Your battery holds how many amp hours? 60? 70? 80? A Blazer probably has a
fairly large one. So how long is the trip, timewise? Can you estimate or
measure how much the ignition, computer, fuel pump, etc draw? Yeah, the
starter will take a chunk of charge out ot it, but probably not too much. For
example, if you are drawing 30 amps, in theory you have about 2 hours worth of
charge in a perfect 60 amp hour battery. Reality is probably somewhat less,
but probably not half. Stay out of traffic jams so your electric fan doesn't
come on, as those can draw a bunch of amps.
My guess is that you should make it easy.
I had to do this same calculation in my head on the entrance ramp to I-95 in
Portland Maine, as my Tiger's generator died, when heading home to Wrentham,
MA, right on the RI border. A 3 hour drive, all interstates.. I could see on
my ammeter that I was only drawing a couple amps with everything off, so I
pressed on and made it with no problems.
Stu
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