Renogy Rover Controller : Float voltage

[greg_mustang]

Hi there,

Recently upgraded to a Renogy Rover MPPT.
The PV is 4x Renogy 100W panels. The battery storage is 2x 12V deep cycle lead acid (newly purchased) in parallel.
The Rover detects the lead acid batteries and set itself to FLD and 12V, OK.

The float voltage is set, for that configuration, to 13.8V. Is this maybe a bit too high?

Also I cannot find any setting linked to the <estimated> battery charge, i.e. when it says 100%, what voltage is it reading?
I asked because every evening, after dark, the estimated battery charge drops from 100% to 80%. In the morning when I wake up and daylight it shows 100% again.

Thanks for your advice
Greg

 

[mikefitz]

estimated battery charge drops from 100% to 80%

Disregard the SOC reading on the Renogy controller. It's based on voltage of the battery, after a rest , off charge, the battery voltage will fall.
From the manual,
"The Battery Capacity (SOC%) is an estimation based on the charging voltage."

Thus whilst the battery is only under charge the SOC may be a useful indication, but at rest or when there is loading on the battery, the SOC will be very inaccurate.

To accurately monitor SOC a battery monitor will give a reasonably accurate reading. With lead acid batteries the Victron battery monitors will give a more accurate reading of SOC.

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If you are charging from solar and cycling the batteries than 13.8 volts float is OK, for long term storage a slightly lower voltage float would be ideal.

 

[greg_mustang]

Thanks so much. Yah,i know the soc is stated as only an estimate, i just wondered if there was a setting of voltage i might need to adjust.
I will look into the battery monitors!

 

[greg_mustang]

After thinking about it, I still find it strange that it systematically shows 80% or less by midnight when the batteries are fully charged.

 

[chrisski]

Thanks so much. Yah,i know the soc is stated as only an estimate, i just wondered if there was a setting of voltage i might need to adjust.

I would stick to the charging spec on the battery for float.

Nothing you can change for float will affect the nightime SOC discrepancy you are seeing.

A better SCC will be able to do a temperature compensation for flodded lead acid based off the battery temperature. This is more important the farther away from a comfortable room temperature you keep your battery. What that temperature is and the amount of mV per degree will be in the spec sheet.

 

[Tomthumb62]

After thinking about it, I still find it strange that it systematically shows 80% or less by midnight when the batteries are fully charged.

Write this on a sticky note and post it on your bathroom mirror:

“The SoC % on the Renogy Rover is to be 100% ignored.”

lol

But seriously, it’s such a very rough and poor estimation that it doesn’t react to the battery voltages in a meaningful or reasonable manner. So best to just ignore it and get a battery monitor. A battery monitor is essential for a lead acid battery bank, and a nice thing to have for lifepo4 (IMO, as long as the lifepo4 BMS has Bluetooth with a built in no frills monitor).