Human electric hybrid work bicycle.
 

My neighbor had a Toyota truck that he sold for parts due to extensive structural frame rust and we have the goal of building a better option to haul stuff around town, the hauling needs include hauling lumber, compost, dirt and other stuff common with owning a house and having a garden, for really heavy hauling there are other people around town that have pickup trucks but for the light hauling of lumber and compost we are thinking that a bicycle with a trailer should work great!
To make hauling longer distances easier the bicycle is going to be outfitted with a Crystalite Cruser hub motor, a 36v 40a speed controller, a 20amp hour lithium battery and it will all be mounted on a bicycle with an extra cycle frame extender that makes the bicycle about 2 feet longer with a huge rear rack/deck and canvas saddle bags, add to that what will most likely be a home made trailer altho I do have a burly bicycle trailer that is already used from time to time by a bunch of us in the neighborhood.

I really like the Bikes At Work bike trailers but $700 for a trailer seems like a lot so I came up with an idea that I have yet to build using square tubing that nests so we can make sections that slip together and get pinned keep it allowing for the whole thing to come apart quickly, the trailer to be shortened or have more added on or to even have a long center beam added in to haul long lumber or a canoe.

Other add on idea for the trailer is a set of lead acid batteries for the long hauls, my thought there is to have the batteries built in to a trailer section that they stay strapped down to, set it on a rolling platform when not in use then connect it to the wheels and hitch when you want to use it.

I already have the electric drive train, battery, controller and charger.
My neighbor has the bicycle and extra cycle.
I have a welder, use of a milling machine, lathes, welder, brazing torch.

I'm hoping that as soon as the weather gets warmer we can start on this project, we both bike in the winter and I really like the idea of having a human powered vehicle that replaces a truck.

I know that these motors do ok towing small loads, 100 to 200 pounds, but I'm not sure about 500+ pounds so I'm planing to pull the side plate off the motor and epoxy in a thermocouple so we can track how hot the motor is getting, I already have some nice fine wire thermocouples and a hand held reader, much cheaper then you might think!

Once it's all together I'd also like to see how it does heat wise for long distance riding, I'm thinking a 36v 200 amp hour lead acid battery pack of batteries that I already have will give it a decent range, maybe 150 to 200 miles, but I don't know if the motor can dissipate that much heat.

Aren't the batteries themselves a couple hundred pounds? I used to work with 96Ahr lead acids and they were over 60 pounds each.

If the motor could handle it I'd get a controller that could handle at least 48 volts to lower the current draw.

JJ

I know the 48V kit I have can pull along 400lbs... but according to the OEM that is the limit. The e-bike I tried before starting my current project had four 12V 18ah batteries. The batteries themselves weighed 52 lbs. I know that doesn't sound like a lot but the bike itself weighed about 60lbs... With a 180lb rider and a few bike accessories you are chugging along with over 300lbs!

A friend of mine built a box bike that I thought would be a perfect candidate for electrification.
Along these lines:
http://ic.pics.livejournal.com/behoo...326048_600.jpg

6 T105 golf cart batteries weigh around 400 pounds and would give 150+ miles of range, I also already have those batteries.
The 20 amp hour 36v lithium battery is around 20 pounds and is a great size to have on the bike.
I agree that going with a higher voltage is a good idea because at 20mph the motor is seeing the same voltage no matter what the pack voltage is, but right now I have the 36v controller and I could use the money so I'm giving my neighbor a great price!

The motor it's self is designed to handle up to 72v and there are people using them with 96v controllers and a few who are using them with over 100v.
There is also someone on EV albums who has a side by side tandom recumbent with solar panels on top, that bike weighs 320 pounds and they said they have space for 100 pounds of cargo, so around 800 pounds total pushed around by the same hub motor.

Heat is what really kills motors and I plan to put a thermocouple inside the motor on the windings, because they are what is going to get hot first.

I really like the design of some of the cargo bikes, but one goal here is to be able to haul 8 foot and longer lumber and dirt, for stuff like that a trailer just seems more practical, move the weight away from the bike and keep it low to the ground.

What dies when the heat gets too high? Is it an "over time" thing, where too many amps over a period of time cause something to degrade quicker than normal, or is it something that happens quickly?

There can be a number of problems. Lacquer can be burned off the copper coil windings causing shorts. Epoxies can let loose say from the internal magnets. Too hot and even the insulation can melt. Bearings can wear more rapidly. I'm sure there are a few I've left out.
JJ

A 20" rim could be laced onto the hubmotor if it would benefit from a lower "gear".

This is a brushless motor, so it's pretty much down to the varnish on the motor windings and the other insulation and glues that hold it all together and keep everything from shorting out, each grade of varnish has a heat rating where that varnish should last for 10,000 hours or more at or below the rated temp, as you go higher the life is cut back, I think I read every 10 degrees above rated temp cuts the motor life in half, class H motor insulation is good for 180c while class A is only good for 105c if I remember right.

On motors with brushes, the brushes and commutator are the weak points, brushes break down with heat and the commutator has insulation and glue that break down with heat.

So yes, it's both time and heat, more heat and insulation doesn't last as long so the motor doesn't last as long or "burns up" in the case of a saw that I was using at work, blue flames shoot out when the last of the insulation burned off, but I could also see the heat damage on the brushes and commutator and could clearly see that it was under a lot of stress, cheap motor tho and that tool we run till it burns out so I kept running it and it burned out.