# Like to convert 3-wheeler Urban Transport to Electric



## Duncan (Dec 8, 2008)

Hi Omar
Welcome to the site
Sounds like a great project

My crude suggestions
Used Forklift motor - a small one would do 6 to 7 inches in diameter
http://www.diyelectriccar.com/forums/showthread.php/using-forklift-motor-and-choosing-good-7598.html
(I paid $100 for mine)
OpenRevolt Controller
http://ecomodder.com/forum/showthread.php/paul-sabrinas-cheap-diy-144v-motor-controller-6404.html
($600)

Batteries
Not sure how much power you will need but at below 30Kph - it will be low

Guess - 80watt hours/Km for 150Km = 80 x 150 = 12Kwhrs
Use 80% of pack
12Kwhrs/0.8 = 15Kwhrs
That is a reasonable sized pack 44 off 100Ah cells and is going to weigh 150Kg and cost about $7,000

If you can reduce your required range you will be able to reduce the battery size (and cost)


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## digimart (Aug 4, 2013)

Hi Duncan
Thanks for your reply.
Do you suggest a chain drive for the motor ?
The estimated battery pack size you mentioned, please let me know which type of batteries you suggesting ?

Thanks

Omar


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## jk1981 (Nov 12, 2010)

Hello Omar, few things spring to mind reading that.

The first is that you're unlikely to ever see a return on investment for the conversion unless the fact it's electric attracts higher value custom or you can get some sort of sponsorship or subsidy to help fund it.

The chassis looks pretty light, presumably these are just strong enough and no more for normal use. That's something you'll have to look at if you want to carry a fairly heavy battery plus people and maintain stability/reliability especially if this is a work vehicle operating on broken road surfaces.

Around town your driving is presumably going to be stop start in traffic. This uses and wastes a lot of energy requiring a big battery which adds weight making the situation worse. The good side to this is that you're only ever going fairly slowly which is good for energy consumption and you can potentially recover a lot of energy from the frequent stops allowing you to run with a smaller battery pack. More good news is that a 200cc 4stroke doesn't make a lot of power, maybe 4kW for a good one meaning you probably don't need a very big motor to maintain decent performance for maneuvering in traffic.

Assuming you do want to recover energy while braking I'd look for a small AC system. Maybe an alternator conversion with a constant (or controllable) field current provided by a modified DC-DC converter (maybe a PC supply). I don't know what main 3 phase controller would best suit and be available to you but as the power requirement's are modest there should be a good range of golfcart sized options available to use directly or hack.

I don't know how much energy you will need in your battery. If I were you I'd calculate this as best you can before going any further, it may spoil your plan. The easiest way is to look at how much petrol a days work uses then consider gasoline contains ~35MJ/L, of that your little petrol engine is probably converting 30% into useful work. An electric conversion will probably achieve about 80% efficiency from battery-road.

So if a days work uses 3L of fuel:

3 * 35,000,000 * 0.3 = 31.5MJ of useful work which is 8.8kWH in more familiar units

8.8 / 0.8 = 11kWH of required battery capacity. You want your battery to be a little oversized so you use perhaps 85% of it for reliability (getting home every time) and service life of the battery.

11 / 0.85 = 12.9kWH of battery

Now your regenerative braking may save you 15% over the course of a day, this one is a bit of an unknown, it really depends on the driving style and vehicle use. The more energy you recover the less battery you need or the less you spend on charging or the more work you can do in a day.

12.9 * 0.85 = 11kWH of battery

That's pretty expensive and heavy compared to 3L of petrol and it's an up front capital cost which the petrol isn't. If you need 2 packs, one on charge that's a huge cost.

Looking at the solar charging: If you get 8 good hours of sun per day and 90% charging efficiency you'll need at least:

11 / 8 / 0.9 = 1.5kW of solar power which itself will be expensive.

I really admire the ambition but please do the sums before you start spending money on batteries rather than an engine refurbishment kit or a slightly newer tuc-tuc. I hope you can make it work.


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## digimart (Aug 4, 2013)

Thanks Jk1981
very sensible advise
thanks


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## Duncan (Dec 8, 2008)

digimart said:


> Hi Duncan
> Thanks for your reply.
> Do you suggest a chain drive for the motor ?
> The estimated battery pack size you mentioned, please let me know which type of batteries you suggesting ?
> ...


Hi Omar,
Chain drive would be OK 
The motor and controller I mention are probably overkill - but may be cheaper 

Batteries 
Definitely Lithium
I was thinking CALB
BUT you need to determine what is the best bet locally

Re-Gen
This sounds like a good idea but it is not such a good idea in practice,
Basically you get a lot of energy return if you drive "hard"
Powering forwards and braking fast
If you drive gently - then you get very little energy return
How much do you use the brakes on your Tuk Tuk ?

"I really admire the ambition but please do the sums before you start spending money on batteries rather than an engine refurbishment kit or a slightly newer tuc-tuc. I hope you can make it work."

I couldn't have said it better - so I have copied it


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