Storing with Solar and LiFePo

[jb603tipper]

Greetings,
I am storing my Travel Trailer for three months and location that is quite far away, so I can’t check up on it. I have solar charging and a 280AH LiFiPo battery. I am debating whether to unplug the solar and disconnect the battery altogether, or to leave the solar and battery on for trickle charging throughout that time. My fear is that the solar stops charging and parasitic draw takes a battery down. What do most people do? When the solar is not charging, there’s about a half an Amp of draw on the battery. There are no battery or solar shut off switches so I would need to disconnect the solar on the roof. The battery is located in the front storage compartment
Thank you
John Benson
Grand design Imagine 2800 BH

 

[Soundsailor]

Assuming there is some sun in your storage location, you should be fine leaving the solar setup to maintain your charge for a few weeks. That said, it would be a good idea to install some switches to make it easier to shut things off when needed. There really should be a switch to shut off the solar, with a mini breaker you would add circuit protection. For winter storage, either get a switch for just before the battery or remove the negative cable before storage to protect against parasitic draws.

 

[ajg617]

I installed a dual pole circuit breaker between the panel and the solar charge controller after talking to the engineering staff at the manufacturer. They recommended not disconnecting the battery while leaving the panel putting in Amps to the charge controller. Might be dependent on manufacturer but I agree with @Soundsailor. I also installed a master shut-off switch which only allows the battery heat blankets to draw (I have a CB on those as well so the master switch shuts everything off if needed). If the temps get below -10F-ish (at least for my LiFePO4s), permanent damage can occur and yes, in southern NH we hit -13F early Feb 2023 with my RV at the dealer the entire winter waiting for maintenance. Below 32F, your BMS will likely prevent any battery charging and of course at night or panel covered with snow/ice panel output is nil so solar recovery isn't guaranteed. There are a lot of variables but installing CBs and a master shut-off makes it a lot easier/safer to remove the battery if necessary.

 

[Second Chance]

Our Solitude is in outside storage on an Army installation right now. I shut down the secondary panel (operates the fridge and a few things off the inverter), switched the inverter off, and left solar and batteries (4 Battle Born 100 AH batteries) up and running. the smart shunt history shows that everything is fine as far as voltages and charging cycles.

Rob

 

[TimtheToolMan]

This brings up some really good questions. How are most people handling storing LifePO4 batteries where temperatures get quite low (10F or maybe even -25F)? Just cutting power to/from batteries and hoping for the best, removing batteries or heating batteries (or camper) to keep them above a safe charging temperature?

I use Anderson quick connect connectors on two 100Ah batteries and remove them to keep them from excessive temperature in the summer and quite cold temperatures in the winter. Thanks to light weight LifePO4, removing is not difficult. This was not reasonable with the GC2 lead acid batteries that I previously had before, which really don't like these temperature extremes either (rarely -25F and 103F).

I guess the good part about LA being too heavy is I did not consider removing them until they die. With cost as low as they can be the LifePO4 are no longer a major cost when they fail so perfection in not a must.

I do have option to use battery heaters that I added and robust solar system (brush off snow?) and leave everything running in the winter (hope heaters do not fail) and let the batteries just deal with the heat, while never removing them. Simple...until I think of the numerous risks...

Added:
LiTime states: The recommended storage temperature for LiFePO4 batteries falls within the range of -10°C to 50°C (14°F to 122°F). Storing batteries within this temperature range helps maintain their capacity and overall health, preventing degradation. Battle Born says -15 to 140F also to remove when below -10F. Very impressive!

 

[Soundsailor]

@TimtheToolMan, I simply use a switch to turn off all access to my four LiFePo4 batteries. This has worked fine for a couple of seasons, with no noticeable effect on the batteries. Temps here can often get down to 20 below although that isn't happening as often as it used to.

 

[Butcher]

All too often we think LA but talk about LifePo4.

You can't discharge a LifePo4 battery so low you will damage it. You can with LA. You can't over charge a LifePo4 battery but you can with LA.

Yes, I am assuming that the BMS is working properly. If the BMS is not working properly, the LifePo4 battery did not fail, the BMS did, which caused the failure. We tend to forget that the LifePo4 battery has a lot of safeguards that prevent most of what we are worried about.

I store my 29RS inside my mostly heated shop. If I needed to store my trailer unhooked, I would just turn off the battery by way of the BMS.

 

[justusdj]

We don't have a LifePo battery, but our camper is currently sitting in FL and we're in WI. We won't be down there for at least 2 months and the camper is covered. I installed a cut off switch straight from the battery so it shuts everything down. I also installed a charge controller and am using the plug on the front of the camper to attach a small solar panel. This supplies a maintenance charge to keep the battery topped off.

 

[COGrandDes]

This brings up some really good questions. How are most people handling storing LifePO4 batteries where temperatures get quite low (10F or maybe even -25F)? Just cutting power to/from batteries and hoping for the best, removing batteries or heating batteries (or camper) to keep them above a safe charging temperature?

I use Anderson quick connect connectors on two 100Ah batteries and remove them to keep them from excessive temperature in the summer and quite cold temperatures in the winter. Thanks to light weight LifePO4, removing is not difficult. This was not reasonable with the GC2 lead acid batteries that I previously had before, which really don't like these temperature extremes either (rarely -25F and 103F).

I guess the good part about LA being too heavy is I did not consider removing them until they die. With cost as low as they can be the LifePO4 are no longer a major cost when they fail so perfection in not a must.

I do have option to use battery heaters that I added and robust solar system (brush off snow?) and leave everything running in the winter (hope heaters do not fail) and let the batteries just deal with the heat, while never removing them. Simple...until I think of the numerous risks...

Added:
LiTime states: The recommended storage temperature for LiFePO4 batteries falls within the range of -10°C to 50°C (14°F to 122°F). Storing batteries within this temperature range helps maintain their capacity and overall health, preventing degradation. Battle Born says -15 to 140F also to remove when below -10F. Very impressive!

Here in CO, it gets a little cold in the winter and can go down to 0*F but I error on the side of caution and remove my batteries and keep them in my warm shop for the winter. The RV is under a carport so the solar panels are not charging anyway. I then re-install them early May when our weekend-warrior camping season begins. Even though the batteries can handle the temp extremes.....in my opinion---no need to expose the batteries to them especially if I am not using the camper during those times.

 

[reubenray]

To the one's that remove their batteries what trickle charger are you using?

 

[Soundsailor]

To the one's that remove their batteries what trickle charger are you using?

You don't need a trickle charger when storing LiFePo4 batteries. An inexpensive LiFePo4-aware charger could be used to top the batteries up before installing them in the RV prior to camping season.

 

[justusdj]

To the one's that remove their batteries what trickle charger are you using?

Not sure what they use, but we have 7-8 batteries that come out of our toys to be stored indoors for the winter. I have several of these https://www.amazon.com/gp/product/B0051D3MP6 and also have some Noco brand that I like as well, like this https://www.amazon.com/gp/product/B004LX3AS6

 

[Soundsailor]

Not sure what they use, but we have 7-8 batteries that come out of our toys to be stored indoors for the winter. I have several of these Amazon.com and also have some Noco brand that I like as well, like this Amazon.com

Neither of those is lithium-compatible, they are designed for LA or AGM only.

 

[reubenray]

You don't need a trickle charger when storing LiFePo4 batteries. An inexpensive LiFePo4-aware charger could be used to top the batteries up before installing them in the RV prior to camping season.

I bought this last year to keep my AGM battery charged. I don't think it will work on a lithium battery.

Amazon.com

 

[justusdj]

Neither of those is lithium-compatible, they are designed for LA or AGM only.

I also have one of these Noco which is Lithium compatible. https://www.amazon.com/dp/B07W46BX31
Those are brands that I have and like. A quick amazon search will likely give you lithium versions.

 

[Jomani]

@Butcher - I don’t completely agree with the statement in the context of this thread.

You can't discharge a LifePo4 battery so low you will damage it. You can with LA.

Yes the BMS will prevent the LiFePo4 from discharging to the point where damage will occur, but there will be an approximately 3% monthly self discharge rate that the BMS can’t control. If something happens where the LiFePo4 became fully discharged and the BMS cuts off, irreparable damage could occur in as little as a couple of months due to self discharge.

I am of the opinion that the battery should be disconnected (battery and solar disconnect switches are fine) anytime the rig is being stored at a location that isn’t readily accessible. I typically leave mine at around 80% SOC if I know it will sit for a while.

 

[reubenray]

@Butcher - I don’t completely agree with the statement in the context of this thread.

Yes the BMS will prevent the LiFePo4 from discharging to the point where damage will occur, but there will be an approximately 3% monthly self discharge rate that the BMS can’t control. If something happens where the LiFePo4 became fully discharged and the BMS cuts off, irreparable damage could occur in as little as a couple of months due to self discharge.

I am of the opinion that the battery should be disconnected (battery and solar disconnect switches are fine) anytime the rig is being stored at a location that isn’t readily accessible. I typically leave mine at around 80% SOC if I know it will sit for a while.

How do you get the battery to around 80% SOC?

 

[Jomani]

How do you get the battery to around 80% SOC?

When I first installed my LiFePo4 batteries, I disconnected the 12v supply coming from the 7 pin on the truck. I do have DC-DC charging capability if I need it.

Depending on how far I am going, I may turn off the solar before I head home. By the time I get home, disconnected, level, slides out and back in for cleaning and unloading, and of course my needy 12v refrigerator, I seem to always be around 80% SOC by the time I am ready to flip the battery disconnect switch. If not, I may leave the refrigerator run for another day - solar off of course.