Battery replacement issue (big one)

External Since: Jan 10, 2004 Posts: 88

Steve writes:

> Joe Pfeiffer wrote:
>
> > remember some unbelievably ignorant questions I asked the first time
> > I did a tuneup on a car with an automatic transmission...)
>
> Hmmmm.... sounds like I may have forgotten a good story... Wink

It started with, "it has to be in Drive when setting the idle speed,
right?" and went downhill rapidly from there.

External Since: Feb 28, 2009 Posts: 3

"Henry Bemis" wrote in message

> Very true. Diodes don't like reversed voltage. A co-worker put the battery
> in backwards on a ThermoKing refrigeration trailer, loaded of
> course......Guess who got to fix his screw up? Yep, me.
>
> That unit never did work right after that, even after replacing nearly
> $1,000 in parts. So, yeah, depending on what you do it to, it can be
> expensive. Sometimes though not always in parts, but the time (also
> expensive) to find what else got fried.
>
>> The actual voltage was applied everywhere, but 12 volts the wrong way
>> isn't going to hurt anything. It's too wimpy.
>
> 12 volts wimpy? Here's an experiment.....lay your sweaty arm across the
> leads of a 12 volt automotive battery. Please report back. When there 700
> amps available at 12 volts, somethings gonna give.
>
>> You could take a postive ground vehicle and convert it over to negative
>> ground with no big deal. The generators had permanent magnets in them,
>> so you'd have to rewire that to get it to work at full output, but again,
>> that was no big deal. A motor with no permanent magnets will work either
>> way, and obviously all the lights and other resistance loads like that
>> don't care.
>
> That's the point we're making. Duh! Wink

(humor mode here).
>
> There were even older cars that had positive to earth voltage setups, if I
> recall. I'd ask my Uncle Bob, but he died long ago.
>

lol...beat me to it...it's not the volts that kill you, it's the amps. i was
working on a 24 volt (2 12volt batteries) electric wheelchair once and i
hadn't noticed the owner had put a non-standard plug on the charger cable.
it had exposed prongs and it touched the metal frame....wow....fireworks
and the plug welded itself to the frame while burning a hole in it...and
this was heavy gauge chromed steel...and that was only a 100 amps system...

as you say, 700 amps can create quite a show.