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#11
06-15-2011, 02:57 PM
 Bowser330 Senior Member Join Date: Jun 2008 Posts: 1,683
Re: Starting new build: BMW 3-series (E46) - high-performance electric

Quote:
 Originally Posted by Yabert Hey! be careful. You don't have enough battery power because your voltage is too low! 800 x 0.0009 = 0.72 - 3.2 = 2.5v x 90 = 225v. 800A x 225v = 180Kw from cells and roughly 200 hp at motor shaft....... so, not enought! You probably need at least 250 hp....
The conversion from kw to hp seems low in your calculation....

180kw / 0.745 = 242hp

#12
06-15-2011, 03:50 PM
 valerun Senior Member Join Date: Nov 2010 Posts: 1,534 Blog Entries: 1
Re: Starting new build: BMW 3-series (E46) - high-performance electric

Quote:
 Originally Posted by Bowser330 The conversion from kw to hp seems low in your calculation.... 180kw / 0.745 = 242hp
I think Y meant mechanical hp - after taking into account ~80% motor & drivetrain efficiency...
#13
06-27-2011, 12:33 AM
 valerun Senior Member Join Date: Nov 2010 Posts: 1,534 Blog Entries: 1
Re: Starting new build: BMW 3-series (E46) - high-performance electric

Hi Guys,

still musing over the details of this conversion.

Narrowing down the DC motor choice to Warp11HV mated with 340V CALB pack. It just have to have a big DC motor to provide the power we need.

However, we are going to do some long-range demo drives in this car and every bit of efficiency counts so I was thinking of adding something like an AC50 system to the big DC motor. AC50 would then soak up braking / downhill and provide most of the 'baseline' load on freeway etc. Being AC and therefore more efficient, it should further add to the economy.

What do you guys think? Has anyone done it before? Any links / pointers?

Thanks,
Valery.

#14
06-27-2011, 12:53 AM
 DavidDymaxion Senior Member Join Date: Dec 2008 Posts: 1,377
Re: Starting new build: BMW 3-series (E46) - high-performance electric

Several of the 914 ev guys use ACXX motors, you could do a search at http://groups.google.com/group/914ev .
Quote:
 Originally Posted by valerun Hi Guys, still musing over the details of this conversion. Narrowing down the DC motor choice to Warp11HV mated with 340V CALB pack. It just have to have a big DC motor to provide the power we need. However, we are going to do some long-range demo drives in this car and every bit of efficiency counts so I was thinking of adding something like an AC50 system to the big DC motor. AC50 would then soak up braking / downhill and provide most of the 'baseline' load on freeway etc. Being AC and therefore more efficient, it should further add to the economy. What do you guys think? Has anyone done it before? Any links / pointers? Thanks, Valery.
__________________
#15
06-27-2011, 01:11 AM
 valerun Senior Member Join Date: Nov 2010 Posts: 1,534 Blog Entries: 1
Re: Starting new build: BMW 3-series (E46) - high-performance electric

Quote:
 Originally Posted by DavidDymaxion Several of the 914 ev guys use ACXX motors, you could do a search at http://groups.google.com/group/914ev .
Thanks David. Do you know if anyone did it in a DC-AC hybrid mode, though? AC50 by itself will barely make a 3500lbs BMW move (well, in my frame of reference, anyway ;-)
#16
06-28-2011, 05:30 AM
 Yabert Senior Member Join Date: Feb 2010 Location: Québec, Canada Posts: 1,484
Re: Starting new build: BMW 3-series (E46) - high-performance electric

Do you only compare the coplete efficiency of the AC50 vs WarpHV????

DC = 99% controller efficiency x 87-88% motor = 87% efficient than seem good to me....

What about AC50?.... 94% x 92% = 87%???????

My final advice: Put a bit more cells. They costing less and they weighting less than an AC50 systems!!
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#17
06-28-2011, 09:15 AM
 valerun Senior Member Join Date: Nov 2010 Posts: 1,534 Blog Entries: 1
Re: Starting new build: BMW 3-series (E46) - high-performance electric

Quote:
 Originally Posted by Yabert My final advice: Put a bit more cells. They costing less and they weighting less than an AC50 systems!!
good point. 150lbs of cells are ~20 miles of range, after all...
#18
06-30-2011, 11:05 AM
 Bowser330 Senior Member Join Date: Jun 2008 Posts: 1,683
Re: Starting new build: BMW 3-series (E46) - high-performance electric

Quote:
 Originally Posted by valerun good point. 150lbs of cells are ~20 miles of range, after all...
90 Calb 100AH cells (288V nom * 100AH = 28.8kw)

you will definitely not be needing more than 28kwh to achieve 100 mile range @ city speeds...

http://www.evconsultinginc.com/artic...dc_system.html

The article above points out that the average car only needs 5kw to cruise @ 40mph (city speeds). So a 100 mile distance @ 40mph requires 12.5kwh
#19
07-04-2011, 03:15 AM
 valerun Senior Member Join Date: Nov 2010 Posts: 1,534 Blog Entries: 1
Re: Starting new build: BMW 3-series (E46) - high-performance electric

Quote:
 Originally Posted by Bowser330 http://www.evconsultinginc.com/artic...dc_system.html The article above points out that the average car only needs 5kw to cruise @ 40mph (city speeds). So a 100 mile distance @ 40mph requires 12.5kwh
Hi Bowser,

this would be awesome. However, I think these guys either missing some power loss contributions or talking about purely mechanical power or using really streamlined / lightweight car example or all of the above. I've used Formulas from the book 'Build your own electric car' before and am coming out at 27hp required for a 3500lb BMW to move at 60mph (as opposed to 15hp that these guys quote). My calculation gives me ~330 Wh/mile which is in the right ballpark for 60 mph.

This gets me the range of just shy of 100 miles at 60 mph. At 40 mph, it's 140 miles or 40% higher.

V
#20
07-08-2011, 04:46 PM
 valerun Senior Member Join Date: Nov 2010 Posts: 1,534 Blog Entries: 1
Re: Starting new build: BMW 3-series (E46) - high-performance electric

ok guys! FINALLY some good stuff to look at ;-)

\$1K in the friendly shop gives you an EV-ready beemer! Engine, radiator, gas tank and exhaust systems are out

design work is starting today. Everything in CAD to be replicable for our E46 kits.

V
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