LIfepo4 charging in winter.

[donkey07]

HI Lifepo4,
Not sure if this helps but we just installed a BYD Li Ion battery with our Arrays as a stand alone system in an area which reaches up to -9deg c over night. Overall the performance of the battery has been excellent but if the temp drops to far for to long (usually 2 days) causing the core of the battery to become to cold the battery management system limits the inverters keeping the battery to about 55% in order to protect it. We found that if the battery does become limited by the management system simply heating up the area around the battery fixed the issue and ensured the battery charges to properly.

[Raul]

Victron have the new edition (black case) see on they're website, with bms integrated.
Also another alternative to that, is ultra max monolit blocks of 12v also with bms integrated. This is what I chose for my campervan. A 12v 200ah lifepo4.
Another alternative, is winston cells with bms, you can find them in EU for less than 400 quid per kWh.
I have a friend off grid, that charges Nissan Leaf bank kept in a unheated garage with minus 15-20C outside.

[somawheels]

You were mislead. LFP batteries are the safest of the Li family. They are not as safe as lead acid. It seems every month, a new way for Li batteries to fail, appears.

The shortcomings of Lead Acid batteries have been well know for 70+ years. The shortcomings of poor Li installations, improper BMS choice, not matching battery to BMS to charge source to load, just keep multiplying. A well engineered LFP system (not only the battery, but the whole system) is pretty decent but you still have hazards below 40F / 5C and if it does light off, you have some very toxic fumes to worry about.

Reading this has put me off the idea of assembling my own LFP battery. I dont have enough experience with this kind of thing to be confident in doing it properly.

[Mike90250]

Oh dear, thats terrible. Were these lithium systems using Lithium Iron Phosphate batteries? I had read they were relatively safe compared to lead acid.

You were mislead. LFP batteries are the safest of the Li family. They are not as safe as lead acid. It seems every month, a new way for Li batteries to fail, appears.

The shortcomings of Lead Acid batteries have been well know for 70+ years. The shortcomings of poor Li installations, improper BMS choice, not matching battery to BMS to charge source to load, just keep multiplying. A well engineered LFP system (not only the battery, but the whole system) is pretty decent but you still have hazards below 40F / 5C and if it does light off, you have some very toxic fumes to worry about.

[Ampster]

50%?! Surely companies arent charging 50% for simply assembling the battery for you?

Oh no they don't do that. LOL They sell you a nice package with a bow on it. Actually the bow is the guarantee and the software that makes if plug and play. The prices I have seen for those drop batteries is USA$1000 per kWh. You can buy the components for probably $500 per kWh.

[somawheels]

50%?! Surely companies arent charging 50% for simply assembling the battery for you?

[Ampster]

SimpliPHI and Victron batteries do this (Although for Victron, you have to buy the BMS separately).

Then the question is do you want to pay the price for a SimpliPhi or assemble your own to save over 50%.

[somawheels]

I would not be surprised to find out that some of the more expensive drop-in lithium batteries can do that. My BMS has a couple of temp sensors but I have never checked to see if it can control the charge ready signal with a temperature low point. That is probably not a difficult thing to do with a couple of redundant thermostats and some relays on the charge ready control line.

It seems you are correct! SimpliPHI and Victron batteries do this (Although for Victron, you have to buy the BMS separately).

[Ampster]

If only there were lithium batterries that automatically refused to charge at low temperatures. This way there would not be any risk of accidentally ruining the battery.

I would not be surprised to find out that some of the more expensive drop-in lithium batteries can do that. My BMS has a couple of temp sensors but I have never checked to see if it can control the charge ready signal with a temperature low point. That is probably not a difficult thing to do with a couple of redundant thermostats and some relays on the charge ready control line.

[somawheels]

i have cleaned up 2 burned out Li systems and both were replaced with lead acid.. I mean flames and burned sheds, nearly a forest fire.
Li batteries are not something to play with unless you understand all the ways they can fail catastrophically, and take proper steps to avoid that.

Oh dear, thats terrible. Were these lithium systems using Lithium Iron Phosphate batteries? I had read they were relatively safe compared to lead acid.

[Mike90250]

Im not sure what you mean mike.

Have any of you guys had Lithium offgrid systems before? What was your experience with them like?

i have cleaned up 2 burned out Li systems and both were replaced with lead acid.. I mean flames and burned sheds, nearly a forest fire.
Li batteries are not something to play with unless you understand all the ways they can fail catastrophically, and take proper steps to avoid that.


https://batteryuniversity.com/learn/article/safety_concerns_with_li_ion

https://batteryuniversity.com/learn/article/safety_concerns_with_li_ion

Incorrect uses of all batteries are excessive vibration, elevated heat and charging Li-ion below freezing. (See BU-410 : Charging at High and Low Temperature.) Li-ion and lead acid batteries cannot be fully discharged and must be stored with a remaining charge.

https://batteryuniversity.com/index....w_temperatures

[FONT=Arial]Li ion can be fast charged from 5C to 45C (41 to 113F). Below 5C, the charge current should be reduced, and no charging is permitted at freezing temperatures because of the reduced diffusion rates on the anode .

[somawheels]

Relion has a "Low Temperature" LiFePO4 battery that works down to -20C and -2F.
It has an internal heater.
Add 6" ( 3 x 2" layers ) of solid foam and you will have no problem keeping the battery warm enough to recharge.
Charging warms the battery.

Relion batterries are nice, but unfortunately, are way far more expensive than other LiFePO4 batterries.
If only there were lithium batterries that automatically refused to charge at low temperatures. This way there would not be any risk of accidentally ruining the battery.

[Ampster]

.....

Have any of you guys had Lithium offgrid systems before? What was your experience with them like?

I have had some Lithium experience with a EV conversion I did 7 years ago and owned or leased 5 different production EVs in the past 7 years. I don't have any offgrid experience but have also had good luck with two hybrid grid tie systems using Lithium batteries. I agree with your assessment that they last longer if you conservatively charge and discharge them. They also do not need to be fully charged all time like lead acid. Most of the knowledge and experience on this forum is with lead acid. Although I would guess that many have a cell phone and laptop that has worked well for them.
I have not however had any cold weather experience. If you can find a solution to the few times a year your weather is at or below zero Celsius they could be cost effective for you. Everything in life has risks, it is how you manage those risks that matters.

[NEOH]

Im not sure what you mean mike.

Have any of you guys had Lithium offgrid systems before? What was your experience with them like?

Relion has a "Low Temperature" LiFePO4 battery that works down to -20C and -2F.
It has an internal heater.
Add 6" ( 3 x 2" layers ) of solid foam and you will have no problem keeping the battery warm enough to recharge.
Charging warms the battery.

[somawheels]

it's even worse ! Below 40F. ( 4.5C) power output starts to fall off, and you need to be careful recharging. You usually don't get the full package of data sheets till you purchase the battery and start filling out the warranty registration forms.

But foam sheeting and a modest blanket heater should keep them warm enough IF you lay out the heaters well.

Im not sure what you mean mike.

Have any of you guys had Lithium offgrid systems before? What was your experience with them like?