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?

[SFVdave]

Well, I called BB Batteries and they said not to worry as their batteries come with the BMS that will only let the batteries charge within the proper temperature range... Their batteries will not accept a charge below 25 degrees F and will not discharge below -5 degrees F. Also, their batteries will not over charge. That was per BB Batteries tech. So no need for me to be concerned in Yosemite, I just need to try and get the batteries back up in to charging temperature range should the temperature drop below 25 degrees F.

[noteven]

Hurricaner wrote:
I believe all lithium batteries designed for rv use have low temp charging protection built in to the BMS. This is from the battle born manual.
High temperature: > 135F
The BMS will not allow a charging or discharging current.
Low temperature: < 25F
The BMS will not allow a charging current

Sam

Built in controls! Who knew?

Thanks Sam

[Hurricaner]

I believe all lithium batteries designed for rv use have low temp charging protection built in to the BMS. This is from the battle born manual.
High temperature: > 135F
The BMS will not allow a charging or discharging current.
Low temperature: < 25F
The BMS will not allow a charging current

Sam

[noteven]

GordonThree wrote:

noteven wrote:
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.

I don't understand this complaint? What does 4 seasons have to do with the battery temperature? I use my RV 4 seasons, and keep my AGM batteries inside the heated (and cooled) living space. Is this not possible with lithium batteries?

I am not “complaining”. I like lithium tech except for warnings about charging below 0C. I was visiting away from my trailer for a few days so it was parked and winterized. Today it was -16C inside and out when I started the furnace and generator. A guy could configure heat to lithium batteries and leave them disconnected from charging until they warm up when you wake up a cold rv I guess.

[LittleBill]

GordonThree wrote:

MEXICOWANDERER wrote:
Hoe much HEAT does max charge rate develop in a lithium battery? I'm thinking a dedicated line from the hot water heater, volume throttled by a return line orifice might be better than nothing. Means foam covering the lines and a teensy pump.

Nissan does this, and maybe Tesla. Water cooled batteries. I think they use electric heating pads for cold weather. Haven't seen any aftermarket "drop in" types setup for water heating or cooling.

Really surprised at the prices that are charged for these batteries that heating pads aren't included along with a BMS that knows how to use them.

they don't use heating pads in Tesla, the entire thing is built into a 2 part pump system built primarily out of the coolant tank. which uses a heat ex changer.

to generate heat, the drive motors are intentionally stalled, to generate the heat needed to heat the battery packs. i don't remember how the cooling is done, prolly just fires the air conditioning up and reroutes it to the heat ex changer again.

[2oldman]

MEXICOWANDERER wrote:
Hoe much HEAT does max charge rate develop in a lithium battery?

Perhaps there is some, but nothing noticeable.

[GordonThree]

MEXICOWANDERER wrote:
Hoe much HEAT does max charge rate develop in a lithium battery? I'm thinking a dedicated line from the hot water heater, volume throttled by a return line orifice might be better than nothing. Means foam covering the lines and a teensy pump.

Nissan does this, and maybe Tesla. Water cooled batteries. I think they use electric heating pads for cold weather. Haven't seen any aftermarket "drop in" types setup for water heating or cooling.

Really surprised at the prices that are charged for these batteries that heating pads aren't included along with a BMS that knows how to use them.

[MEXICOWANDERER]

Hoe much HEAT does max charge rate develop in a lithium battery? I'm thinking a dedicated line from the hot water heater, volume throttled by a return line orifice might be better than nothing. Means foam covering the lines and a teensy pump.

[Itinerant1]

2oldman wrote:

LittleBill wrote:
um not really, once the battery hits a certain voltage, current drops,that last 10% can take quite a while

Not on my Li battery. It goes to full voltage quickly as per spec. Yes, the current drops, but in far less time than an acid tub.

X2 with my lfp also.

Maybe littlebill can tell us about his lfp batteries he's using on his trailer.

[2oldman]

GordonThree wrote:
.. and keep my AGM batteries inside the heated (and cooled) living space. Is this not possible with lithium batteries?

Yes, it's possible.

[2oldman]

LittleBill wrote:
um not really, once the battery hits a certain voltage, current drops,that last 10% can take quite a while

Not on my Li battery. It goes to full voltage quickly as per spec. Yes, the current drops, but in far less time than an acid tub.

[GordonThree]

noteven wrote:
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.

I don't understand this complaint? What does 4 seasons have to do with the battery temperature? I use my RV 4 seasons, and keep my AGM batteries inside the heated (and cooled) living space. Is this not possible with lithium batteries?

[LittleBill]

2oldman wrote:

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

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

um not really, once the battery hits a certain voltage, current drops,

that last 10% can take quite a while

[SFVdave]

I'm going to have to insulate the step well battery compartment for sure.