How to achieve 60-80% SoC during motorhome winter break

DIY
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1

How can I limit the state of charge (SoC) of my 480Ah LiFePO4 battery in my motorhome to 60-80% during the winter break? - There is permanent shore power during this time (also 560 Wp PV - if there is sun). I want to keep the battery in a narrow, well-tolerated corridor, neither in a permanent float state nor triggering unnecessary charging cycles. Due to an additional electric heater and a winter base temperature of 6°C, the motorhome repeatedly has AC loads of up to 1,200W on cold days, even for hours at a time.

My configuration: MultiPlus 12/3000/120-16, CerboGX, SmartShunt-500A, SmartSolar Charger MPPT 150/35, SmartSolar Charger MPPT 100/15.

2

Try setting the voltage down to 12.5 for a 12v system.

Or disconnect the lifepos when at 50% and connect an old lead battery instead.

But actually I wouldn’t worry about it, mine are cycling from ~85 to 100% every day since 4 years…

3

Easiest to be done with a Node Red flow. Happy to share

4

Which is the SOH on the batteries after 4 year?
And which batteries?
Thanks.

5

Dumme cs-batteries aus München ohne jegliches Interface, da kommt wenigstens kein Blödsinn raus.

6

Ditto - nothing to worry about despite the doomsday theorists among us.

Our 300Ah 4 cell Sinolpoly LiFePO4 battery has survived 11 years of full-time of RV travel at the same typical 85 to 100% SOC.
My last annual November capacity test converted to Ah shows a whopping c6% loss. Down from the original. 315 to just 299.

With all that abuse they may only last 19 years and 11 months instead of a perfect 20.
I will never know!

2 Likes
7

Hi @Nev and @Ludo

Which were / are your bulk and float voltages for the cells ?
Especially those of Nev’s, as 11 years are “far out” … :innocent:

8

14.4. / 13.9

9

Keep in mind LFPs need a float charge cycle to balance the cellls. As others have said just charge normally. 100% doesnt hurt anything

10

Maximum charge source 14.1V.
The battery is ALWAYS at 100% SOC once the battery terminals reach 14.1V whether charging at 5 or 130A.

I occasionally give it 10-20 minutes of absorption time or force it to 14.50V but that takes a few seconds at 30A. Just a few mWh of energy added.

“Float” is 14.1V while driving and 13.45V while stationary and the sun shines.