Author Topic: Fuses in VV/VW Mods (Read 17130 times)

JonGio · « **on:** February 26, 2014, 09:25:42 PM »

So I just wanna make sure I have all the information about fuses correct before I start burning out chips and stuff. So you want to use a fuse that is about equal to the chips max amp rating correct. Fuses wired in parallel add the amps and half the resistance. And what about fuses wired in series. Is there any reason for that and if so what is the result. There is so much info out there in so many places it's a bit confusing I think I've almost got it but I'm just checking. Any help is greatly appreciated.

CraigHB · « **Reply #1 on:** February 27, 2014, 03:50:24 PM »

There's no reason to run them in series since that would double the resistance which is something to avoid.

For a single fuse or for two in parallel you can run the total hold current equal to the maximum demand, but you'll get better protection and smaller size if you run a bit closer to the trip current. I would recommend using a fuse that lands the maximal current demand around halfway between the trip and hold current. Since the fuse does not have to carry current continuously (less heating), it provides some extra margin to run closer to the trip current. That provides better protection since the fuse will trip faster when a fault current occurs.

You don't want to run more than two in parallel since it causes derating issues that reduce the effectiveness too greatly.

JonGio · « **Reply #2 on:** February 28, 2014, 12:00:23 PM »

thanks Craig. So that would be to say for the OKR 10 which has a max current of ten amps i can run one 10 amp fuse or two 5 amp fuses in parallel correct. what role does the wattage play in this equation. The OKR can put out 50W max so do I need fuse that is rated for 50 watts or is the current what we are really looking at. I am currently building an OKR Prototype to be an alternative to the more expensive DNA 30 model. The problem is I Have it all bread boarded correctly. According to the thread on this site. The problem is the atty will fire for a short time and then cut out. I have replaced all wires with 20g solid copper. buttons and switches are all rated for 6amps. I have run it with a ten amp fuse, two fives and no fuse at all and still the same result. here is a pic if you could help me out.

Breaktru · « **Reply #3 on:** February 28, 2014, 12:10:01 PM »

See this about breadboards --> HERE
Same holds true for splicing wires.

And PLEASE no advertising about selling mods
This forum is about helping people make mods. Not for making mods for profit

JonGio · « **Reply #4 on:** February 28, 2014, 12:25:19 PM »

Quote from: Breaktru on February 28, 2014, 12:10:01 PM

See this about breadboards --> HERE
Same holds true for splicing wires.

And PLEASE no advertising about selling mods
This forum is about helping people make mods. Not for making mods for profit

Shit breaktru I'm sorry. I'm new here. No mention of my company again. I didn't know. Shoulda figured there was no supplier forum. To be honest I am a registered supplier on EcF but since I found this forum through Mamu forum I've been. Neglecting EcF. I'm learning so much here. Everyone is so helpful.

JonGio · « **Reply #5 on:** February 28, 2014, 12:32:59 PM »

thanks Break. That makes sence. so the breadboard cant handle the heavy load so it just cuts out. Otherwise the circut looks correct to me. So Battery + and - directly to PCB and and +510 lead pcb. Everything else can be breadboarded. I meamn the batts i prototype with are stronger in terms of amps and c rating that any e cig batts for the most part so you dont think it could be the 2 cell lipo messin anything up.

CraigHB · « **Reply #6 on:** February 28, 2014, 05:07:15 PM »

Yes, that was my first thought. Those types of breadboards are good for a lot of things, but you need to be aware of their limitations. They introduce a lot of parasitic impedance. In other words, the connections have resistance, inductance, and capacitance that can interfere with your circuit. For high currents, the connections don't have enough contact area which results in too much resistance. You'll introduce big voltage drops that will effect the performance of your test circuit.

In any case, two 5A fuses in parallel is equal to one 10A fuse with a caveat. There is some derating that goes on with paralleling fuses. It results in a slightly lower hold current and slower trip time. Two fuses in parallel is a reasonable trade-off for the reduction in size and resistance. More than two fuses in parallel introduces unacceptable derating issues.

JonGio · « **Reply #7 on:** March 01, 2014, 03:18:12 PM »

I still can't get this thing to fire for more than 2 sec. I don't get it. I ditched the breadboard and soldered the whole thing up with 20 g wire. Using two 5 amp fuses in parallel from +batt to 3 amp ck components push button. I had a slide switch but removed it I thought maybe it wasn't rated high enough. That wasn't the problem. ,y thoughts it must be the chip. I had to have shorted something and didn't realize it.

Breaktru · « **Reply #8 on:** March 01, 2014, 03:57:20 PM »

Sure have a lot of splices.

It's really hard to tell in the photo but something doesn't look right with the pin connections/wiring on the OKR to PCB. I may be wrong because of the photo. I would double check the pin numbers. See the datasheet.

Also run time for a 430mah hour will be a very, very short run time. Perhaps you exhausted your battery.

JonGio · « **Reply #9 on:** March 01, 2014, 04:05:40 PM »

Battery is still over 8 volts. Pcb looks weird cuz I cut off pin 1. Ill rewire with no spices and hope fpr ythe best. Is it possible that i shorted out the atty output pin or something.

mamu · « **Reply #10 on:** March 01, 2014, 09:42:57 PM »

Like breaktru said, there are quite a few splices. Splices, as well as varying wire ga and the length of the wire run, will add to the circuit resistance.

Also, did you try a different battery, say 2x 18650 high drain batts in series, and get the same result?

JonGio · « **Reply #11 on:** March 01, 2014, 11:48:29 PM »

No i didn't try 18650s but i did try a 1000 mah 50c 2 cell lipo with the same results . Im just gonna re wire everything with no splices and all 20 g wire.
If it still doesn't work it has to be something with the chip. That would be my assumption. I've exhausted all other options. Oh and i will run it with two 18650 30 amp high drain. Either orbtronic or Sony. by the way anyone know where you can get the real Lg 30 amp 18650s. And one more question if I may. Anybody try and recommend the new Efest purple batts. I have used Efest as my go to for a while. Preferred over AW. That's just me so I'm wondering how the new ones are.

CraigHB · « **Reply #12 on:** March 02, 2014, 06:06:32 PM »

A good quality splice should not make or break the operation of a circuit. A crappy splice can though. Same with the length on the wires. For example, an 18 gauge wire has a about 33 mOhms per meter. With a wire a foot long, your looking at 10 mOhms. With a current flow of 10 Amps, that's a voltage loss of only a tenth of a volt, should not be enough to cause a malfunction.

In general, you should limit splices and wire lengths as much as possible, but for testing, it should not make your circuit fail. Two 50C LiPo cells are going to have very low battery resistance, lower than two of the Sony ultra-high drain 18650s. Your power supply is not going to be your issue.

At this point, I'd say you either have a wiring error or a failure in the module you're using. Those things are not bulletproof and if you miss-connect one, it would be possible to fry it. They don't design those parts for that kind of abuse. I'm pretty experienced with this stuff and I've fried lots of parts that way myself. Sometimes makers do surprise you with the robustness of their parts. A few times I've thought for sure I fried something only to find it remained intact.

JonGio · « **Reply #13 on:** March 02, 2014, 09:02:27 PM »

I must have shorted something out by mistake. I just put in a new OKR and it worked perfectly. I was about to throw all my bread boards away. lol good thing I didn't.

Breaktru · « **Reply #14 on:** March 02, 2014, 09:12:16 PM »

Glad you got it going Jon

JonGio · « **Reply #15 on:** March 02, 2014, 10:11:16 PM »

thanks. Very frustrating though trying to figure it out. what i think i did was when i was breadboarding (if thats a word. I had wires connected to live connections first and i may have touched a live neg terminal to a live pos terminal. Specifically the live switch which was not off (dumb ass) to the 3rd pin which was already grounded and hooked up to batt. I figured it had to be the chip. I wired and rewired and soldered and re prototype like 10 times. Finally i realized the OKR was getting hot and nothing was even happening. Checked data sheet, no mention of hea tsink. Not like the lm317 which is a oven so it had to be the chip. Tossed it and hooked up a new one and it was all good. Not as painful as breaking a DNA screen or melting the ribbon when soldering which i have done to 3 chips so far. But I'm new to all this and totally self taught, well you craig and mamu mostly and its gonna happen. Hopefully my days of killing DNA's are over. My business cannot afford to. LOL Off topic but does anyone know where I can get a Nivel chip. Or should I just get a zmax chip for 1/3 the $$ and call it a day.

JonGio · « **Reply #16 on:** March 02, 2014, 10:15:09 PM »

Busardo just reviewed the SoveMesto Semovar that has the nivel in it. Hes got the chip too. I want that chip

mamu · « **Reply #17 on:** March 03, 2014, 12:16:35 AM »

Quote from: JonGio on March 02, 2014, 10:11:16 PM

...Very frustrating though trying to figure it out.

Welcome to the world of modding.

The Nivel can be bought here: http://nivelchip.com/

It's a nice board to mod with, comes pre-wired and needs no external components. However, it's very expensive at $67 and only has a 3.5A limit. It would be a more viable converter if the amp limit was higher. I don't know if there are plans to up the amp limit though.

CraigHB · « **Reply #18 on:** March 03, 2014, 01:08:39 AM »

Glad to hear you got is sorted JonGio, troublshooting can be a bitch sometimes. Even on my own stuff there's failures that would be pretty much impossible to troubleshoot, I'd have to pitch the whole board. In any case, it happens, parts get fried sometimes. I don't think I could hold all the parts I've fried over the years in one hand. You kind of learn your lessons the hard way with that. Working with live wires is one you learn quick. Voltages are low so it's not a safety issue, just risky for parts. I could probably still have that to happen to me though, sometimes I forget the lessons I've learned.

3.5A would be a little low. Probably 10A is as high as I'm going to go. You can use those 20A modules which is good for experimenting, but I really don't ever see myself actually using that kind of amperage regularly. I typically use 4 Amps so 10A is plenty for me.

JonGio · « **Reply #19 on:** March 03, 2014, 02:03:24 AM »

Quote from: mamu on March 03, 2014, 12:16:35 AM

Welcome to the world of modding.

The Nivel can be bought here: http://nivelchip.com/

It's a nice board to mod with, comes pre-wired and needs no external components. However, it's very expensive at $67 and only has a 3.5A limit. It would be a more viable converter if the amp limit was higher. I don't know if there are plans to up the amp limit though.

I have sent so many emails to try to get the chip from there and no response. I mean 3.5 amps isn't much, and it only goes to 15 watts i believe but I got a friend who is sucking the Nivel's D*#K hard and wants a bottom feeder with that chip. I dono. I think one with and OKR a DNA or even a regulated 5 volt would be just as good with a nice Low ohm atty. Most bottom feeders aren't even regulated. The woodville is and is so hard to get Bogger makes a few but they have the worst customer service on the planet. Not to bash any companies but i paid Bogger over $500 in Oct for two mods and have not received them nor have I gotten a response to one of my 100 emails or phone calls. So as far as im concerned they don't exist. Which sux cuz i have gotten parts from them in the past for bottom feeders. I'm trying to find someplace else to get the metal pipe and the nice drip cups. Everything else is no problem. But o well what you gonna do right.

Hear are a few of my most recent mods just to show off. LOL

And my bad habit of buying Vape stuff. Better than a carton of reds a week. Thats for S&^T sure.