[RE-wrenches] Gen preheat in cold climates

[drake.chamberlin at redwoodalliance.org]

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.

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?

Thanks,

Drake


> Hi Gary,
>
> We have implemented a preheat strategy that has really worked well at a
> site using dual sunny islands.  They have a load shed function built in
> with the control relays.  We are using that function to add the block
> heater load.  When a generator start is likely (~50% SOC) it triggers a
> relay that energized the block heater.  The generator start is then
> programmed at a lower SOC (~30% SOC).  It takes some guesswork to know how
> many watt hours its going to take to get the block heated up, but we
> conservatively chose and have fiddled with it.  I imagine this can be done
> with either the Radian or the XW, and you could trigger with voltage
> instead of SOC, but SOC is a superior way to do it.
>
> Another way is to use a propane block heater.  This will work well, but
> they use quite a bit of propane, and are very expensive (~$1500).
>
> Good luck
>
> On Thu, Apr 2, 2015 at 8:47 PM, Gary Higbee <gary at windstreamsolar.com>
> wrote:
>
>> Wrenches,
>>
>> I'm curious what strategies you use to preheat a propane gen in cold
>> climates. This is a large off-grid design in a sub-zero winter climate
>> and
>> ideal would be to turn on a block heater an hour or two in advance, then
>> run the gen cycle. We plan to use either a Schneider XW or Outback
>> Radian
>> configuration (still very interested in which you'd use and why). We
>> could
>> set up a logic/relay system to first send the gen request to the heater
>> for
>> a while and then turn off and initiate a gen cycle but that would
>> eliminate
>> the ability for autostart on short notice. I've read of heat lamps on a
>> thermostat, just wondering if you have seen other solutions.
>>
>> Thanks!
>>
>> Gary
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>
> --
>
>
>
> Mac Lewis
>
> *"Yo solo sé que no sé nada." -Sócrates*
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