FYI Cold temps and LiFePO4 batteries in aviation

[Neal]

The temp issue is an issue for sure with LiFePO4. I believe it's why my ETX-900 died at two years. I've had discussions with EarthX in the past about this as from what I learned of LiFePO4's is they cannot be charged below 32F (0C) or Lithium Plating can occur. It's been single digit cold in VA this past month so I know the battery has been cold soaked. While not on a charger, but once when I believe it was warm enough, once you go fly with a cold soaked battery, then what? EarthX or whomever it was recommended running the pitot heat 30 seconds prior to using the starter battery to internally warm it. I think that is a good idea but probably not enough to bring the cells where they need to be, uniformly. The LiFePO4 (Victron) batteries on my RV have a heating pad that is triggered by a thermostat. EarthX must come out with internally heated batteries and it sounds like TCW has done this. I know EarthX has their theories but my theory is if people knew they could not use the battery (charge) below 32F it would kill their business. I know what LiFePO4's need and this has been a big concern of mine. If this happens again, battery failure after two years, I need to rethink my options but probably consider a heating pad solution like my RV has.

I need to put a thermometer in my hangar. I know it's been cold outside but it didn't feel THAT cold in the hangar. But I need numbers.

 

[Cubonaut875]

Interestingly, Tannis make a cabin heater: Avionics/Cabin Heater Archives - Tanis Aircraft Products I have thought about this as even my G5 needs to be rebooted in cold weather,I flip the master on and no G5, I have to hold the button down for 5 seconds and get it to reboot. My lower limit for flying here in Central Illinois is 10F, the hangar will get down sub zero at times. I've often thought about getting a cabin heater, but about the time I get serious, like now, Spring arrives.

 

[Neal]

Interesting idea. As all of my batteries are now LiFePO4 so heating the interior would be an ideal solution. The question is what is a safe way to do that without ending up in the news?

 

[Neal]

I created a new thread to focus on cold temps related to avionics and aircraft batteries

 

[Neal]

I was looking for a heating pad solution to install when I put the new EarthX battery in this week but @Cubonaut875 brings up another idea of warming the cockpit. In my case with all LiFePO4 now it's something to consider.

Safety is an obvious concern, not creating a fire hazard. But would something as simple as this work?

https://www.amazon.com/Amazon-Basics-Portable-Protection-Lightweight/dp/B074MX8VN5/

or

https://www.amazon.com/dp/B0CCTTBLGK

 

[Neal]

Here is the heating pad I found and saved but it would only warm the starter battery.

Amazon.com: JUWEVAZU Silicone Battery Heater Warmer Pad with Thermostat Kit, 8-1/2'' x 7-7/8'' Silicone 120V 60Watts, for Automotive Battery Heating Applications : Automotive

Buy JUWEVAZU Silicone Battery Heater Warmer Pad with Thermostat Kit, 8-1/2'' x 7-7/8'' Silicone 120V 60Watts, for Automotive Battery Heating Applications: Heaters - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

 

[Cubonaut875]

As a clarification, is it important to always keep the LiFePO4 batteries above freezing, or best to preheat them before use?

 

[Neal]

As a clarification, is it important to always keep the LiFePO4 batteries above freezing, or best to preheat them before use?

They can be used (aka discharged) at very cold temps. But to charge them requires that the cells be 32F or higher. This is the big problem with LiFePO4 and I don't trust that my optimate is temperature aware, haven't research that thoroughly. But the problem is you crank, good, and now the alternator is providing charge current to a battery that has all cells at 10F for example. Some will claim the starter battery will internally warm by cranking your engine. I'm sorry but I need to know the temps of the cells like my Victron batteries show me. The BMS needs to actually control this and not allow the charge when the temps are too cold, as my Victron setup does in my RV. I'd offer most BMS's do this but you need to verify for each battery manufacturer and I don't know that I ever got an answer from EarthX about this beyond the cranking generates heat.

 

[Cubonaut875]

I have been using a product, SwitcheOn Home - SwitcheOn to start my engine preheat, it has two outlets and could easily start the Tannis avionics preheat at the same time.

 

[Cubonaut875]

In reviewing the Optimate charger directions, I do recall it saying it does not charge below 32F.

 

[Neal]

I dare say the Tanis solution is a far more expensive version of the $15 Amazon solution. For example:

TAHP3094-500 - Tanis Aircraft Products

Avionics/Cabin Heater (for free standing / occasional use)

www.tanisaircraft.com

vs

https://www.amazon.com/dp/B0CCTSYJM6

I bought the Amazon one. If I use it I'll put it on a metal surface like a cookie sheet.

 

[Cubonaut875]

I like your idea better. The Tannis cost is probably why I just passed it off at the end of every winter.