Looking for on-grid battery charger to maintain LiFePO4 while in storage

[tripseven]

I'm putting together a 24v off-grid LiFePO4 setup as seen here. This will be used for camping so a lot of not-in-use time will be involved.

It seems these batteries do better at ~50% SOC for storage purposes. Are there on-grid battery chargers available that can maintain this SOC while this setup is disconnected from the panels during storage?

The battery bank is composed of 8 200ah Sinology LiFePO4 in series for 24v.

 

[electric]

If battery is disconnected and BMS load is minimal , in the mA range, then there is nothing to maintain, it will sit at whatever SOC you left it.

 

[electric]

Also, calendar aging is about the same between 10% and 90% SoC, doesn’t need to be exactly 50%. What is important is temperature, try to keep the battery as close to what would be comfortable for humans. Below 40C and above 15C is the best storage range for longevity.

 

[offgriddle]

EVEN LITHIUMS need a little tlc during long term storage. This should do the trick: https://ampedoutdoors.com/products/copy-of-lifepo4-battery-2-4-charger

 

[tripseven]

Also, calendar aging is about the same between 10% and 90% SoC, doesn’t need to be exactly 50%. What is important is temperature, try to keep the battery as close to what would be comfortable for humans. Below 40C and above 15C is the best storage range for longevity.

I've done quite a bit of research on storing LFPs and the general consensus is to store them at ~50% SOC. Not saying you're wrong but rather my research shows otherwise on a grand scale. Can you link me to info supporting your statement? I only ask due to the cost of these little marvels.

 

[tripseven]

EVEN LITHIUMS need a little tlc during long term storage. This should do the trick: https://ampedoutdoors.com/products/copy-of-lifepo4-battery-2-4-charger

Thanks for the reply. But that charger is for 12v up to 85ah. Mine is 24v 200ah bank. And it's not clear to me how this would be able to maintain ~50% SOC. Seems to me it would need to be programmable regarding voltage output like a charge controller. I'm total newb to this is why I'm here asking.

 

[offgriddle]

Thanks for the reply. But that charger is for 12v up to 85ah. Mine is 24v 200ah bank. And it's not clear to me how this would be able to maintain ~50% SOC. Seems to me it would need to be programmable regarding voltage output like a charge controller. I'm total newb to this is why I'm here asking.

this place has two lithium 24 vdc chargers that plug into 120 vac. There is a phone number you can call to ask about floating etc.. Also, golf cart supply companies are getting into lithium chargers. Good luck.

Buy 24V LiFePO 2A Charger LithiumHub | Free Shipping

Buy 24V LiFePO 2A Charger now with free shipping. LithiumHub has the best value lithium battery accessories on the market with the best warranty and free shipping.

lithiumhub.com

 

[tripseven]

OK, let me ask a different way...

Is there a 24v battery charger with adjustable output voltage that anyone here knows of?

 

[offgriddle]

Why would you want to adjust the output voltage?

 

[tripseven]

Why would you want to adjust the output voltage?

Wouldn't that somewhat control the SOC as shown in this pic from one of Will's tutorials?

Oddly enough, all eight of my batts were delivered at 3.10v exactly.

 

[offgriddle]

Cool, there are 24vdc smart chargers that do that, for example: https://www.amazon.com/Battery-Char...=2025&creative=165953&creativeASIN=B07R77J39H

 

[gnubie]

Maybe this is all just a lot of hand wringing for no good reason. lifepo4 self discharges at around 5% or less per month. Run it up to 80% then you have 7 or 8 months at which time it is down to 50%. 80%, 50%, that's all fine in my books. How long on you plan on leaving the battery unused might be a question to consider.

 

[tripseven]

Cool, there are 24vdc smart chargers that do that, for example: https://www.amazon.com/Battery-Char...=2025&creative=165953&creativeASIN=B07R77J39H

I saw that one but it's not for lithium. Thx for the link though!

 

[offgriddle]

Lithium ion 24vdc chargers are available also

 

[tripseven]

Maybe this is all just a lot of hand wringing for no good reason. lifepo4 self discharges at around 5% or less per month. Run it up to 80% then you have 7 or 8 months at which time it is down to 50%. 80%, 50%, that's all fine in my books. How long on you plan on leaving the battery unused might be a question to consider.

I'm only going by research showing anywhere from 40%-60% SOC as being ideal for storage regarding longevity for these batteries. Not only that, if it could charge 12v also then I would have a backup charger for my 12v batts.

 

[tripseven]

Lithium ion 24vdc chargers are available also

Yes, I see that...many available. Yet I see none that are programmable to cut off at a specific voltage. All the 24v chargers I've seen will keep a 100% SOC.

 

[offgriddle]

Yes, I see that...many available. Yet I see none that are programmable to cut off at a specific voltage. All the 24v chargers I've seen will keep a 100% SOC.

I have the 12 volt version of this charger for my lifepo's. It charges 10 Amps and yes then drops to a constant trickle. It works for me because I only plug it in when my generator is running. Not sure if constant trickle is a bad thing for lifepo I will post the question in the forum?

UY240

This series charger apply for all kinds of lithium ion battery and lead acid battery.

www.yunyang-china.com

 

[azgrogg]

I was hoping to get an answer to this question as well. I'm putting together a solar generator that will be used in emergency situations to keep fridge, freezer and so.e other key items running. So, it may be in storage for a considerable stretch. Hence, I would like to keep it charged up because you dont k how when the lights are going off. Now, I could use this as well for various events where portable power is needed. I do go camping but my RV has solar and all my power needs are covered. I will plan on having some portable solar panels but they will not be set up all the time. They will be in storage as well. I guess I could pull it out of storage every once in awhile and fire it up. But, I'm looking for an easy to maintain protocol.

So, with that use case in mind, is there a charger on the market that would maintain 2 12v LIfePo wired in series for 24v 200ah.

Thanks

 

[offgriddle]

I was hoping to get an answer to this question as well. I'm putting together a solar generator that will be used in emergency situations to keep fridge, freezer and so.e other key items running. So, it may be in storage for a considerable stretch. Hence, I would like to keep it charged up because you dont k how when the lights are going off. Now, I could use this as well for various events where portable power is needed. I do go camping but my RV has solar and all my power needs are covered. I will plan on having some portable solar panels but they will not be set up all the time. They will be in storage as well. I guess I could pull it out of storage every once in awhile and fire it up. But, I'm looking for an easy to maintain protocol.

So, with that use case in mind, is there a charger on the market that would maintain 2 12v LIfePo wired in series for 24v 200ah.

Thanks

Yes, I have been using this one for my lifepo's since summer, 2019 very happy with it, it is available in many input and output voltage and amperage combinations including the one you are looking for. You can get it from a place called "energized outdoors' or Amazon and there are probably other outlets to buy from as well. It's nicely constructed and not too expensive. When fully charged, the red light goes out and a green light comes on, so at least it can realize when the batteries are full. How or if it floats I am not sure. https://www.yunyang-china.com/products/uy240/

 

[tripseven]

I was hoping to get an answer to this question as well. I'm putting together a solar generator that will be used in emergency situations to keep fridge, freezer and so.e other key items running. So, it may be in storage for a considerable stretch. Hence, I would like to keep it charged up because you dont k how when the lights are going off. Now, I could use this as well for various events where portable power is needed. I do go camping but my RV has solar and all my power needs are covered. I will plan on having some portable solar panels but they will not be set up all the time. They will be in storage as well. I guess I could pull it out of storage every once in awhile and fire it up. But, I'm looking for an easy to maintain protocol.

So, with that use case in mind, is there a charger on the market that would maintain 2 12v LIfePo wired in series for 24v 200ah.

Thanks

Ok, after some extensive research I've found some better info than "hand wringing" here...

DIY LiFePO4 Batteries On Boats - Marine How To

DIY LiFePo4 On Boats Last edit;3/26/23:The base of this article was written a number of years ago (2010) but this does not mean the information here is outdated. We have been keeping it updated and have added to it when ever we had the time. This article deals

marinehowto.com

It appears these folks are not your typical DIY types as their testing lab is pretty decent and quite knowledgable. This website is a very long read and gets quite technical but well worth the research. And they respond to questions by emails quickly.

The way to put LFP batteries in storage for months or even weeks is to store them at 40-60% SOC. This can be done with a quality charger designed for LFP with the ability to allow the user to define an absorption and float value to around 13.0v and disable temp sensor.

The charger you are looking for is here...

*SALE* Sterling ProCharge Ultra Battery Chargers - Starting At:

Sterling ProCharge Ultra Battery Charger, Pro Mariner ProNautic-P Battery Charger

shop.marinehowto.com

It's quite spendy at $367 w/shipping for the 24v 20a model but protecting my system calls this a good investment.

 

[tripseven]

Yes, I have been using this one for my lifepo's since summer, 2019 very happy with it, it is available in many input and output voltage and amperage combinations including the one you are looking for. You can get it from a place called "energized outdoors' or Amazon and there are probably other outlets to buy from as well. It's nicely constructed and not too expensive. When fully charged, the red light goes out and a green light comes on, so at least it can realize when the batteries are full. How or if it floats I am not sure. https://www.yunyang-china.com/products/uy240/

You might want to research the links I gave in reply to azgrogg as it appears you are trickle charging your LFP batteries. This will put them in an over charge condition and lessen their cycle time. And quite possibly cause a fire.

 

[Will Prowse]

You might want to research the links I gave in reply to azgrogg as it appears you are trickle charging your LFP batteries. This will put them in an over charge condition and lessen their cycle time. And quite possibly cause a fire.

Can you provide proof of creating combustion with a non-combustible battery? This chemistries properties make thermal runaway a non-issue. No need to even fuse individual cells in a pack. I need to see proof that you can cause a fire from float charging lfp.

And the downside to floating at high state of charge is reduced capacity over time. At least that's all I can find in the literature. Ambient temperature also plays a huge role. Easy to fix. Just float at lower voltage. Charge to 14.1.

 

[tripseven]

Can you provide proof of creating combustion with a non-combustible battery? This chemistries properties make thermal runaway a non-issue. No need to even fuse individual cells in a pack. I need to see proof that you can cause a fire from float charging lfp.

And the downside to floating at high state of charge is reduced capacity over time. At least that's all I can find in the literature. Ambient temperature also plays a huge role. Easy to fix. Just float at lower voltage. Charge to 14.1.

Hello Will...First off I never laid claim that float charging LFP will cause fire. My reply to offgriddle clearly stated "possibly" due to so much info on the web projecting all kinds of differing opinions in this regard.

Yes, I have already seen the Relion PDF claim you posted soon after my reply to offgriddle. But when it comes to personal property and most especially my family's lives I refuse to put full trust into ANY claim by a company that has skin in the game. Show me an independent study without skin in the game in a fully funded lab test and I will consider it as serious enough for public safety.

Meanwhile, over at RUIXU regarding LFP4 this is claimed...
"Over charging causes heating within a cell and prolonged or extreme overcharging has the potential to cause a fire."
ruixulithiumbattery.com/index.php?route=extension/megnor_blog/blog&blog_id=27

And at marinehowto.com/lifepo4-batteries-on-boats/ this is claimed, although not claimed due to float charging...
"...it is a fallacy & myth to believe that LiFePO4 batteries can’t achieve thermal run away and catch fire. LiFePO4 batteries can catch fire and they can suffer from thermal run-away it is just much less common than other Li-Ion chemistries. If an LFP battery does catch fire, you don’t want to be near it."
Being as these are cruise boat folks laying this claim, if that alone doesn't cause one to be on full alert in this new technology then that would be ones own choice.

 

[Will Prowse]

Yeah I have read that from ruixu as well and considering how much they do not know about their own BMS specs, and some I had to test and find out myself, I wouldn't take their word with much weight. Pretty sure they put that in their for shipping reasons because its lithium battery and they have to get it through customs etc. I posted relion article because they are a trustworth B2B battery company that sells primarily to installers. They are on a different level compared to ruixu.

I do respect marine how to .com though. I would like to see proof of it. I am surprised that thousands of these batteries are sold, and we do not have a single video or picture of one on fire. It will gas and make a nasty mess, but it will not combust or destroy cells next to it.

Can you post a picture or video here of one "one fire" from thermal run away?

Now for my proof: https://www.osti.gov/servlets/purl/1395736



Temperature can increase as in some studies if you bring the cells to 200 degrees celcius, then over charge. It is possible, but at that point, it is possible to combust literally any material at a high enough temperature. For our use, its practically impossible. Even simpliphy has a paper stating that its non-combustible, and they are UL listed. I am trusting government papers and UL listed manufacturers before I trust ruixu shipping label and some random how to article. But anyways, I would LOVE to see a video or picture of a lifepo4 on fire. I know that the electrolyte does not create oxygen like other chemistries, and this is another reason why the temperature increase does not occur (as in graphs above). But I would love to be proven wrong here. Battle born ceo actually talked about this in a interview.

Also, case in point of lifepo4 safety is parallel cells being directly connected without fusing in packs. Commercial or in the diy powerwall community. My friend does this and has them fail all the time because he uses unmatched cells, and never has a fire or combustion of any form ever occur.

 

[offgriddle]

We all have a bit of PTLD, (Post Traumatic Lithium Disorder), resulting from earlier Lithium based battery technology at times overheating and combusting. Under the right, (wrong), circumstances gasoline and natural gas based technologies can also explode. I'm not saying throw caution to the wind regarding battery technology, in fact, I'm still grappling with my own PTLD as I try to figure out how to build a non flammable insulated box for my lifepo's, even though I have heard that lifepo design has eliminated combustibility! I will probably end up doing something totally unnecessary involving cinder blocks! I have more reading to do on the subject before making my final decision regarding constructing an insulated battery box. And how about battery box airtightness, is an airtight box okay to house lifepo's?