Lithium battery warming idea

[booster]

Originally Posted by Van_Dreams

You can’t charge them at 0 C or colder. Starting at -4 C, the cold may start to damage their chemistry permanently.

I think most of the specs, although some vary, will show no charging below 32*F/0*C and no storage under -4*F/-20*C.

[markopolo]

No charging at 32F or lower is often cited. It's stated on many LFP battery spec sheets.

From all the stuff I've read so far, I think that it's a combination of charge rate and temperature that we need to be concerned about starting at around 40F.

For Trojan Trillium batteries (5000 cycle rating): (rates approximated for this post)
>73F 1C charge rate permitted
41° to 73°F (5° to 23°C) 0.5C charge rate permitted
32° to 41°F (0° to 5°C) 0.13C charge rate permitted
14° to 32°F (-10° to 0°C) 0.05C charge rate permitted

Relion also states to limit the charge rate if the batteries are cold. It's very similar to what Trojan recommends. From Relion:

When charging lithium iron phosphate batteries below 0°C (32°F), the charge current must be reduced to 0.1C and below -10°C (14°F) it must be reduced to 0.05C. Failure to reduce the current below freezing temperatures can cause irreversible damage to your battery.

In their low temperature battery, it looks like the heating element comes on at 41F. No coincidence there I bet.

Battle Born's BMS prevents charging when the temperature drops to 24F. I doubt that charging at a 1C rate at 25F is a good idea though! They suggest to "keep the temperature up" but don't seem to provide specifics.

We do suggest insulated battery boxes, or heating blankets to help keep the temperature up on the batteries.

You could keep it simple:
Keep the batteries at 40F or higher & limit the charge rate to 0.5C. An additional benefit is that the discharge performance will also be better with the battery above 40F.

[Davydd]

I've had lithium-ion batteries for 5 years and knew you should not (could not?) charge below freezing. If manufacturers said otherwise take it with a grain of salt. It doesn't permanently damage the batteries but does deteriorate them. Drop-in manufacturers probably got into it with some amount of ignorance, assumed in most B's the batteries would be stored in a conditioned space underway, didn't think many people traveled and camped in cold weather, or maybe wanted to present their batteries in a favorable way compared to AGMs. Think about the ignorant or assuming situation, we all carry around our lithium-ion powered cell phones in cold weather.

in my van, the inverter does not have to be turned on when charging batteries or for operating 12V resistant electric heating pads which consume power off the batteries but don't consume anywhere near what the batteries are being charged. 10 watts total keeps an 800ah battery bank above 41F if ambient temperature gets down to -20F. That is the most efficient way other than storing the whole van in a conditioned space (heated garage). Then if you choose you could just totally disconnect the batteries which store longer than AGMs. Drop in batteries maybe could be taken out of the van and stored inside a house. Good luck with high capacity battery bank of 16 block cells strapped and wired together like mine. it would be impossible unless you had a vehicle lift and then a hydraulic jack and a few friends to drop down about a 400 lb. total assembly cage. The Volta 48v systems are probably going to be stored in place in the B though I don't know much detail about them other than seeing them in place. The way ARV straps together and wires drop-in lithium-ion Valence batteries in group 27 profiles in an 800ah battery bank inside the B, I doubt anyone would remove and store inside.

[avanti]

I have a question:
Do lithium batteries keep themselves warm via self-heating while in use, assuming a decent load? If so, that removes one worry from the equation.

IMO, frigid-temperature storage is a big deal. Below-freezing charging is not. If I have power to charge, I have power to heat. If I am driving off on a cold morning, I can wait the half-hour or so it might take for engine-power and/or coach heat to bring the house batteries up to charging temperature.

[markopolo]

Discharging will cause a temperature increase. That would lessen heater on time.

[markopolo]

Originally Posted by avanti

......... If I have power to charge, I have power to heat. If I am driving off on a cold morning, I can wait the half-hour or so it might take for engine-power and/or coach heat to bring the house batteries up to charging temperature.

That's a good example of why a charge prevention solution is needed. In your example you'd likely want to prevent charging from the alternator.

A manually operated solution would work but automated like this - https://www.victronenergy.com/blog/2...ithium-update/ - would be better

[Davydd]

Originally Posted by avanti

I have a question:
Do lithium batteries keep themselves warm via self-heating while in use, assuming a decent load? If so, that removes one worry from the equation.

IMO, frigid-temperature storage is a big deal. Below-freezing charging is not. If I have power to charge, I have power to heat. If I am driving off on a cold morning, I can wait the half-hour or so it might take for engine-power and/or coach heat to bring the house batteries up to charging temperature.

In the other thread I gave the status of my batteries in storage while plugged into shore power. When they received no charging and when the draw off the batteries were about 4 amps, the batteries cells were about the same as the ambient temperature and the hottest was 3 deg. F. hotter. When underway and charging with the second alternator, a good rule of thumb is about 10F hotter in most of my observations. It varies.

The whole idea is to never let your batteries to get below freezing. If so, then you have to have a BMS that doesn't let you charge. Then you can drive off immediately and when your coach and batteries gets up to temperature they will resume charging.

I'll say it simply. Don't buy lithium-ion batteries if you are in a cold weather storage situation without at least a 15a 120VAC source with a battery warming device or heated storage space.

[Cokkie]

So 32 degrees f. My manual say -20c. Do you have any links ? I had it for 2 years and skied with it a lot very cold. It’s a road trek so they are useless right now.

[markopolo]

Originally Posted by Cokkie

So 32 degrees f. My manual say -20c. Do you have any links ? I had it for 2 years and skied with it a lot very cold. It’s a road trek so they are useless right now.

Ecotrek modules had heaters.

[Van_Dreams]

Davydd — Which 12v warming blanket do you use? How do You have it positioned (under the cells, above, how does it contact the cells, etc)?

[Davydd]

Originally Posted by Van_Dreams

Davydd — Which 12v warming blanket do you use? How do You have it positioned (under the cells, above, how does it contact the cells, etc)?

This is not my battery bank but one under assembly at ARV with the same Elite Power Solutions batteries. ARV installs the heating pads between two batteries like this. There are four battery assemblies with four 3.4v 200ah blocks in series to make up an 800ah block, so two 5 watt pads total. It is not evenly covering the batteries as you see but the temperature range is only about 3-4 degrees and the thermostatic pads are powered on until the last battery maintains 41F. My observation is the heating pads are off more or less than on until the ambient temperature gets down around 20F. There is not a lot of energy draw on the road and it would be an absolute maximum of 240ah in a day and driving can recharge that in about 45 minutes. You would have to be a very hardy winter camper to endure that scenario. Last winter it took us two nights of boondocking after leaving Minnesota to get to above freezing temperatures in Texas and the first night it got down to -15F but we could endure.



What kind? I don't know, but I think thermostatically controlled 12v electric resistant heating pads sold to stick to RV Fresh, grey and black tanks could do it for a DIY effort.

[eric1514]

Originally Posted by markopolo

That's a good example of why a charge prevention solution is needed. In your example you'd likely want to prevent charging from the alternator.

A manually operated solution would work but automated like this - https://www.victronenergy.com/blog/2...ithium-update/ - would be better

Why wouldn't that protection be part of the BMS? Seems it would be fairly simple to do.

[booster]

Originally Posted by eric1514

Why wouldn't that protection be part of the BMS? Seems it would be fairly simple to do.

I think the integrated systems like Volta would have full alternator control via the BMS, but most just battery systems don't really control much of anything, just protect themselves.



You can't just shut off accepting power from an alternator or solar because they can throw a bike voltage spike if you do and have no other battery in the system. You need to control the turn on for alternator and switch the solar panels off first for the solar (reverse going back on) for instance. Shore chargers may or may not have similar issues. Many of the various systems also need/require to have a battery in the system to restart the charging, so any cutoff charging, cold or hot shutdown, or other shutoff needs a way to recover.

[@Michael]

Originally Posted by Davydd

What kind? I don't know, but I think thermostatically controlled 12v electric resistant heating pads sold to stick to RV Fresh, grey and black tanks could do it for a DIY effort.

FWIW Battleborn warns against using any heater other than their own (expensive) heater, claiming that others may warp the case. From what I see it's made by the same company that makes tank heaters, but it's lower wattage and more more surface area. I just ordered one, so I'll know more in a few days.

Many pad type heaters have high wattage, high temp thermostats, and or small surface areas. Those seem unsuitable for this purpose.

[booster]

Originally Posted by @Michael

FWIW Battleborn warns against using any heater other than their own (expensive) heater, claiming that others may warp the case. From what I see it's made by the same company that makes tank heaters, but it's lower wattage and more more surface area. I just ordered one, so I'll know more in a few days.

Many pad type heaters have high wattage, high temp thermostats, and or small surface areas. Those seem unsuitable for this purpose.

That is a good point, for sure. If you can get the detailed specs on this type of heater, you usually should get a watts/sq inch or similar callout, which should be in the heated area only. Overall watts, and size, can be deceptive sometimes as they might have a large unheated area around the perimeter compared to others.

[Davydd]

Originally Posted by @Michael

FWIW Battleborn warns against using any heater other than their own (expensive) heater, claiming that others may warp the case. From what I see it's made by the same company that makes tank heaters, but it's lower wattage and more more surface area. I just ordered one, so I'll know more in a few days.

Many pad type heaters have high wattage, high temp thermostats, and or small surface areas. Those seem unsuitable for this purpose.

It is obviously a moot point in the batteries like Battleborn that have their own built in heaters. I have an 800ah battery bank with thermostatically controlled electric resistant heating pads as I have previously described in this forum and designed by ARV so I know they can absolutely work.

But yes, a DIYer has to have common sense and design a system that works. I would hope they have enough knowledge before attempting. With the absence of a turnkey solution what would one recommend otherwise for outside storage in a climate that could get down below -4F?

[avanti]

In choosing heating pads, note that they come in two kinds: those with internal thermostatic controls and those without. If you are buying the former, you need to pay attention to the temperature rating. The uncontrolled ones tend to be much less expensive, but you need to be careful with them. They can indeed get too hot if not externally controlled. The other way to use them is to reduce the wattage by wiring them in series. I did this in my 4-season conversion in a few areas where I wanted a bit of extra mild heat for plumbing protection.

[Van_Dreams]

Here are my current plans:

I have two of these on order from amazon:

Namsan Warmer Pet Heating Pads - Dog Safety Indoor Bed Cat Electric Heating Blanket with Free Cover, Red (11.8") https://www.amazon.com/dp/B01JOMIG32..._HMv3DbM4QNERP

This seems suitable because it has thermostatic controls but no timer (most of human oriented electric blankets have timers). I also like the fact that it seems weatherproof etc — anything intended for your pet has got to have some reasonable failsafes, right?

I plan to place a normal blanket with insulation as a first layer on top of my cells. Next I will place the pet warmer. On top of the pet warner, I will place an old well-insulated winter coat to prevent the what I anticipate to be rather modest heat from escaping.

[@Michael]

Originally Posted by Davydd

It is obviously a moot point in the batteries like Battleborn that have their own built in heaters.
[...]
With the absence of a turnkey solution what would one recommend otherwise for outside storage in a climate that could get down below -4F?

Battleborn doesn't have internal heat. It has an external heater that adheres to three sides of each battery available at extra ($220) cost. Expensive, but still cheaper than the competitors 100AH battery with internal heat. It's 30W spread out over three sides of the battery. I think it's made by Ultra-heat. I ordered one & should know more in a week.

As far as DIY heaters, I have bookmarked alternatives such as:

Ultraheat AM0900 Tank heater: size OK, but too high wattage (55 watts). Would need thermostat.

Icstation 12V 7W Flexible Polyimide Heater: would need a thermostat, small size - would need an aluminum heat sink between it and the battery

Facon 3" x 13" Elbow Pipe Heater Pad: Only 7.5W, large enough area that it might work.

Facon 7 1/4"x25" Water Holding Tank Heater: too large, but might be able to wrap around battery.

Kat's 22600 80 Watt 11"x 18" Battery Pad Heater: It's 120V, not 12V. Too high of wattage. No thermostat.

Dorman 628-040 Universal Seat Heater Kit: Apparently in use by some outfitters.

Zerostart 3400039 (Wolverine Model FH-50) Silicone Pad Diesel Fuel Filter Heater: No thermostat, too hot.

After playing with this for quite a while, I decided that rather than chance wrecking a new $1000 battery, I went with the factory heater.