question

gary-rogers avatar image
gary-rogers asked

Lithium battery balancing parameters.

The system is cutting out battery capacity at 70% when voltage is still reading a good 52V, so I assume it’s the BMS protecting the batteries as 1 or more cells must be unbalanced.


My questions are.

1. What voltage does the internal BMS of the battery start it’s top balancing?

2. What is the nominal balancing current of the internal battery?

3. Does the external VE.Bus BMS do any balancing between the 4 x 12V batteries in series, if so what is the top balancing voltage and balancing currents?

4. Is the only way of reading cell voltages is via a VE.Bus Smart dongle and would I have to update multiplus firmware?


System

Multiplus 48/5000/70-100 Firmware 407

Colour control GX V2.71

Solar Charger MPPT 150/85 v1.19

VE.Bus BMS

8 x Smart Lithium 60Ah connected 4S2P

Also have MK3 programmer

Lithium Battery
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2 Answers
Paul B avatar image
Paul B answered ·

1. What voltage does the internal BMS of the battery start it’s top balancing?

when any one cell reaches 3.4 to 3.5v then balancing starts on that cell ONLY. I dont know the exact trigger voltage figure.

2. What is the nominal balancing current of the internal battery?

the balancing current will be around 500ma to 1 amp. I dont know the exact cell balancing amps figure

3. Does the external VE.Bus BMS do any balancing between the 4 x 12V batteries in series, if so what is the top balancing voltage and balancing currents?

The external VE BMS does NO balancing AT ALL, it only turns the inverting off or charging off, based on the relay outputs or via the VE BUS if connected to a multi or Quattro, ( A assistant must be setup in the units)

4. Is the only way of reading cell voltages is via a VE.Bus Smart dongle and would I have to update multiplus firmware

No you cant read the cell balances at all even using a VE BUS smart dongle will not help

you need a smart battery to do that

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klim8skeptic avatar image
klim8skeptic answered ·

One has to ask the OP if they fully charged each battery before connecting them in series?

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