Winter Shut Down

[ddutton]

I have a new 280 aH 24 volt system and was wondering the best method for shutdown. I know it is not good to have them sit at 100% so.... charge to around 70% and disconnect solar? BMS bluetooth will have small draw.

 

[OffGridInTheCity]

To me, if you're shutting down for a long period (winter = 4 months?) then turning off the BMS would be part of my procedure. Perhaps a switch on the power the BMS (depending on the model you use). I have Lithium-ion and store at 3.7v/cell - but I'm not sure the best for LifePo4.

 

[HRTKD]

Depending on your BMS, the draw is minimal. Bluetooth adds to that, of course. In the Overkill Solar manual, Steve documents the draw.

I'm doing something in the my trailer throughout the year, so I chose to keep the batteries warm and active all year.

 

[chrisski]

I have a new 280 aH 24 volt system and was wondering the best method for shutdown.

I would like some documentation in a manual to see the best method. I am receiving Eve 280 ah cells and am wondering that myself.

My problem is a little different than yours, I have a summer shutdown where compartment temps will reach 120 if I leave the batteries in, so I'll probably do something different than you.

Lack of any tech data popping up, I plan on going through the manuals for batteries like Battleborn and see what they say to do. If a few of those manuals say the same thing, I will apply that to my cells. Even if I get good guidance, I will be checking this against some other manuals.

 

[Steve_S]

Generically, storage is best closest to 50% SOC or 3.200. Many manufacturers will set them to 3.350 prior to warehousing, hence why most LFP cells arrive between 2.390-3.300. Also when Binding/Clamping, it should be done at 25C/77F temp and 3.200Vpc. I use Maker Spec Sheet info and not prebuilt packaged companies datasheets.

Many of the offshore ones are nuts with even insisting that cells should be charged to 3.650 shortening their lifecycles intentionally. High End brands like BB, ReLion etc are not entirely the same because they are using Premium Matched & Batched cells and their have their own custom BMS' (which are over rated for safety margin & longevity) IE, their 100AH packs usually have 120AH cells.... Their 100AH BMS's are typically 120-150AH but locked down to prevent being overdriven. They do it as Warranty Safety as well to prevent ding-a-ling from getting too cocky and creating claims as a result.

 

[HRTKD]

In their 2019 specs (should be in the resources section if you want to look at it yourself), EVE says that the storage temperature range is -20° C to 45° C. However, it also defines that as short term (within a month) storage. Long term (within a year) is 0° C to 35° C.

Chris, it looks like you're outside both of those ranges.

 

[chrisski]

Chris, it looks like you're outside both of those ranges.

Looks like I will be pulling these out of the RV in the summer and keeping them indoors.

 

[OffGridInTheCity]

Looks like I will be pulling these out of the RV in the summer and keeping them indoors.

I know what you mean. I converted a 7 x 14 cargo trailer -> camper this year and it has a mini-split and a lithium-ion battery bank So far - I'm using the mini-split to keep temps in range. I guess this will work as mini-splits should run OK for years.... its not like they wear out fast. The 1200w of solar panels on the top are enough to run it 24/7 and I have the option to bypass the inverter and use external 120v directly.

But... I don't know... long term storage when the fun (of using a camper) wears off? - agree that temp extremes not good for lithium batteries. I wonder if a lot of folks take the battery bank out.

 

[chrisski]

I know what you mean. I converted a 7 x 14 cargo trailer -> camper this year and it has a mini-split and a lithium-ion battery bank So far - I'm using the mini-split to keep temps in range. I guess this will work as mini-splits should run OK for years.... and the 1200w of solar panels on the top are enough to run it 24/7.

I plan on having a workable AC by the end of 2022. I will not leave it on just to cool the batteries for four weeks while in storage between trips.

I may use that as an excuse to move in the RV full time....