Equivalent rated Brushless motor to my modded motor?

[flyingbeekeeper]

I've got an old 600W Wilderness Energy kit motor (AOTEMA) that I put into a bike. It ran fine for a few years but then I tweeked the bike this year.
Designed for 36V SLA, I bumped the voltage up to 48V LiFePo. Modded the controller to put out signal to a Cycle Analyst.

I've been doing some long multi day rides with it. I've put 1000 miles on this motor and know I need a little more oopf on hills, some I can't climb all out 30A and peddling hard. I live in Texas hill country, and these hills have some nasty gradients...like 20% in some places. So I want more hill-climbing power, but I don't know what the equivalent of my current brushed motor is in brushless terms. I'd hate to buy a new motor that has less hill-climbing power than my current one.

At this point, basic math says I have a (48/36)600 = 800 W hub motor. So what is the equivalent motor in Brushless? Just to get a ballpark idea of where to start so I can get a little more torque.

 

[Drunkskunk]

Austin hills are fun. I found one that hit 31% grade. sadly they look flat on video. https://www.youtube.com/watch?v=ZzAsLGhC7TE

The brushed Aetoma motors best converts to the brushless version of the same thing. Crystalyte and Wilderness Energy both made the same size and spec motor but called it a 500 watt, and that's a little closer to what the Aetoma motors actually were. Sadly those motors aren't made anymore. But newer motors are even better.

The specs they gave weren't it's total output, but rather it's nominal output at 100% duty cycle. In other words, it could put out 600w (500w) for hour after hour without overheating. It could pump out a huge amount more power for short periods of time, or a little more power for a long but not indefinite time. I have a brushless version of that motor that can pump out 3000 watts for a moment, and sustain 1000 watts output for longer than my largest battery would last. It's still a 500 watt motor.

Virtually any 500 watt motor made will have the same power as what you have now. The 9C/MXUS/GM 901 clones are all about the equivalency of that motor, though a bit more advanced. A little more torque, more efficiency, better cooling. But you also have a lot more options now. For example, a Geared motor like a MAC V4 would pull up the hills even better. You could also look at motors like the 1000 watt Ebay cheapys, or the Clyte HT3525 if you want to go for more power.

 

[flyingbeekeeper]

Well, I'm not sure on equivalancy here. If it is a 500W motor at 36V, is it really a 500W motor at 48V? It definitely goes faster, seems to have more torque. Am I simply running it at higher watts at that point? Well, yea. I push 1500W into it when I'm climbing hills.

Some of those hills are way brutal. And I built an ebike because I hate pedaling up hills.

What I don't want to have happen is upgrade to a bigger motor and *still* not be able to go up the damn hills. So if I go to a 800 W motor and push 2000W into it for 60 seconds can I make those hills or do I need to go with a 1000W motor and push 3000W for a minute?

 

[Drunkskunk]

Changing the voltage doesn't change the motor's rating. The power rating is based on the motor's design, and independent of voltage.

The best answer for those hills is to fit the biggest, most powerful motor you can afford, and afford the batteries to power. Or the biggest you can put up with. My 5000w motor pushing out 10,000 watts peak handled Beauford blvd just fine. But that's overkill. You can do them on less.

Try this motor simulate here: http://www.ebikes.ca/tools/simulator.html
Try the Clyte HT3525 for an example. Set it at at 66 volts, a 40A controller, and the slider over to a 20% grade. That's a very big motor and will do the hill at 9.5mph, and can manage that output for 4.9 minutes before overheating.

 

[amberwolf]

You could just *add* another motor in the other wheel, and just use it when you need the extra power.

If you use a geared motor, generally those are freewheeling when not under power, so don't add much drag to the vehicle when not being used. They don't put out as much power for as long as a Direct Drive (DD) hub, but this one wouldn't need to--you could easily use a 300-500w-rated geared hub to give you enough extra push to make the hills, as long as you ensure it's wound for the speed you want out of it under the loads it'd be under, at the pack voltage you'd use.


FWIW, I use two DD hubs on my bike and my trike, and it much more than doubles my acceleration from a stop (and if I did any hillclimbing it'd also do similar help with that).

I only really use one motor once I'm past the acceleration phase, but having two also means that if I know I'm pushing one of them pretty hard pulling heavy loads in the summer heat, I can trade off using one and then the other to spread the heat between them and let one cool off, or I can just use both (harder to do to get the load even between them).

 

[flyingbeekeeper]

I'm not hip to add another motor. I've got much greater interest at building a new recumbant ebike with full suspension before I do that. However, I was going to wear out this brushed motor first. But I so hate those hills that I may upgrade early to a torque-ier motor. I really want to tour a thousand miles across the central US without having to huff puff pedal up hills.

My battery is a sunthing 48v 50A capable battery. I don't want to have to buy another one, so the upgrade motor must be 48v capable.

 

[amberwolf]

All the *motors* are capable, the controller is your limiting factor.

Teh thing about a motor is taht you need to be sure you pick one that's wound for the speed you want at the voltage you'd give it--meaning, at full throttle on your battery pack, does it give you the speed you're after in the situations you want?


If you look at the http://ebikes.ca/simulator you can check out different motors, controllers, and batteries, setting up systems and comparing them to each other, under the speeds and loads you're expecting, to get an idea if they will work for you.



BTW: if you're buying another motor and controller anyway, then as long as it is not using the same end of teh bike the present motor is on, there's not much reason not to put it on there at the same time. (it adds a few pounds of weight, but it's own capabilities outweigh that, usually).

Not that you have to do it...just sayin'.

It takes a little bit to learn to use it, but there is info there and in a few ES members' posts (like Teklektik) that detail exactly what to do with it. I'm not expert enough; I just poke at it with the motors/etc I already have to see what they might do under certain conditions.

 

[wesnewell]

Any of these will provide a lot more power than what you have and be more efficient too.
http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=48v1000w%20rear&LH_PrefLoc=1

 

[Triketech]

Austin has a lot of short steep hills, we've done a good bit of riding there ourselves over the years, sans power assist.

The trouble with direct drive motors (DD) is if you need to start up a steep hill from a stop or low speed, be prepared to pedal. At low speeds DD motors aren't at their best. True you can go with a larger motor, but you'll still be throwing watts to the wind at low speeds. The good news is on the roller coaster terrain you can be in regen mode more, but its not very likely that you'll ever recapture the lost watts of a DD over the higher efficiency that you'll see with a geared motor. DD motor does make a nice downhill brake.

If you're considering a recumbent a couple things to know:

The forward position of the pedals limit the hillclimbing ability. Lots of theories on why, I've got my own, but the point is they need more boost up hills, and typically are already rear biased on weight. You must clip on to pedals or risk your foot slipping off the pedal. It takes a bit of practice to ride a 2 wheel recumbent, once that's mastered it rides pretty nice.

Mid drives are a bit funky to mount on a recumbent; not so bad on a trike, not so good on a bike. As the boom of a recumbent is cantilevered it needs to be stout for a mid drive, else the boom will bend a bit under load. Look at the length of the boom and tube diameter. Most recumbent bikes tend to have a large angle >20° at the chain idler to the rear wheel, which really stresses the idler for a mid drive.

A geared motor like the MAC would generally be a pretty good option for a 2 wheel recumbent on short steep hills like in the Hill country.

I've got a handful of motors I've recently ordered to see what would work best on a trike in the Arizona mountains. The two best options for me are the MAC and BBS02, both of which I have new but its looking like only one will actually ever get mounted. Both provide adequate power for hill climbs.

Visit Easy Street Recumbents in Austin. Mike Librik is widely renowned among recumbent riders as a great guy to deal with.

 

[flyingbeekeeper]

Austin hills are fun. I found one that hit 31% grade. sadly they look flat on video. https://www.youtube.com/watch?v=ZzAsLGhC7TE

Holy Shit, Drunkskunk, I rode both Jester (14% grade) and Beauford today on my little Huffy Hauler. OMFG I didn't make it halfway up before I had to lay the bike down and flop on my back to recover from the exertion. Two people stopped and asked if I was OK. I was afraid I might be having a heart attack coming on and I reflected that it wasn't such a bad place to die given the view. But I had to push my bike up the rest of the way. Jester I was doing tolerable until the constant 35 amps melted my battery connector (bad designed connector that comes with sunthing batteries).

How the hell did you build a bike that can take on the bastard Beauford road? Holy shit that is one ugly hill. I feel like a man that at least I cleanly made it up 1/3 the hill.

 

[Drunkskunk]

I feel your pain. I tried to pedal up Jester for fun. That was a huge mistake.

That bike's running a Crystalyte 5404 motor pumping out 10,000watts peak. it's a bike I built in part to race Pike's Peak. It can climb a little.

I'm assuming you got that 14% from Mapmyride, because it gave me the same numbers if I put the beginning and end points at the base and top of the hill. However, if you move the points closer, you get a different result. Helpful on hills that change grade many times in a short run like that. Here's my results: Jester, Beauford
However, I wasn't relying on that. I have a phone app called Clinometer. Android , iTunes It's a great app, and came in handy down there in Austin. I set that on the road in several places and came up with the results.