12S charging

[jamesshuang]

Hi,
I'm transitioning from RC battery chargers to using a BMS. I have two 6S lipo batteries that I've been using in serial, and I'm ready to order the HCX-D167 from bestechpower. A very simple question -- is it safe to use a 54.6V charger on a 12S battery pack? I know that is technically rated for a 13S battery, but I haven't been able to find a straight answer whether using a higher voltage charger is safe or not with a BMS.

 

[Ykick]

Hi,
I'm transitioning from RC battery chargers to using a BMS. I have two 6S lipo batteries that I've been using in serial, and I'm ready to order the HCX-D167 from bestechpower. A very simple question -- is it safe to use a 54.6V charger on a 12S battery pack? I know that is technically rated for a 13S battery, but I haven't been able to find a straight answer whether using a higher voltage charger is safe or not with a BMS.

In theory OVDV (over voltage detection voltage) “should” trip the BMS power circuit when reached. IIRC that’s about 4.22-4.25V/cell?

54.6V across 12S = 4.55V/cell so unless you terminate charge much earlier than that, it’s going to hammer OVDV and protect every charge cycle.

Of course, that’s fine if you wish to trigger balancing on these BMS/PCM’s but I would rather not charge my RC Lipo to 4.22-4.25V/cell on a regular basis.

I’d use a different, more moderate charger voltage (50V) and reserve the 13S charger for occasional balancing and/or max range riding, if needed?

 

[jamesshuang]

Mmm that makes sense. Unfortunately, it seems to be very difficult to find a 50.4V power supply, yet 54.6V chargers are a dime a dozen on ebay. Any idea if it's possible to mod a a standard "48V ebike charger" like this one to output 50.4 instead of 54.6?

 

[wesnewell]

Put a 20 ohm 30W resistor in series with the + output wire. That should keep end voltage down around 50.4V.
http://www.gtsparkplugs.com/Dropping_Resistor_Calc.html

 

[Joachim]

open de charger and look for a pot-meter....you can turn the output voltage down to 49.8V and you are in the save range including the bms.

 

[dogman dan]

You might be able to turn it down to 12s, or not.

The solution is simpler than you think though, 13s bms is as common as 13s charger. You need a few more cells so you can run 13s