Author Topic: Tinkering with the Naos Raptor - 20A, 120W dc/dc converter... (Read 389209 times)

CraigHB · « **Reply #50 on:** January 29, 2014, 03:34:30 AM »

LG puts prints a different part number on the cells than they use as a model number. For lack of a model number, I've just been referring to the part number.

Internal impedance is the defining characteristic for drain limit. The internal impedance for the LG cell is listed as 13 mOhms which is inline with what a couple people here have measured. That's about right for a battery with a 30A continuous limit. I have some 14 Amp flat cells that are specified at 25 mOhms and some 44 Amp flat cells that have a 6 mOhms spec. The 30A Sony cells are 12 mOhms.

timesarerough · « **Reply #51 on:** February 05, 2014, 06:02:53 AM »

Here's the pdf for model number LG 18650HE2....found by (SonHouse)

https://drive.google.com/file/d/0By-7aw3qPc-oa09ENnNFMUtxTFU/preview?pli=1

So I'm guessing that the cycle life radically SUCKS if used beyond is rated discharge of 20A?

Visus · « **Reply #52 on:** February 05, 2014, 07:14:23 AM »

Quote from: timesarerough on February 05, 2014, 06:02:53 AM

Here's the pdf for model number LG 18650HE2....found by (SonHouse)

https://drive.google.com/file/d/0By-7aw3qPc-oa09ENnNFMUtxTFU/preview?pli=1

So I'm guessing that the cycle life radically SUCKS if used beyond is rated discharge of 20A?

The discharge chart, if used with an ego board 0.2c you'll only have to charge it once per year lol

It is a sweet battery, revolutionary it looks like and with our use under 10 amps it will go at least ~1000 cycles before it starts to degrade beyond use. Very nice post TimesR..

CraigHB · « **Reply #53 on:** February 05, 2014, 03:10:06 PM »

So it's rated fora 20A continuous discharge which makes it an 8C battery. Sellers must be using the burst limit when listing it as a 30A battery. An additional 50% on the continuous limit is typical for burst limits.

The cycle life looks typical for an IMR cell. You can see that it's an IMR cell by the chemistry specification. Cycle life is longer for lower loads, but it's not going to be hugely better. Probably lose 20% after 500 cycles instead of the 300 at higher loads as shown in the specification.

In any case, the specs don't deny it's an awesome battery.

doobedoobedo · « **Reply #54 on:** February 10, 2014, 01:55:07 PM »

This is probably a stupid question, but I'm trying to get my head around how the zener diode works to shut off the switch below 6.2V input voltage. Can anyone explain? An equation would be nice for varying the shutoff voltage too

.

warlordxxx · « **Reply #55 on:** February 10, 2014, 04:18:51 PM »

In one direction the current can flow through a zener diode normally however in the reverse direction it will only allow the current to flow when it's over the breakdown voltage. This allows the zener to run normally and effectively set a cut off point for the undercurrent protection of the batteries .. Here's a bit more technical info if you would like to go into the how and whys

http://en.wikipedia.org/wiki/Zener_diode

doobedoobedo · « **Reply #56 on:** February 10, 2014, 07:22:05 PM »

Thanks I'd already had a quick look at wikipedia

I understand about the zener diode only allowing reverse current through when over a set voltage is applied (5.6V in this case I believe) - OK I should have read further down the wikipedia page - the zener always has 5.6V across it if over 5.6V is applied I think.

What I really don't understand is where the values of 4.1V for the on voltage came from (unless it was experimentation) as the datasheet only says 'logic level voltage', and how it was determined to use a 7.5k resistor, unless that was experimentation as well?

Please forgive my ignorance, it's a long time since I did basic electronics. I'm better at maths

.

CraigHB · « **Reply #57 on:** February 11, 2014, 03:36:28 PM »

Well, 90% of electronics is just math so you should be good there

There are theoretical methods to determine the ideal resistance and ideal voltage for this particular circuit, but sometimes bench testing can be more effective at determining ideal values for stuff. That can be true even when designing involved circuits that require extensive design calculations. It's pretty rare anyone can go from paper to an actual working circuit without the need to tweak something on the bench.

In this case, the stated resistor value produces a reasonable current flow when the diode is conducting and the value for the diode allows the logic to transition at the desired level. You could do the calculations and bench testing yourself to find these values, but why re-invent the wheel. Someone else has already done the work for you.

A diode itself is the most basic element of a solid state device. It was the first solid state device developed and everything else came from that. Even the first active electronic device was a diode in the form of a vacuum tube back in late 19th, early 20th century. A Zener diode is simply a standard diode with the reverse breakdown voltage tuned to a particular value. Standard rectifying diodes behave the same way, but the breakdown voltage for those is much higher, usually over 50V. If you understand any diode, you understand Zener diodes.

doobedoobedo · « **Reply #58 on:** February 11, 2014, 05:36:35 PM »

Thanks Craig.

This board looks like it could be used to create a monster of a mod. I'd use a 2S LiPo pack instead of the 18650s Mamu used, and I'd prefer to shut down at 6.6V rather than 6V so I'd need a smaller resistor than 7.5K, or guess I could add one before the remote on/off to create a voltage divider. I originally thought the zener was acting as a resistor above it's threshold to create a divider. I think I need to do some more reading...

On the other hand I might just add a LiPo alarm if there's room

.

CraigHB · « **Reply #59 on:** February 11, 2014, 06:47:03 PM »

To increase the shutdown voltage, you'd want to use a Zener with a slightly higher voltage. You can pretty much just add the same voltage to the diode as you do the shutdown voltage. The resistor is only there to limit current flow when the diode is conducting and provide a voltage tap for the regulators enable pin. The diode will try to always maintain the breakdown voltage across its terminals and the resistor is required so it can do that.

If you use a resistor value too high, leakage currents will drive voltage at the resistor above the logic threshold and the circuit will never shut down the regulator. If you use a resistor value too low, power consumption will be too high when the diode is conducting which wastes power and can overheat the diode.

doobedoobedo · « **Reply #60 on:** February 11, 2014, 07:55:28 PM »

Thanks Craig. That's really handy to know.

Visus · « **Reply #61 on:** February 12, 2014, 01:07:08 AM »

Couldnt ya just use a 7.5k resistor at 5% or 10% and find the one thats under for a few volts to bring shutdown up a lil higher at the diode.

sej016 · « **Reply #62 on:** February 20, 2014, 07:42:24 AM »

I have not been here for a good while and was pointed here for this build of the Raptor. Very nicely done and documented, thank you.

bapgood · « **Reply #63 on:** February 24, 2014, 07:02:33 PM »

Added a housing for the 0.28" digit volt meter at shapeways - https://www.shapeways.com/model/1736356/volt-meter-housing-0-28-quot-digit.html

sej016 · « **Reply #64 on:** February 26, 2014, 12:24:18 PM »

Very good ! So how do we go about buying these from the UK and what's the postage likely to be, please?

bapgood · « **Reply #65 on:** February 26, 2014, 12:43:22 PM »

Quote from: sej016 on February 26, 2014, 12:24:18 PM

Very good ! So how do we go about buying these from the UK and what's the postage likely to be, please?

Whatever Shapeways tells you it will be, they handle the ordering and shipping. I think they might have a facility in the UK, but I'm not 100% on that.

Breaktru · « **Reply #66 on:** February 26, 2014, 01:48:29 PM »

Quote from: bapgood on February 24, 2014, 07:02:33 PM

Added a housing for the 0.28" digit volt meter at shapeways

Great baps. Another great contribution. Thanks for sharing.

sej016 · « **Reply #67 on:** February 27, 2014, 06:56:34 AM »

Quote from: bapgood on February 26, 2014, 12:43:22 PM

Whatever Shapeways tells you it will be, they handle the ordering and shipping. I think they might have a facility in the UK, but I'm not 100% on that.

Understood now. You are not them. :-)

Iamthebadass · « **Reply #68 on:** February 28, 2014, 06:08:22 PM »

HELP!

So i am familiar with OKR builds and so on, so i tried my hand at this build using the 120w raptor.

Everything works fine at 3.5v, but with a .5 ohm coil I tried at 4+ and it fires for a quarter second, and then stops, and sometimes makes a buzzing sound.

What could this be?

I used a MM to check for shorts and everything seems to be working fine. I built it as per Mamus build, minus the V display.

Any help is appreciated. This is so frustrating.

And thanks Mamu and breaktru for all the awesome info, this forum and such is downright amazing.

Breaktru · « **Reply #69 on:** February 28, 2014, 06:22:58 PM »

Buzzing sound indicates that the board is starved for voltage.
Put a voltmeter across the batteries and see what it drops to when firing the atty

mamu · « **Reply #70 on:** February 28, 2014, 06:41:53 PM »

What breaktru said.

Firing .5 ohm at 4v is only 32 watts and the board can def handle that with the proper batts.

What batts are you using? Also, what batt holder did you use? If it has high contact resistance contacts you're prob getting a huge voltage drop under load. Did you use the SoShine case or one of your own? I replaced the contacts that came with the SoShine case and am using the Keystone C sized contacts.

Iamthebadass · « **Reply #71 on:** February 28, 2014, 06:43:39 PM »

Batts are at 7.5 when not firing

7.10 when firing.

They are SONY VTC4s

Iamthebadass · « **Reply #72 on:** February 28, 2014, 06:45:26 PM »

@Mamu

I am using a cheap 650 holder I got for free with a purchase.

It could very well be the holder.

I have some beafy holders at home. Once I get off work I will try a new one out.

Thank you.

mamu · « **Reply #73 on:** February 28, 2014, 06:52:46 PM »

You tested 0.5 ohm @ +4v and that's the result you got?

That voltage drop under load is aok, and those Sony batts can def handle that kind of load.

Does the batt holder's contacts get hot or very warm when pressing the fire switch? Good idea to switch the holder out and try a quality holder with contacts rated for higher amp load.

Iamthebadass · « **Reply #74 on:** February 28, 2014, 06:57:02 PM »

I turned it to 5v, and yes that was the V drop, all it did was buzz.

I will try a better holder. Thanks so much.

Breaktru · « **Reply #75 on:** February 28, 2014, 07:35:59 PM »

Now put your voltmeter at point on the Raptor where the battery leads are soldered to and firing up the atty.
This will show if the battery holder and wiring is at fault.

Iamthebadass · « **Reply #76 on:** February 28, 2014, 09:26:46 PM »

Breaktru and Mamu,

You two are God(ess)s.

Swapped out the holder and its running fine. Squeezed it all into a 1590G case. Tight as hell.

How did you know what the buzzing meant?

thejewk · « **Reply #77 on:** March 01, 2014, 04:57:38 AM »

Cracking mod there. I have only made mods using the kis3r33s 4 amp step down boards so far, but I am either looking at this or the okr t6 for my next regulated project. I won't be pushing the limits of the board by any stretch but I would love to be able to run dual builds on a regulated device at both low and high ohms.

mamu · « **Reply #78 on:** March 01, 2014, 11:22:29 AM »

Good to hear you're good to go now, Iamthebadass.

The whine, or buzz, is typical from these converters when they're not able to output and are being stressed. If you were getting any kind of output you'd also note it was being pulsed - rapid on off on off on off type of thing with very little vapor.

banshee · « **Reply #79 on:** March 01, 2014, 11:34:41 AM »

Quote from: Iamthebadass on February 28, 2014, 09:26:46 PM

Breaktru and Mamu,

You two are God(ess)s.

Swapped out the holder and its running fine. Squeezed it all into a 1590G case. Tight as hell.

How did you know what the buzzing meant?

Yup they are.

Glad you got it all sorted out badass

Iamthebadass · « **Reply #80 on:** March 01, 2014, 04:52:44 PM »

Does this chip have reverse polarity protection?

Could I use a diode on the neg of the battery sled if not?

CraigHB · « **Reply #81 on:** March 01, 2014, 05:00:02 PM »

No, diodes are very lossy and ones that can handle high currents are quite large. You can use a fuse or a P-channel MOSFET to provide reverse polarity protection. You need something there, the board probably does not provide reverse polarity protection, most don't, though it should provide short circuit protection.

Iamthebadass · « **Reply #82 on:** March 01, 2014, 08:05:46 PM »

I am somewhat new to this...

So uh... How would I use a p channel MOSFET for this?

mamu · « **Reply #83 on:** March 01, 2014, 09:24:26 PM »

An input fuse will protect from reverse polarity (see post #16 for the fuse wiring).

Iamthebadass · « **Reply #84 on:** March 01, 2014, 09:32:59 PM »

I am already using 2 PTC fuses in parallel. So I'm good?

mamu · « **Reply #85 on:** March 01, 2014, 09:44:25 PM »

Iamthebadass · « **Reply #86 on:** March 01, 2014, 10:23:32 PM »

Mamu, every day I like you more.

You are seriously a champ.

sphearion · « **Reply #87 on:** March 01, 2014, 11:35:37 PM »

I am using 2x http://www.digikey.com/product-detail/en/RGEF900/RGEF900-ND/1045803 in parallel wired according to Mamu Schematic, and when i put the batteries in reversed. things get HOT quickly and its not hte fuses, its the negative (positive) wire I am using 18g wire for all my current carrying wire. I am Unsure if these PTC's will actually keep a battery from venting as things are getting warm, and even melting doesnt seem like a good thing. I have tried a PFET - IRF9540N and this works great so long as you never need to get over about 4.8 volts output, or the Naos Raptor just goes into like a cutoff mod and humms loudly.

Iamthebadass · « **Reply #88 on:** March 02, 2014, 12:42:47 AM »

The humming is from the chip being starved for voltage. The V drop is too high. Mamu helped me with that earlier.

sphearion · « **Reply #89 on:** March 02, 2014, 12:49:06 AM »

I think my Fet is not effient enough. Maybe a different part would fix this? I am kinda at the mercy of those that know better than myself, I understand how it works. just don't understand how to get the max performance out of it and build it so when i get a bit too much to drink i don't blow up my chip or batteries

mamu · « **Reply #90 on:** March 02, 2014, 01:40:13 AM »

I hadn't actually tested the fuse with this Raptor for reverse polarity. I had assumed both the converter and the batts would be protected with the fuse.

I did test input fuses with the DNA and it does protect the entire circuit, including the batts, from reverse polarity if one or both batts are put in backwards as long as there is an independent fuse for EACH batt. If there is a common fuse for dual parallel batts, there is no protection for the batts from meltdown, there is only protection with independent fuses on each batt.

So after reading your post, sphearion... I just tested my Raptor for reverse polarity and holy moly it is NOT protecting the batts from reverse polarity, but does appear to protect the converter as there is no damage and it is still functioning aok.

When I put the batts in backwards, the lead negative spring collapsed and that batt started smoking.

So once again, the way I have this wired - the batts are not protected from meltdown if put in backwards. I should have tested this when I initially wired it.

I will work on it and see what's what. gawd this sucks.

Iamthebadass · « **Reply #91 on:** March 02, 2014, 02:30:00 AM »

Holy crap Mamu that's crazy.

I am also searching for ways to do this (easily).

Could you explain how a fuse on the positive side of things would protect in the event of reverse polarity? (It works in my OKR and DNAs)

I am just curious.

mamu · « **Reply #92 on:** March 02, 2014, 02:52:07 AM »

lol for sure, badass.

You have an OKR mod with an input fuse and if the batts are put in backwards, both batts are protected from meltdown?

If so, I have no idea why a fuse is not protecting the batts for the Raptor as the wiring is essentially the same with the fuse on Vin.

It may have something to do with the on/off control pin and possibly a fuse needed there instead of Vin, but am not sure. Just throwing out a thought going through my head.

Simply put, a fuse is a current protector - it breaks the circuit when there is an excessive input current present. In the case of reverse polarity where the batts are put in backwards a HUGE amount of current is dumped into the circuit from the batts. The fuse opens at its trip current which breaks the circuit, stopping all current from flowing, and thereby protecting the circuit.

For best protection, the fuse is placed at either the batt + or at the batt -. If the fuse opens, it stops all current flow at the batt level not letting the current get past the fuse and on to the circuit.

Iamthebadass · « **Reply #93 on:** March 02, 2014, 02:52:24 AM »

I have heard of people using N channel fets for reverse polarity with almost no V loss. I have not tried it however. Considering there are thousands of different fets, it's gonna take a while to pick the right one.

Iamthebadass · « **Reply #94 on:** March 02, 2014, 02:56:04 AM »

Also, yes on the OKr.

I just tried it where I put the batts in backwards. I turned it on and nothing happened.

I am not using the control pin though, that may be why the raptor is being finnicky.

Thanks for the write up on fuses. I'm still confused how it would trip if the fuse is essentially between V in and batt pos, yet all current is being dumped directly into ground.

Breaktru · « **Reply #95 on:** March 02, 2014, 07:44:16 AM »

That is puzzling that the fuse works with series batteries in the OKR but not w/ the Raptor. Maybe someone would like to try the diode and the fuse as described HERE

CraigHB · « **Reply #96 on:** March 02, 2014, 05:37:24 PM »

I don't get that either. If the fuse is in series with the power supply and a fault current occurs, the fuse should trip. There's no other possibility unless the fuse is failing to trip or there's some alternate current path around the fuse.

BTW, PTC fuses don't actually break the connection. I know what you meant by saying that, but they actually transition to a high resistance state when they trip. So, they don't stop current flow, just greatly reduce it. It works in protecting things from reverse polarity by limiting current flow to what the components can tolerate, doesn't matter that it's flowing backwards, just that it's within tolerance. Most essentially, it comes down to heat and as long as components don't get too hot, they're safe. A PTC fuse keeps them from overheating due to excessive current flow regardless of the direction of current flow.

mamu · « **Reply #97 on:** March 02, 2014, 06:26:07 PM »

Thanks for the parallel diode diagram, breaktru. I've got a 9A Schottky diode on hand and will tinker with that to see what's what.

mamu · « **Reply #98 on:** March 03, 2014, 01:00:34 AM »

No go with the diode as the batts are still not protected.

The diode itself, the fuses (2x 9A in parallel), the wiring from the fuses to the batts, the batt contacts, and the batts get hot hot hot when putting the batts in backwards. The rest of the circuit is fine.

So... I disconnected the on/off control pin, removed the diode, then put the batts in backwards and the entire circuit including the batts are protected with the fuses. Without using the on/off control pin on the Raptor the batts are protected with the fuse - the same setup as with not using pin 1 with the OKR.

Is there anyone using the on/off control (pin 1) for the OKR module and also a fuse? Can you test reverse polarity with this configuration?

I'd like to see if this is an issue with using the on/off control with just the Raptor, or with both the OKR and Raptor.

sphearion · « **Reply #99 on:** March 03, 2014, 01:02:43 AM »

that control pin should not even be "part of the circuit" until the button is pressed..... i bet even without the control pin, if you hit the button on the mods not using the control pin they see the same issues we are.

Unless it has something to do with the resister we use to pull the control pin to ground.

While I don't like the idea of firing the raptor under load like the easy okr, what is the downside of doing it this way?