Looks can be deceiving with welds, the only way to know for sure is to try and tear it off.
You should end up with the welded spots tearing the unwelded nickel, and you usually end up with some nice vicious spiky bits of nickel left on the cell if your welds are good.
Another thing to note is that it’s advisable to avoid welding near the center of the negative terminal. There’s stuff and things inside the shell that can be damaged by welding in the centre of some cells.
The rule of thumb that I go by is that each single (good) weld spot should be good for about 5 amps continuous. For most packs I do 3 sets of welds per terminal.
The only other thing i’ll mention is that the nickel looks a little anaemic…
If you’re crazy focused on weight, the options I’d look at specifically would be:
LiFePo4, maybe A123 if you can get your hands on them. Juice them up with like a 5-8A charger, you’ll only have 80-120Wh to work with but given it can be charged in 20 minutes, that may suite your needs. You’ll have way more power than Liion, for the same weight. Some can be gotten for REALLY low prices too, I know @hummieee had them for sale for a while
If you want more range and don’t really mind having a less powerful board, just use P42A. The pack is small anyway so no point using lower power cells which will sag like hell toward the end of the ride.
You can consider the higher capacity ones, LG M50LT etc. but they’re really lower power, you should only consider a single motor. Assuming this board is situational and you have a larger one you know you’ll take when you’re out riding longer, I’d go for LiFePo4 for the power and charge speed.
Yes they’re lighter but thay take up more space there have better cycle life but you suffer in performance in discharge amps and sag.
Only use them if life span of battery pack is your main gole (about 2-3 times the life span) I fined the max discharge volt sag main issue on any board up to 4p. Unless the chemistry has made a big leap.
My mistake I was confusing my self with the CR123 LifePo4. Short stubby cell boosted boards use to use A123 50a-70a discharge some thing I’d need to look in to more but thay are a big 26mm diameter so not a real comparison vs 2170 or 18650 cells as ther double the area of the 18650. Up side is thay are a more stable safer chemistry.
You could even throw Headway cells into the mix… Youd need at least 14 of them for good voltage, but they literally charge at effectively any pace, you could easily charge them well within spec at 50 amps for a 15 minute charge time 0 to 100… Of course a 50A charger would weigh more than the board but don’t write off LiFePo4
A shame the lifepo4 K2 26650 with 3800mah is no more. It was in a league of its own and up to lithium-ion energy density.
I found it was made by Trojan who make lifepo4 car batteries. The potential for an energy dense lifepo4 is doable and they were even cheap … why is it gone?l
Someone said has voltage sag. I see it having the opposite in that it can kick out big amps without sagging. And it has a nice flat discharge curve. Besides all it’s other attributes and resilience, and safety. Under appreciated
Board isn’t functional as of recent but i just got around to following what you said, and over 2 days watched the 0.075 difference go to 0.020. Cells sitting at 4.1v. I gave it another 20-minute charge and the voltage difference shot back up 0.071
Voltage is now at ~4.16 (0.060 difference) and watching it slowly balance back. Its discharging the 17/18 packs back down to match the single lowest p-group.
haven’t been able to discharge it like you said, as the board won’t be running due to belts until at least next week
