Another Electric Kart

[Jonas]

Hello everyone,

Like many other people here, I'm looking to make myself a little electric cart but don't really know what I'm doing. I'm home from school right now on summer vacation and would love to do the whole project wrapped up before returning in September, so it will have to be fairly simple I think. Given that I live in the middle of nowhere, the cart will have to be a little heavier, a little more towards buggy than shifter cart, to support some added weight from bigger wheels/tires and a little more ground clearance. This will also call for some extra power to handle that weight. Given the time constraint and my lack of experience in welding, I'm thinking that buying a frame would be better than trying to make my own. Therefore:

Right now my idea is to buy a Manco Dingo frame on Craigslist, throw two MY1020 motors on it, put two 12V SLA batteries on either side of the driver in parallel (I don't really understand this part yet) to try to meet the motor's power needs, and go.

Major questions I've got:

1. How loony is this plan? I'm not terribly worried if it's just a little out of whack, since I want to be learning a lot on this project, but if there's anything terribly far out, I'd love to know.

2. What is the consensus on dual vs. single motor setups? Dual seems like a good option here to me, but that's coming from someone with absolutely no experience on the matter. I'm thinking, though, that it would be good since it would offer 2KW of power for not a huge amount of money. Also, if one motor were to go bad, it could be easily replaced. But how does one wire this kind of setup?

3. I'm realizing now that a 48V motor is probably a little too high; thoughts? And if so, any recommendations for alternatives?

4. Batteries: I still don't really understand batteries well. Does teh motor's voltage have to be matched by the batteries? If so, why? And if I were to do a dual-motor rig, would I send power from one set of batteries to one motor and the other set to the other motor or just combine all the power and divvy it up once it got to the motors?


5. Controllers: is there any particular brand that people prefer here? I have no idea what to be looking for in controllers except that they should not be overpowered by the batteries. I don't care about regen or anything fancy like that, so I was just thinking the best value 48V controller I could find would do.


Any thoughts/recommendations are more than welcome. Thanks for the help everyone.

~Jonas

 

[itsid]

uhoh.. dual electric motors are ALWAYS a PITA to set up properly..

So, if you order the motors.. do it at once and ask the seller to pick to motors from the exact same batch (best two successive serial numbers)

that way the motors are 'as identical as humanly possible' which you really want.

well batteries and wiring is actually easy:..
parallel adds capacity (NOT voltage)
and in series adds voltage (NOT capacity)

so in order to move a kart (fo a noteworthy amount of time)
you need to first get to the voltage (i.e. 4 batteries in series per batpack)
and then add a number of such batpacks in parallel to gain the capacity you need.

For now I'd say anything less than eight full size (~65Ah) car batteries are pointless
but that depends on you.. if you're happy with 12min driving time and 12hr charging time.. then 4 might do as well (purely estimated numbers here)

the same 1000W my1020 (actually ZY1020 IIRC) is made in 36V too.. a little less torquey, but I guess still worth a try.

Anyways.. controllers..
That is -I'm afraid- the wrong question
and here's why:

if you mount the two motors on either rear wheel, without a live axle (say a differential)
you MUST use two controllers and a very sophisticated controlling mechanism to lower the speed of the inward wheel driving motor
(did I mention, that setting two motors up properly is a pain??)

on a live axle though, there's no point, a single controller 'might' work here;
but still even the most identical motors, attached by wires of different length will
stress one motor more than the other (overheating, loss of power.. and eventually.. failure)
(again, I said it's a real pain, right???)

So two controllers might be the better bet again.
that on the other hand requires a good understanding on how the throttle works, if you need two, a single one and a multiplier, a single one and a controller to split... or *shrugs* I'm sure I have forgotten a few options.

Anyways.. two motors... sounds cool, but it's hard work; tons of math, maybe even code to write on your own...

'sid