AnswerID: 83264 Submitted: Saturday, Nov 06, 2004 at 17:36
Member - Collyn R (WA)
replied:
The Internet is quite a place for generating and reinforcing info that is simply not true. So may I just kill one such right now before it gets added to the great campfire mythology bank.
That is a comment on this thread that a car starter motor
draws a heap energy more than an Engels
fridge.
Well it all depends on how long you run that Engels, but a starter motor in fact
draws a great deal less energy than most people suspect (assuming the engine is in good order). You can win bets in the pub with this one!
Here's the facts.
A typical starter motor
draws 350-400 amps (that's about 100 times the draw of an Engel). But it typically does so for only two to three seconds
In three seconds the starter motor
draws 400 amps divided by 3600 seconds times three seconds (in amp/hours). That's way under 1 amp/hour - it's TINY!!!
An Engel
fridge typically
draws 3.0 -3.5 amps/hour (taking a 50% duty cycle into account that's still 1.5 amps/hour). More than the starter motor - eh?
When the engine starts, that energy is typically replaced within a minute.
The starter battery is typically 70% charged - and starting the battery typically drops that to a mere 68-69%.
Another way of looking at the energy required is to remember that a vintage car can be hand cranked by one hand and with ease, by even a slightly built person. I spent my formative years driving them and my girl friends then could readily hand crank my 1927 4.5 litre (4cyl) Bentley (mind you I did like strong girls!)
I should add that whilst you may get away with running the
fridge from the starter battery you really are pushing your luck! If it really had that energy to spare the bloody car industry bean counters would have cut it back in size decades ago!
Trust this is of interest.
Collyn Rivers
 | Collyn
"The problem is not so much what people don't know - it's what they think they know that simply isn't true."
Ample Power Company, USA |
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