I just have a quick question, because I am baffled by this. I have a 12 ah 12s4p battery pack, used to charge it with 2a charger and it took 20+ hours to get it to full charge ( the pack sat for a year almost fully charged so I thought that’s the reason it takes so long)… Yesterday I bought a 4a charger and my battery got charged from 30 to 100 percent in around 60-70 minutes… That’s not even physically possible, the Math here doesn’t click… Does anyone have any ideas? I don’t wanna burn down the house… I went from 20 hours to 60 minutes by doubling my amperage…???
How are you measuring charge?
I have a regular battery indicator, shows %
Maybe your previous charger was not 2a? 
For my 11s4p hg2 pack I needed about 70-80min for a full charge cycle with a 5a charger.
I mean 2a without losses will charge max of 2ah per hour… I thought so too… My old charger was bad… But how can a 4a charger charge 8+ ah in one hour… that just doesn’t make sense
Check if your indicator can give you voltage instead.
Can only show % I will go ride tomorrow and see if it lasts
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Ah damn didn’t see the 12ah in your post…
What’s even weirder is that the final balancing is up-to BMS, charger has no say here… (Before with my old charger even when I charged it to 100%, If I disconnected the charger and turned the battery on it would drop immediately to around 93, 94%… Now after that 1 hour it charged to 100% and when I turn it on it already stays at 98%… So the end result is my battery is charging insanely fast and my BMS is on steroids balancing about 10 times faster than it was in the past…
Wait, just that i‘m sure I don’t get something wrong. So you have 4 12ah batteries in parallel? Or is it a 12s4p pack out of 3ah cells? For a 12s4p of 30q cells I think 1-1,5h for a full charge would be realistic.
12s4p, samsung 30q 3000mah… 2a charger will charge 2ah per hour and anywhere I look they say it charges less than that… That;s the fact I know and can’t get around 
8-9 ah in 60-80 minutes…?
My 12s4p would take 16 hours with a 2a charger cause it wasn’t always charging at 2a it would vary depending on battery percentage so after 75% it would drop dramatacily and take for ever to finish. My 4a charger fully charges the same battery is 3.5 hours.
Wow, that doesn’t explain how mine charges from 33 to 100 in 60-80 minutes but the difference between 2a and 4a is obviously so huge… Thought my charger must be broken… So it seems normal for 2a chargers to charge that freaking long…
If you have 12ah and get a full charge in 3,5 hours with a 4a charger seems exactly on the spot
I must do some tests… Drain it all the way down and then charge it cause I just can’t get over the fact how the battery charge loaded up like a pc game
You would have to ride the board and monitor it to make sure nothing is out of the ordinary. See if the range was affected dramatically and check again after a recharge.
wait a minute, you let your battery fully charged laying around for a year? that is rly damaging to your battery, could be those batteries have suffered severe capacity lose…doenst sound rly safe.
I bought the board used and the guy told me that… He never rode it, only like twice… And thought keep oit at full charge is a good idea
…jesus christ
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Good idea, I will do that…