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michelbeausejour avatar image
michelbeausejour asked

Is it good for the batteries to keep them fully charged all the time

I am most of the time connected to shore power, the inverter keeping the batteries charged in float mode. Every morning, the MPPT starts a change cycle in bulk mode. Am I over charging the batteries?

battery charging
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2 Answers
Justin Cook avatar image
Justin Cook answered ยท

@MichelBeausejour, the MPPT will always start in bulk; that's simply the way it works. Once it sees that your batteries aren't taking current (because your inverter/charger has been keeping them topped off), it will switch to its absorption/float cycles. So long as the charge voltages of the MPPT are set appropriately to your battery manufacturer's recommended charge specifications, you don't need to be concerned about overcharging them.

LFP banks are of course more susceptible to overcharge than FLA or AGM banks, so if you're running LFP, make sure to double-check your manufacturer's specific recommended charge profile and then, just to be safe, I would set the charge voltages in your MPPT a tenth or so of a volt under the recommended charge profile.


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michelbeausejour avatar image michelbeausejour commented ยท

Thanks. I have AGM batteries.

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Tom avatar image
Tom answered ยท

If lead it is good to store at full charge. Li Ion do not store at full charge.

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michelbeausejour avatar image michelbeausejour commented ยท

It is not in storage. I am travelling.

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spirou avatar image spirou michelbeausejour commented ยท

simple then... don't connect every time you stop somewhere.

Also, while the mppt will start in bulk mode in the morning, before it figures out the batteries are indeed full, the power generated will be so low it's not even worth bothering with.

But in general, keeping the batteries under constant charge is not ideal.

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