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Battery reporting over voltage when fully charged

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Hi Guys,

Not sure whether to be concerned about this or not but I have a Alpha ESS 10.1kw battery hooked up to a Sunsynk 5.5kw inverter and ive noticed the battery complaining that its over voltage when its charged up fully every day. 

Is this damaging the battery or normal behaviour? The BMS comms seem to be working ok although I see sometimes the temperature or voltage etc goes to random numbers but it doesnt report any issues other than on the battery as below.

The error is as below:

image.png.4755a21a0b774ecb13087851460a8481.png

Tried to ask Sunsynk if the battery is on their compatibility list ?

What voltage does the inverter see on the battery ? Does it match with the voltage seen by the BMS ?

If you can not see that , try to set the inverter to Voltage mode and compare battery voltage by BMS and voltage seen by the inverter.

  • Author
41 minutes ago, Jaxone said:

Tried to ask Sunsynk if the battery is on their compatibility list ?

What voltage does the inverter see on the battery ? Does it match with the voltage seen by the BMS ?

If you can not see that , try to set the inverter to Voltage mode and compare battery voltage by BMS and voltage seen by the inverter.

Its on the list in the manual so should be fine.

The inverter does match what the battery specs say as well, at a bit of a loss, I think a firmware update messed this up but not sure, there hasnt been a new firmware for a long time though

On 2022/08/22 at 10:47 AM, MakoShark said:

Not sure whether to be concerned about this or not but I have a Alpha ESS 10.1kw battery hooked up to a Sunsynk 5.5kw inverter and ive noticed the battery complaining that its over voltage when its charged up fully every day. 

What voltage are you reading, if possible with a multimeter? Has the battery 15 or 16 cells? What setting do you have for floating voltage?

Looks like that is a cell over-voltage, not total over-voltage. Most likely the cells are out of balance and some are charging higher than others and giving the error. Are you able to see individual cell voltages?

5 hours ago, jumper said:

Are you able to see individual cell voltages?

That depends on your BMS and the corresponding computer software. Actually on the BMS of the Leoch 10048 I can read the individual cell voltages on its own built in display. But it is way more convenient to read them on the computer with corresponding software via i.e. an RS232 or RS485 cable and adapter. See example below:

BMS-21.thumb.jpg.dad8e68706e67000d19b0ebc8e33f038.jpg

  • Author

Thanks guys but im not able to check individual cells, I am assuming the BMS \ inverter comms will be handling all these settings as its a lithium battery, also not sure how many cells it has....im not much help! 😂 

1 hour ago, MakoShark said:

I am assuming the BMS \ inverter comms will be handling all these settings as its a lithium battery

This is what most people are relying on, but, from other posts in the forum, it seems that at least some BMS's are not able to handle when the battery doesn't charge properly and cells become too unbalanced.

  • Author
1 minute ago, jumper said:

This is what most people are relying on, but, from other posts in the forum, it seems that at least some BMS's are not able to handle when the battery doesn't charge properly and cells become too unbalanced.

Do you know if a fix for that? I think the manual settings I have entered for the battery are correct but did also expect the bms to handle this 

Nothing I have had to do, but apparently allowing the battery to drain and then charge it full using manual settings and no comms cable and once full, change back to lithium mode and reconnect comms cable. If you have no comms cable, maybe a full discharge and recharge will work, otherwise it is a manual process of opening the battery and charging up the low cells or draining the high ones... not something I'm keen to have to try though.

  • Author
20 minutes ago, jumper said:

Nothing I have had to do, but apparently allowing the battery to drain and then charge it full using manual settings and no comms cable and once full, change back to lithium mode and reconnect comms cable. If you have no comms cable, maybe a full discharge and recharge will work, otherwise it is a manual process of opening the battery and charging up the low cells or draining the high ones... not something I'm keen to have to try though.

Thanks I might try that on mine, it does have a comms cable so will see whats needed but might just let it drain down once and see if it helps

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