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Leave panels attached to lithium battery?

goldenstate

New Member
Joined
Apr 6, 2022
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I recently installed PV panels and a controller on my sailboat to help keep my house batteries charged.

My question is if I can leave the panels on all the time without damaging my lithium batteries or if I should have some disconnect mechanism.

I have:

2@ 100 watt flexible panels
connected to
Renogy 20amp Rover MPPT controller
connected to
Renogy 50aH LiFePo battery

From what I have read one should not regularly float charge/trickle charge a Lithium battery. Instead should charge it up, deplete the battery, then fully charge it again. I would like to be able to use my boat for a weekend, then walk away for 5 days and come back and find the batteries charged via solar.

I can charge my battery quickly via my alternator, but I want to minimize the high C rate charge cycles (where I am offering 50 amps to my 50aH battery). I think my batteries will last longer if I give them the 5-9amps that my panels seem to produce and is closer to the Renogy specified charge rate of 0.2C.

Is there a "normal" or frequently used solution like a timer or something similar that will allow me to (without physically operating a switch myself) disconnect the panels from the batteries once they are charged so as not to continually be offering electricity to them?

Thanks in advance for guidance.
 
In a cyclic application, LFP batteries need to be floated such that the PV will power loads based on the battery float voltage. If there is no float, the MPPT will not use PV until battery voltage drops to float or re-bulk voltage.

Drop float to 13.1V. This will allow the battery to drift down to a lower SoC and maintain it there.
 
I recently installed PV panels and a controller on my sailboat to help keep my house batteries charged.

My question is if I can leave the panels on all the time without damaging my lithium batteries or if I should have some disconnect mechanism.

I have:

2@ 100 watt flexible panels
connected to
Renogy 20amp Rover MPPT controller
connected to
Renogy 50aH LiFePo battery

From what I have read one should not regularly float charge/trickle charge a Lithium battery. Instead should charge it up, deplete the battery, then fully charge it again. I would like to be able to use my boat for a weekend, then walk away for 5 days and come back and find the batteries charged via solar.

I can charge my battery quickly via my alternator, but I want to minimize the high C rate charge cycles (where I am offering 50 amps to my 50aH battery). I think my batteries will last longer if I give them the 5-9amps that my panels seem to produce and is closer to the Renogy specified charge rate of 0.2C.

Is there a "normal" or frequently used solution like a timer or something similar that will allow me to (without physically operating a switch myself) disconnect the panels from the batteries once they are charged so as not to continually be offering electricity to them?

Thanks in advance for guidance.
If it was me I would make sure my controller was set properly for my particular battery and just enjoy it I doubt the increased longevity of the battery would be worth the hassle of micro management.
 
In a cyclic application, LFP batteries need to be floated such that the PV will power loads based on the battery float voltage. If there is no float, the MPPT will not use PV until battery voltage drops to float or re-bulk voltage.

Drop float to 13.1V. This will allow the battery to drift down to a lower SoC and maintain it there.

Little bit of a PITA when you have multiple chargers (inverter/charger, solar charger, DC-DC charger). Gotta remember to lower all of them, and then remember to put them all *back*.
 
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