What equipment/skills are necessary for building/repairing battery packs?

It kind of blows my mind to hear about people building their own packs. But I want to know, how difficult would it be to do something like - rewiring the balance leads on a CBXR to work with an Ennoid BMS instead of FM’s? or- replace a dead cell group on an otherwise good battery? What is the most difficult part of building a battery?

I would slightly hate to be the bearer of bad news, and to be so discouraging however while possible to take a CBXR and redo the wiring to connect to something like the X lite is entirely possible, the X lite is set up for a maximum of 24S. And the CBXR is 15 S. And unfortunately in order to get the X lite to work you need to make sure you are utilizing all 25 of those wires For the balance leads. Which means that you would need to tap in nine extra wires. Forgive me it’s late if my math is wrong but the point being it would be an excessive number of wires that you would have to add into the whole system just to satisfy the requirements for the Xlite. The other thing is you would need to be soldering all of the leads on the CBXR of which they use extremely thin gauge wire and insulation that is not very heat resistant so any attempt to solder those wires especially from one wire to another wire will result in burning back too much of the insulation to retain any structural integrity. And not to mention you would need to make sure that you have both the 13 and the 12 pin balance Harness ready to go for such an operation. And you would need to add in a xt 30 connector/wire set up since the X lite is a charge only set up. You would also need to flip the XT 60 on the CBXR as it is wired backwards per future motions absolute BS system.

TL/DR Not at all worth it. The amount of headache and potential room for error yes through the roof. If you’ve never touched a soldering iron forget it.

Regarding replacing a bad cell group. Is it possible, yes… What I recommend it… No absolutely not. You will have to pull the nickel off of at least two of the cells depending on which battery due to the fact that it is in a 2/3P configuration And then the other consideration is that if the battery has any sort of significant wear on it, 1000+ miles swapping in new cells with much lower internal resistance than the old cells in the pack while it won’t necessarily cause any issues should it be hooked up to a BMS just doesn’t seem like it’s worth the effort in my opinion.

And to answer your third question about building a battery. There is a wealth of good information out there on the Internet on the practice and at the same time there is also plenty of examples and information from people that should not be building and should not be further providing information or advice on how to build packs to others. In most cases there is a little bit more available room than what we are currently dealing with in these limited space set ups. And due to the fact that there is limited space you really have to keep in mind proper design considerations and building the safest pack possible. Which, if this was to be your first pack to build I wouldn’t necessarily recommend doing it for a one-wheel. And then another one is individuals are more than content to buy and use used cells, however again regarding the limited size constraints the thought of using used cells in this application is not one that I would really entertain.

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This specifically isn’t astronomically difficult. However it does take a set of skills, and a base knowledge of batteries, DC circuits, etc. If you don’t know how to read a pin out diagram, and you don’t know why the first 0 wire of a balance harness goes to the pack negative, then that is something you may want to stay away from until you build up some knowledge.

Then there’s the manual skills part of it, and if you’re not comfortable quality checking your own work, then it’s also likely that your battery work will be poor, and possibly dangerous.

The most “difficult” part of building batteries mostly revolves around the welding. Getting a welder is one thing, but getting a good one that can work consistently for whatever conductors you intend to use, is something else. Finding an appropriate power source for it is something else. Then you have to get familiar with the welder, and what good welds look like, and why they are good.

A lof of the nuance has to be felt and observed as the work happens, and having one weld be too cold is something that should be corrected before the next weld. Ideally, before you even start welding on the pack’s actual cells.

Equally as important is understanding insulation. Where it should be, why it should be there. What each kind of insulation does, and what its realistic abilities are.

On the CBXR, specifically, it’s my opinion that it’s not worth attempting to repair. It’s built in such a way that trying to extract an actual parallel group from it is near impossible to do well, or particularly safely.
Chi themselves usually replace one of the halves. It’s rarely worth it to do more than that.

If you want to get into battery building, this forum thread on esk8.new is what I would consider required reading to start with. All of it.

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I find the same thing with a lot of packs that i come across. I took one (a repair) on recently that i thought would be a walk in the park but just ended up opening a can of worms and costing myself time/money.

Get the battery built well in the first place so that the likelihood of future maintenance is minimal.

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