LifePo4 Charge Performance

OOPs! Just read that Relion uses the charger to heat up the battery and:

"With the low-temperature RELiON RB100-LT 100Ah battery, it takes about an hour to warm from -20°C to +5°C before charging begins"

(5C is that 41F)
------------

EDIT--reading that BB has been called out by some for that 25F charging since you can't really charge LFPs below freezing except at very, very low current.

Issue is the slow ion movement in cold temps where hitting them with normal current will damage the battery (plating for one thing)

Comments on the lack of data showing proper current limit vs temperature so you know how much is ok at below normal range--ie below 5C. (Trillium guide is unusual for that it seems)

--------------

Battle Born says their BMS will not allow any charging below 25F compared with Relion's -4F.

I can't find BB charging specs except the 0.5C recommended. I wonder what their reduced amps threshold temp is below 37F, if any.

They mention the industry standard:
IEC 62133 certification mandates that charging has been certified between 37F and 113F (3C
and 45C).

BFL13 wrote:
Relion lets you recharge at lower temperatures below freezing, and doesn't start requiring reduced amps until below freezing.

https://ceb8596f236225acd007-8e95328c173a04ed694af83ee4e24c15.ssl.cf5.rackcdn.com/docs/product/RELiON_Charging_Instructions_090220.pdf

kinda matches the specs for the cells I posted eh.. I think the reason there is so much confusion around is people who build batteries and put the warenty on them realize that that cold charging area is a fine line and has the most capability to dammage a battery. they set the internal BMS charge cutoff at 0 and say they cant be charged under 0 degrees. and realy in our aplication this is what they should be doing. if you build your own I would recomend the same settings. unless there is areason you want to buy a constant voltage adjustable current power supply and sit there and babysit your charging.

but also remember people confuse this with ambiant tempature which it is not. it is the tempature of the battery cells themselves. so yes if the trailer has been shut down for a while and sitting outside they will proabably be the same. but discharging or charging in its self warms batteries so you can discharge for a little bit of you need to warm them slightly, but that may not be practicle. but if you build it in an interior space your golden, and this is possible as they are smaller and lighter than traditional batteries.

Steve

EDIT--Relion uses the charger to heat up the battery before charging begins:

"With the low-temperature RELiON RB100-LT 100Ah battery, it takes about an hour to warm from -20°C to +5°C before charging begins"
( 5C is about 41F)
Relion lets you recharge at lower temperatures below freezing, and doesn't start requiring reduced amps until below freezing.

https://ceb8596f236225acd007-8e95328c173a04ed694af83ee4e24c15.ssl.cf5.rackcdn.com/docs/product/RELiON_Charging_Instructions_090220.pdf

Upon context re-read (then edit):

“If you can't restore the AH needed because of low amp charging restrictions, you can't go. So it would be nice to know that for sure. Trilliums say up front they would not be suitable for that job.”

Well, I can’t comment on trillium brand’s outlier specs - but I’m quite happy to save that one for those wise gurus over at Trojan Inc...

I do feel however that ‘context matters’ and for the most part your criticism here (the ghost from X-mas past - lol) has been addressed (per topic re-read), at least to the larger majority of prospective LFP users (e.g. those more moderate climate folks with an occasional excursion into below freezing temps)...

But where one’s concern does in fact manifest (as with an extended period in below freezing climate), those seeking the advantages of LiFePo4 might simply do as I’ve done and find a workaround (say, heating pad, or interior batt placement-repurposed batt box) or, simply choose the SiO2 option. Either way, I kinda see SiO2’s as a technology that’s been ‘primarily’ adopted for below freezing weather conditions (though performance overlap exist - thus, this thread’s committed SiO2 acolytes), though I recount this at the risk of having further nuanced this topic which has already been aired, tortured (insatiably so.......) and then recycled for yet another round of talking points....MO

3 tons

Lots is known about what batteries work best below freezing, but IMO not enough is known about LFPs for camping when it is between freezing and 41F, which it mostly is around here when camping up-Island December-March.

If you can't restore the AH needed because of low amp charging restrictions, you can't go. So it would be nice to know that for sure. Trilliums say up front they would not be suitable for that job.

We know it can be done with FLA, AGM, and SiO2. No skin off my nose, since I don't have LFP, but if I did or was thinking about getting LFP, I would be all over tech support for the brand I was looking at.

Over to those with brands other than Trojan to try to get a straight answer from their tech supports and report back to the Forum. :)

Hi 3tons,

Well said!

As a champion of SiO2, I see NOTHING wrong with LiFePo4, except the elephant in the room (for me) of cold weather.

There is also the discharge rate--but any self respecting boondocker is going to have 200 to 400 amp-hours, so that is doesn't existent as a problem, except in the tiniest of Rv's where only one battery might fit. In that singular case, SiO2 would win on discharge rate. The rest of the time, it is a non issue.

I'd still love to have 1000 amp-hour 2 volt cells in series, but that will have to happen in another life time.

Though not necessarily of the OP’s original “LFP Charging Performance” question, much of this thread has been devoted to pontifications about the perceived benefits of one battery technology over another (SiO2 vs LFP), merits which have been mostly centered around a limited criteria of an unheated battery box (or with no heated battery blanket) while in below freezing weather...

In the context of what (from my view...) is ‘mostly’ this one specific constraint, I believe SiO2 is a overwhelming alternative (AFAIK) to nearly all other battery types...

However, in the interest of objectivity (and to a less extreme weather criteria audience), I’ve also listed (on pg 8 of this thread) my own admittedly subjective opinion (due to geo-region) regarding my consideration of SiO2 batteries (Note that I have a heated interior battery compartment).

A conscious effort seems to have been made here (including my own real world experience) to provide some clarity regarding LFP’s, so it would seem that most of the aspects of LiFePo4 types (whether attributes or disadvantages, whether actual or even perceived...) have mostly been discussed. Consensus is not always possible, but at this lengthy juncture, hopefully a cogent case has now been made for either battery type....

3 tons

“ Beware of your solar amps, might have to switch off solar.”

True enough (i.e. unheated batt compartment), but bear in mind a ‘sweet spot’...

Let’s assume a real-world correlation regarding inclement weather and reduced harvest amps - for the broader audience, lets say somewhere within the vicinity of the 40th’ish parallel...

My sweet spot experience having 200a/hrs of LFP and 440w (Max rated) of solar, I’ve yet to see a single episode when solar amperage neared an unacceptable level - often where even a much reduced harvest-charge rate might be acceptable (or easy to manage) to as low as even 25f.

With appropriate component sizing (batts, and solar) this consideration can often be a relatively self-tending matter, or at least relatively easy to manage... Having a parallel solar set-up (panel count roughly divided between two separate switchable controllers), can also help.

3 tons

BFL13 wrote:
Looks like LFP owners should have a 10 amp ordinary car battery charger along as part of their kits. Often recommended anyway in case of converter failure so you can keep on camping.

Procedure for recharging LFPs that are below freezing:
1. heat them up to above freezing
2. charge at 10 amps till they are above 41F (charging will continue to heat them up) Leave heater on if gen can do both.
3. swap over to your high amp charger once they are above 41F

Beware of your solar amps, might have to switch off solar.

If the LFPs are outside on the tongue and never get above 41F, get more gas for your generator to keep charging at 10 amps for the month of Sundays that will take.

Have a way to measure your LFP battery cell temperature (as mentioned by itinerant1)

no need for that, we use them at work on the big trucks, they take full charge at 0 and they arn't replaced any more than any other battery just get a proper Li compatable charger and go camping. bettery yet get a tempature compensated Li charger that throws a temp sensor on the battery pack. I dont know why your hell bent on trying to say you have to go lower current till 41F as no cell speck I have looked up has sed that, but if you go LiFePo4 and want to carry another charge then by all means.

but lets just check this out, here is the specs for some higher quality 271ah cells

Model RJ-LFP71173200-271
Casing material for single cell Aluminum shell
Nominal Voltage 3.2V
Capacity 271Ah
Core size D71*W173*H200MM
Cell Weight 5.4KG
Charging Current Standard Charging:0.2C
Max Charging:1C

Max Discharging Rate Continuous Discharging:2C
Cut-off Voltage Charging:3.65V
Discharging:2.5V
Internal Resistance 0.5m? (At 0.2C rate, 2.0V cut-off)
Working Temperature Charging: -10°C~55°C
Discharging: -20°C~70°C
Storage Temperature 1month: -10–45°C
3month: 0–30°C
6month: 20±5°C
Life Cycle >6000 times (100% DOD)

so if I build a two battery set up for the rv then I would have 542AH @ 12V so yes you can charge them at 1C wich would be a 542A charger, but lets not kid anyone who is going to do that? if you read the specs they recomend a 0.2C charge wich would be 108A , really who is going to do that even. so lets say that we use a 75 amp charger (one of the bigger rv setups. I have seen 90amp converters but not very often) thats a 0.14C charge rate which would mean your always charging a lower rate anyways so even if one banufacturer says to charge slower in that first 5 degrees , you always are.

if you also look at the specks it has charging from -10C - 55C

so alot of these "other requirments" may deal with different types of battery housing formats, or maybe they are just battery companys ways to increase the life so they wont have to replace stuff under warenty if some one uses it outside of there secs or maybe there just using lower quality cells.

Steve

Looks like LFP owners should have a 10 amp ordinary car battery charger along as part of their kits. Often recommended anyway in case of converter failure so you can keep on camping.

Procedure for recharging LFPs that are below freezing:
1. heat them up to above freezing
2. charge at 10 amps till they are above 41F (charging will continue to heat them up) Leave heater on if gen can do both.
3. swap over to your high amp charger once they are above 41F

Beware of your solar amps, might have to switch off solar.

If the LFPs are outside on the tongue and never get above 41F, get more gas for your generator to keep charging at 10 amps for the month of Sundays that will take.

Have a way to measure your LFP battery cell temperature (as mentioned by itinerant1)