warm battery

[bobnoffs]

yesterday i planned to fly but the battery wasn't up to it.
engine was preheated to 60 deg f but nights have been neg15 f.
my guess is battery was still too cold from night temps, even though it had ''warmed'' to 15 deg f. by 11 am.
what experiences has anyone had with battery heaters? it's the fire aspect that makes me ask.
battery started engine fine last 20 deg day but night temps were much milder.

[John-G]

Bob,

If the battery is in the engine compartment, perhaps a circulating warm air system would get the battery warm enough.

At my home field a gentleman uses one of the older models of the Aerotherm Heater no longer available. The new models are pricey but supposedly better. The heater can hang from the prop and has two hoses which attach to the cowl's ducts ... it recirculates warm air throughout the entire engine compartment. For maximum effect my friend covers the engine compartment with a blanket, blocks cowl openings around where the hoses enter the cowl and turns the unit on the night before a flight ... everything in the engine compartment is warm in the morning.

Admittedly, your temps get much colder where you are, so it may take more time for the heater to do the job. However, I was told the amount of heat generated is controllable and the unit can be left on 24/7 if desired.

Happy flying,

[BillL]

Bob, no experience except softening a battery with a 100 watt drop light. Kat makes a low wattage pad - 60 watts. Plastic does not transfer heat very well so a low density, low wattage is the way to go. I would not leave it on unattended, nor for a long time - maybe an hour at most. Maybe less to test it.

[lr172]

I would also be looking at other causes for loss of cranking capacity. I have the Power Sonic battery that matches the PC680 specs. it is two years old and has 220 flight hours on it. I routinely start my engine in 10-30*F ambient conditions and notice no significant degradation in cranking compared to summer months. My oil gets nice and warm (50*) via the sump heater, but the battery can't be above 30*F during the colder days. I use cowl plugs and a cowl blanket to help get the whole engine area up above ambient, but it never matches the oil temp.

It did crank a bit slower on the 5* days, but not enough to create a problem.

Larry

[N42AH]

When I lived in the hinter lands of northern Quebec many many years ago. Canadian Tire sold battery blankets. It allowed my battery to be warm and toasty even in -40 below and start my car.

Our friends operating in that part of the world can probably shed more light on keeping a battery warm in cold extremes.

[bobnoffs]

thanks for the replys.
i have a couple stick on engine heaters that work great on the engine.yesterday made it to airport 3rd day in a row and got to fly.i have resigned myself to the fact that if it is too cold for the batteries it is colder than i want to go flying and i think this will work!

also, quite a few years ago i had a battery warmer ''wrap'' melt and char itself on my skidsteer. maybe i had it installed incorrectly .