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Old 02-14-2012, 08:23 AM
joamanya89 joamanya89 is offline
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Default What motor and amperage should I use?

Hi,I'm trying to convert a Mitsubishi Lancer, because it is not a heavy car, and also I like it and it has enough space for the batteryes.

My question is what kind of motor should I use? I've seen a FB1 4001A or a Warp 9 (they are almost the same), as you see I'll use a DC system.

Are those ok for my car? or is to much?

And then I would like to have a range of 200km - 240km with one charge and be able to drive at 90km/h - 130km/h.

So what amperage should I use? Because I was thinkin to do it with lithium batteryes but those may be to expensive...
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Old 02-14-2012, 09:48 AM
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Default Re: What motor and amperage should I use?

You'll need lithium (and lots of it) for that range.... lead just won't cut it. The thing would weigh as much as a tank. You're looking at a pack that is at least 38kwh worth of batteries, give or take a few percent.


I'll expand:
Amperage isn't really as important at this point in the design phase, Watt-Hours determines range. Estimate that a car like that is going to be ~300wh/mile give or take a little depending on many factors.... but it's close. Then say ~125mi (200km). 300wh/mi * 125mi = 37500watt-hours. If you need 240km, that's 150mi * 300wh/mil = 45kwh.

Speed is limited by Voltage in a DC system, acceleration is limited by torque. Top speed is limited by HP, which is a factor of volts and amps. I think you're well below what a 11" motor could produce, and if you have a pack big enough with decent quality batteries, current won't be an issue. 130kmh should be possible, but it depends on the voltage you run at, and the gear ratio of your transmission.
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Old 02-14-2012, 10:27 AM
joamanya89 joamanya89 is offline
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Default Re: What motor and amperage should I use?

Thank you very much!
Can I ask here about where's a good place to buy the lithium batteryes?

Because, I'll have to import it, and that's not an easy issue.
Calculating that W= amp(i) * volt, I suppose that W/h= a/h * volt so there is a balance between A/h and Volt.

For example: I can get my 37500W using 375V * 100A/h, or using 144V * 200A/h.

So, in my first example I will have my 37.5KW on my energy storage, but if I use 144V *33a/h (that would be 3C discharge capacity isn't it?) I'll have 4752 W moving my motor, so what you have said is that I'll have a range of 200km + or - but a speed that my motor can give me with 4752W, did I understand it well?

And the controller it's what is gonna regulate the Volts that goes to the motor?
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Old 02-14-2012, 10:43 AM
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Default Re: What motor and amperage should I use?

Please use correct units. Kw is power. Kwh is energy. We're talking about energy. Also amps and amp hours are different.

100Ah * 375V = 37,500Wh of energy
200Ah * 144V = 28,800Wh of energy
Completely different energy packs.

Also, 3C discharge on 100Ah cells is 300A. 2C is 200A. It's a multiplier of the Ah capacity of the cell.

If you have a 100Ah pack at 375V, and you discharge at 3C, that's 300A. The voltage will sag a little bit, lets say 12%, so down to 330V. That would be 99,000Kw of power. With a 37kwh pack, you should have no problem with power using 100Ah cells that can discharge at 3C. But realize, discharging at 1C would give you 37kwh of energy. Discharging at 3C, you'd need a larger pack to get 37,500kwh out. The higher the current you discharge, the less energy you get out of the cell.... so expect to get a larger pack to get 37kwh out. Something with at least 20% more energy at 1C.

Basically, you're going to be spending a lot of money on this vehicle to get that range, so be sure you are sold on the idea, because it's a lot of work and lots of time.

The controller regulates voltage and current to the motor, yes.
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Old 02-14-2012, 10:52 AM
joamanya89 joamanya89 is offline
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Default Re: What motor and amperage should I use?

I apologize for my mistake in the units, obviously I didn't know the difference.

Could you tell me, what volt and amperage may you use on these case?
Or perhaps, I should change my goals on these car a bit?
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Old 02-14-2012, 11:27 AM
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Default Re: What motor and amperage should I use?

Start by looking at prices of lithium. Right now, things are ~$1.25 per Ah. 100Ah is ~$125, and you'd need ~118 batteries @3.2V to get ~375V, so 118 * $125 = $14750 just for batteries, then add motor, controller, some sort of battery monitoring or management system to monitor the pack and a charger, contactor, fuses, cabling, DC-DC..... it's going to be well over $20k USD.... plus shipping and import fees.

100Ah batteries should be ok at that voltage, but it boils down to what motor you're using. It'l be about the same cost for batteries, but if you have a 144V motor, then you should go for a 144V pack and batteries that are ~260Ah.
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Old 02-14-2012, 11:40 AM
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Default Re: What motor and amperage should I use?

Ok, but I can't expend that money just on batteryes, so, for example I'll leave the clutch, I've been told that I can get more speed using less W, so the speed wouldn't be a problem.

Then the range would become my only issue.

I know that I'm bothering you, but it's my first convertion, and will need to import it all, so I wanna be sure about everything, so could you please explain me again what you said before, about the difference between W and W/h and also, if I've got X W/h how does the motor expend it, cos I've got a bit confused before...
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Old 02-14-2012, 11:49 AM
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Default Re: What motor and amperage should I use?

Quote:
Originally Posted by joamanya89 View Post
...., so could you please explain me again what you said before, about the difference between W and W/h and also, if I've got X W/h how does the motor expend it, cos I've got a bit confused before...
Hi Joam,

W/h is a non-unit Wh is a unit of energy. It is pretty confusing to the beginner. Maybe you can learn here:
http://www.diyelectriccar.com/forums...redir_from=668

Regards,

major
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Old 02-14-2012, 11:57 AM
joamanya89 joamanya89 is offline
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Default Re: What motor and amperage should I use?

Thank you verry much!
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Old 02-14-2012, 12:42 PM
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Default Re: What motor and amperage should I use?

top speed is directly related to Volts, more volts will give you more speed and is more efficient, so you want to go as high as you can here (limited by battery space, and motor/controller/and charger limits)

range is related to Volts*ah so adding volts (cells) and ah (bigger cells) will give more range.
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