Question about wheel motor application

[300MPH]

Hey everybody, I'm new here and am contemplating a custom pedicab build for a design that will be able to carry 8 people. Obviously the more people I can carry comfortably, the more money I will make. LOL!

My background is in turbo system and roll cage fabrication. I am not that well versed in electricity.

For thise who are unfamiliar, a pedicab is kind of a man powered pedalled taxicab to transport people around downtown areas and at stadium events where people need tp go someplace too far to walk. I have been pedalling people around but saw others with electric motors helping out. When my legs started cramping and these people were blowing by me I got the idea to make something better for myself!

I see the tricycle design pedicabs that have a 1000 watt motor on the front wheel and they might go through 2 sets of 20 amp hour battery packs in a day.

Since the speed only needs to be 5-10 MPH for this application, do I still need to run 48:V or would it be more advantageous to run less volts as the motor speed does not need to be that great. I also would use a motorcycle or moped rim and tire for durability with the smaller OD to give the motor a mechanical advantage to get things rolling as opposed to a 26" wheel and tire combo.

My questions are the following:

1. Are the ebay or amazon chinese electric wheel motors at this point of development high enough quality to mess with or not?

2. Who makes the most reasonably priced and reliable battery pack? I live in Florida so I am in a fairly hit humid climate.

3. How critical is it to have a solid axle without the wires coming out ofthw center of a hollow tube from a wire damage and an axle strength perspective?

4. What about regenerative braking? Is it possible to have enough regen braking power to not have to put on disc brakes? Also different websites have information about how much benefit there actually is to the extension of battery charge/range with regen braking.

If somebody reading this thread does not want to spend the time to post, they can call me at 407 223 0053 and kust give me rhe low down, that would be great too!

Any help would be greatly appreciated!

 

[d8veh]

I would say hat the best way to do it is with a rear motor. You mount the motor in drop-outs halfway betwen the crank and thevrear axle. You use normal derailleur gears on the right side of the motor using the normal gear fittings. Instead of the brake disk on the left side, you mount a sprocket, and run a chain from there to the rear axle. By changing the relative size of those two sprockets, you can run the motor at its normal speed with normal voltage and run the axle at a much lower speed, so that you double or triple the torque. We did it like that on a two-seater plus driver pedicab, using a 500w geared hub-motor with a final 2:1 reduction. For max speed about 12 mph.

 

[amberwolf]

My first recommendation is to look at the other pedicab threads for hints and tips that might not get posted to this one:
https://endless-sphere.com/forums/search.php?keywords=pedicab&terms=all&author=&sc=1&sf=all&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search
(that lists all threads that mention the word, you can search differently to narrow it down to relevant stuff)

I've posted some stuff inline below, and d8veh above has good advice.

Hey everybody, I'm new here and am contemplating a custom pedicab build for a design that will be able to carry 8 people.

Before you build it, you should check that a motorized pedicab is legal where you are--some places it's not, and being a business it would impact you much harder when they stop you for it.

I see the tricycle design pedicabs that have a 1000 watt motor on the front wheel and they might go through 2 sets of 20 amp hour battery packs in a day.

With that kind of a load, you're probably going to need a huge battery pack, with extremely fast recharge capability, or a lot of little ones you can swap out every trip, that you can leave recharging all the time unattended.

You can use various online calculators findable with google or in the ES wiki or various threads on ES to determine what power levels you'll need for various speeds and loads, and you can use other calculators or data from posts around ES to determine how much power you'd need to accelerate to your cruising speed at a sufficient rate,

Once you know that, you can estimate how many Wh (watt hours) you'll need for your battery pack, and then use that and whatever voltage pack you've decided on to determine how many Ah (amp hours) that pack has to be.

Then you can start looking for batteries that meet all of your requirements, including how much current they can put out without sagging in voltage, to give you the watts you need to accelerate to your cruising speed.

Since the speed only needs to be 5-10 MPH for this application, do I still need to run 48:V or would it be more advantageous to run less volts as the motor speed does not need to be that great. I also would use a motorcycle or moped rim and tire for durability with the smaller OD to give the motor a mechanical advantage to get things rolling as opposed to a 26" wheel and tire combo.

You're better off using larger wheels for comfort and placing the motor in the chassis, driving thru chain, shaft, etc. Heavy duty Peerless differential is probably your best bet, to drive both rear wheels.

Voltage is determined by what motor you choose, and what gearing ratios you use from it to the wheels, vs the speed and acceleration you want.

The lower the voltage, the higher the current has to be for the same power, so the bigger the wires, controller, motor, etc.

1. Are the ebay or amazon chinese electric wheel motors at this point of development high enough quality to mess with or not?

Yes and no--it depends. Read around the forums to see people's results with various vendors and systems.

2. Who makes the most reasonably priced and reliable battery pack? I live in Florida so I am in a fairly hit humid climate.

There's no single answer to that, because you're probably going to have to build your own from large-format cells to give you the power you're after for the amount of range/operation time you're after.

There's lots of threads discussing various battery and cell vendors, good and bad, and everyone has their own opinions based on various factors.

3. How critical is it to have a solid axle without the wires coming out ofthw center of a hollow tube from a wire damage and an axle strength perspective?

For your speeds, I wouldn't use a hubmotor in the wheel, so you wouldn't have to worry about it.

But as one data point, I'm using two different kinds of hubmotors in my rear wheels on SB Cruiser (see my signature for thread full of data) that both just have a slot in part of the axle, and the rest of the axle is solid. No problems yet.

But these axles have been broken about as often as hollow axles, by various ES members, depending on their application. You can search on broken axles and find some posts and threads about that, and judge if it would matter for your application.

4. What about regenerative braking? Is it possible to have enough regen braking power to not have to put on disc brakes? Also different websites have information about how much benefit there actually is to the extension of battery charge/range with regen braking.

The charging isn't that big a deal, you might get a few percent at best.

But the braking advantage is huge; I can stop quickly with just the two rear motors' braking.

However, the disadvantages of a hubmotor wheel for your application are larger than the advantages, because it's kinda hard to find motors already wound to run at the speeds you want even if you had the tire on the spoke flanges to make the wheels tiny. (and smaller wheels will be harsher ride even with fatter tires, with the loads you're looking at, especially if there's any bumps, potholes, etc).

You'd want good mechanical (non-electric) brakes anyway in case of a power system failure, so you can stop just as well with either. It would suck to have a full load, the motor or battery or controller just suddenly dies (can happen, usually a wire problem) and then you have zero electric braking. What do you do then, if you don't have mechanical brakes that can stop you?

 

[LewTwo]

My thoughts are going to be contrary to everyone else's so call me the devil's advocate (or even the devil).

"I see the tricycle design pedicabs that have a 1000 watt motor on the front wheel ..."

There is a reason for that ... probably several. Replacing the front wheel with a motorized hub is less challenging than having to deal getting the modified gear train right especially when dealing with adding a mid mount motor in a trike. Secondly a front hub motor is sufficient for the task. At the low speeds and loads you are dealing with the biggest challenge is getting a hub motor with a low spend winding. The first thing I would do is check with EM3EV to see if they had something suitable (a 12T MAC in a 24 inch wheel comes to mind). As most of the load is on the rear, a front hub motor negates your concern about the "hollow" axle.

A thought on batteries: Many of us two wheelers are trying to get a battery with as much power as possible in the smallest lightest package. With the weight of the bike, 2-3 passengers, packages and driver the battery weight becomes less of a concern. You are looking for longevity and convenience (ability to swap packs). I would look at 36 volts with 17-20 Ahr (maybe a couple of them). An extra 10 pounds of battery is not going to make much difference.

Keep in mind you are talking about a pedi-cab not a Tuk-Tuk.

 

[amberwolf]

With the weight of the bike, 2-3 passengers, packages and driver the battery weight becomes less of a concern.
<snip>
Keep in mind you are talking about a pedi-cab not a Tuk-Tuk.

With 8 (eight) passengers (presumably plus driver and any packages they have), it's more like a Tuk-Tuk than a pedicab, for loading/power usage.

See quote of OP below:

custom pedicab build for a design that will be able to carry 8 people.

 

[LewTwo]

You are right ... I missed that detail
I have seen lots of pedicabs but never one designed to carry 8 passengers.
Then again I have also seen a family of six on a vespa that was barely designed for two.

 

[spinningmagnets]

The only motor I would recommend for this is a Lightning Rods big block at 48V. I can go into detail about each facet of this recommendation, if you like.

 

[dogman dan]

Sounds like job for a golf cart rear end, grafted to a bike somehow.

But if it's flat enough, then a huge hub motor, geared down like mad, should work. the hub motor will drive a second chain, going to a sprocket on the other side from the pedals.

Get my picture? you pedal a set of gears on one rear wheel, the other rear wheel independently driven by a huge motor geared very low.