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### Electric Car Engine Powering Need Questions

07/31/2010 3:20 PM

Not sure how to phrase this question thread, but here goes:

When an electrical car engine is running, the batteries that make it run, deliver how much energy/voltage(?) I am speaking of a battery only based vehicle non-fuel powertrain. As it delivers its power for a 200 mile per recharge cycle. So I guess my questions are:

1. in use - how much power is being delivered from the batteries to run the engine?

2. how much power is needed to recharge those batteries?

Pathfinder Tags: batteries Electrical Car
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Guru

Join Date: Jun 2009
Location: South of Minot North Dakota
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#1

### Re: Electric Car Engine Powering Need Questions

07/31/2010 3:34 PM

It depends on how heavy the vehicle is, how fast its going, and how much external drag or loading from other sources are involved (wind, hills, vehicle aerodynamics) plus the total distance traveled with all of these other factors accounted for.

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#2

### Re: Electric Car Engine Powering Need Questions

07/31/2010 3:53 PM

1. in use - how much power is being delivered from the batteries to run the engine?

The batteries supply all the power required to run the motor. And anything else that runs. So, you can't quantify the answer.

"2. how much power is needed to recharge those batteries?"

Depends how quickly you want them to charge. So, see above.

I'm sure there are websites that deal specifically with the subject of EV's.

Good luck.

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#3

### Re: Electric Car Engine Powering Need Questions

07/31/2010 3:54 PM

I can only provide ballpark numbers based on a few simplified assumptions:

"1. in use - how much power is being delivered from the batteries to run the engine?"

Highway cruise at ~67 [mph] requires about 20 [HP]
Efficiency of battery charge is ~ 75%
Efficiency of motor and controller is ~ 100%

20 [HP] = 20 * 745.7 [W] = 14.9 [kW] <(answer 1)

"2. how much power is needed to recharge those batteries?" (DEPENDS on the time.)

200 [miles] / 67 [miles/hr] = 3 [hr]

14.9 [kW] * 3 [hr] = 44.7 [kW-hr]

Typical US household recharging outlet

240 [VAC] * 30 [Amps] = 7.2 [kW] <(answer 2)

44.7 [kW-hr] / 7.2 [kW] / (0.75) = 8.3 [hr] <(answer 2)

Total energy used

44.7 [kW-hr] / (0.75) = 59.6 [kW-hr]

per mile

59.6 [kW-hr] / 200 [miles] = 0.298 [kW-hr/mile]

cost per mile using 0.10 [\$/kW-hr] would be

0.298 [kW-hr/mile] * 0.10 [\$/kW-hr] = 0.03 [\$/mile]

About 3 cents per mile is a pretty standard estimate for a pure electric vehicle with favorable operating conditions. Hope this answers your questions.

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#4

### Re: Electric Car Engine Powering Need Questions

07/31/2010 4:48 PM

Nicely done.

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#5

### Re: Electric Car Engine Powering Need Questions

07/31/2010 7:12 PM

1. Depends on lots (lots and lots.)of variables.

2. The power used on journey.

Power can not be created or destroyed apparently...just converted.

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#6

### Re: Electric Car Engine Powering Need Questions

08/01/2010 12:12 AM

It depends on the car and so on. But what are you trying to get at with those two questions? The efficiency of the set up? You will, of course, need more kwhs to put into the storage than you get out. And what you get out won't be entirely converted into work moving the vehicle. ~~ Nehmo