Stopping solar panels from charging batteries

[Rowls1958]

I have Fogstars and turn of charging at the battery app, I imagine that is okay I do intened to fit a switch when I get chance

Hi, I spoke to Fogstar and they advised me I should not stop charging on the App. Seems ridiculous to me, why have that switch on the App if you shouldn't use it !! Anyone know why ?

 

[Fazerstorm]

I just turn off the charging in the victron solar app. I have been doing that for the last 2 years without any issue. It says for maintenance, but that could mean anything. It wasn't safe to do so, it wouldn't allow you turn it off.

 

[Ingwe]

Well that’s settled then. On balance, I’ll leave them be and let them sit at 100%. It’s the path of least resistance and no significant risk. Thanks all for the advice.

Me too.

 

[Peregrinator]

I understand that lithium batteries are optimumally stored when holding a 40% charge. My question is how to keep them at a 40% charge when they’re connected to solar panels. My Victron solar charger can be turned off (but it warns that this should be for maintenance purposes only) and I can pull the fuse from my Voltronic charger. Am I going to damage my chargers by turning them off in this way and does it damage to solar panels to have the sun shining on them but nowhere for the electricity they generate to go?

Use the BMS to keep the cells at 3.4v, then it will be ok.

 

[Peregrinator]

I understand that lithium batteries are optimumally stored when holding a 40% charge. My question is how to keep them at a 40% charge when they’re connected to solar panels. My Victron solar charger can be turned off (but it warns that this should be for maintenance purposes only) and I can pull the fuse from my Voltronic charger. Am I going to damage my chargers by turning them off in this way and does it damage to solar panels to have the sun shining on them but nowhere for the electricity they generate to go?

You could connect a switch like the one in the photo, but make sure it's for DC and not AC, see photo I circled the the DC symbol.

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[Hymer Tony B]

Fitted breaker switch between solar panel and mppt controller.

 

[sfrain145]

The BMS is really a last resort to protect the battery always best not to exceed it's parameters.

Agreed

 

[the1andonly]

If you wish to control the level charged at it is quite simple to use the relay output of a victron BMV712 (eg SOC )to switch a DC DC SSR. Photo is an example not precise one I use. The values can be set to whatever you want and create a set of saved file settings that can be imported quickly, eg winter, summer lo, summer hi. Doing this you can allow the battery drop to 40% but then be charged back to 80% (or whatever values you decide). When i set this up 4 years ago people were much less gung ho about keeping LiFePO4 at 100% charge all the time.