More Power or Less weight?

Biff

100 W
Joined
May 26, 2008
Messages
192
Location
Kelowna, BC
If you were looking to replace a ME0709 with a brushless equivalent, (same mounting / shaft / outside Diameter / RPM) would you rather:

A) select a motor with the same mass (around 16kg) that could deliver 3x the continuous power (around 24kW continuous 50kW for 2 minutes), and cost around $800

or B) was 2/3 the weight and delivered about the same amount of power (8kW continuous 16kW for 2 minutes) and cost around $450

-ryan
 
Depends: Would the application be helped enough by the weight savings to make up for the power difference?

I suspect in most applications where that kind of power is being used that the small difference in weight vs the difference in available power would not be worth it, and that the higher power unit would be the choice most of the time.

If it were on a bicycle application, for a racer or cargo hauler/etc. on the flats, the higher power motor might well make a difference where the lighter motor might not.

If it were on a bicycle application, for a very fast commuter/etc. on hills or constant start/stop riding, the lighter motor might well make a difference, if the bike and rider are already light enough that the weight difference of motor is a significant part of the mass of the whole bike/rider, as it will mean that much less power is required on hills, especially steep ones. But the extra power might make enough difference that (assuming enough battery would fit on such a light bike to use the power) it would be better to have that than the lesser weight.

It all comes down to the actual numbers on the project itself. And of course, your budget. ;)
 
Hi Biff,
I would go for 'A', because 'B' is already available in shape of the turnigy ca120-70. ( and cheaper too )

What would the kV /target voltage be of the A-motor?
How come, it's peak power is only 2x the nominal? ( 2.5-3x nominal is common)
Which controller is it tested with? ( e.g. Kelly 144V would be great)

We are currently using the HPGC AC50 with curtis 1238 controller a lot. Maybe your motor is an option for a 1000kg car without shifting gears?

cheers
Olaf
ececars.nl

<edit> Hmmm it seems mars electric has a new website/owner? http://www.motenergy.com/me0709.html
 
Good question, as I'm doing just this, replacing a heavy ME0709 with a much smaller and lighter brushless motor. I'd go for a smaller, lighter motor over one the same weight and size but three times the power, simply because the small motorcycle project I'm (very slowly) putting together is short on space in the frame.

The main problem with these big brushed motors is that not only are the motors themselves big and heavy, but their controllers are as well. Switching to a smaller motor has freed up a lot of space in my motorcycle frame for batteries.

Jeremy
 
John Fiorenza is still president for Mars/Motenergy.

OP: Are you thinking about the ME0913?
 
phyllis said:
OP: Are you thinking about the ME0913?

I am just trying to figure out what more people would want, and why. So far the responses have been very informative, thanks.

-ryan
 
I would say it depends on what you are starting out with.

Option B allows you to only replace the motor in the whole system and increase your performance (lower weight). You also have $350 to improve performance with a controller, or faster charger, etc. (oh forgot you will need a new controller too

Option A will only make your performance better if you upgrade your batteries and controller.

Personally I would buy option A for both a new project and as an upgrade because it offers me much greater performance and the potential to upgrade my system incrementally. As reference to the point of view I have an '89 suzuki katana with an agni, kelly, and GBS 60ah cells and plan to build a performance AC motorcycle in the future.

Kyle
PS-safe to assume similiar effeciencies in the two options?
 
Smiles are directly proportional to power.

Option A FTMFW. :mrgreen:
 
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