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Charging profile question

raykeating

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Jun 21, 2022
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On my boat, I have a system with two Renogy 200 amp hour batteries. I want my house batteries always full when i leave the dock, but they drop to 12.5v before the charger cuts in, if I use the standard lithium charging profile.

I can use a custom profile, but it’s asking me to “set the battery low voltage recovery charge. This will be the voltage that the battery discharges to before the inverter-charger charges the battery to the predetermined maximum charging voltage”. My question is, what value should I set this to, and can I keep the batteries always topped up without causing damage?

Thanks!
 
So “low voltage recovery charge” is the same thing as float?

I don't know. "Low voltage recovery charge" sounds more like what is referred to as "re-bulk," i.e., where the battery drops to a voltage that initiates a new bulk/absorp/float charge.

Some Li charge controllers stupidly omit float for LFP since "LFP batteries don't need float" (unless they're in a cyclic power system, and you want to keep them fully charged and power loads with solar).
 
I don't know. "Low voltage recovery charge" sounds more like what is referred to as "re-bulk," i.e., where the battery drops to a voltage that initiates a new bulk/absorp/float charge.

Some Li charge controllers stupidly omit float for LFP since "LFP batteries don't need float" (unless they're in a cyclic power system, and you want to keep them fully charged and power loads with solar).
Yeah, if I set it to “Li” it drops to basically 0ah and 12.5v before it starts charging again. If I set it to “custom lithium” I don’t get a float voltage option, only a charge voltage and this “Low voltage recovery charge” setting. I’ll try setting that to 13.6, and will monitor it I guess.
 
Yeah, if I set it to “Li” it drops to basically 0ah and 12.5v before it starts charging again. If I set it to “custom lithium” I don’t get a float voltage option, only a charge voltage and this “Low voltage recovery charge” setting. I’ll try setting that to 13.6, and will monitor it I guess.

Even if it runs another full charge cycle, it beats the snot out of having an empty battery at the end of the day.
 
Yeah, if I set it to “Li” it drops to basically 0ah and 12.5v before it starts charging again. If I set it to “custom lithium” I don’t get a float voltage option, only a charge voltage and this “Low voltage recovery charge” setting. I’ll try setting that to 13.6, and will monitor it I guess.

Same issue I am having with my Renogy inverter/charger. I've found the AGM2 profile keeps them topped up but it's basically constantly doing a low amperage charge every 4-5 mins if you have any low amount of draw. The lithium preset makes no sense to have to wait until 12.5V to get a charge. I've been trying to find a happy balance between keeping my batteries reasonably topped up and not having it start to charge every few mins.
 
On my boat, I have a system with two Renogy 200 amp hour batteries. I want my house batteries always full when i leave the dock, but they drop to 12.5v before the charger cuts in, if I use the standard lithium charging profile.

I can use a custom profile, but it’s asking me to “set the battery low voltage recovery charge. This will be the voltage that the battery discharges to before the inverter-charger charges the battery to the predetermined maximum charging voltage”. My question is, what value should I set this to, and can I keep the batteries always topped up without causing damage?

Thanks!

Did you ever figure out any settings that work for you?
 
I've been trying to find a happy balance between keeping my batteries reasonably topped up and not having it start to charge every few mins.
While Float is not generally recommended with Lithium batteries, I use a voltage slightly above resting voltage for a Float setting. My inverter is always loading the batteries and charging is only from solar so that is limited at the most to five or six hours.
 
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