[RE-wrenches] Gen preheat in cold climates

[James Jefferson Jarvis]

On 4/3/2015 9:32 AM, drake.chamberlin at redwoodalliance.org wrote:
> We are dealing with a generator that absolutely won't start when cold, so
> I was considering a block heater. Below 20 deg F it has proven worthless,
> and we can see -20 F on occasion.

I had a generator like that. Below zero it wouldn't start. Replaced it's 
cranking battery with a bigger battery and it starts great. There are 
also super-capacitor based solutions to get better cranking. If you have 
a 24 volt system and your generator is near your battery bank, you may 
even be able to put a 24 volt starter on the generator and start from 
your battery bank.


> My concern is using power from a low battery on a cold cloudy day to heat
> a generator. How long does it take to make a difference? Has this method
> proven 100% reliable?

What type and how big of engine are you talking about? How big is the 
block heater? My limited block heater experience with vehicles, 
tractors, etc is that an hour won't be enough. A couple hours is needed. 
With coolant heaters and fuel injected engines, an hour can actually 
cause problems. A pocket of coolant gets warm and tricks the engine 
management computer into thinking the coolant is warm. Then it tries to 
do a warm start and fails.

Getting a generator that starts reliably is the best solution I see for 
a moderate sized off grid installation. Otherwise you are putting a lot 
of energy into warming up an engine that might not start. And leaving 
you in a worse situation than you started.

-James Jefferson Jarvis
APRS World, LLC
+1-507-454-2727
www.aprsworld.com