Lithium battery charging at or near freezing

[SFVdave]

Here's an issue I have come upon, freezing temperatures. I see the Lithium batteries will discharge down to 0 degrees F and shouldn't be charged below freezing 32 degrees F. So how would you handle waking up in the morning in the Sierra's with an outside temperature of 25 degrees F and your Lithium batteries in the cold step well. How would you recharge the batteries, open the step well battery cover and and wait for the batteries to warm? Would turning on the furnace and lights causing a discharge and hope it is enough to warm them up? Perhaps insulating the step well or leaving the step well battery cove up all night?

[noteven]

Minimum battery resting temperature to begin charging lithium of 32F is not workable for me. I want 4 seasons capabilities.

Everything else about lithium is great.

[2oldman]

SFVdave wrote:
Lithium is much faster, like 3 times faster..

And you can to go 100% without any slow absorb time.

[Itinerant1]

Are you changing your charger to a larger one for faster charging to cut generator time to almost nothing?
Using a Magnum 3000w inverter/ charger and a Honda 2000w generator will charger at 100ah and when that's needed 2 hours is all I want to listen to that noise maker for a 200ah power boost equaling a increase of 40% SoC.

[SFVdave]

Checked on the Carbon foam and they are 13 1/2" in length, group 31. 2 would not fit in my step well battery compartment as it takes group 27.. They are 30% faster charging than regular flooded. Lithium is much faster, like 3 times faster. That's the reason I am looking at the Lithium is to cut generator use to almost nothing.

[MrWizard]

yes carbon foam cost more than AGM
but are purported to have performance level closer to Lithium
higher percentage of usable ampHrs for the same rated capacity

I have AGM

[free_radical]

noteven wrote:

MrWizard wrote:
what is the reason to go with Li battery

why not the Firefly carbon foam battery

it has similar cycle life, and no cold weather problems
cost is similar, but there is No 'weight savings'

This battery looks like a viable option for Canuck land.

Carbon foam batt. is quite expensive last time I checked.
Regular AGM does the same job,at bit lower price..
And keeping it charged up it wont ever freeze.

[noteven]

MrWizard wrote:
what is the reason to go with Li battery

why not the Firefly carbon foam battery

it has similar cycle life, and no cold weather problems
cost is similar, but there is No 'weight savings'

This battery looks like a viable option for Canuck land.

[MrWizard]

what is the reason to go with Li battery

why not the Firefly carbon foam battery

it has similar cycle life, and no cold weather problems
cost is similar, but there is No 'weight savings'

[GordonThree]

2oldman wrote:

GordonThree wrote:
Discharging the battery will not heat it up, at least it shouldn't unless you're talking a huge load like a traction motor.

I could heat up a set of acids pretty good by running the air with a 12v inverter.

yea that should do it 🙂

[jharrell]

2oldman wrote:
could heat up a set of acids pretty good by running the air with a 12v inverter.

The most effective way to heat a lithium by discharging would be to run an electric heater in the same space as the batteries. 😉

I believe some lithium packs are being made with integral heaters now that automatically keep them up to a reasonable temp.

[MEXICOWANDERER]

If you have enough BTU in remaining battery capacity to run a thirsty heater then charging is not really needed, eh?

Electric heating is voracious in consuming ampere hours. And one single screwup in calculations and bang your wallet goes dead. HVAC coupled with thermal hysteresis calculations is no place for amateurs. Batteries are not a block of wood, INTERNAL TEMPERATURE must be calculated. If you feel lucky go for it, otherwise use thermal dynamic protocol which is strict adherence to scientific fact. But this is not my money nor my risk...

[Itinerant1]

If your using lfp you won't be using temp off the controller.

[SFVdave]

My thought is to never let them get down to freezing and place the space heater down in the step we’ll with the generator running and charging at the same time bringing them back to room temperature. My solar controller has a battery temperature probe so I can tell how cold the compartment is.

[ItsyRV]

First, is the battery box exterior only or exterior/interior? If a dual box, they can be easily converted to an interior box and insulated against outside temperatures. This means you only need to maintain a minor heat source to keep the temperature properly regulated. So start with the actual box as that dictates what needs to be done.

[2oldman]

GordonThree wrote:
Discharging the battery will not heat it up, at least it shouldn't unless you're talking a huge load like a traction motor.

I could heat up a set of acids pretty good by running the air with a 12v inverter.