Storing SOK motorhome batteries?

[chateau_nomad]

Two 100Ah SOK LiFePO4 batteries in motorhome, 600 watts of rooftop solar. Solar keeps batteries at 100% SOC. Consider this is in Ohio from mid November until early April. Temperature can range anywhere from 40°F to possibly below 0°F.

Question... should I disconnect solar (PV switch) and drain batteries to 70 or 80%? Will they degrade if left fully charged in sub-freezing temps? Not convenient to remove them, but if necessary... Or are they okay? Recommendations appreciated!!

 

[Samsonite801]

'They say' that 50-60% SoC is ideal for long-term storage.

 

[chateau_nomad]

'They say' that 50-60% SoC is ideal for long-term storage.

What about extended storage in sub-freezing temperatures?

 

[Samsonite801]

What about extended storage in sub-freezing temperatures?

Well, according to SOK specs listed on their website I'm seeing this:

Temperature Information:

Discharge temperature:-4°F~140°F

Charge temperature: 32°F~113°F

Recommend storage temperature: 23°F~95°F



Then just pulling up off some random site from a Google search, for generic LiFePO4 type battery, you can see storage recommendations like this:

How to store LiFePO4 batteries? - Canbat Technologies Inc. - 24/7 Support

Learn how to store LiFePO4 batteries during the off-season. Weather you're storing them for a month or even a year, here's what we recommend.

www.canbat.com

HOW TO STORE LIFEPO4 BATTERIES?​

How do I store my lithium battery? A question we receive from our customers on a daily basis, especially in the Winter season. The answer depends on the temperature you are storing the batteries in and the period of time. Here’s a summary of how to store your LiFePO4 battery:

• Recommended storage temperature: -5 to +35°C (23 to 95 °F)
• Storage up to 1 month: -20 to +60°C (4 to 140 °F)
• Storage up to 3 month: -10 to +35°C (14 to 95 °F)
• Extended storage time: +15 to +35°C (59 to 95 °F)

It is highly recommended to store lithium batteries indoors during the off-season. It is also recommended to store LiFePO4 batteries at about a 50% state of charge (SOC) or higher. If batteries are stored for long periods of time, cycle the batteries at least once every 6 months. Do not store batteries that are discharged.




If you don't use the RV at all during Winter, and don't want to worry about it much, just pull the batteries out and put them inside your house if you want.

 

[chateau_nomad]

While I COULD remove the batteries, doing so would be a major inconvenience... especially when needing power in the motorhome over the winter - which I do. I exercise the generator once a month, and the LiFePO4 house batteries are the starting power source. Also at that time I need lights for general inspection... watching for water leaks, rodents etc.

So... here's a couple ideas...

I have a Sungoldpower 3k inverter/charger wired to the batteries. What are thoughts of leaving the inverter on idle? It consumes 55 idle watts (a lot) according to specs. Rounding up, that's 5amps, or 120Ah per 24 hour period. Does that sound correct? The batteries are buried under the bed in a double-walled fairly insulated space. The inverter is mounted on one of those walls, and likely would generate enough heat to keep the battery compartment well above freezing. The 600 watts of solar "should" average 90 - 120Ah per day in winter. Stupid idea to cycle them in this manner for six months??

Idea #2: Plug the motorhome to a 20amp shore power outlet. When on, the inverter switches to bypass allowing 120v to appliances and outlets. The charger then becomes active... BUT I'm not sure of it's power consumption on bypass. The thought is to discharge the batteries to 50% to 60% of capacity... then disconnect them via the battery disconnect switch AND disconnect the solar panels via a PV switch. Any heat generated by the inverter in bypass would again keep the batteries within the storage temperature.

Thoughts?

 

[Samsonite801]

While I COULD remove the batteries, doing so would be a major inconvenience... especially when needing power in the motorhome over the winter - which I do. I exercise the generator once a month, and the LiFePO4 house batteries are the starting power source. Also at that time I need lights for general inspection... watching for water leaks, rodents etc.

So... here's a couple ideas...

I have a Sungoldpower 3k inverter/charger wired to the batteries. What are thoughts of leaving the inverter on idle? It consumes 55 idle watts (a lot) according to specs. Rounding up, that's 5amps, or 120Ah per 24 hour period. Does that sound correct? The batteries are buried under the bed in a double-walled fairly insulated space. The inverter is mounted on one of those walls, and likely would generate enough heat to keep the battery compartment well above freezing. The 600 watts of solar "should" average 90 - 120Ah per day in winter. Stupid idea to cycle them in this manner for six months??

Idea #2: Plug the motorhome to a 20amp shore power outlet. When on, the inverter switches to bypass allowing 120v to appliances and outlets. The charger then becomes active... BUT I'm not sure of it's power consumption on bypass. The thought is to discharge the batteries to 50% to 60% of capacity... then disconnect them via the battery disconnect switch AND disconnect the solar panels via a PV switch. Any heat generated by the inverter in bypass would again keep the batteries within the storage temperature.

Thoughts?

As long as your SOK have valid freezing temp charging shutoff, they should be safe for charging on and shut off if they get too cold..

Honestly, I don't worry about the 50-60% SoC for storage thing. I just follow this thread (below) these days and charge up to 3.52v per cell max, and call it a day. Even if I leave my motorhome for weeks or longer, or am here, I don't care about what they'll do, whether I'm there using them or not.

Best LifePo4 charge controller settings known to man for Maximum Service life and Minimum battery stress!!! 5,000-10,000+ cycles?

---ORIGINAL TITLE---- Best charge controller settings to achieve 10%-90% usage on lifepo4 ? EDIT-UPDATE and the ANSWER to this question. . . This post is a accumulation of all the great and wonderful information given to me by all the great people on this thread. I consolidated all of this...

diysolarforum.com

The way I look at it, these batteries will last for 10 or so years, and eventually wear out, and at the rate of change based on today's tech, there will be better, cheaper batteries in 10 years from now.

That's just me though, individual strategies may vary...