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Old 04-29-2012, 07:15 PM   #26 (permalink)
chrisoverson
The Mad Technician
 
Join Date: Apr 2012
Location: Devon, England, UK
Posts: 31

Rover - '98 Rover 218 iS
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Quote:
Originally Posted by pete c View Post
There is another thread discussing this very topic where someone brought up the fact that alternators are AC motors, not DC. So, this complicates things. Turning an AC motor gets kinda complicated, especially when you want to do it with a DC power source and control the speed of it. So, I think the way to go is with a DC motor.

As for how fast to turn it, do you mean pulley ratios? I would gear it as low as possible. Figure out what rpm it is capable of and gear it so that it reaches something close to max rpm at engine redline.

I think such a system would allow you to get the considerable percentage of your power from the electric motor at cruise speed. You might even get away with leaning out your fuel/air ratio a fair bit as the motor wouldn't be working all that hard, kind of like honda does with the insight and VX under low load situations.
Hmm, well I had planned on making the car run lean anyway. I might need to incorporate EGR with that to offset the higher emissions though.

Ok I didn't realise that about alternators, so it would have to be a DC motor in that case then . I didn't mean the pulley ratios etc no, I meant in order to lighten the load on the engine does it basically just have to try and spin the engine at the same speed it was trying to go anyway? If that makes sense... So if the engine is running at 2000RPM then you make the motor attempt to spin the engine at 2000RPM. Or does it have to be slightly faster etc... basically a mechanical/physics question rather than a practical one.

Thank you for your input nimblemotors it's greatly appreciated! I understand the 5th wheel idea is probably better in the end than electric motor assist, but on my part it would probably require less mechanical work and is easiest to install and remove. I know that it won't necessarily give the same benefits as it can't drive the car on just electric but saving fuel around town isn't my main concern as most journeys are to customers houses where fuel is paid for anyway, its saving fuel on longer trips I'm interested in .
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