FINISHED!

Have you made or bought a converted vehicle if so this is for you
MalcolmB
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Postby MalcolmB » Thu Aug 14, 2008 10:58 am

It's really encouraging to hear you're pleased with your conversion. I've just been looking back over your posts to see what motor you're using, but couldn't find details. I know you started with a lift truck motor and had problems with it. Did you eventually import a motor from the states, and if so which one?

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geekygrilli
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Postby geekygrilli » Thu Aug 14, 2008 5:45 pm

Hi

Still running the forklift motor - I decided that if it was going to cost me £1000 I didn't need to run at anything more than minimum current on my Zapi! So I stuck with the 47v Nelco 132M motor.

Details of the motor are here, sort of: http://www.coopercontrols.co.uk/components/n132m.htm

The system is 96v 110Ah, just wet leisure batteries, which were £40 each.

I have another 48v forklift motor that is a little smaller, and older looking, but it has adjustable timing, which would be avantageous, maybe.

I'd like to give the other motor a run, but the thing is, swapping the motor is quite time consuming as I need to remake the plate, adaptor and battery trays, by the time I've done that I might as well convert a different, slightly larger car.

So I think that when the time comes, and I fancy a change I'll sell the rolling chassis with the motor and batteries in place, just remove the controller and charger....Or maybe I'll go for a 120-144v system with LiFe cells, and sell the lot, hmmm, decisions, decisions!

MalcolmB
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Postby MalcolmB » Thu Aug 14, 2008 6:12 pm

Thanks Chris
To get 25 miles range from that system it sounds as if your'e doing pretty good to me. With Peukert losses you're unlikely to get much more than 60 Ah from your batteries. That makes your available pack capacity just under 6 kWh, so for 25 miles range you must be doing better than 240 Wh/mile, or did I go wrong somewhere?

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geekygrilli
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Postby geekygrilli » Thu Aug 14, 2008 6:42 pm

Yeah, I suppose thats about right considering the energy consummed in driving. 230Wh/mile seems to be in teh right region compared to teh guys on evalbum.com.
I have no idea what Peukert value to use in calcs.

I total energy consumed and 100% efficiency of charger:

110Ah at 96v = 10.56 KWh

So, 25 miles is 422 Wh/mile. In truth its more than that due to charger ineffiiency :(

Its cheaper per mile and 'locally cleaner' than my diesel berlingo, though. Most importanly, though, its a hobby, so I don't have to justify it financially :lol:

visioninthedark
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Postby visioninthedark » Fri Aug 15, 2008 12:47 am

Good God.... What a performance!!!!!! I thought that sort of thing only happened to me when dealing with 'The Numbskulls'. Glad to see you got through it though and you seem well pleased with the results. I would be too... :) . Looks like youv'e done a real good job on the fitting out too... :D

MalcolmB
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Postby MalcolmB » Fri Aug 15, 2008 7:16 am

Quoting the energy consumption at the plug of course gives a truer picture of the efficiency of an EV system. I'm just a little obsessed with consumption at the battery as I'm trying to work out the minimum I can get away with for a LiFe pack. From your conversion and Greg's little Fiat it seems that around 150-200 Wh/mile is achievable for a lightweight conversion :D

Like vision says, that's a very neat conversion. I can't see Paul calling it another science project :lol:

Reading back through your progress reports makes me realise how many possible pitfalls there are. Well done for seeing it through!

hyve
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Postby hyve » Fri Aug 15, 2008 9:10 am

On the website you posted I see the motor is rated 24-72V, but you're using 96V. Is there any kind of rule of thumb for upping voltage like this on these industrial motors ?

Thanks,
Peter Ph

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EVguru
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Postby EVguru » Fri Aug 15, 2008 9:43 am

So, 25 miles is 422 Wh/mile. In truth its more than that due to charger ineffiiency


Ouch! That does seem rather high. I'm sure it will get better as you improve your driving technique and find the best gear to run in.

I was able to get 300Wh/mile from the Scirocco commuting along the M1 from J11 to J9 and the along the A5 and into Harpenden, a distance of 10 miles. This is a fairly reliably figure measured on a household consumption meter in order to determine the electricity bill for my parking/charging space at work (no charge when they saw the figures).
Paul

http://www.compton.vispa.com/scirocco/
http://www.morini-mania.co.uk
http://www.compton.vispa.com/the_named

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EVguru
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Postby EVguru » Fri Aug 15, 2008 10:34 am

On the website you posted I see the motor is rated 24-72V, but you're using 96V. Is there any kind of rule of thumb for upping voltage like this on these industrial motors ?


Motors are just energy conversion devices, you can pick all sorts of operating points.

If a series motor was rated at say 10hp at 3000 rpm on 72volt and 130amp (approx 80% efficiency), then the rpm per volt at that current would be 41.666.

You could run it at 120volt and at the same torque output it would rev to 5000rpm (41.666 * 120).

The torque output at 10hp would be 10 * 5252 / 3000 = 17.5 ft/lb, so the power at 120 volt and 130 amp (same torque) would be 17.5 * 5000 / 5252 = 16.66hp.

The heat produced in the motor is mostly due to copper losses (I2R), which are the same as before, but you may well have more cooling from an internal fan at higher rpm.

You can keep increasing the voltage until the on-load revs are too high (you have to limit no load revs with a series motor whatever the voltage).
Paul

http://www.compton.vispa.com/scirocco/
http://www.morini-mania.co.uk
http://www.compton.vispa.com/the_named

MalcolmB
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Postby MalcolmB » Fri Aug 15, 2008 11:41 am

Paul, is there any simple way of estimating torque at different currents from a single operating point?

My motor is rated at 5 hp at 2500 rpm on 36V and 130A (so torque = 5 x 5252/2500 = just over 10 ft lbs).

I'd like to know the torque at 400A

Looking at performance curves for a motor of similar size and weight the torque values at various currents are:
130A = 13 ft lbs
260A = 33 ft lbs
390A = 57 ft lbs
so, it's not a linear relationship?

EDITED initial question


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