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LiPO 48V 200ah in parallel with more than 2v Voltage difference. Growatt 5000 ES Inverter.

Olasitu

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Aug 6, 2022
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Hello all,

I have 2 LiPO 48v 200ah batteries in parallel with a 2 Growatt SPF 5000 ES Inverters in parallel.

Inverters shut down with Error The battery voltage/SOC is too low. Technician has been in and we traced the fault to Low DC Voltage been set to 42V rather than 47V. So Inverter failed to cut off before battery fully discharged. This was in the middle of a power outage.

System has been reset and now on Float charge. However, 1 battery is at 58.7V and the other 56.6V. Supplier has indicated they will look into it. I however need to know if this is major issue and if I should be pushing for a replacement. Whole system is less 6 months.

Would appreciate any feedback on how problematic this is and what can be done.

Please see attached picture.
 

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Thank you @timselectric .

How long do you think this should take to balance? There is minimal load on the batteries on a day to day. They are strictly for back up.

Are there other things that can be done to accelerate the balancing?

Or should I just leave things as they are if there is no harm or damage being done to anything?:)
 
If the battery really got down to 42V that is 2.62V per cell and I would be concerned. That’s not a level to cause permanent damage but I would wonder if individual cells got lower.

At the very least I would want to know how low the cell voltages got.

Not familiar with that battery but the BMS may have protected it and may have logged how low the individual cell voltages got before shutdown. I would want those questions answered.

It sounds like you hired an installer to set this up for you and they meant to set the LVD at 47V but didn’t. Setting it at 42V was definitely a mistake.
 
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I would expect it to only take a few hours. Definitely less than a day. You can speed up the process by only discharging from the higher battery. Or only charging the lower battery. But in the end they will have to balance with each other on their own.
Personally I would just let them do their thing.
 
Thank you all for the responses.

The BMS cut off the discharge. So hopefully that was done at a safe SOC.

The expectation was for the Inverters to have done that which did not happen since it was set at 42V.

I will monitor the batteries for a week. Fingers crossed.
 
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