Dual motor setup for cargo trike?

[Anonymous]

Hi all, first post. I've been doing bikes forever so i'e got a solid foundation of the basics, i used to build both gas and electric bikes years ago but i've been out of the loop lately and could use some hints for setting up a dual motor cargo trike.

I'm thinking of doing two 500w front hub motors (laced to motorcycle/moped rims) on either side wheels, but with the cargo trike configuration (two wheels up front, like a tadpole) i'll need to somewhat synchronize the motors to keep it tracking straight.

Are there any controllers on the market that can balance a two motor setup like this or do i have to do something else?

Would 'something else' be two separate controllers fed the same throttle signal, or would it be something like throttle/pas signal fed through a PID algorithm, or maybe hijacking the hall sensor signals with an arduino and spoofing the throttle/pas input?

An other ideas? I was considering a single rear hub motor but i'd rather have two motors for climbing torque,my trike is a food cart and i live in the mountains. I need to climb short, steep sections at low speed, like 5mph with pedal assist. I'm currently pedaling with 24/20 gearing and can get about 5mph at cadence. I plan to run a bank of 6 golf cart batteries charged from a 500-1000w solar array, so power supply won't be an issue.

Any suggestions? Thanks in advance, I'll post a pic of my cart from my phone as soon as it charges!

 

[Anonymous]

Here's the trike...
I'm going to do sandwiches, tacos, drinks, ice cream, and novelty stuff.

 

[999zip999]

https://bmsbattery.com/ebike-kit/607-s09pp-72v35a-1kw-torque-simulation-dual-driving-controller-ebike-kit.html this looks good.
Lead is dead. Get out of the cave and into the light. We rarely talk lead.
Where you located. ?
One rear muxus 3,000 motor 60- 72volts.
Welcome to E.S.

 

[flat tire]

Yes, get a lithium battery for sure. Lead is a waste of time and money, as in you already spent a bunch of money on e-bike stuff and now you're going to make your creation suck by weighing it down with awful batteries.

 

[Rassy]

Somewhere on the forum there is a tadpole trike with two hub motors on the front wheels. Worked out good using two controllers and one throttle. Okay, here's the thread:

https://endless-sphere.com/forums/viewtopic.php?f=2&t=35209

 

[Anonymous]

Hi all, thanks for the replies!

The lead acid bank is going to run the fridge, freezer, and other systems anyways, so i figure i'll just pull power from that rather than needing a separate system. I'm going to do a 750 to 1000 watt mppt solar array, i think a Li chemistry battery of that size is out of reach. I'm planning in doing 6- 6 volt 235ah golf cart batteries, which can withstand deep discharges and cycling better than Li.

I'll probably go with a small 6s lipo on my bike, but the cart is getting lead acid for appliances onboard.

I'm in Bisbee, AZ. It's a mile high and i get plenty of sun for solar.

So, assuming i've got batteries covered for a 36v system, is there a controller out there that will allow me to control two motors from a single throttle/pas signal or do i have to buy two controllers and build a circuit to sync rpm between them?

Rassy, thanks for the link, i'm going to check that out!

 

[flat tire]

You want to use one controller per motor.

 

[dogman dan]

Two identical motors, two identical controllers. One throttle can control both. The motors won't be synched, nor do you need it. You just need the same throttle signal fed to identical controllers, and you will power your motors evenly enough. Ideally, get two low rpm winding motors since you will be going so slow.

Your trike is the type that can use front hub motors too, btw. Most have a different kind of axle and cannot.

You can also opt to have regen braking on both motors, controlled by one push button on the handlebars. This would be good, because that's a lot of weight to stop with a rear coaster brake.

One larger rear motor is also a good option, but for that solution you will have to weld a disc brake mount to the frame, or the whole trike would have no brakes.

I can't see the bottom bracket on the bike,, if it's a square taper, or you weld a BB on to it for square taper, then you could opt for a very low geared mid drive. Again, some modifications to the bike, rear disc brake, and a derailleur for gear choices that are needed with mid drives. Mid drive could well be the best possible solution.

And dude,, golf cart batteries cannot stand deep cycling better than lithium. But if you get enough of them, and cycle them properly, preferably to 50% dod max, then they will last as long as they do on golf carts. Typically 18 holes cycles a cart to about 50-60%,,then they go back to the barn. It might be cheaper for you to do this initially, but you should consider lithium for the motors. Likely you want 48v for the motors, which may not be the voltage you need for the fridge.

 

[flat tire]

And dude,, golf cart batteries cannot stand deep cycling better than lithium.

Word...the SOLE advantage of those lead acids is they are less expensive in terms of cost up front. They are much worse batteries in every other respect. You live in the mountains, you probably want to ride more than a mile at a time, and weight kills. You can replace all 6 of those lead acid batteries with a lithium battery that weighs less than a single one and has BETTER performance...and your vehicle overall will have WAY better performance, especially climbing, because you have now eliminated a ton of weight.

Also, as far as everyone saying you can't go fast, well, it depends on how athletic you are but you can probably get that thing flung around pretty good depending on the wheelbase and cg. Try leaning your whole body off the trike.On a trike with food service stuff aero will limit you from going faster than the 20s with only 1000 watts so nothing too crazy will be going on anyway.

 

[MadRhino]

Just a hint: One big motor is better, simpler, easier, etc... than 2 small ones. :wink:

 

[flat tire]

Just a hint: One big motor is better, simpler, easier, etc... than 2 small ones. :wink:

In this case I don't think that's true. The hardest part will be splitting his battery off to the 2 controllers and splitting his throttle signal and that's simple. Otherwise he's just bolting in some hub motors, and he'll want two of them to prevent uneven thrust.

Explain how he would put in a single motor, and not have a compromised setup without doing a lot more work and going for a mid drive.

 

[e-beach]

Hi all, thanks for the replies!

The lead acid bank is going to run the fridge, freezer, and other systems anyways, so i figure i'll just pull power from that rather than needing a separate system. I'm going to do a 750 to 1000 watt mppt solar array, i think a Li chemistry battery of that size is out of reach. I'm planning in doing 6- 6 volt 235ah golf cart batteries, which can withstand deep discharges and cycling better than Li.

I'll probably go with a small 6s lipo on my bike, but the cart is getting lead acid for appliances onboard.
.........!

Funny how things go in cycles....I just posted this link for another guy who needed dual motor info. Check out this thread: https://endless-sphere.com/forums/viewtopic.php?f=2&t=33429

(Thank You King Fish)
Hint: check out page 3 for a wiring example.

So how much are those lead batteries weigh? 450lbs? And due to the nature of lead-acid you will only get about 1/2 the rated amp hours before the cells are effectively dead. And if you deep drain them every day, they will only last a year or so before they start loosing power. How do I know? My first e-bike ran on lead batteries. A year later I went to LiFePO4 and have been happy ever since. (well...except when I got hit by a car a couple of weeks ago. But that is a different story.)

So help us out here. How much do those lead batteries cost? How much do they weigh? What is your amp draw going to be. Give us numbers like you are not using your solar array. Maybe we can help with a cost breakdown to see if Li isn't out of reach.

 

[dogman dan]

Lowest cost per mile I ever saw on my ebikes was my first pingbattery lifepo4. But we'll never see prices like that again, that was when he was still using the V1 cells.

Cost out lead replaced every 2 years, and twice the Ah, vs three years for half as much.

At one point I was running lead,, and had a big hill to climb. I had 36v 12 ah, and got the bright idea to add another to have 48v 12 ah. Because of the extra 10 pounds on that hill, I actually ran out sooner than with 36v. That's how much every pound can matter on a hill. It did climb the hill real good though, on 48v. 8)

 

[MadRhino]

Just a hint: One big motor is better, simpler, easier, etc... than 2 small ones. :wink:

In this case I don't think that's true. The hardest part will be splitting his battery off to the 2 controllers and splitting his throttle signal and that's simple. Otherwise he's just bolting in some hub motors, and he'll want two of them to prevent uneven thrust.

Explain how he would put in a single motor, and not have a compromised setup without doing a lot more work and going for a mid drive.

It is a trike, the simple job is to put a single motor in the single wheel. A big motor in a small wheel, neat, simple and easy.

 

[e-beach]

It is a trike, the simple job is to put a single motor in the single wheel. A big motor in a small wheel, neat, simple and easy.

As long as it is a big motor because he wants to haul a lot of weight up that hill. 500lbs or more by the way he described it.

 

[Anonymous]

Okay, so two controllers? Nobody makes a dual drive setup yet? I'll start making my list.

What i really need to do is yards, not miles uphill. I need to be able to climb for up to 500 yards at a time around 4-5mph My whole sphere of operation is within a mile radius, but it's all hills. 20mph on this thing would be insane, it's not for speed, and there isn't a place i could even ride that fast. Once a week i might make a 2 mile shallow hill trip out to the farmers market. 10mph with this thing is about the top speed, and that's too fast for the uneven, potholed surface i've got to ride on. Pretend i have to weave througha maze of cones up and down hills with it, that's what i need. My stops are about 100 yards from each other. As for riding ability, i've been riding BMX, MTB, MX, and biketrials since '79, i can make a bike(or trike, quad, board or whatever) do whatever needs to be done, but i can't see myself making tight hairpin turns through a crowd and traffic at 20mph, hanging off and dragging a knee like it's a superbike race.

I DO want to get another one of these trikes and chop it , then put a recumbant style frame on the rear, make it low and sleek, with a body and a fighter jet style canopy, something like those new Polaris reverse trike motorcycles, but that's a whole different beast.

And weight, it's going to be heavy, that's kind of the point of it. If i were interested in keeping things light i'd ride it as is , right now i can pedal it around and carry food and drinks in ice coolers. By the time i'm done this thing is going to have gardens around it, box planters all the way around the bottom edge with herbs growing, using greywater from the sinks for irrigation, and as much other stuff as i can fit on it. It's about the aesthetic, not peak performance, it's basically all for the sake of street art and having fun. Part of that art is the fact that i'm basically going to have an entire restaurant on here, so i'll be at weight capacity no matter what and will be towing a trailer eventually. I'm working with my local health insprctor to get an entirely self sufficient working kitchen on wheels. It might even mean daisy-chaining another cargo trike on the rear.

I was even thinking of going with some kind of mid motor kit for each front so i can gear it down for more torque.

And batteries, i'd gladly buy Li if price wasn't an issue but it's not my only expense, i still need motors fridge, freezer, signage, solar equipment, health dept fees, and a stock of product and merch. Once i need new Pb batteries i'll be able to swap to Li, or whatever the best battery tech is by next year. The trike is rated for 250 kilos but with tougher rims i can up that. Another thing i'm considering is a propane fueled quiet generator on a trailer to suppliment power and basically work as a hybrid.

So you can call me crazy if you want, i know it's true,

 

[e-beach]

If you really want two motors I would consider at least 1000w per side. No reason to over heat a little 500w motor. And, the 1000w motors don't cost much more the the 500w motors. Geared hub could be a way to go unless the weight of your rig grinds the gears to sunder. Maybe a slow wind DD setup for the torque. 48v at least. Maybe 56v.

 

[Anonymous]

So, what would a replacement for a 36v Pb bank of my size look like in Li chemistry?

I need at least 120w continuously from the bank, 500 during business, and 1000 intermittent before I run the motors. Can Li do it reliably?

I'm not opposed to building a pack from cells if I can get the price down to something workable,, what cells are typical these days? Can I order a case of 18650's, match the cells and tab them together in series parallel?
Thanks again for all the input, I appreciate it!

 

[haulincolin]

Cheapest way to get a big chunk of Li battery without screwing around with potentially unreliable Chinese Lipo packs is to find someone selling parts from a scrapped electric car. I have 18s of lithium from a Chevy Volt on my big cargo bike. Just like this: http://www.ebay.com/itm/Li-ion-72vdc-50ah-3kwh-NEW-2015-VOLT-Batteries-EV-Electric-Car-Boat-Golf-Cart-/181947585813?hash=item2a5cebd515:g:zdUAAOSwrklVHpkT&vxp=mtr. >3kWh of excellent quality US-made cells for $850. You could probably find one cheaper if you checked around. The Volt cells are "conservatively" rated at something like 7c so it'll hardly notice 1000 W of draw.

 

[e-beach]

.........I need at least 120w continuously from the bank, 500 during business, and 1000 intermittent before I run the motors. Can Li do it reliably?.......

Yes all Li can do it reliably. The cost depends on your configuration.

How may volts is your inverter going to need. 12v? 24v?

Also, how many watts peak is the inverter.

Is the 500w continuous or total watts needed in a day?

 

[flat tire]

Look at the 18650-30Q from samsung. These cells will fulfill your power requirement without much of a sweat.

 

[dogman dan]

Ok, lets back up a bit, take a breath or two, and re think some stuff.

You weld, and are willing to make changes to the bike. At first, I was taking it as gospel, this is the trike I'm using, as is. It is a trike that could just have two front hub motors put on it, and that's still a viable approach.

But maybe another approach will be better, with a few mods to your frame.

1st, change the bottom bracket to one that takes a standard square taper bottom bracket. This is the size that a mid drive kit like the Bafang BBs02 will fit. Then, because it's a mid drive, you need lower gears in the back. Replace the back wheel with a regular MTB wheel, with low gears. But now you got no brakes, so while welding on the bike, add disc brake mounts to the frame in back.

Now you have good rear brakes, low gears, and a motor setup that is designed from the start to grind up hills at 5 mph.

Re the batteries again, it might be a good idea for you to power up with a tiny generator, using it to charge batteries that run your motor and your freezer. You can always de power the freezer when in motion to lower the total load a bit too. then your battery size, weight, and cost can be more tolerable.

 

[Anonymous]

Hi sorry I haven't had much time to respond but my laptop has been down and I've been having to do everything through my phone. I've also been busy getting the cart ready for this weekend, I'm going to open.

I'm not a big fan of big motor kits installed quite a bit of them and they don't seem like they have a lot of drag in the Driveline doing it that way. The bottom bracket can be anything I need it to be its BMX sized shell but I can put a euro convertor into it. If I was going to run a mid motor setup I'd rather just get 2 of them and put them on the front wheels rather than pollute the pedal drive line with that friction and complexity. I need to run a fat chain on the back and most of those dual sprockets for Mid drive up front would probably interfere with them

.
After this weekend is over hopefully I will be able to fix my laptop and do some more research. Thanks for all the ideas!

 

[amberwolf]

Honestly, if you are only moving a few (dozen) yards at a time, and need slow speeds and a lot of torque, you could use a pair of brushed powerchair motors, and even just a big pushbutton switch and relay at 12V (or 24v if you put the motors in series) would probably do just fine. 24v on each motor if you needed more torque and speed. Brushed controller (with motors in series so you don't need two controllers) if you need actual throttle/speed control.


You could either use the original wheels off the powerchair and friction-drive your front wheels with them (tire to tire) or leave the wheels off and use the hubs to mount chaindrive or beltdrive sprockets on, and mount corresponding ones on the trike's front wheels.


Many of the powerchair motors have a mechanical clutch in the gearbox to disconnect it from the motor, so you aren't backdriving the motor and most of the gearing when pedalling without power, if you chaindrive it.

If you friction-drive it you can mount them on a slide with a latch so you can release the wheels from each other when just pedalling without power.

 

[dogman dan]

Silly me,, thinking changeable gears and mid drive might help such a trike.

I could try to sell you lower rpm direct drive motors for the front, but I thought the mid drive would be better for that much weight, and that slow speed. A stokemonkey type mid drive might be ideal in fact. Put the sprocket for that on the left, and you could leave your original gears and chain intact. Just change the right hand front sprocket size to make the thing gear even lower if needed.

In any case, your new twin hubmotors will have disc mounts, so put some disc brake mounts on those front forks. With the hubs, you'll end up going faster than you have been planning on.