2a Charger Is Taking Longer To Charge Battery Than Expected?

I recently changed my 10s board from charging with an Imax B6 charger to charging with a BMS. I picked up a 42v 2a charger from ebay. And one major thing I’ve noticed is that it takes way longer to charge than it should. The battery pack on my board consist of 2 5s 5000mah batteries connected in series, both wired up to a BMS. Now, if the charger is sending 2a into the board, then shouldn’t the board take 2.5 hours to charge (since 5ah/2a = 2.5)? Instead it takes 5 hours. Can someone explain what’s going on? I’m so very confused.

Happy to provide any photos or links if anyone can help me figure this out :slight_smile:

What BMS? It balance charges at the very end of charging process and some BMS have really low balance charge current.

Or maybe your ebay charger is not actually 2A.

I actually only wired up the battery to it, not the charger. Is that a problem? (B-,B1,…,B10,B+)


This is it, I really hope I didn’t get ripped off :sweat_smile:

Your charger only outputs 2A when there is high enough voltage differential. As your battery voltage gets closer to full voltage, the actual charge current decreases. At near full capacity it is going to be less than 1A. Cutoff is usually around 500mA for most chargers

Install a power meter and see for yourself

Oh OK, that makes sense, thanks for clearing that up for me.