Lithium battery blies

[Whalby]

I have 2 100ah lithium batteries wired in parallel and after having them on the charger they read 100% on my VictronConnect battery shunt. When it gets to around 99-97% the power cuts abruptly and when I plug the charger back in it reads 100%. Any thoughts? Are my batteries shot? They are both barely used. Help!

[dzl_]

Originally Posted by Whalby

I have 2 100ah lithium batteries wired in parallel and after having them on the charger they read 100% on my VictronConnect battery shunt. When it gets to around 99-97% the power cuts abruptly and when I plug the charger back in it reads 100%. Any thoughts? Are my batteries shot? They are both barely used. Help!

Which batteries?



Which Shunt?


What is the precise voltage when the battery disconnects?


And when you say "When it gets to around 99-97% the power cuts abruptly and when I plug the charger back in it reads 100%"


Are saying that it cuts off while plugged into the charger at 97-99%, then you disconnect the charger, then you plug the charger back in and it shows 100%?


And finally, when you say "the power cuts abruptly" do you mean all power, or just charging is lost?

[Whalby]

Yeah, I guess I should be more specific. They are “smart battery” brand. 100ah each. It’s a VictronConnect shunt. The charger is disconnected and reads 99% when all the power cuts out. Then when I put the charger back in it the meter reads 100%.

[Whalby]

Yeah, I guess I should be more specific. They are “smart battery” brand. 100ah each. It’s a VictronConnect shunt. The charger is disconnected and reads 99% when all the power cuts out. Then when I put the charger back in it the meter reads 100%.

[john61ct]

Disconnect bypass the meter for now, test without using a plain DMM and ammeter.

Are you sure it's wiredup correctly, was it a DIY job or installed by an experienced tech / dealer?

Are you sure the maker has designed the internal BMS to allow connecting two of those in parallel like that?

[dzl_]

Not familiar with that brand battery, do you have a manual or link to the product description?

Also can you clarify what charger you are using, what specific voltage is set as the max (this may be called absorption)?

Regarding the Shunt there is no such thing as a Victron Connect Shunt, that is the name of their Bluetooth app it would be either the BMV (shunt with battery meter) or the Smart Shunt (shunt only)

And if you have a multimeter, next time the problem occurs, measure the voltage across the main battery terminals right after it disconnects.

Am I correct in understanding your situation:

1. You have 2 lithium batteries being charged by a ______ Charger.
2. You have a Victron Shunt which shows 99% when you lose all power (to/from the battery) (take a multimeter voltage reading at the battery terminals here)
3. You "disconnect" the charger (what does this mean? Physically disconnect?)
4. Some amount of time passes (how long?) (take a second multimeter reading at this point)
5. You "connect" the charger and the system powers back on, the shunt now shows 100%.

My suspicion is that it may be your BMS acting to protect your battery as you may be overcharging it, but its really impossible to say with any confidence without more details, it could be any number of things, this is just speculation.