building a electric enclosed 3 wheeler and need input

dexdrako

100 µW
Joined
Oct 16, 2021
Messages
7
hey everyone I'm trying to make a electric city car.

the idea is an enclosed reverse trike with tandem sets (1&1 or 1&cargo), I'm taking inspiration from a few experimental designs like the "one sharp rickshaw" (https://www.yankodesign.com/2017/01/12/one-sharp-rickshaw/) and even the dymaxion. the two front wheels will be independently controllable with a steerable or caster back wheel. making it a mixed steering setup and will give the car a zero point turning radius at slower speeds

so I've bought two 4kw proud eagle motors used on e max scooters. max power of 6kw, max current of 100A, more then 80n.m torque, can take a 11 degree hill with a 600kg vehicle and at 72 votes can do 50mph/80mph (all from the makers website)

so i need help choosing the controller and the kinds of battery.

first question obviously i at least need a 72 vote 4000w controller but they're harder to come by and more expensive. would I correct in believing I could use a 5000w controller instead with no adverse effects?

second question is about the batteries.

I'm planning on starting with a 72 vote 60 amp set up, thats 4,320w so i should be able to drive the motor for at least an hour, then hopefully double that later. I've settled mostly on choosing between the 30amp or 60amp the LiitoKala lifepo4 batteries. the only reason i have for the 30amp is because i believe the max discharge amps should scale like normal amps but im not sure that matters. both the 60 and 30 amp batteries say they have a CD of 100 amps or more (60 says 180a) and a MD 300a for both. that beyond the max amps for both the motor or any controller i was looking at.

then am i wrong in thinking that I should just go with the 60a batteries then?

i would love any input you can give me
 
A few thoughts; Rear wheel steering is not good for high speed. Drive something with it and you will see what i'm talking about.

Need to learn the difference between Amp Hours (ah) and amps (a) don't mix the two. ah is a capacity rating of the battery and Amps is the discharging current. You have Continuous and Max rating on batteries.

You have two motors you will need two controllers, one for each motor. If each motor will draw 60a then 60 * 2 = 120a.
Not knowing what the motors will be driving can only guess at what you will need for an Hour. Example if you pull 60a at 72v for hour then at least 72ah battery or 5kw with max discharge at 120a and 60a continuous. Just an example.

If you have an idea of the weight and drag something closer can be guess at.


by dexdrako » Oct 16 2021 10:56pm

hey everyone I'm trying to make a electric city car.

the idea is an enclosed reverse trike with tandem sets (1&1 or 1&cargo), I'm taking inspiration from a few experimental designs like the "one sharp rickshaw" (https://www.yankodesign.com/2017/01/12/ ... -rickshaw/) and even the dymaxion. the two front wheels will be independently controllable with a steerable or caster back wheel. making it a mixed steering setup and will give the car a zero point turning radius at slower speeds

so I've bought two 4kw proud eagle motors used on e max scooters. max power of 6kw, max current of 100A, more then 80n.m torque, can take a 11 degree hill with a 600kg vehicle and at 72 votes can do 50mph/80mph (all from the makers website)

so i need help choosing the controller and the kinds of battery.

first question obviously i at least need a 72 vote 4000w controller but they're harder to come by and more expensive. would I correct in believing I could use a 5000w controller instead with no adverse effects?

second question is about the batteries.

I'm planning on starting with a 72 vote 60 amp set up, thats 4,320w so i should be able to drive the motor for at least an hour, then hopefully double that later. I've settled mostly on choosing between the 30amp or 60amp the LiitoKala lifepo4 batteries. the only reason i have for the 30amp is because i believe the max discharge amps should scale like normal amps but im not sure that matters. both the 60 and 30 amp batteries say they have a CD of 100 amps or more (60 says 180a) and a MD 300a for both. that beyond the max amps for both the motor or any controller i was looking at.

then am i wrong in thinking that I should just go with the 60a batteries then?

i would love any input you can give me
 
ZeroEm said:
A few thoughts; Rear wheel steering is not good for high speed. Drive something with it and you will see what i'm talking about.

Need to learn the difference between Amp Hours (ah) and amps (a) don't mix the two. ah is a capacity rating of the battery and Amps is the discharging current. You have Continuous and Max rating on batteries.

You have two motors you will need two controllers, one for each motor. If each motor will draw 60a then 60 * 2 = 120a.
Not knowing what the motors will be driving can only guess at what you will need for an Hour. Example if you pull 60a at 72v for hour then at least 72ah battery or 5kw with max discharge at 120a and 60a continuous. Just an example.

If you have an idea of the weight and drag something closer can be guess at.

I would classify it closer to a skid-steering then Rear wheel steering. the plan is to take advantage of the fact I'd need two motor controllers and drive it like those simple two wheel drive robots. meaning I'll turn by running the outside motor faster and at slower speeds I could even drive them in opposite directions to turn on the axis. this means the back wheel could honestly be a free wheeling castor but I feel having some control over the back wheel would be good backup if anything fails.

as for the weight and drag im still in the design phase so can't say for sure but I'm aiming for a vehicle below 1000lb and the plan is to make as aerodynamic as possible. tear drop shaped with minimal frontal area and wheel covers

this helped me with just this, as I'll likely need more voltage then i thought anyway
 
Zero turning radius lawn mower does that.
Aerodynamics' is the thing to study. Makes a big difference at higher speeds. What has come into my mind is the frontal area should be the widest part, then taper. This keeps the friction down along the body. Look at some of the rockets, they have a big cone then wedge down to the body. The widest part is not long, this will have the most friction. This is why tadpoles (tear drop) are great a design.

The wireless control is starting to appeal to me. You get rid of all this linkages and gear boxes. New technologies are opening area's that was deemed undoable. There is a 6 wheel drive all terrain on ES some where. I'm sure he is steering his the same as your thinking. Could get some ideas. Can not find it at this time will keep looking.

Before you worry about Voltage to much. Start with the wheels/tire diameter and motor kv, then you can tune the voltage to the setup. Then you figure out amps and then Ah's. I like higher voltage but cost more money to deal with.



by dexdrako » Oct 21 2021 1:07am
I would classify it closer to a skid-steering then Rear wheel steering. the plan is to take advantage of the fact I'd need two motor controllers and drive it like those simple two wheel drive robots. meaning I'll turn by running the outside motor faster and at slower speeds I could even drive them in opposite directions to turn on the axis. this means the back wheel could honestly be a free wheeling castor but I feel having some control over the back wheel would be good backup if anything fails.

as for the weight and drag im still in the design phase so can't say for sure but I'm aiming for a vehicle below 1000lb and the plan is to make as aerodynamic as possible. tear drop shaped with minimal frontal area and wheel covers

this helped me with just this, as I'll likely need more voltage then i thought anyway
 
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