Lifepo4 cold temp cut off 23F or 32F?

[jaycocreek]

Reading on LFP cold cut off I see Expert Power has 23F as there cut off on there batteries and I thought it was 32F?

Expert Power wrote:
Question: Do these have low temperature protection. Will these work for solar power systems?

Answer:Yes, the do have low-temp cut-off (23F for charging / -13F for discharging)

Which is it or?

[jaycocreek]

StirCrazy wrote:
I wonder if he can post a screen shot of all the settings.

I personally enjoy seeing the screen shots of different battery makers and there specs like Trojans new LFP, I had not seen(interesting)..I never thought for a minute it was irritating to some..Lesson learned and duly noted...

Thanks for the heads up

[3_tons]

pianotuna wrote:
3 tons,

You camp at -32? or is that a typo?

Oops, a huge typo, meant 32f!!… I appreciate the correction…

3 tons

[StirCrazy]

time2roll wrote:

StirCrazy wrote:
personaly I think 32 was chosen because of lack of knowledge and a carry over from other Li chemistry.

Two of the largest manufacturers, EVE and CATL, give 0c as the minimum to charge.
Ignore factory specifications at your own risk.

I just went and checked because they were the ones that used to be listed at -5C and there was a big discusion about it on here. seems there page has changed since I ordered my cells. oh well no biggy mine would never be subjected to charging at cold temps anyways but ya it is interesting for the OP now. I wonder if he can post a screen shot of all the settings.


Steve

[pianotuna]

.

[3_tons]

For those with space available (per my solution, repurposing batt box for other storage?), mounting LFP’s inside in a under-dinette cabinet space have solve my 32f charging concerns…

3 tons

[BFL13]

Previously, Trillium info was to limit charging amps on a sliding scale from just under freezing to well above freezing, but their data sheet now shows full 110amp charging right from freezing on up, and reduced charging amps below freezing to a lower temp than before.

No idea if anything new with the LFPs that take heat from a charger before allowing charging, but it was 5C/40F before they allowed charging to start.

I kept asking on here about what to charge at between freezing and 5C and how you could throttle the amps of your charger to do that, but got nowhere. Seems Trillium has changed their story lately. if true for all LFPs now, it is moot.

Perhaps there has been more experience /data with LFPs or they have changed the formula a bit for making the cells, not a clue.

Lesson is to keep up with the latest on all this, because what you learned last year might now be wrong. Eg I see Trillium has "retired" the Trillium Owners Guide, but do have the new charging guide in the Data Sheet

[otrfun]

I believe there's general agreement the majority of lifepo4 manufacturers specify >32f as the minimum temperature you can "safely charge" a lifepo4 at it's maximum rated charge current. Safely charge defined as charging that results in no reduction in a lifepo4's long-term performance---the ability to deliver 3000-4000 charge cycles while maintaining at least 80% of the original ah rating of the battery.

As StirCrazy alluded to earlier, if a particular manufacturer specs their lifepo4 as capable of maximum charge current at <32f, my guess, it's just a marketing strategy. Their bean-counters have probably determined any increased costs for warranty claims (to support the lower charge cut-off temp) is more than offset by the increased sales to folks who actually believe they have a better lifepo4. Again, more than likely marketing strategy vs. a battery/cell with any real added capability.

Lastly, some see the lifepo4 32f low-temp charge cut-off as all or nothing in terms of charging--ok to charge at 33f---not ok to charge at 32f. That's not necessarily the case. It is possible to safely charge at <=32f . . . if you're willing/able to reduce the charge current (and have a BMS which permits charging at <=32f). I find it very interesting that Trojan actually specs the maximum allowable charge current for their 110a Trillium lifepo4 down to -4f (-20c).

[jaycocreek]

You would think they would fix there typo..lol

My cheapo 100ah lifepo4 battery is pretty generic temp wise as I assume most of them are...The 23F cutoff just caught my eye...

[Tom_M1]

jaycocreek wrote:

From ExpertPower web site:

Discharge: -4 — 140°F
Charge: 32 — 140°F

https://www.expertpower.us/products/ep12100-100ah

The Amazon listing is a typo.

[S_Davis]

I am heating my two 12v 280ah batteries, will be using a separate small agm charged by the trucks alt. I don’t plan on letting them get below 40 under normal conditions but will probably test after they cold soak once for a idea just Incase.

Twin 280ah LifeP04

[Itinerant1]

Manufacturers seem to have their own recommendations. My GBS cells recommend -20C (-4f) to 65C (149f) for discharging, 0C (32f) to 65C (149f) for charging. Which the BMS protects for these temps.

[time2roll]

StirCrazy wrote:
personaly I think 32 was chosen because of lack of knowledge and a carry over from other Li chemistry.

Two of the largest manufacturers, EVE and CATL, give 0c as the minimum to charge.
Ignore factory specifications at your own risk.

[jaycocreek]

StirCrazy wrote:
23F is -5C, which is the lowest cold weather charging temp listed by the Prismatic cell manufactures, so thats not the brands limit thats the actual cell manufctures limit. most rebranders/assemblers would put that to 32F to give them self a bit more protection from warenty claims.

Steve

That really makes sense to me,kinda like the truck manufacturer axle ratings vs the actual axle manufacturer ratings,both different numbers..

Thanks

[3_tons]

Oops, please disregard…