Storing SOK rack batteries

I‘ve had my 48 volt rack batteries for over a year and hope to install them this fall. I got worried about the state of charge so I topped them off with the aimes charger. Now they will sit in my closet till around December.

Do I need to worry about storing them fully charged? And if there an easy way to bleed off some charge for storage?

Something cheap and easy would be great.

Many thanks

Hook up the BMS and turn it on. It will use a few watts. Batteries also self discharge about 5% per month.

It doesnt look like SOK says anything about storing their batteries in the manual. But this is from the EG4 LL and LifePower4 manuals.

Battery State
The state of the battery when placed into storage will affect how long it can be stored for as well as the
condition when you begin using it again. EG4 recommends that each battery is brought to a SOC (state of
charge) of 100% prior to placing it in storage. Lithium iron phosphate batteries will lose a certain
percentage of their total charge while in storage, depending on how long they are stored and the
conditions they are stored in. Our recommendation is to ensure they are fully charged to allow them to be
stored as safely and for as long as possible.

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Recommended to store at 100%, but I think thats so that if you forget about checking on them, they dont drop too low. The battery itself would probably be happiest stored around 50% SOC. If you are willing to check on them monthly and possible recharge them, it could be best to store at 75% and then recharge if they drop below 50%. But I dont think you will have any issues storing at 100%. If I were you, I would just leave them at 100% and not worry about micromanaging them

LFPs can handle sitting at near 100% a lot better than other Lithium Ion chemistries. Some real world examples being Tesla recommends most of their cars only be charged to 80% unless you need the range for a longer trip. But for their LFP cars, they recommend always charging to 100%. LFPs are not like iPhone batteries, if youve seen iPhones have added a smart charge feature where it will only charge to 80% when it thinks you wont need the battery (overnight) and will only top off the last 20% right before it thinks you will wake up.

Not that I’m a little obsessive about taking care of my batteries…?

Bluedog225 said:

Not that I’m a little obsessive about taking care of my batteries…?

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And you’re not the only one. Surely someone will come by and predict armageddon and complete chaos if you don’t store them at 50% SOC.

That is best practice but I have an 8 year old LiFePO4 that I always kept at 100% SOC for years before I knew better and it still had 95% capacity last time I checked.

95%. Jeeze.

I’m sorry for your loss. ?

I would worry about it only from a warranty perspective ... what does the vendor want, that would preserve the warranty (or not be a sticking point).

If you got these from CurrentConnected.com (supposedly the exclusive SOK dealer in the US), just email them and ask for the specific recommendations, if the actual wording isn't in their online doc for the battery.

@HighTechLab

I’ve looked over the current connected.com website and the extensive documentation here:


But don’t see any guidance.

I do like the idea of turning on the BMS for a while and bringing the charge down to whatever point is optimal for storage.

Full is good. I'll add some guidance to the manual.

Remember the BMS can't account for self-discharge, as the self-discharge doesn't go through the shunt of the BMS - so if you are using the BMS as a gauge of how full they are in storage, it's wrong. You can always be certain the battery is full if you've topped it up to 57.6v.

Email them (the distributors support link) ... and also consider emailing SOK themselves (the vendor).

50ShadesOfDirt said:

also consider emailing SOK themselves (the vendor).

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We (CurrentConnected) contracted SOK to build these 48v batteries based on our design...asking them technical questions about them likely won't get you far.

Storing any lithium battery above 90% SOC is a bad idea and will shorten its lifespan.

The first rule is to store them as close to just above 32 degrees as is practical. The closer they are to freezing, without actually freezing, the longer the battery will last in storage.

The second rule is to store them discharged. Generally speaking, the lower the SOC, the longer the battery will last. Problem is, since all bats have a self discharge, if you store them at too low of a SOC, they can self discharge and go below their minimum voltage, which would be bad. Its also worth noting that there isn't any significant advantage to being below 60% to 70% SOC. The real trick is to store them at some mid-range charge state that is below 90%.

These rules come with some obvious pitfalls. If you won't be able to check or do any maintenance on the battery for a long time, then you are restricted to a SOC that is high enough to ensure they don't go below their minimum voltage.

Regardless of what the manufactures claim, the rules for storing all lithium batteries is the same.

Well ... I think we've all tossed out enough (conflicting) info that OP is as in the dark as I am ... if we can't look to the vendor to state what is required, and what preserves warranty, what are we left with?

This needs to be hashed (researched) out ...

Thanks for the note on CC's "special" SOK rack battery design (and others that you sell?) ... now I know how to pitch it, when I point folks at your site.

50ShadesOfDirt said:

Well ... I think we've all tossed out enough (conflicting) info that OP is as in the dark as I am

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are you sure about that? are you sure you dont want even more conflicting info, cause I got it and im gonna post it lol



I found these when I was researching "calendar aging" a short while ago. Talking about different temps and SOC that batteries are stored at.

I guess at 0% SOC you want them to be frozen solid?? (this research was from a paper analyzing battery chemistries in regards to space exploration).



here is my original post about it

In doing some research, I'm finding different results with the various battery types (Lithium-Ion, Lithium-Polymer, and LiFePO4) ... so it could be that "storage facts" for small form-factor Li-Ion batteries (18650) might not be as relevant for our storage batteries of large LiFePO4 cells (what is within your typical SOK 12v100ah product, or any other design).

In other words, when I see a "scary" storage message, it seems to be related to smartphone batteries & such ... and then, not much more detail on LiFePO4 specifics.

Perhaps this is where the confusion comes in ...

Still digging ...