Solar lithium battery charging question

[Tarleton lad]

If a 6.3kwh lithium solar battery has been instore for a year or so and not charged will it charge OK again if it is added to an existing operating system comprising 2 x 6.3kwh batteries

 

[johnb2713]

Extreme caution here.

Measure the terminal voltage of the battery and the terminal voltages of the existing battery, if theyre miles apart connect a power supply to charge the battery up until the voltages are about the same. If you connect them in parallel without checking first, theres a danger that the stored battery may be in a potentially dangerously low state of charge and large current may flow from the existing operating batteries.
Stick a meter on them first and see what voltages are present.

 

[Tarleton lad]

Thanks John, What equipment would I need to charge the proposed additional battery if that is necessary? or could I just allow the existing batteries to drop down to the new batteries voltage?

 

[Bruspark]

Are they simple DC batteries, what voltages are they ?

 

[Tarleton lad]

Solax Triple power Lithium-ion Gen2, 6.3kwh and 85-118 volts

 

[binky]

Perhaps you could connect the battery to the inverter without the other batteries and allow it charge up, which may take a couple of days if completely flat.

 

[johnb2713]

Perhaps you could connect the battery to the inverter without the other batteries and allow it charge up, which may take a couple of days if completely flat.

Now that’s a good idea, the inverter should fail to charge them if they’ve gone too low etc, great idea.

 

[johnb2713]

Are they simple DC batteries, what voltages are they ?

Usually either 50v or 100v, 16 cells or 32 cells in series.

 

[binky]

Now that’s a good idea, the inverter should fail to charge them if they’ve gone too low etc, great idea.

I was thinking that the inverter/ BMS should be able to trickle charge the battery safely.

 

[MHarv]

Solax V1 are Master then Slave, only Master has BMS, check DC voltage with multimeter of Slave, check the Master via Inverter Battery Charger Settings for readings, Voltage and % of battery capacity , run master down
to approx % voltage of new slave and connect; recharge both batteries together, will take time for all to be 100%

Seems this will be the 2nd Slave of 3 battery system. 100 volts per unit, total 300 volts check inverter for readings Battery Charger 100%
when running, hopefully all good with Firmware on Inverter

 

[MHarv]

https://www.solaxpower.com/wp-content/uploads/2020/02/Triple-Power-4.56.3-Installation-Guide-1.pdf
Look at Commissioning with DIP Configuration to set for 3 batteries

 

[johnb2713]

Solax V1 are Master then Slave, only Master has BMS

That doesn't sound right, how does it cope with cell balancing on the slave units? It sounds like a fire waiting to happen.