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Can active cell balancers be paralleled up for faster charge transfer?
Can active cell balancers be paralleled up for faster charge transfer?
By Julian
Youtuber, shed dweller, solar charge controller aficionado
australian andy showed some active balancers and realized that not every cell is chosen for balancing others .. this made me think in a too big system 300 amp cells i could make independent balancers on relays to maximize the capacity drain!!! ..
Bravo……..I seen wire digram……4 parallel and 4 series …..they feed power from top … 4 switchs ..4 cap..parallel …..4more switch …4 more caps ……they would switch between on and off …..back and forth …….active balance…….cheers
next time, read the datasheet of the balancer. it start transfering current as soon as voltage is 0.1V different between 2 adjacent cells. before that nothing happens. it stop when voltages are as close as 30mV. check the cells voltages instead of the whole pack.
These ETA3000 I.C. balancer have a good switcher that can pump from upper to lower or lower to upper cells. They are leap frog overlapped to transfer current up or down the stack of cells.
The problem is with the voltage sensing which is just a comparitor to determine which of two cells per I.C. has the greater voltage. A single I.C. only measures voltage comparison when its balancing pump is idle. Problem is all the chips run asynchronously. This causes interference with adjacent I.C. causing the comparitor to sporatically report the wrong cell with higher voltage and results in balance pumping current is wrong direction. The more wiring resistance to cells the worse it gets.
So if you buy a 21S board, could you connect it so it would work the same as parallel 7pcs of 3S boards?
very informative, video thanks for sharing
If you want to play with lithiums in a similar situation, use tiny lithium cells harvested out of e-cigs or dollar store drone toys.
how exciting sir! how bout an experiment using 4s and 5s instead of 8s, 4s and 5s connects on the 4th battery, lets see if two active balancers can communicate with each other, please do an experiment on this, thank you so much and morepower
What I'm doing is using a bms for safety, w and using a balance charger ever so often, or as needed, keeping an eye on the cell voltages, my battery bank is over 25kwh, and 7 series cells, and I stay between 3.2v and 4.1volts,
If you have good cells and ballanced packs, they should not really need balancing regularly, unless they are cycled hard,
I think cable lengh of the balancers should be exactly the same on both of them and to each cell comming from the connectors in order to get the same resistance/behavior on both boards. Even minor diferences in cable lengh and/or solder joints could trigger slight diferent readings on the balancer board when we are dealling in millivolts range. Try to switch place of balancers boards when one of them shows imbalance and the other one not to see if they show the same thing, if for instance the right one showed imbalance but the left not or the right one showed imbalance on the first cell and the left showed imbalance on the last cell switch sides of the balance boards to see if they still show the same. Then you will be sure that it's the cable lengh that plays role in that behavior.
Can you remind us where you got the power supply?