Battery compartment heater???

**creativepart** · 11-14-2022, 01:42 PM

I came across this... home sidewalk heater mats company for snow melting. They run on 110v and they come in a zillion sizes.

It kind of looks like that could be used in a Lithium battery compartment to keep everything above freezing. They aren't too expensive - a small one is under $100. They are water proof and weather proof.

Quote:

How hot does the mat get?
The Mats will maintain an average temperature of 40 degrees above the ambient temperature. If the ambient temperature is 0º Fahrenheit, the Mat temperature will be approximately 40º Fahrenheit.

What do you folks think? A small 20" by 30" mat would be enough to cover my batteries.

You can even get a remote on/off key fob to turn the power on and off though that does cost a bit extra.

https://heattrak.com/

Ontario Don · 11-14-2022, 02:23 PM

I think you are on to something. Why not?

I've had great success keeping my Battle Borns warm using a therapeutic heating pad, so something that is designed out of the gate for an outdoor environment sounds like a winner.

I insulated my battery box, and have the two batteries sitting on the 12 x 24" pad. The trick is to get the heat on well in advance of sub-zero temps, as the batteries have quite a mass to bring up to temperature using the gentle heat that comes from a pad. Experiments I did showed it took about eight hours to get a 10 C rise from 0 C, as measured on the battery post that Victron use for their temp measurement.

Depending on how much current your pad pulls, you might be able to use it practically while dry camping as well. My pad pulls about 5 amps DC via the inverter, so very usable for a night of winter dry camping.

Let us know how you make out with this mod! Great idea.

Cheers,

Ray,IN · 11-16-2022, 06:09 PM

Since heat rises, covering your batteries might not work out well. Ontario Don did it right. I think I would opt for self-heating Lithium batteries though.

**creativepart** · 11-16-2022, 06:45 PM

My Batteries have low temp cut off in their BMS. So, I'm not too worried about it. My batteries have been below freezing twice already and all was fine. But I thought maybe these might be a nice help in the occasional freezes we see in our travels.

bostonmary · 11-20-2022, 06:05 AM

There is a plug you can buy that will turn on at 37degrees or so. It is like the timers that plug in and has a plug for heater, heat tape etc .
RV stores sell them. Very reliable. Several available on Amazon, not the one I had.

Lv2Roam2 · 11-20-2022, 06:47 AM

When I researched lithium batteries a few years ago aquarium tank heater pads were often suggested as an alternative - could be worth doing some quality / price comparisons. I think some lithium brands now come with built-in heaters. Otherwise - I've always enjoyed the dialogue here and on IRV2 to help develop alternatives to consider and test - sure expands my knowledge about all this RV stuff!

Jakm · 11-20-2022, 07:44 PM

Quote:

Originally Posted by bostonmary

There is a plug you can buy that will turn on at 37degrees or so. It is like the timers that plug in and has a plug for heater, heat tape etc .
RV stores sell them. Very reliable. Several available on Amazon, not the one I had.

Just to add another factor to your equation that would work with your mat idea. My coach is winterized and parked in the back yard. I use one of these temperature controller outlets in the winter months here with an oil filled radiator type heater plugged in on medium setting(900w). Nights here can get down into the 20’s and days in the 50’s. I have the controller set to 40 degrees on/45 degrees off. It eliminates the wide night/day temperature swing to help control humidity. Have a wireless thermometer with the sending unit in the coach and the monitor in the house to keep an eye on temperature.

https://www.amazon.com/KETOTEK-Therm...15&sr=8-3&th=1

Ray,IN · 11-20-2022, 09:20 PM

Quote:

Originally Posted by bostonmary

There is a plug you can buy that will turn on at 37degrees or so. It is like the timers that plug in and has a plug for heater, heat tape etc .
RV stores sell them. Very reliable. Several available on Amazon, not the one I had.

Thermo-cube is the name. Under $10 on Amazon.

tim myers · 11-22-2022, 12:59 PM

I have also thought about heating pads for under my batteries if and when I do convert to LiFePo4, but will only do so if said batteries have the low temp cutoff. If the heat isn't doing the job, I want them to prevent charging. This is especially important in my case as the batteries will be exposed to the weather in the existing battery trays.

Ontario Don · 11-22-2022, 02:16 PM

Right - I agree that a built in battery management system is an important requirement when considering purchasing these expensive LiFePO4 batteries. For those that have one in their battery, the concern about cold weather charging and damage to the battery is gone. The heating pad addition really becomes an operational convenience - it sure is nice to know that you are going to be able to charge the batteries in the morning after a night of cold temperature dry camping, or if on shore power, it is great to have normal electrical operations 24 / 7.

I think if the LiFePO4 batteries with a built in heater had been around when we bought our lithium batteries, we likely would have gone that route. If dry camping, and we need the battery heat, we need the inverter on to power our 120V heat pad. I have not seen the numbers, but I'm guessing that a BMS controlling the 12V battery heat directly, as needed, would be more efficient than running a 120V heat pad full time via an inverter. Simple sounds good.

(Having a battery heat system that is warrantied to protect the battery is also good for piece of mind...)

Cheers,