pretty much a no go, all I'm finding from them is SMD's
Title: Re: Low Battery Indicator
Post by: blkbd on May 10, 2014, 04:43:19 PM
Finding someone that stocks those resistors in a through hole configuration is proving to be challenge, Digikey, mouser are pretty much a no go, all I'm finding from them is SMD's

Thanks for the heads up,  :rockin smiley: Yeah the ones at Radio Shack have a 5% tolerance. I'll Google SMD and put in a order later this weekend. Thank you!  :thumbsup:

I take it 1/4 Watt is OK as long as the Ohm and 1% tolerance is correct?
Title: Re: Low Battery Indicator
Post by: Visus on May 11, 2014, 02:43:46 AM
Put together the parts list for future reference  digikey has everything in stock..
97 cents to build the 7.4v circuit..

http://www.digikey.com/product-search/en?WT.z_header=search_go&lang=en&site=us&keywords=TL431BCLPGOS&x=18&y=10&formaction=on

http://www.digikey.com/product-detail/en/MFR-25FBF52-10K/10.0KXBK-ND/13219

http://www.digikey.com/product-detail/en/RNMF14FTC2K20/S2.2KCACT-ND/2617481


http://www.digikey.com/product-detail/en/1622461-1/A105959CT-ND/3477538

http://www.digikey.com/product-detail/en/1622500-1/A105962CT-ND/3477542


Title: Re: Low Battery Indicator
Post by: blkbd on May 11, 2014, 03:09:15 AM
Put together the parts list for future reference  digikey has everything in stock..
97 cents to build the 7.4v circuit..

http://www.digikey.com/product-search/en?WT.z_header=search_go&lang=en&site=us&keywords=TL431BCLPGOS&x=18&y=10&formaction=on

http://www.digikey.com/product-detail/en/MFR-25FBF52-10K/10.0KXBK-ND/13219

http://www.digikey.com/product-detail/en/RNMF14FTC2K20/S2.2KCACT-ND/2617481

http://www.digikey.com/product-detail/en/1622461-1/A105959CT-ND/3477538

http://www.digikey.com/product-detail/en/1622500-1/A105962CT-ND/3477542

I owe you a beer or a six pack for that matter as I would have had to order from  different places, If your in NH drop me a PM.  :beer-toast:
Title: Re: Low Battery Indicator
Post by: Visus on May 11, 2014, 05:18:41 PM
I owe you a beer or a six pack for that matter as I would have had to order from  different places, If your in NH drop me a PM.  :beer-toast:

Hope you have a sister who's a cheerleader or supermodel, hot geek will do nicely as well   :laughing2:   :thumbsup:
Title: Re: Low Battery Indicator
Post by: blkbd on May 11, 2014, 06:54:28 PM
Hope you have a sister who's a cheerleader or supermodel, hot geek will do nicely as well   :laughing2:   :thumbsup:

No hot supermodel cheerleader sisters but if you piss me off I can introduce you to my ex-wife.  :laughing2:
Title: Re: Low Battery Indicator
Post by: Jasen on May 12, 2014, 12:54:46 AM
I was looking for 1/8W which were near impossible to find anywhere.
Title: Re: Low Battery Indicator
Post by: Visus on May 13, 2014, 12:08:36 PM
No hot supermodel cheerleader sisters but if you piss me off I can introduce you to my ex-wife.  :laughing2:

Im really not very choosey, are we talking one or two bags here.   :whistle::  jk

Hows that circuit coming along..   :stirpot:
Title: Re: Low Battery Indicator
Post by: CraigHB on May 13, 2014, 02:25:46 PM
I was looking for 1/8W which were near impossible to find anywhere.

You must have been looking in the wrong place;

http://www.mouser.com/Passive-Components/Resistors/Film-Resistors/Metal-Film-Resistors-Through-Hole/_/N-7gz41Zscv7?P=1yzaok0Z1z0wljo
Title: Re: Low Battery Indicator
Post by: blkbd on May 13, 2014, 05:22:02 PM
Im really not very choosey, are we talking one or two bags here.   :whistle::  jk

Hows that circuit coming along..   :stirpot:

She's cute but turned into a shallow evil succubus who would not give you a ride or a bottle of water if she found you crawling on your stomach in Death Valley at high noon while she was driving a semi full of spring water, And parts are on order.
Title: Re: Low Battery Indicator
Post by: Jasen on May 13, 2014, 07:33:27 PM
You must have been looking in the wrong place;

http://www.mouser.com/Passive-Components/Resistors/Film-Resistors/Metal-Film-Resistors-Through-Hole/_/N-7gz41Zscv7?P=1yzaok0Z1z0wljo


 ;bow;

Apparently so, I think I found 1 of them at mouser.


I have an arthritic search finger, yea that's it.


Title: Re: Low Battery Indicator
Post by: mamu on May 15, 2014, 11:40:04 AM
I've been working with this and my setup must be funky as I can't get it to work with one red LED and the 10K (the LED is lit above my 6.3v cutoff, although dimmer at higher voltage), but it does work when using 2 red LEDs (LEDs off >6.3v and clear on <6.4v) like this...

(http://www.mamumods.com/pics/lm431.jpg)

schematic modified from here... http://homepages.paradise.net.nz/bhabbott/lvw.html (http://homepages.paradise.net.nz/bhabbott/lvw.html)

I'm using the LM431 and red flashing LEDs so maybe that's the reason.

Maybe I'll just tuck one LED behind the scenes.  :laughing:
Title: Re: Low Battery Indicator
Post by: Breaktru on May 15, 2014, 12:12:07 PM
I've been working with this and my setup must be funky as I can't get it to work with one red LED and the 10K (the LED is lit above my 6.3v cutoff, although dimmer at higher voltage), but it does work when using 2 red LEDs (LEDs off >6.3v and clear on <6.4v) like this...

I'm using the LM431 and red flashing LEDs so maybe that's the reason.

Maybe I'll just tuck one LED behind the scenes.  :laughing:

I'm using a single standard red LED and set for 6.0V as shown in the O.P.
Check the forward voltage spec of your LED and the ma rating. I'm using 2.0v, 20ma
You will also need a limiting resistor if using one LED
Title: Re: Low Battery Indicator
Post by: blkbd on May 17, 2014, 12:45:00 AM
Going off of Kortts diagram and comparing it to Breaktru's schematic is this correct for a dual battery setup?

The 15K will be replaced by the 10K
240 willbe replaced by the 2.2K
the 4.7K will stay the same
and the 22K will be replaced by the 3.3K

Here is a pic using Kortts diagram. http://i1262.photobucket.com/albums/ii617/blkbd/kortt-LVI-2cell_zps9803df59.jpg
Title: Re: Low Battery Indicator
Post by: Jasen on May 19, 2014, 01:34:57 AM
So as usual I've learned some very useful info here which got me taking a second look at things.
I'm going to run the Panasonic NCR18650PD High drain 2900mAh 10A in my PTR08100 build. What I learned tonight is they have a max discharge of 2.5V I'd like to tweak the low batt indicator to say 2.7V is that a matter of changing one resistor up or down, which one, or is it more involved then that.  I could sort it out myself w/ a little direction on where to start.
Title: Re: Low Battery Indicator
Post by: memoevapor on May 19, 2014, 07:09:06 AM
Jasen, I am curious as to how much vape time is gained by having the indicator come on .6 v below the one in the OP?
Title: Re: Low Battery Indicator
Post by: tommygun on May 19, 2014, 07:43:13 AM
So as usual I've learned some very useful info here which got me taking a second look at things.
I'm going to run the Panasonic NCR18650PD High drain 2900mAh 10A in my PTR08100 build. What I learned tonight is they have a max discharge of 2.5V I'd like to tweak the low batt indicator to say 2.7V is that a matter of changing one resistor up or down, which one, or is it more involved then that.  I could sort it out myself w/ a little direction on where to start.

Jasen, use Breaktru's diagram for the single battery set for 3V: http://breaktru.com/smf/index.php?action=dlattach;topic=804.0;attach=1634;image (http://breaktru.com/smf/index.php?action=dlattach;topic=804.0;attach=1634;image)
Running the battery down to near max discharge can't be good. You will be safe at 3v. What will you gain by running down to 2.7v? A few more puffs?
Title: Re: Low Battery Indicator
Post by: blkbd on May 19, 2014, 07:45:47 AM
Going off of Kortts diagram and comparing it to Breaktru's schematic is this correct for a dual battery setup?

The 15K will be replaced by the 10K
240 willbe replaced by the 2.2K
the 4.7K will stay the same
and the 22K will be replaced by the 3.3K

Here is a pic using Kortts diagram. http://i1262.photobucket.com/albums/ii617/blkbd/kortt-LVI-2cell_zps9803df59.jpg

Can someone confirm the diagram is correct for a dual batteries?
Title: Re: Low Battery Indicator
Post by: Visus on May 19, 2014, 07:53:32 AM
There has to be a way to toss in a trimmer to dial  this circuit..  I am not sure where to place it and what resistor value to change.  My guess would be add a 4.7 resistor in place of the 10k and a 10k trimmer.   :Thinking:
Title: Re: Low Battery Indicator
Post by: Breaktru on May 19, 2014, 09:30:21 AM
Can someone confirm the diagram is correct for a dual batteries?

Yes, that would work for two series batteries with an indication at 6.0V
Title: Re: Low Battery Indicator
Post by: blkbd on May 19, 2014, 09:33:59 AM
Yes, that would work for two series batteries with an indication at 6.0V

Thank you very much you  :rockin smiley: I guess watching some of those tutorials is paying off.
Title: Re: Low Battery Indicator
Post by: CraigHB on May 19, 2014, 04:00:16 PM
Running the battery down to near max discharge can't be good. You will be safe at 3v. What will you gain by running down to 2.7v? A few more puffs?

More wear occurs at the end of the discharge curve than anywhere else so you do gain some longevity by not taking a cell down to the minimum allowable discharge voltage.

However, how much capacity you leave behind depends on the battery and the load.  In general, the discharge limit applies under load.  If you look at a cell's discharge curves, you can see a big difference there.  So you have to consider the battery characteristics and the load it's under when a discharge condition is detected. 

A high drain battery does not dip in voltage as much under load as a standard battery and that can make a big difference in detection.  For any battery you'll find the voltage higher when you check open circuit voltage open after a discharged condition has been detected.  Voltage can be quite a bit lower when the battery is loaded.

(http://lygte-info.dk/pic/Batteries2012/Orbtronic%2018650PD%202900mAh%20(Black)/Orbtronic%2018650PD%202900mAh%20(Black)-Capacity.png)

Looking at the curves for the NCR18650PD, you can see that taking the battery to 3V with a maximal load leaves about 500mAh untapped.  However taking the cell to 3V with a 3A load only leaves about 100mAh untapped.

Panasonics cells are unusal in that they don't have as tall of a curve as other cells.  If you do the same check with a higher drain cell, you'll find the difference much smaller.

(http://lygte-info.dk/pic/Batteries2012/LG%2018650%20D1%203000mAh%20(Pink)%204.35V/LG%2018650%20D1%203000mAh%20(Pink)%204.35V-Capacity.png)

For this cell, there's a difference so small you can't even see it really.
Title: Re: Low Battery Indicator
Post by: Visus on May 19, 2014, 06:10:39 PM
Noone answered my question, booo lol  I found another circuit that did.

Because some batts best at 3.2-3v some IMr ok at 2.9v and having a dialer option would be awesome when swapping out batts after old and not have to dig in there because specs are worse or better 6v is a little low for me on the series.  I swap mine out at 6.6-7v.

Heres another 2 LBI circuits..

The data sheet circuit figure 26 so many ways to skin a cat --uber fun,  I need some parts.. lol
http://www.ti.com/lit/ds/symlink/tl431a.pdf

.

Title: Re: Low Battery Indicator
Post by: Jasen on May 19, 2014, 08:37:51 PM
Visus, I'm not going to answer your question either, because I don't know ;)

Just thought it might give me a bit more vape time, but it looks like it's pretty much a mute point.
Title: Re: Low Battery Indicator
Post by: Visus on May 19, 2014, 10:37:05 PM
Thats why I loaded more circuits jasen, you can also dial down breaks origin circuits   more stuff for us to play with, the parts are so inexpensive its also fun learning how to do it another way and the professors way.  One good thing about electronics is, there's probably a hundreds ways to sunset to get there.

the formula is in mamu's post.
Quote
When the device is operating with two external resistors (see Figure 2), the total dynamic impedance of the circuit is given by:
which is approximately equal to .     (1+r2/r3)



 I wanted to intensify the led with very slight turn on if possible and have higher turn on so woot more stuff to play with.  My complements to having so many lessons learnable on here thought pattern, "Don't just copy visus blow some shiz up lol..."
Title: Re: Low Battery Indicator
Post by: SilenTDoGz on May 28, 2014, 10:11:50 PM
I found it!
That's what i was looking for...

Do you think this will work???

hi Pako....i was looking at your circuit diag and wondering why it didnt work.....so decided to try it myself ! :).....didnt work for ME either...

so i played about with the 2 resisters and finally got this

now...granted, i only had a BC547B available so i dont know if that was the difference....but now i get....

4.2V fresh battery = Strong green light

3.4V                       =Still Green but dimmer

3.3V                       =Green AND RED

3.2V                       =Red light dim (ish) but gets stronger as you drop to 3v

now i am no expert....so maybe someone can work out if other parts are stressed or not....or what the total power consumption would be....but i feel sure it can also be tied to the fire button to just display when your using the mod....
Title: Re: Low Battery Indicator
Post by: SilenTDoGz on May 29, 2014, 04:22:50 AM
Oh...and  i Know this is an old Post now...but as i had the previous circuit set up for single cell, i decided to modify it for Dual cell tricolour leds...think this one May suit Visus's needs

8.4V  ~   6.6v     = LED shows Green

6.5V  ~   6.2V     =LED shows Orange

6.1V  ~   Down   =Led shows Red

Once again, NO expert, but had it breadboarded and seems to work fine. Check it out yourself before you glue together huh :)....
Title: Re: Low Battery Indicator
Post by: CraigHB on May 29, 2014, 05:35:57 PM
now i am no expert....so maybe someone can work out if other parts are stressed or not....or what the total power consumption would be....but i feel sure it can also be tied to the fire button to just display when your using the mod....

The draw on that ciruit is always at least as much as the LEDs so you definitely would not want the circuit powered other than when the trigger button is pushed.  Since voltage is higher with series cells power consumption will also be higher.  As far as components being stressed, there should be no issue.

--------------------------------------

For anyone interested, here's how you would estimate power consumption for all the components in the single battery circuit;

Voltage at the 1k resistor will be that of the transistor base pin which is always about 700mV (the base-emitter junction of a bipolor transistor is like a diode).  Current through that resistor is 700mV divided by 1k which is 700uA.  Using I squared R, power consumption at the 1k resistor is small, about 500uW.

Voltage across the 340 Ohm resistor will be battery voltage minus the LED drop minus the diode drop minus the base drop.  For a worst case, that would be 4.2V minus 2V minus 700mV minus 700mV which is 800mV.  Current flow is 800mV divided by 340 Ohms which is 2.4 mA.  Using I squared R, power consumption at that resistor is small, about 200uW.

Power consumption at the diode would be LED current times the voltage drop which is 2.4mA times 700mV for 17mW, no problem for a 250mW diode.

Currents through the transistor base will be that of the LED less the current flow through the 1k resistor.  The 1K resistor is drawing 700uA so that's 2.4mA minus 700uA for 1.7mA through the base of the transistor.  Multiplying by the base voltage drop, it's 700mV times 1.7mA for 12mW on the transistor, no problem there.

When a bipolar transistor is biased and conducting, the voltage drop at the collector to emitter junction is small so there's negligible power considerations for the transistor on the opposite side of the circuit.  Though, for big currents in other applications it can be a consideration, but not here.

Power consumption at the 110 Ohm resistor has to be considered under under two cases, when the transistor is on and when it's off.  When the transistor is off, voltage across that resistor is battery voltage less the drop from the LED.  The LED part of the circuit does not fully conduct until the transistor shuts off around 3V battery voltage. 

So voltage on the 110 Ohm resistor would be 3V minus 2V.  Current flow through the resistor will be 1V divided by 110 Ohms which is about 9mA, Power consumption there is about 9mW, well within the 250mW limit of a typical through hole resistor.

The highest power consumption occurs when the transistor is on and the 110 Ohm resistor is carrying the full voltage drop of the battery.  The worst case is 4.2V divided by 110 Ohms for 38mA.  Power consumption for the resistor is 160mW.  That's a bit high, but still within tolerance of a 250mW through hole resistor.

You could add up all the nodal currents I pointed out to find total draw.  I'm not going to crunch the numbers, but it's not going to be hugely more than that of the LEDs.  These are not big currents, but they're also not currents you would want full time on a battery.

For the circuit with series cells, I'm not going to go over the nodal analysis there, but you get the idea if you want to try it as an exercise.


Title: Re: Low Battery Indicator
Post by: SilenTDoGz on June 05, 2014, 07:40:58 AM
hmmm....post is cocked up :)...wait, let me try this..


i was having a think about this, and if it was tied to the fire button, would there  not be a false voltage reading due to the load on the batteries?


The draw on that ciruit is always at least as much as the LEDs so you definitely would not want the circuit powered other than when the trigger button is pushed. 


Title: Re: Low Battery Indicator
Post by: blkbd on June 05, 2014, 11:14:33 AM
The circuit or battery indicator is always on there for always drawing power, No big deal but if you leave it for a week in a weakened condition could over discharge the batteries, That how I see it but then I'm definitely not a electrical engineer.   
Title: Re: Low Battery Indicator
Post by: Breaktru on June 05, 2014, 11:28:25 AM
I always use an on/off switch at the battery
Title: Re: Low Battery Indicator
Post by: blkbd on June 05, 2014, 11:44:39 AM
While we are at it what is the specs or model number for the tricolor LED?
Title: Re: Low Battery Indicator
Post by: SilenTDoGz on June 05, 2014, 01:35:19 PM
ah well.....the exact model i cannot give you.....a box of these things.....sorted as 5mm standards....but i am sure they are very close to this or equivalent

http://www.rapidonline.com/electronic-components/kingbright-5mm-red-green-led-tricolour-clear-56-0685
Title: Re: Low Battery Indicator
Post by: SilenTDoGz on June 05, 2014, 01:59:11 PM
I always use an on/off switch at the battery


..and i agree with that also!....especially if you have many mods you use.....but if you did not want the circuit to be connected full time Mod is on, then maybe consider a small tactile switch just to make the circuit to check on occasion the state of charge. Many ways to do things i suppose
Title: Re: Low Battery Indicator
Post by: Visus on June 05, 2014, 05:41:48 PM
Wow this post went for a run again I found what I was looking for haven't built the circuit yet.  Busy and its on the burner I know when I need to change batts except when outside the house cannot hear the darn thing pwm rattle lol I need the circuit after all..

Thanks heres where I found it, also super fun circuits to play with..
http://talkingelectronics.com/projects/200TrCcts/101-200TrCcts.html#BatteryLowBeeper

Thanks craig for the defining of it..

15 bucks and you get a lot of play with items..
Title: Re: Low Battery Indicator
Post by: SilenTDoGz on June 05, 2014, 06:06:30 PM
$15......??? Jeez , you must be MADE of money...... oh_my:
Title: Re: Low Battery Indicator
Post by: Jasen on July 22, 2014, 09:47:38 PM
Can someone take a look at this battery health set up.

 
I based it off of SilenTDoGz's set up here.

(http://breaktru.com/smf/index.php?action=dlattach;topic=804.0;attach=2824;image)


Title: Re: Low Battery Indicator
Post by: blkbd on July 22, 2014, 11:16:47 PM
Not sure about the schematic but doesn't the DNA 30 already have a battery indicator?  But if you want it that schematic
by SilenTDoG requires two LED's, One green and one red. But I'm no expert and I know someone will check it out that can give you a proper reply to your post as this forum is the best I have been to.
Title: Re: Low Battery Indicator
Post by: Jasen on July 22, 2014, 11:23:54 PM
Yes, but I wanted something in my face. It would also make for a quick easy check w/o really looking to see if it's off or on before I toss it in my pocket,
Title: Re: Low Battery Indicator
Post by: CraigHB on July 22, 2014, 11:46:53 PM
It should work, but you might have to tune it on the bench a bit, should be around 3V though.  Didn't someone already do that in this thread? (not going to go re-read the whole thread).

The one issue with that circuit is it draws Vin/110 plus the bias current for the green LED when the transistor is on and the red LED is off.  That's going to be about 40mA so it's not something you want to power all the time or it will drain the battery.  You'd have to set it up so it's powered only when the atomizer is triggered which will require another transistor slaved to the atomizer.
Title: Re: Low Battery Indicator
Post by: Jasen on July 23, 2014, 12:25:53 AM
I was using the IPD mosfet based off Break's touch switch and using the fire switch as a trigger for the mosfet to initiate the LED.

I figured I could not wire it to the atty power because the V will not be a constant w/ the V/V V/W of the DNA.

Craig, this is the post I and I believe you are referring to.

Quote

SilenTDoGz
Jr. Member

hi Pako....i was looking at your circuit diag and wondering why it didnt work.....so decided to try it myself ! :).....didnt work for ME either...

so i played about with the 2 resisters and finally got this

now...granted, i only had a BC547B available so i dont know if that was the difference....but now i get....

4.2V fresh battery = Strong green light

3.4V                       =Still Green but dimmer

3.3V                       =Green AND RED

3.2V                       =Red light dim (ish) but gets stronger as you drop to 3v

now i am no expert....so maybe someone can work out if other parts are stressed or not....or what the total power consumption would be....but i feel sure it can also be tied to the fire button to just display when your using the mod....

(http://breaktru.com/smf/index.php?action=dlattach;topic=804.0;attach=2824;image)
Title: Re: Low Battery Indicator
Post by: CraigHB on July 23, 2014, 02:26:54 AM
That's the post I was thinking of.

It's not a problem switching battery power to the monitor circuit with a mod that uses a main power switch to fire the atomizer, but if you want to run the detector with a controller board, the problem you run into is the board does not switch battery power.  It only switches atomizer power.  In that case you need to switch battery power to the monitor with a transistor slaved off the atomizer.


Title: Re: Low Battery Indicator
Post by: Jasen on July 23, 2014, 08:55:05 PM
Chraig, so I'd do it like this and I just need to sort out what transistor to limit the power from the atty to the mosfet trigger lead?

Title: Re: Low Battery Indicator
Post by: Visus on July 24, 2014, 01:34:10 AM
Jasen I would email Brandon @ evolv there may be a way to do it off the dna board but of course tiny soldering but ya,  Mamu did a really awesome display led on a nivel chip direct off the board so I figure it may be possible to do it off the dna, I may be way out in left field but much less parts count is always the plan..

Other wise there a post is about using an ic comparator with one part and resistors not a mosfet and two trans etc. that will do exactly what you want.
Tinker Ray was making his do exactly what you want..---->
http://www.e-cigarette-forum.com/forum/battery-mods/509605-raptor-flip-top-vv-mod-20a-120w-dc-dc-converter-24.html#post13274740
Title: Re: Low Battery Indicator
Post by: CraigHB on July 24, 2014, 01:52:31 PM
Using a comparator would be the smarter way to set up a detector, but even so you still have the issue of access to battery power when using a controller board.  A comparator circuit would consume less power than the posted circuit, but you still would not want to power it full time. 

With a comparator based monitor and a controller board, you still need to slave the monitor power supply off the atomizer.  The DNA switches battery power to the converter, but you would need to solder a wire to a component pad on the PCB.  Not something I would not do myself, really sketchy, could rip up the pad pretty easy and I doubt Evolv would warranty damage like that.

It's not a complicated task to switch power to the battery monitor, just use a small power MOSFET in an SOT23 package which is not terribly small or hard to work with.  You don't need the transistor with the question mark.  Just the one MOSFET will do.  The MOSFET gate is driven by the atomizer.  The drain and source of the MOSFET switch the power supply to the monitor.

To work with the logic polarity of the atomizer (high = on, low = off) you need to use an N-channel MOSFET configured as a low side switch.  The low side (battery negative) for the monitor is switched, not the high side (battery positive).   The connection is as follows;

Ground for the detector connected to NMOS drain. 
Battery negative connected to NMOS source. 
A pull-down resistor connected from gate to source.
Atomizer positive connected to the gate.

You can reverse logic polarity by adding another transistor (the transistor with a ?) enabling you to use a high side PMOS switch instead of a low side NMOS switch, but there's really no need to do that.


Title: Re: Low Battery Indicator
Post by: Jasen on July 24, 2014, 08:05:37 PM
Visus, Craig, thanx for the guidance, I'll do my research into both of your ideas this weekend.
Title: Re: Low Battery Indicator
Post by: Jasen on July 24, 2014, 10:15:38 PM
I think this N-FET meet's my needs for a single 18650 and standard red/green LED 2V-2.2V, it's also the lowest resistance I could find at 23 mohm.

Infineon BSR802N L6327


Transistor Polarity:   N-Channel   
Vds - Drain-Source Breakdown Voltage:   20 V   
Vgs - Gate-Source Breakdown Voltage:   8 V   
Id - Continuous Drain Current:   3.7 A   
Rds On - Drain-Source Resistance:   23 mOhms   
Configuration:   Single


http://my.mouser.com/ProductDetail/Infineon-Technologies/BSR802N-L6327/?qs=sGAEpiMZZMshyDBzk1%2fWi4GEWCr0KJSEQWPFR6yCrBE%3d (http://my.mouser.com/ProductDetail/Infineon-Technologies/BSR802N-L6327/?qs=sGAEpiMZZMshyDBzk1%2fWi4GEWCr0KJSEQWPFR6yCrBE%3d)


I'm kinda clueless as far as  pull-down resistor though.


Trying to figure out LTspice but I can't for the life of me figure out how to add a new component and it's values to LT's component list.
Title: Re: Low Battery Indicator
Post by: CraigHB on July 25, 2014, 12:55:33 AM
You have to use the stock components in LTSpice unless you import your model, which is not terribly hard to do, but rather involved.  What I usually do for a quick check on a transistor circuit is use a canned part with similar specs if I can't find the exact part number in the library. 

To add a transistor to the schematic in LTSpice, press F2 to get the parts list and then select the generic NMOS or PMOS as required.  Add the generic part to the schematic then right click on it to get the option box.  Click the "Pick New MOSFET" button and select your part number.  Don't use the generic ones in an actual simulation, they don't work right.  They're only placeholders to provide a way to call up proper part numbers.

That FET you selected should do the job just fine.  You could even go as high as a 1/2 Ohm "on" resistance since the currents required to power the monitor are pretty low reducing the effect of switch resistance on voltage drops.

Pull down resistor values are not critical, anything between 4.7k and 47k should be fine.  10k would be a typical value.
Title: Re: Low Battery Indicator
Post by: Jasen on July 25, 2014, 02:02:32 AM
Craig, if you ever need some guidance in hanging a door, setting a window, installing some cabinet's, you just let me know and I'll be glad to talk you through it.

Thanx again
Title: low voltage indicator
Post by: mrbump82 on August 29, 2014, 11:06:44 PM
I have a unregulated mod running with a mosfet and an led button that lights up and I'm working on some kind of low voltage indicator for it. My thought was adding a zener diode on the resistor so that if it reached the low point the button wouldn't light up when pressed. Does that sound like it would work?
Title: Re: Low Battery Indicator
Post by: CraigHB on August 30, 2014, 06:58:29 PM
People like to think Zener diodes are digital devices for some reason, either on or off.  They're not.  They're analog devices.  They gradually increase current with voltage then quickly increase current with voltage after their breakdown voltage.  What you'll get is a light that brightens as voltage changes which can work I suppose, but it's not going to give you any kind of pass/fail indication.  You need to use a comparator or voltage detector to fully light the led when voltage falls below a threshold.
Title: Re: Low Battery Indicator
Post by: jayD on September 11, 2014, 11:41:45 PM
Thanks for the helpful thread, I did build the single battery alert using all the recommended parts, however from 3v-4.2v it's dim and below 3v it's bright. What's needed to make it have no light at all above 3v ? Cheers for any info.
Title: Re: Low Battery Indicator
Post by: CraigHB on September 12, 2014, 04:50:00 PM
You need to use a comparator or voltage detector chip to provide a digital signal, either on or off.
Title: Re: Low Battery Indicator
Post by: nwooley83 on January 23, 2015, 05:30:19 PM
OK my local supply shop had an NTE999 in stock and the rep said that it should work in place of the 431...

Here is the data sheet on it.

http://www.nteinc.com/specs/900to999/pdf/nte999.pdf

It looks like the specs are pretty much identical but I start to hallucinate looking at data sheets right now as I have been doing so much research on components trying to get our first production mod ready for the shelf.


What do you Wise Ones think?

and any idea on what resistor to change for a 1.86V red led with a 25mA draw?
Title: Re: Low Battery Indicator
Post by: CraigHB on January 23, 2015, 05:39:05 PM
That's also known as a shunt voltage reference.  It's a common device used for many applications, typically for an ADC reference.  You may be able to use it in place of a Zener diode, but they normally need a bias current full time so that can be a consideration.  When voltage falls off and bias current falls below the minimum, the part can do unpredictable things.  It may not behave the same way a Zener diode does.  You'd have to try it and see if it works.  I can't say if it would do the job or not without testing it in a circuit.
Title: Re: Low Battery Indicator
Post by: nwooley83 on January 26, 2015, 08:57:47 PM
Thanks CraigHB,

  you wouldn't happen to know how much it would change the voltage that the led would come one at if I used a 220 ohm resistor in place of the 240 on the single cell circuit would you?

and the only red LED that I could get at the shop that was close to 2V is the NTE30041 that has a Vf of 1.86 and 25 mA draw which needs a lower resistance.

Update:  Protoboard setup with the 220 resistor (closest i had) and the 1.86Vf LED ... If my multimeter is correct at 3.14 the red led just barely lights up... draining the battery now to see if it gets brighter as it gets closer to 3v

Gah it is lighting up about the same at 3.86 as well... and getting dimmer at 3v

Gonna have to figure out where my breadboard went.... gonna burn something up soldering(probably my fingers) :facepalm:
Title: Re: Low Battery Indicator
Post by: CraigHB on January 27, 2015, 02:50:49 PM
Shunt references behave similarly to a Zener diode through much of the voltage range, in fact they are often represented as a diode symbol in schematics.  You're finding that current falls off in a parabolic manner as voltage falls off similar to a Zener diode, not surprising, but that's not a normal operating range for a shunt reference.

Like I said before, for an indicator to provide an off or on visual indication you need a digital signal.  Zener diodes and shunt voltage references are analog devices.  You need to use a comparator or voltage detector.

Recently I've come across a device that's pretty simple to wire and has a detection range 400mv to 20V.  Check out the Texas Instruments TPS3700.  I'm actually doing a 2S voltage detector circuit right now using that part, not for an e-cig though.
Title: Re: Low Battery Indicator
Post by: Zanderist on February 05, 2015, 10:11:33 PM
I found it!
That's what i was looking for...

Do you think this will work???
Could this work with a 2N3904 transistor?
Title: Re: Low Battery Indicator
Post by: jct on April 30, 2015, 01:02:22 PM
You need to use a comparator or voltage detector chip to provide a digital signal, either on or off.

Or you can try this (Download TPS3809 datasheet from Texas Instruments web site, alternative MAX809 from Maxim; available in various voltages from 2.5 up to 3.5 I think).