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Bill avatar image
Bill asked

Stopping my MPPT from charging around 80% SOC while the RV is in storage

I have seen other questions like this but the answers were more about folks NOT wanting to do this. I am trying to find out how to do it. I am assuming maybe by changing the voltage, I tried lowering the float voltage to 13.5 from 13.6 and it had no visible effect. Instead of trial and error I am hoping to start in the correct area as my storage facility is far away. (I monitor it via VRM)


PS. I want to do this, so I don't need any info on why folks don't think it needs to be done, I have read all that and still want to do it anyway to lower the cycle count on my older LI batteries.

SOC
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3 Answers
bunya-solar-pl avatar image
bunya-solar-pl answered ·

Could you let us know what gear you've got please?

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Bill avatar image Bill commented ·

Currently have 2 Smartsolar 100/50 controllers, CerboGX, BMV712 and SBS, SOB 8kw LiFePo4. I would like the 100/50's to bring the Lifepo4's to 80% max while the motorhome is in storage, then 100% while traveling. I am thinking I could setup two profiles, but I have not yet figured out what values would need to be changed. I tried lowering the float voltage in two steps, but it appears to have done nothing at all. -Bill

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derrick thomas avatar image derrick thomas Bill commented ·
You could probably achieve this with os large and node red
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justinford avatar image
justinford answered ·

You could use a Battery Protect connected to one of the solar charge controllers that it would shut down the power from the solar array when your SOC reaches 80% with the relay control in the BMV 712. Use a separate battery protect for each controller or just shut one controller off when in storage. When traveling just disconnect the relay control.

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Bill avatar image Bill commented ·

I though I read you cannot leave the controller connected to the PV panels if the battery is disconnected from the controller? I am getting the impression I cannot setup the controller itself to stop charging at some voltage that is close to 80%?

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Bill avatar image Bill commented ·
Yes, there are things running on the batteries, a few cameras and a cellular router. Ah, so battery connect disconnecting the Solar Array instead of the batteries.
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djsmiley avatar image
djsmiley answered ·

I would manually set it to 60% SOC or so and disconnect the battery. (Assuming its a LiFePO4). Most vendors recommend 50-60% SOC as optimum for storage of the batteries. Self-discharge is almost zero, so no MPPT or charging required, unless you need to run some applications while in storage


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