Two years ago i was stopped by police and i didnt touch the board since then.
I just reactivated it and after getting a new receiver for my remote just got back from a test ride. Everything is fine but my battery is a bit bad.
12s4p 40t pack, charge only bms and the charger stops at what my app tells me is like 75% charge
Is there anything i can try to make things better again, before i send it to my battery guy so he replaces some batteries/the entire pack?
The chance for recovery would have been before you charged it up again. Low-voltage cells have high internal resistance and typical charging currents can cause a lot of heat and damage. Ideally, you would have charged it back up at a super low current to avoid this. I would be cautious using this pack again.
Oh well, more money for my battery guy 
Are p42a still the 21700 cells of choice or are there other cells you guys would recommend?
P45B if you’re feeling wealthy
Ill check with my battery guy how much he charges more for p45b then, thank you.
Any recommendations for BMS? Might as well go the full route this time around, smart bms for charge and discharge. I only know of diebiebms or however its spelled, and that knowledge is over two years old
Discharge is kinda unnecessary, it’s just another part that can fail and leave you without brakes
500 vs 650 for p42a vs p45b
Are the p45b actually worth the extra money?
IIRC my config on the board pulls ~100A peak from the battery
Imo you don’t need the P45b. They’re a nice-to-have tho. P42a’s are a fucking great cell. People are just enamored with the newest tech. My main board is a 12s6p w P42’s and I couldn’t ask for much more nor would I need it.
The only time I would say you should get P45B is if you are making a small battery and plan to put it through a lot of abuse, like a 12s3p AWD
(checks Australian availability…)
When my current battery was built in 2020 or 2021 i JUST missed p42a - they were available already but there werent really boards yet and they hadnt gotten mainstream yet and people couldnt really believe that the cell could be THAT good, but it totally was an option.
So i ordered a 40t pack and by the time i got around to installing it in the board everybody was raving about how amazing the p42a cells are.
Just want to make sure that this time around its not the same, with me getting a great pack but once again having that feeling of missing out
Welp, if avliding FOMO is what you’re after than go w the premium choice. 42s are great but if you wanna future proof the battery and have the funds than go all in 
I think the main deciding factor will be availability, p42a is no problem, p45b might be a problem to get at the moment, wel’ll see
Next topic for me will be what BMS I get, even if its charge only, maybe a diebiebms or something like that would be nice. It’ll have to fit a switchblade eboosted enclosure though so we’ll ahve to have a look
(1 of 2) I just went through a similar issue. My sons and my board, we have 10s4p samsung cells batteries, they haven’t been turned on since december because my son is a U.S. Marine and it was the last time we rode together. I discharged the batteries 50% and the other was 52%. he came home on leave for a week so we were gonna ride yesterday, boards didnt turn on, when i checked voltages on them it said 12% and the other was 14%. Me thinking it was the power switches were bad, i started charging the batteries.
“cont.” The battery packs are 4 yrs old and i always took good care of them, anyway, the packs ended charging up to 100% but the punch line is that one of the packs was feeling kinda warm. about 20 minutes went by and when i grab on of the packs to install back on board, the pack was feeling really hot. I ended up throwing it away, after seeing what happen in N.Y. ebike store fire, it never left me thinking about it.
Anyway, the other pack is fine, it never heated up and until now, its still fully charge. What sucks is that i can’t low charge the battery pack unless i take it apart and charge each cell at 1 amp.
sorry for the long story
Not sure what “12%” or “14%” means in actual voltage but if either pack was below 25v then they’re no longer suitable for esk8 use. That’s how fires start even if your pack charges to full ans didn’t get hot.
Also, when you say you “threw out” the pack, I hope you mean you discharged it and disposed of it in the proper manner. You can just chuck a Liion battery in the garbage bin. I’m sure you know this, but for posterity…
Please tell me that you properly disposed of the battery packs, cause otherwise your local recycling center will go up in flames.
That is LITERALLY the reason why I own a Rosenbauer Panther Airport firetruck - I work in my families recycling company and people keep throwing away LiIon Batteries. They are super dangerous because there is zero warning when they go up in flames. One minute there is nothing, the next minute you will see a jet of flame. I’ll have to check if we saved the security footage from the last time it happened.
Stuff like that is the reason why most recycling companies in my country can not get a fire insurance anymore, and those who do have a fire insurance will not use it until they get the big fire that will ruin the company. Cause one claim and they drop you