Thread: Alternator Mods
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Old 11-24-2008, 09:07 AM   #29 (permalink)
EcoModding Apprentice
Join Date: Aug 2008
Location: UK
Posts: 104

Fizz - '06 Skoda Fabia Combi
90 day: 56.62 mpg (US)
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Originally Posted by gascort View Post
Noone's mentioned using a deep cycle battery and a plug-in charger. This is what I'm planning on doing; running a kill switch on my car and when I'm commuting 15 miles to and from work, running on straight battery when I can. The alternator sees no extra duty and the deep-cycle battery is made to be discharged and recharged with minimal sulfation. Electrical power is more efficiently produced in a power plant than in your car, and with current prices, it's way cheaper too!
I have looked at this and concluded that the cost per cycle of a deep-cycle battery make it not cost effective.

For example in the UK, a deep cycle battery like the "red top" would cost 140 and if you got 500 cycles out of it, that's about 0.3 per cycle, or 0.3 liters of fuel's worth just for the capital cost of the battery. That ignores charging costs, which are low from the grid -but a decent charger will cost something.

What would make it worth it, is if you had regen. braking and an electric assist motor, and could use the energy for more than just starting the car the next day.

I was surprised that the battery would only hold 600Wh, by my calcs equivalent to 55 ml of diesel...
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