Maximum current for Turnigy 80-100

[LHelge]

I've built an electric moped by replacing the ICE with a Turnigy 80-100 on an old Puch Maxi.

Moped

Motor

Drivetrain

The motor is fitted with SS411A hall sensors and rewinded with double strands of 1.5 mm copper wire for 90 rpm/V. I use a Lyen 12 x IRFB3077 controller to run it from 12s2p Turnigy 5 Ah 20C batteries. The motor drives the 17" rear wheel with a 10/43 chain reduction. When I first got the controller it was set to 40 A battery current limit which resultet in a pretty slow and weak moped. I reprogrammed it for 65 A (160 A phase) instead and the moped was extremely nice to drive. I was playing around in with this configuration for 20-30 km during a couple of days, and it worked perfect. I made a GPS log to get some figures of the top-speed and acceleration. The log was recorded back and forth and the peak difference in speed depends on some pretty strong headwind.

speed curve.jpg

Speed curve

(93 KiB) Downloaded 3 times

Top speed 68.9 km/h (43 mph) and a lot of torque.

For some more info about the build, my project blog.

Now to the question:
After several hard accelerations in a short period of time I managed to cook the motor, How much current are you reliably putting through the Turnigy 80-100?

[Miles]

Now to the question:
After several hard accelerations in a short period of time I managed to cook the motor, How much current are you reliably putting through the Turnigy 80-100?

I think you have to specify which one.... A or B - 180Kv or 130Kv

[LHelge]

Originally 180 kv, but as I said, rewinded with double strands of 1.5 mm copper wire terminated in wye for 90 kv. I'm pretty sure that the 180 kv and 130 kv is the same motor apart from the windings.

[Miles]

I'm pretty sure that the 180 kv and 130 kv is the same motor apart from the windings.

Absolutely but, change the windings and you change the resistance.....

[LHelge]

Of course, but as I wrote in the original post, I tore out the original windings and rewinded it myself. I think the original 180 is 6 turns and 130 is 8 turns terminated in delta. My motor is 7 turns terminated in wye.

180 * 7 / 8 / sqrt(3) = 90 rpm/V

[Miles]

The point is, if you ask "how much current are you putting through your 80-100" unless you also ask "and what winding is it" then it means sod all.

[LHelge]

Sure, but I hoped for some kind of discussion around its capabilities. I'm interested in both 130 and 180 rpm/V and of course custom winds.

[Miles]

Ok. I'm only trying to help. Maybe better to ask: "How much torque do you think it's capable of sustaining?"

[Thud]

By lowerig th kv & running on limited voltage, you have really limited the motors power output potentials...the amperage will fry it as you have learned.
In a "best case" senario, these motors are on the edge at 5kw sustained.

do you have a reliable meter to moniter what the amp draws are in use?
given the info above, I would think it should run well with an sustained 2kw input with acceleration peaks of less than 8kw's.

it is important to have a moniter (cycle anilyst is nice) as the XieChang based controllers will overshoot their programed rating by a fair margine under acceleration.

Also, by my math your over geared. 4.3-1=100+ kph.
I would recomend getting it down to 6.75-1 reduction.....that still works out to 70kph unloaded....you will be amazed at the kick in the pants with proper gearing.

I need to really hit the books & memorize the motor math someday....I hate blathering info with no quantifiable data to back it up....all I have is the seat of my pants & 30# of scrap wire from re-winds

[Miles]

I need to really hit the books & memorize the motor math someday....I hate blathering info with no quantifiable data to back it up....all I have is the seat of my pants & 30# of scrap wire from re-winds

And I need to shut up and start blowing things up...

Anyway, we've got the discussion going....

[LHelge]

Great, that's what I wanted!

This is a project me and my brother works on whenever we are visiting our parents, this time was the first opportunity we had to make any testing of the bike and I forgot my current meter. Maybe I'll get a cycle analyst for it at a later stage, but the long term plan is to use it as a base for building my own e-bike platform with controller, bms, charger, dc/dc and display unit. I just want to get it running reliably to have some kind of benchmark.

I'll guess i rewind the motor again and remember to bring my current meter next time. I'll guess this isn't the last time rewinding it, too bad it's so difficult getting hold of spares.

[LHelge]

A picture of how the motor is looking now:

What do you think about mounting a 90 mm tube on the right motor mount plate and a 80 mm fan on the rotating outer part of the motor?

[Miles]

What do you think about mounting a 90 mm tube on the right motor mount plate and a 80 mm fan on the rotating outer part of the motor?

It looks like you have got such a good copper fill that there's not going to be much air flow....

[Thud]

If your going to attEmpt air cooling, I would recomend a standard LRK winding pattern.

Internal hall sensor position will be a problem but that is managable.

[1000w]

The first thing I thought of when looking at your photos was not enough reduction.
Good luck and nice work so far.
Cheers.

[LHelge]

I'll contact the company that made the front sprocket to see if they can custom make a larger rear sprocket for this bike, would you think 10/55 reduction is enough, or should I go for 10/60 ?

[Miles]

I'd go for as large as you've got room for. The more you lower the torque requirement, the better...

[sn0wchyld]

a 60tooth would mean you should maintain the same top speed, assuming that you get to 80% of your no load speed. a 55 would mean you're geared for the mid 70's. personally I'd go for the 60 if it'll fit/can be found, though I have no practical experience with these motors, just some theory.

[Miles]

A 60 tooth would give you a reduction of 6:1.

So the amp requirement depends on: Kt (Nm/A) = 9.54929/Kv (rpm/V) and load (Nm) divided by 6.

For load see: viewtopic.php?p=312555#p312555