$200 diy evolve gt deathtrap (restoration)

Ya, the fluke fuses are usually rated to very high interrupt currents and voltage (read as expensive) and i cant take the risk of a fuse exploding on me. Arcflash is no joke and “a bomb in the hand is worth two in the bush?” I think that’s the phrase.

Sucks man i feel this. A bad bms will just murder a pack, and when you have 20-30hrs into a rework it just kills my morale for the SECOND rebuild.

3.3v is still within the nominal voltage for Lion cells iirc, as long as we are talking about cell voltage and not pack voltage. Edit: 2.5v is usually the cutoff

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I honestly can’t remeber the exact voltage as it has almost been a year since I messed with it, but I just know it was lower than or at least at 3.3v. Knowing that they should be safe if down to 2.5v is helpful though if I ever get a spot welder to put the pack together again better. I previously had just used the existing nickel on the cells to solder to.

Downside was a ton of extra space was needed due to the extra wires between groups and I needed extra space in the battery enclosure to add foam to help with vibrations. No idea how long it would have held up had the BMS not ruined it, but I did ensure that if a connection came loose it couldn’t even come close to shorting anything out. It would have been a pain in the ass to remove the insulation covering each connection if future maintenance was needed.

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This is the welder i use, there is a flaw in the design that makes it self destruct so it needs a repair before you make the first weld but dam it’s cheap. There is a guy on youtube that walks you through the process and it’s a 10c cap. I think I just stole one from a busted pc power supply. If you are confident in your soldering, its a through hole component so not rocket surgery. And if you beef up the traces it will just weld .3 nickel to steel and does a good job of .2 nickel to nickel. If you don’t really need a welder often it’s nice for small repairs

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I feel you. If it didn’t take so much time I’d be more willing.
Such a sick skill to have though. I’m in school full time and always overestimate how much time I can put into my hobbies. For now I’m just gonna wrap the pack and add a bms

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Thanks! Just ordered one

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I’d suggest maybe doing a bit more than that. Check all the groups’ voltages, inspect the pack for any burn marks or evidence of shorts, throw down some fish paper where u can and make sure the series connections are sufficient to carry the current. Post some pics of what u find on the battery thread and get some advice. That would imo be a bare minimum I would feel comfortable carrying out before having the thing in my house.

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Word. I’ll start on this wednesday and post some pics.

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@Pecos I take back what I said. I spent the last couple weeks down the rabbit hole and I’m glad I did.

So the pack seemed to be in good health. All the p-groups measured 3.95 except one was at 3.6. I found that some cells in that group has broken spot welds and had separated completely.

These chargers are hella frustrating though. The EBL is giving me very consistent and accurate capacity measurements. The ir readings not very consistent with 18650 because it sits so low that it doesn’t make solid contact (21700 is consistent though). I did some research and heard great things about the VP4 plus, but the capacity measurements are crazy. They’re way too high and half the time it gives the same capacity for both charge and discharge, which doesn’t seem right. But the the IR measurements using the probes are excellent for 18650. :expressionless:
I would love to have one charger/analyzer that just works. Any suggestions would be greatly appreciated. The only other solid option I’ve found is the mc3000 or the mega cell 16-slot from jag35, but it’s pricey and looks overcomplicated for my purpose.

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This makes sense… if you pour out half a glass of water, you need to pour half a glass back in to fill it up

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That makes sense to me too, but all the tests iv’e seen always have a slightly different rating between the two. Over the past couple days it’s only been showing the same number on slots 1 and 4. This is repreatable whether I retest the same cells or different cells. It kinda feels like something isn’t being calculated properly on those slots. It’s also rating 3 year old samsung 25S over 2600mah. The other one is showing the same cells around 2250-2350mah.

I’d say go with the tool that can give you the good capacity measurements since you can’t as easily test for it yourself. IR are super easy to test and I did mine with just some diodes as the circuit load and then a multi meter.

I have only used a “dumb” charger though that can only charge cells safely but can charge many different battery types. Bought it for NiMh batteries originally but it works on Liion too. So I can’t give any recommendations on brands

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Word. I’m probably way overthinking it. I got the second charger to speed up the process, but I guess I just can’t use different chargers to analyze cells that are going in the same pack.

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I have a liitokala lii-s8 and an opus bt-c3100. I use both for cell charge and capacity testing and only the left most slot on the liitokala for IR if im not using my home gamer ir tester. Don’t mix testing apparatus for the IR test.

Every slot in your or any charger will give you different results and every little parameter change will alter your results. Temp, SOC, rest period, angle of the moon, mars in retrograde, all will change the IR reading so I try to test every cell at the same time and soc and know that the results are only good for relative comparison of the set that i test. Kinda drove myself mad trying to make a good consistent testing rig without success.

I test three times pulling the cell out of the test rig im using each time and take the average discarding any outliers that are probably caused by me not inserting the cell properly, or bad connection, or both.

I spent so much time trying to get consistent results and looking up other peoples testing rigs - a fun but ultimately frustrating rabbit hole as i just don’t have lab grade equipment and want to spend my limited funds on more skateboard parts. :rofl:

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Thank you all for the help! I’m really glad I took this on. I’ve learned a ton about recycling and testing batteries.

I tested all the cells. Tossed 7 that either had high ir, dents, and low voltage. Rewrapped the cells and used repackr.

It was extremely challenging to make the pack slim enough to fit, but also really rewarding.

It was a little too tight with the 12awg wire so I used a long piece of braid instead which made it fit perfectly.



Finally upgraded my old soldering iron. I should’ve done this a while ago, it’s a game changer.

I’m still using the same esc but swapped the motors for flip sky 6354 and threw on 6" bkb tires with eovan aluminum hubs.

I didn’t expect to enjoy this deck as much as I do, so… I’m not done yet.
I just found a mint gt deck and trucks for 150.
I’ll be swapping them out as soon as they arrive.

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