Excess voltage needed for LiFePo4 during charging?

[wanders]

Here's a simple question for all you battery chemistry experts (you know who you are, but I sure don't :wink: )

Given that a nominal 48V (16S) LiFePo4 battery pack has a fully charged voltage of about 16 x 3.7V = 59.2V, what voltage do I need for a CVCC charger to actually charge this pack? That is, do I need (or want) more than 59.2 volts at the charger to charge a 16S LiFePo4 pack?

Thanks in advance!

 

[dnmun]

trade in the charger for one that is CCCV. i don't know what the shunt bypass voltage is with each BMS, but you could most likely figure it out by tracking the voltage across each of the shunts and there should be a common voltage which they rise to and no more until the entire pack increases. that would be the value you would use to set your total voltage. for the RGOS BMS richard and gary developed, they use 3.65V for the shunt transistor as i remember, not sure what ping or headway use. maybe someone else has figured it out.

 

[fifthmass]

Ping recommends 60-61 volts from the charger for his 48v LifePO4 packs.

Bill

 

[GGoodrum]

With our BMS, the shunts are set at 3.68V. What you need is a charger or a supply that is set to 3.7V x the # of cells. It just needs to be a bit over what the sum of the shunt voltages ends up being.

-- Gary