# E-Vader - moped conversion



## frodes (Oct 4, 2008)

Hey all,

I started my first conversion today.. it's called E-Vader, because when the armor is on it looks like darths mask  I think the donor was a Honda..?!

Bin on the left is the ditched bits!










Hurdle 1: the rear wheel/motor. The old petrol engine and its housing formed part of the chassis, so it and the suspension held the rear wheel in place. With it gone, I 'd need to fabricate a new frame to attach the rear wheel to the chassis base yeh? Hub motor or free with belt? 

And what about the dash? the speedo stays the same right? but i'd take out temperature and fuel, and put in volts and amps?

I'm really crap at the calculations, so say I want 60 mile range 30mph max (100km rage 50km/hr max) then what am I looking at battery wise, with a 2KW motor?

So much to learn


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## frodes (Oct 4, 2008)

So, after a bit more research, I _think_ i'm looking at 
48V 1500-2000W motor
12V 38Ah x4 battery system

how does that sound? 

The real kicker will be scavenging, or finding this stuff cheap!


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## oddpowers (Dec 9, 2008)

I not 100% sure I have my calculations right but i'll try......Watts=Amps X Volts so with that said.. (your motor)2000w=41.67amps X 48V. 42amp motor with 38ah batteries. your batteries will withstand approx 38amp draw for one hour. so in this case 42 amp draw will last approx .9 or 9/10 of an hour. At 30mph your looking at 27 mile range. Of course there are a lot of other variables that will change this a bit. (start/stop driving, hills, speed, ect) But I am willing to bet you probly wont get more than 35 mile range.
Keep in mind this is "on paper" figures.
If you want 60 miles you ould need to have 84 ah batteries. or only pull 38 amps at 60 mph.....

27 miles is very good distance for a moped, I would be happy with that.
Dont give up that looks like a good conversion. Be sure to keep us posted along the way.


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## frodus (Apr 12, 2008)

you forgot that you shouldn't discharge lead past 80% DOD, AND the peukert effect of lead.

I'd take 70% of that figure for Wh capacity of the pack.... 48V 38Ah is 1824Wh... 70% of that is 1276Wh useable. IF and ONLY IF he manages to get a rolling resistance low so he can get less than 75wh/mile (which he should if he rides it less than 30mph and doesn't gun it alot), he should be able to get ~17 miles.

If you want 60 miles, get some lifepo4 and pack the entire moped with batteries.... you'd need at the least 4500Wh to get even CLOSE to 60 miles.... at 48V, you'd need some 100Ah batteries (lead would be very large and heavy and would break the frame)... 

Just being realistic, thats all. Better to err on the low side range than expecting to get 60miles and only get 15.


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## frodes (Oct 4, 2008)

Whoa, thanks oddpowers! I've not read the calculations like that before, sooo much easier to understand! 

I'd love to wack $1500 down on some LiFePOs, but i'm using a pretty shitty donor, and I'm trying to do this scavenging or for as little as possible, to show it CAN be done. Yeh it may only travel 10 miles, but thats better than walking 10 miles to meet a friend yeh?!

Anyone else want to add to it feel free.....!


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## frodus (Apr 12, 2008)

frodes said:


> Whoa, thanks oddpowers! I've not read the calculations like that before, sooo much easier to understand!
> 
> Anyone else want to add to it feel free.....!


Well, the calculations he used are in the right direction, but a little inaccurate... he's trying to do a range calculation from the max power of the motor...... If you want to do it that way, 2000W in an hour @ 30 mph would be 2000Wh, you want 60 miles? then 4000W/h in 2 hours, still 2000W and 30 miles in an hour = 66Wh/mile. Thats with 100% of the watts going into the motor going to forward movement (which is not accurate, you have electrical and mechanical losses).... Its not a heavy motorcycle, so something between 66 and 100wh/mile is accurate. Lets stick with 66, just for kicks.

The general rule for calculating range is as I stated above. Almost all EV'rs use that calculation to roughly gauge range. You want 60miles? 60*66 = ~3960Wh... another -25% for losses.... 4950Wh.

Then chose batteries that can give you that. 12V and 38Ah battery is 456Wh... you'd need 11 of those batteries to get 60 miles Each battery is what, 30 lbs? so a total of 330lbs.... weight of lead is directly proportional to range.

Range for 4 38Ah 12V batteries would be 1824Wh.... 75% of that is 1368Wh.... 66wh/mile is 20 miles at the very max.


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## oddpowers (Dec 9, 2008)

As I was saying you will be hard pressed to get 60 mile range. As for the calculations Frodus's is certainly more accurate.
I wouldnt get hung up on those exact #'s, I got over 20 mile with 33ah batteries.


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## frodus (Apr 12, 2008)

very true, the real numbers depend on aero drag, mech drag, efficiencies... it could go up or down depending... ans as I said, the right direction... and no way in hell you can get 60 miles... you'd have to get 23wh/mile 

I got CLOSE to 20 miles with my setup of 12 18Ah batteries (6 in series, 2 in parallel) with 2550Wh pack....but they sucked as batteries.


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## frodes (Oct 4, 2008)

Ok, so I just found a potential motor!! (don't laugh at me, i have NO idea haha) 

It's from an old battery powered floor cleaner. 36V DC 2.25HP (1670W) 2500rpm ~ $150.. sounds good right? but it's massive! about 30cm long and a few kg's at least! normal?

I found 3 12V 70Ah SLA's on trademe for $600 kiwi. So..

Range for 3 70Ah 12V batteries would be 2520Wh.... 75% of that is 1890Wh.... 66wh/mile is 28.6 miles (46 km) max, is that right?

81kg battery pack though, with motor and that it would probably be a 95kg addition to the frame, + me, another 85kgs.. can a scooter handle that weight? all the gear i tore off it would only be about 40kgs, so I'm adding 55kgs..


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