Hey, could someone check out my battery question, i posted on my build thread but i am out of options and do not want to make the wrong choice regarding safety.
This pack is 4 x 3s6p 30q, it was made modular to fit in a few different enclosures. Each pack has a main negative, and ascending voltages through the mt30.
To hook up the bms i plug the packs in series, then hookup the main negative, and connect the batteries to the bms dongle in order. Then plug the dongle into bms.
The pack was charging fine like this in its orignal 12s6p config, prior to the modular build.
Yeah i have another charger that is confirmed working as well, behaves the same way. A group might be dead although i cannot detect via multimeter. I guess ill have to inspect all the welds. The first time this happened i measured all of the paralell groups to be very, very close i wrote them on the packs in the picture.
Using a kweld, how would I go about adding 0.1mm copper to an ebike pack that’s capable of up to 400A (12p of p42a). I work with 0.2mm nickel for my builds, Do i have to add copper to all parallel connections or can I just get away with copper on the positive/negative terminals? Would 0.2mm + 0.1mm copper be sufficient?
What’s the purpose of adding copper versus stacking nickel?
Have you done the maths and come up short with the current carrying capacity of a shingle sheet of nickel?
I’ve not done the nickel-copper sandwich myself but imo it’s typically unnecessary as it doesn’t afford any advantages over stacking nickel that are well-demonstrated. There are, however, several drawbacks. Your Kweld will be taxed and at full jules in order to get good welds. This obviously will make things much more laborious. Lots of heat, stress on components and your lipos. It also remains to be seen how the welds will hold up long term.
This might give some ideas but tbh, I think nickel is the way to go until we have evidence that copper is worth the trouble.
There’s not enough information here to give a reasonable answer. How much and where you need to add copper is dependent entirely upon your pack design and layout.
stacking nickel kinda went over my head, probably the better move.
Its a 16s12p tower-style pack, split into 2 sides. Using 30mm & 50mm strips to cover the 130mm of width I need to connect the P-groups
a single sheet of nickel is fine for the capacity cells since the max output would only be ~170A, but i wanna know how much more material is required to add if I’m using high discharge cells like p42a’s
It doesn’t really matter what cells you use, but it does matter for how much current you intend to use. Just because your battery can put out 400A, that doesn’t necessarily mean that it will, or it needs to.
for an “AUX pack” like exway does, like a secondary topmount battery pack for underslung battery boards… how should I go about connecting it?
my initial instinct was to just run a parallel port in my underslung enclosure and parallel the batteries when both were at a similar SOC
then I thought of running it into the charge port, but more questions came up, like would that work with the underslung BMS? how would charging need to work?
Assuming that this is how you would be connecting the groups, you’d be looking at a piece of nickel that would be ~120mm wide. At 0.2mm, you’d be good for around 300 amps continuous with a single sheet. If this is for an esk8, you’ll never pull even close to that. If it’s for another application (Surron for e.g.) I’m not sure what the current draw would be like even if the controller is capable of a 400 amp draw. You’ll have to sus that out.
In any case, p42a’s in a 12p arrangement would only be good for about 300 amps continuous. The 45 amp rating that Moli gave these cells does not hold up irl. Mooch rated these at 30 amps cont but I personally try to run them at 25 amps per cell to avoid sag. So:
Best idea imo is just using it as a swap-pack. Store it on the board, charge it separately, and use a swap cable to switch between the internal pack and the top mount
I want the underslung enclosure to be self-contained and semi-permanent. Would this mean I need to fit a second loopkey port to disconnect the internal pack and connect the external one? Or rather, I guess I’d just run it into the parallel port, and have the loopkey disconnected while using the swap pack, having the loopkey port between the internal battery and the parallel port.
Now the question is, what port to use for the external pack? It’s gotta be different to my charge port and I don’t like the idea of XT90E-M.
There are a couple ways you can do it, I would probably put a mounted connector into the side of my underslung and just have an external cable that runs between the two. You could do it internally in the top mount with a switcher plug as well
XT90 or XT60
I don’t use either of those for charge, they’re a bit clunky for that
