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Old 05-10-2012, 09:56 AM   #4 (permalink)
topcat
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Join Date: Jun 2011
Location: England
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Celica VVTI - '05 Toyota Celica GT VVTI
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Quote:
Originally Posted by Daox View Post
This effect will only last a few seconds at most. The battery voltage will very very quickly drop down to whatever the alternator is putting out. If you're looking for gains in the alternator area the best way to go is to put a deep cycle battery in and delete the alternator in some way.
I think it would last longer than you suggest. The volts will match the alternator, but the fully charged battery will not be able to take much current out of the alternator. Therefore not much power is taken.

If I charge it with 2Amp x 12.6V for 2 hours that is 0.05 kWh of energy put in.
There is ~9kWh in 1 litre of petrol, a 33% efficient engine means there is 3kWh of usable motive energy in 1 litre.

So it could potentially save ~1-2% of a litre. Not a lot, but worth having. Minus of course the cost of the electricity from the socket. But electricity is £0.10 per kWh instead of the £0.14 /kWh petrol which is £0.44 / kWh assuming 33% efficiency. (Using UK prices).
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