Moved: Conversation on Top and Bottom Balancing

cinergi

1.21 Jigawatts
Maybe this analogy will work.

You have 4 empty containers. 3 are 1000ml and 1 is 750ml. They are connected together with equal tubes for filling from a common funnel. You're given 4000ml and you pour all 4000ml into the funnel. 3 will become exactly full and one will overflow.
In order to prevent the overflow, you'd need to pour only 750 * 4 ml (3000ml) into the funnel. They would all have 750 ml in them. 3 would be 3/4 full and 1 would be completely full.
With LFP, this is very difficult to do because of the flat voltage curve. It can see the difference between 3900 and 4000ml but it can't see the difference between 2900 and 3000ml.
The only reliable way to charge a bottom-balanced bank is with a BMS that instructs the charger to stop charging once one of the cells enters the top knee. Most of use do not have this kind of equipment.
 

Just John

Photon Sorcerer
Maybe this analogy will work.

You have 4 empty containers. 3 are 1000ml and 1 is 750ml. They are connected together with equal tubes for filling from a common funnel. You're given 4000ml and you pour all 4000ml into the funnel. 3 will become exactly full and one will overflow.
In order to prevent the overflow, you'd need to pour only 750 * 4 ml (3000ml) into the funnel. They would all have 750 ml in them. 3 would be 3/4 full and 1 would be completely full.
With LFP, this is very difficult to do because of the flat voltage curve. It can see the difference between 3900 and 4000ml but it can't see the difference between 2900 and 3000ml.
The only reliable way to charge a bottom-balanced bank is with a BMS that instructs the charger to stop charging once one of the cells enters the top knee. Most of use do not have this kind of equipment.
Yes, I am currently trying to figure out if the SBMS0 can be programmed to do this without a lot of efforts in the source code. Most BMS's can't, but Dacien is more flexible.
 
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