new member introduction/plus-size cargo trikes

[murdock4905]

hello
I'm the fleet mechanic for a delivery company that uses electric motor-assisted cargo trikes. I'm trying to put together a new system that replaces our old SLA/Brushed arrangement with 36-48V Lithium batteries and a BLDC motor, but choosing the right type of motor is proving to be harder than I thought. I want to use a brushless motor, but I have somewhat limited gear-reduction options, so I need to find a motor that runs at relatively low RPM, high torque, with no brushes to maintain.

I've read that series-wound motors are designed for this, but are they all brushed? Many EV conversions use a synchronous motor, but from what I've read they seem to be intended more for stationary use (like running a pump or some other kind of equipment) or high RPM/speed applications. I'm having trouble keeping track of all the variations (series-wound, compound-wound, synchronous, PMAC, PMDC, sepex, etc.) and their attributes/benefits.

Can someone help me to understand the primary differences between all these types? Our vehicle is quite heavy (500lb. empty, up to 800lb. payload, plus rider weight), but top speed is not a priority (10-15 mph ideally). There are more details, of course, but I'm trying to keep this post short... :?

thanks

 

[gestalt]

Great looking grime frame! Looks kind of like a mainstreet pedicab, but the differential looks way different or maybe some kind of cover. To get something that is comparable to the Agni motor you have in there you might want something like a MARS motor, or one of golden motors 5kw or 10kw motors. I like the setup on yours how it is save for the lead acid, I don't like pulling the 12ah sla's that we use for lighting on our cabs all day, I can imagine I would loath that big deep cycle even more.

A question I have for you is how do your riders use the electric assist on a regular basis? I've been thinking a lit about how to engineer a assist for pedicabs that wasn't the usual front hub motor routine. That battery you have I wouldn't think could power the trike loaded up for all to far, but if you wanted more range you sacrifice cargo space. You could cut your losses a bit space and weight wise if you went with lipo. In an average shift I pedal probably 30-50 miles and sometimes more, so I couldn't conceivably put a battery in a cab to power the trike all of those miles, but it could be used as a hill helper. There is a big hill separating the two halves of downtown and it makes me hesitant to take cross town rides. If I could just get over heartbreak hill with maybe half the effort it would make a huge difference. I don't know if where your comPany is located has many hills or is mostly flat. That would probably make a big difference in how you want to mod your cargo trikes.

And if you do start swapping out your system, any chance I could have first crack at buying one of the old motor/controller combos off of you?

 

[murdock4905]

O yes, the grime...the trikes are Cycles Maximus, made in the UK. They're typically used as pedicabs, and I'm pretty sure they're the most high-class platform out there for that sort of thing (not trolling!), but we modify them to fit a huge insulated cargo container for inner-city light-freight purposes. The "factory option" motor-assist kit is decent but crude/heavy, and I'd like to replace it with something more efficient.

 

[LI-ghtcycle]

Now that is one beefy frame!

I'm guessing that frame alone breaks the scales over 100lbs?

For the weights you are talking about there are a couple motors I would think would work, but I have not the experience with such a heavy set-up.

I have electrified a Chinese Pedicab with a brushed 600W motor running at 48V, however, I don't believe it would be quite up to the task of 800lbs with any real range.

Golden Motor has a few here that I would check out and see about matching the specs of your current motor:

http://www.goldenmotor.com/

I don't know the specific specs of your current brushed motor, but I imagine that you are running low voltage (12 or 24v?) and that is common for your application, however, I would think with the right gearing, a 48V Lithium Iron battery would be much, much lighter and efficient.

The real big question however, is how complex you want to go, and if you are willing to use a form of transmission (assuming you don't already, can't tell from the picture) then you can increase your range 3 times.

Check out the bike build at the bottom of my signature and you will see how I set up a smaller "800 Watt" brushless BLDC pedicab motor on my bike with a NuVinchi rear hub for transmission, and you can see how the concept I am describing works.

I would think that with the 48 ft/lbs of torque the NuVinci can handle would be more than enough for your application, but I haven't tried an industrial grade cargo bike with it, so I would have to defer to some one who has, but I would call Fallbrook Tech (the manufacturer) and ask, I understand that the hub was originally designed with LEV's in mind, and later designed to work with bikes to get a practical test bed while selling their product at the same time.

 

[LI-ghtcycle]

oh, and here is a link to the performance curves:

http://www.goldenmotor.com/eCar/HPM5000B-4x48 Performance Curve.pdf

 

[murdock4905]

thanks for the reply,

I've been looking at the Motenergy/Mars motors, they're very affordable and relatively local (this continent).

Of course there are many sites dedicated to electric conversions for bicycles, but the weights I'm talking about are pretty steep - way beyond the typical eBike - so I'm kind of in between the bicycle world and the motorcycle/golf cart/LEV world.

Which pedicab outfit are you with? There'a a Boston-based company running CM tries that I've had contact with...

 

[gestalt]

Interesting, I have never ridden one of those, but I saw a couple while I was in NYC. You might be right about the high class bit, but I have always liked mainstreet for how they are light weight (compared to a Charlestown) And how parts are available from the manufacturer in the US. They do a bit too much of that proprietary BS with some of their parts, mostly it's the hubs that are a pain to pay so much for. Mostly lime working on a bicycle though, quite easy.

I've also thought that the Most light weight way to electrify one would be to replace the mid drive with a hub motor. It would require quite a bit of frame modification though. But with your trikes already having drive system set up it probably wouldnt make any sense to do something like that.

I work with Boston pedicab right now but have only been working with them for a few months. I worked for Boston rickshaw for about three years previous to joining up with BP. Honestly I liked working for the small company better because I always root for the underdog, but when the owner started taking aderol he became a total asshat and impossible to work with. So I switched over to the big company for the sake of my sanity, perhaps at the cost of my zsoul...who knows. I'm working with a bicycle manufacturer here in beantown on a new pedicab design that would hopefully blow all others out of the water. It would not be such a problem to use the hub motor mid drive system if you were building a trike from the ground up. Here in Boston there are laws against using an assist on a pedicab, but I think there might be room to change that sometime in the future and it sure would be nice to be able to just swap the bicycle midrive with a hubbie.

I actually have one of those golden motor HPM5000-B units just taking up space. Maybe we could work out some kind of trade.

 

[LI-ghtcycle]

Interesting, I have never ridden one of those, but I saw a couple while I was in NYC. You might be right about the high class bit, but I have always liked mainstreet for how they are light weight (compared to a Charlestown) And how parts are available from the manufacturer in the US. They do a bit too much of that proprietary BS with some of their parts, mostly it's the hubs that are a pain to pay so much for. Mostly lime working on a bicycle though, quite easy.

I've also thought that the Most light weight way to electrify one would be to replace the mid drive with a hub motor. It would require quite a bit of frame modification though. But with your trikes already having drive system set up it probably wouldnt make any sense to do something like that.

I work with Boston pedicab right now but have only been working with them for a few months. I worked for Boston rickshaw for about three years previous to joining up with BP. Honestly I liked working for the small company better because I always root for the underdog, but when the owner started taking aderol he became a total asshat and impossible to work with. So I switched over to the big company for the sake of my sanity, perhaps at the cost of my zsoul...who knows. I'm working with a bicycle manufacturer here in beantown on a new pedicab design that would hopefully blow all others out of the water. It would not be such a problem to use the hub motor mid drive system if you were building a trike from the ground up. Here in Boston there are laws against using an assist on a pedicab, but I think there might be room to change that sometime in the future and it sure would be nice to be able to just swap the bicycle midrive with a hubbie.

I actually have one of those golden motor HPM5000-B units just taking up space. Maybe we could work out some kind of trade.

I'm really curious about this motor, have you done much testing with it? I've been eyeing it for a while, thinking it could be possibly the "big brother" to the one I am using right now:

I've just started a E-Bike medium to light cargo delivery business, and would like to know if that motor performs well at the low to mid power range, say 20 MPH and lower.

I'm also thinking it would be really hard to beat the mars for your application murdock, since it's such a high load you are working with, however, the Golden Motor looks pretty interesting too.

 

[gestalt]

There are videos on YouTube I believe posted by golden motor with this motor powering an enclosed recumbent pedicab moving along quite well with passengers and all on a dirt road.

I have done no testing, besides poking around the insides and taking pictures. The motor seemed like too much for a bicycle frame so I went with another motor. But then ol' cool hand Luke shows up and shows me I was quite mistaken. Even upped it to the 10kw.

 

[voicecoils]

...I'm trying to put together a new system that replaces our old SLA/Brushed arrangement with 36-48V Lithium batteries and a BLDC motor, but choosing the right type of motor is proving to be harder than I thought. I want to use a brushless motor, but I have somewhat limited gear-reduction options, so I need to find a motor that runs at relatively low RPM, high torque, with no brushes to maintain.

Do you have the existing motor model number handy? What are the specs on the existing battery setup? (voltage & amp-hours)

It looks like an Agni, and they are actually one of the best motors available (brushed or brushless) in terms of efficiency and power to weight. If the motor is not abused, the brushes should last quite a long time.

If you're currently running the pedicabs with a 24v or 48v setup, you could get a big performance boost by changing to a lithium 60v or 72v battery pack and gearing the motor down more. That would keep the vehicle speeds low but allow the motor to spin faster and develop more power.

It could take a lot of money and a heap of time to get a brushless system with even equal reliability, power and efficiency to a well set up Agni 95R drivetrain.

 

[LI-ghtcycle]

There are videos on YouTube I believe posted by golden motor with this motor powering an enclosed recumbent pedicab moving along quite well with passengers and all on a dirt road.

I have done no testing, besides poking around the insides and taking pictures. The motor seemed like too much for a bicycle frame so I went with another motor. But then ol' cool hand Luke shows up and shows me I was quite mistaken. Even upped it to the 10kw.

Yeah, it's pretty fun to see the amazing stuff he puts together!

I chatted with Luke a while back about this same motor and his advice to me was to just over-volt the motor I have at least for a high-speed exhibition bike motor, because he was seeing even 420 motorcycle chain get destroyed by the motor you have now at high volts! :lol:

I'm not quite ready for the extreme end of E-Biking and controllers that require more than my experience to operate. :wink:

 

[parabellum]

Right, changing batteries will be at least half way to the success. Agni motors are very efficient AFAIK, only downside, brushes. BLDC setup (mostly controllers) is very tricky and needs some experimentation and testing at least in your application visiting short duty cycle BLDC nightmare boundaries.

 

[gogo]

Just curious, how often are you replacing brushes?

 

[John in CR]

He doesn't need the high power of a Mars or Agni. All the gentleman needs is a hubmotor run as a mid drive. Near silence, very little gear reduction, and since the bearings won't see the loads they would with in wheel use, a good motor will need zero maintenance over years of use as long as you don't allow water to follow the wires into the motor, including inside the insulation. Leave freewheels out of the equation for regen braking, which drastically reduces brake maintenance too. For fleet use where big power and speed isn't needed, it's really a no-brainer choice.

 

[murdock4905]

using a hub motor as the mid-drive was my first idea too, it makes a lot of sense, but I disagree about the power requirements. The combined weight of the vehicle (with 80 pound battery), maximum payload, and rider is almost 1500 pounds - The Lynch/Agni setup that I need to replace is barely adequate (based on subjective performance):
With an Odyssey PC-2150 12V SLA battery and Curtis 1204 controller (275 max amp), we have a useable range of less than 10 miles, averaging <10mph.
Unfortunately the Lynch motor has no model designation or rating on it; the badge is blank, and I've not been able to get a response from either Lynch (LEMCO) or Cycles Maximus (they've been in between owners for more than a year).
I'd like to find a way to measure the actual performance of the existing motor, so that I have something to compare. What about a Cycle Analyst? I have one that is being used on another trike running a 36V system, can they be used on a 12V with that much current?

 

[LI-ghtcycle]

Depends on the current, but I think you have already answered your own question.

If you are running on 12V, that is your real problem IMHO, because most of these motors don't see a real efficiency gain until they are run at 36V, and then they peak in efficiency closer to 48V.

Rather than get a high current model of Cycle Analyst, I would get a different controller that is programmable, and then try at 24V and see how much more range you get, even at 24V using your existing set-up, I be you would see a 20%+ efficiency increase giving you closer to 15- 20 miles with adding a second 12V battery if your controller allows.

The other part of the equation is your controller. I am not terribly familiar with the Agni motors, but I imagine there controllers that work even with brushed systems that are more efficient than others, and that might be all you really need.

As far as a high current Cycle Analyst, they do make them, but not sure how high on the amps your are drawing, I would imagine in excess of 250A peak, and close to 100 - 150 continuous to move that kind of weight.

Here is a link to the high current CA:

http://www.ebikes.ca/drainbrain.shtml

And add this shunt:

And you're set for 250A constant, and 800A peak, but personally, if you're going to spend money on a CA, I would just get a standard one and run a more efficient voltage, that IMHO will save you money in the long run, and will allow you to up-grade with a brushless set-up with a newer motor.

I have built up a Chinese Pedicab (not one just made in China, but one that is hand-built locally for those who use them IN China) and they are using a brushed 600W motor at 48V and 20 amps about this size here:

I know it sounds crazy that a smaller motor would handle those loads, but I can tell you with absolute certainty that they can and do on a daily basis in China.

Your difficulty is more a symptom of inefficiency rather than anything else. When you are running any DC motor at 12V and lugging around that kind of weight, you're going to be extremely inefficient, since running so much more power in amps than volts, approximately 50+% of your battery power is going into waste heat, and when you are running that inefficient, you absolutely do need a large motor like that Agni to keep from burning up since it would smoke anything with less beefy stator to get rid of the waste heat.

 

[murdock4905]

Your difficulty is more a symptom of inefficiency rather than anything else. When you are running any DC motor at 12V and lugging around that kind of weight, you're going to be extremely inefficient, since running so much more power in amps than volts, approximately 50+% of your battery power is going into waste heat, and when you are running that inefficient, you absolutely do need a large motor like that Agni to keep from burning up since it would smoke anything with less beefy stator to get rid of the waste heat.

thats exactly what I thought...

 

[amberwolf]

With an Odyssey PC-2150 12V SLA battery and Curtis 1204 controller (275 max amp), we have a useable range of less than 10 miles, averaging <10mph.

The two problems with that setup that cause you (probably lots) of inefficiency are:
--SLA
--12V
Probably in that order.

At the currents you are probably pulling (hundreds of amps? at least at startup), the SLA is likely to give you maybe half it's rated capacity (100Ah), if that, and that's assuming you run it down to 100% DOD, which is likely to greatly shorten their lifespan. You'd have to actually test with a wattmeter to find out the real usage, but I'd guess that you are drawing >50A most of the time, and way more than that at startup (probably only limited by the Curtis' internal limiter, after it has time to react).

Changing battery systems also probably means changing chargers and power monitoring on the vehicle, too, so you'd need to factor that into the cost. But changing to almost any other battery chemistry would likely double your range for the same rated capacity, and possibly halve the weight of the battery. But that also depends on the system voltage and current draw, because some chemistries would do a lot better at lower current draw and higher voltage. (well, really any would but some are much less of a problem at the opposite).


At 12V, as pointed out above, you'll be pulling pretty high currents all the time. Agnis can be run at at least 48V, probably a lot higher, without an issue. You might need to advance the timing to get best performance out of it, but it's brush holder is rotatable, AFAICR, to easily do that. There is a thread here in the motor tech section on ES showing the disassembly/etc. of one, with a fair bit of technical info. I think it was by Jozzer.

If you run it at even just 24V, you could cut your current draw in half, which will both decrease the wasted power as heat (whcih decreases efficiency more by increasing resistance), *and* probably increase the useful capacity of the SLA by at least a little bit (plus, if you use two of the same capacity/size SLA that you are using now, you'd be doubling the range anyway).

You would need to re-gear the motor-to-drivetrain connection, as the ratio will be wrong for higher voltages with the same motor, since it should about double in speed for doulbe the voltage, etc. So the motor end of the connection would need to go to 1/2 the size, or the drivetrain end doulbe in size, or some compromise between the two that gives you the right ratio to keep the drivetrain RPM the same when the motor RPM doubles.

The Curtis 1204 has several models, some of which can run higher voltage than others. I have a 48V capable version here, and I suspect that yours can run at that voltage too, but that it's LVC is setup for a 12V system, so it will not protect your batteries from overdischarge if you run a higher voltage system. You would need to ensure the operator of the vehicle is notified of low-voltage condition, and does whatever is needed to keep from pushing the battery harder at that point, or put in a actual low-voltage cutoff that automatically disconnects the throttle from the controller or similar. (easy enough to do).


All that said, you can probably get even better efficiency by changing over to a brushless motor setup, but that would require changing out your entire motor, controller, and battery setup.

If you can, you might want to just experiment on one vehicle with a 24V or higher system (I'd go 48V, at least), and see how things work out. Before doing it, use something like the Cycle Analyst to determine your present efficiency and usage, so you have something to compare to.

 

[murdock4905]

thanks for the thorough reply,

any thoughts on brushless vs. brushed? I've seen motors like the Mars/Motenergy ME4201 thats designed for lower speed/higher torque, which is a brushless DC synchronous motor. This sounds like what would work best to me, I need something to help get the thing moving from a dead stop or on an incline, not for speed.

Any advantages to a brushed motor? I'd rather avoid the maintenance issue of brushes...

 

[amberwolf]

Only advantage to brushed I can think of is that the controller can be exremely simple (even just a switch, or set of contactors to connect more batteries in series), vs a brushless controller, which is fairly complex. But that same advantage is also a disadvantage, in that if the controller fails, it will often fail shorted (welded switches, blown FETs) and you end up stuck at full throttle.


In most cases a brushless setup will be more efficient and have less service to do, as long as you get reliable stuff to start with--but that can get expensive, if you are going to go for stuff just barely rated for your uses. If you make sure to over-spec everything enough (25-50%) then it's pretty likely to end up quite durable, as long as it was reasonable quality to begin with.

There are several variations on the Mars motors, so you just need to get the one spec'd for your load/gearing/speed. I'd recommend getting some sort of wattmeter like the Cycle Analyst to use on your existing system first to find out what usage you already have, max power levels, etc., and then go with something that can handle at least that much.


Keep in mind that the amps you see on such a meter will be the battery amps, and not the motor coil amps, which can be much greater depending on exactly what the motor is doing and how the controller is sending the power at any one instant. For more info on that, http://4qdtec.com/pwm-01.html has some pretty good starter info, which is for brushed motors but also applies to single phases of a multiphase brushless motor.