GordonTurner wrote:1. They make these chemical "glove warmers", I think they're reuseable (?), put a pocket on the front of the battery compartment, slip an activated glove warmer in there before you start preflight, remove it when you're ready for start, and (hopefully) voila.
2. Install a very small electric warmer (there must be something out there), and perhaps a second small battery (EFIS backup?) to warm up the starting battery before start.
Some additional complication, but you get the significant weight savings even so.
Per the info below, maybe these batteries don't need to be warmed up if it is at least 32 deg F?. If they do, I'd think it would take a while to do the job, since the heat has to get through the plastic case and warm up a chunk of stuff inside. A warm air heater used to get the engine and everything else under the cowl warmed up over a period of hours before flight might be more effective than a shorter-term application of heat.
From the Ballistic Performance website
http://www.ballisticparts.com/products/batteries/16cell.php:
Operating Environment: -18°C (0°F) to 60°C (140°F)
And here's what their Q&A says about cold weather ops. Its worded in a confusing fashion, but I think they are saying these batteries work well in the cold:
Q: If I use my powersports vehicle in cold weather which battery should I use?
If you regularly operate your powersports vehicle in weather below 32 degrees Fahrenheit (0°C) then we recommend you use the next size battery up from what is recommended in the application chart. All batteries start to lose performance below 32°F (0°C), and LiFePO4 batteries tend to fall off more dramatically. When the temperature of the EVO2 goes below 32°F (0°C) internal resistance starts to build in the battery and the amount of available amperage goes down as well. This should lower the Cold Cranking Amps, correct?
A: No. LiFePO4 batteries have the ability to build their own internal heat energy when a draw is put on the battery. This means that although if may be 0°F (-18°C) outside, the battery has the ability to raise its internal temperature to 58°F (14°C) in seconds with a 100amp draw. As the temperature rises inside the battery, internal resistance lowers and the battery performs just like it does when it is 60°F (15°C) outside. This means that the amount of available amperage does not change based on temperature. Check out our video of Cold Starting Characteristics of LiFePO4 Batteries.
If you operate your vehicle in temps lower than 32deg;F (0deg;C) we do not recommend our batteries. You would best served with a traditional deep cycle lead-acid battery.
That "internal heating" characteristic is something that sounds, well, umm, "very good to be true".
Posted: Thu Dec 06, 2012 1:42 pm