Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Mild electric hybrid using a Permanent magnet PMG 132 motor?

mort · 03-06-2012, 06:32 PM

Hi Ryland,
I don't mean to be discouraging, I'd like to see this work. But here's what I see, you are going to add a fairly large weight of batteries and a motor in order to run your engine a lower and less economical power level. The efficient motor will make up for the inefficient engine. What you do about batteries will make all the difference. If the batteries increase the car's weight by 5%, then the engine efficiency must not fall more than 10% (assuming rolling and wind resistance are equal at cruise). Without a map of the engine nobody knows. But consider that at cruise the engine might be 25% efficient, but at 1/2 cruise power it could drop to 22.5% efficient.
-mort

On reading this I think I sound too pessimistic. The engine will be making 1/2 as much power too, so efficiency could drop by 20% and you could still be ahead. It looks better to me the more I think about it.

03-06-2012, 06:32 PM	#9 (permalink)
mort EcoModding Lurcher Join Date: Dec 2010 Location: Los Angeles Posts: 333 Thanks: 151 Thanked 109 Times in 80 Posts	Hi Ryland, I don't mean to be discouraging, I'd like to see this work. But here's what I see, you are going to add a fairly large weight of batteries and a motor in order to run your engine a lower and less economical power level. The efficient motor will make up for the inefficient engine. What you do about batteries will make all the difference. If the batteries increase the car's weight by 5%, then the engine efficiency must not fall more than 10% (assuming rolling and wind resistance are equal at cruise). Without a map of the engine nobody knows. But consider that at cruise the engine might be 25% efficient, but at 1/2 cruise power it could drop to 22.5% efficient. -mort On reading this I think I sound too pessimistic. The engine will be making 1/2 as much power too, so efficiency could drop by 20% and you could still be ahead. It looks better to me the more I think about it. Last edited by mort; 03-06-2012 at 07:17 PM..