NEM0 - <$1k Electric Dual Sport

[captainslug]

[captainslug]

The batteries are back in and it's running. I'll record a video sometime soon (have to figure out a camera mount first).



It has A LOT of low-end torque. Climbs hills easily even at 25% throttle.
The motor, gear, and chain drive combination sounds very spacey.

[Malcolm]

Congratulations on such a sharp-looking conversion. I especially like the tail light and the SUV-piercing mudguard

[captainslug]

Any notes on Top speed over level ground???

Went for a test drive this afternoon. Top speed on level ground is 38MPH.
Average speed at 25% throttle is 19MPH.
Not sure what the range is going to be.
I need to add a stronger spring to the drive chain tensioner before I ride it any further.

Are you happy with the free-wheel assembly as posted???

Yes very. It coasts easily and allows me to reach slightly higher speeds downhill.

[vanilla ice]

Stumbled in late on this thread but flippin awesome dual motored bikes.. quadruply so because of the budget!

Are those 600w geared motors?

[captainslug]

Upgraded to much heavier springs on the chain tensioners.


I'm going to install a temperature monitor on one of the motors before I do any further testing. Neither of them were getting anywhere near as hot as the previous motor, but I still want to be able to monitor them.

I'm also probably going to add a fan to the chain guard I will hopefully be making by this weekend.

Are those 600w geared motors?

Correct.

[captainslug]

Bad News, and I need a break from this project.

The lower freewheel is destroyed.
I'm going to have to rethink the drive system a little bit. Probably by switching to having just one freewheel, and using static sprockets to link the two motors.

[vanilla ice]

That sucks dude.

..just one freewheel, and using static sprockets to link the two motors.

That makes sense about the static sprockets, I'm sure it will won't be too bad getting her up again. Keep on keeping on.

I'd love to have an off-road capable torquey 35mph moped, 2HPish.. totally get it man. No its not a 25hp motoXer, it just looks like one. Which is cool, so why not. Moped type functionality and affordability with sharp modern motoX looks, good upgrade platform for later too. Great idea.

[jorhyne1]

Sorry to hear about the bike...

That temperature monitor looks nice, where is it from?

[toyguru]

Sorry to hear about the bike...

That temperature monitor looks nice, where is it from?

It looks like the ones from sure electonics, check out their ebay store. I just ordered a power supply and 30v led display from them, expect them later this week.

[captainslug]

Drilled and tapped the small sprockets to M12-1.75. The one on the lower motor will have to be tacked in place to keep it from backing off the thread.

Measured again and then modified the motor-mount plate.

[vanilla ice]

Nemo is my new favorite build! You and FrankG got me daydreaming of doing a similar trail cruiser..

[captainslug]

New power train works great.


But the bad news is that the motors are still getting very hot at speeds above 20mph.
I feel like I'm out of money and out of ideas. As a last-ditch effort I may try to water-cool the motors, since I already have the supplies to do so. Doing so just unfortunately complicates the bike more than I really wanted to.

[captainslug]

Scratch my previous pessimism. After I get the temperature monitor installed I will hook up the battery pack at 48 volts and see if the controller can handle the lower voltage. If it can I would like to do some test runs at that voltage and see if the motors stay a more reasonable temperature.
If the controller doesn't like 48 volts then I'll source a cheap one and do the tests.

I can get the same top speed at 48 volts if I switch the freewheel sprocket to 35 teeth instead of 30. But I need to find out if the voltage drop will resolve the thermal issues.
being at 48 volts will also make it easier to upgrade to a lithium pack later on.

[captainslug]

I forgot that you're running a 60V system, my dual motor config is only at 48V but exhibits little to no heat-rise on the motors, although my gearing is 13t to 51t on a 25" rear wheel, so my top speed is considerably lower @ approx 20Km/hr with lots of low-end grunt .

That's very good to know because I thought you were running at only 36 volts. Some time soon I'm going to start testing at 48volts to see what results I get. But that will have to wait until next week.

Something for you to consider is using high amp relays or just a modular connector to switch your motor wiring from series to parallel. I'm considering doing this myself at some point because it would give me the option of having two driving modes.
Series for high end (38mph max, short range)
Parallel for low end (18mph max, long range)

[captainslug]

Temperature monitor is installed.


And the charger is swapped out for a 48 volt model.

I can do some test runs tomorrow.

Series is half the speed, while Parallel is half the torque.

That sounds right. I get the two terms flip-flopped in my head pretty regularly. Parallel will be twice voltage current. Where-as a series setup will be half the voltage and current per motor. At least presumably, but in Series the motors will have much more current draw overhead before you reach their rated wattage.
Series makes a great 1st gear or "limp mode". I was previously tempted to build this bike in series setup with a 72V battery pack, but I couldn't find any brushed motor controllers in 72 volts.

I looked at different parts to accomplish the change from a toggle switch (which would be way cooler), but using high amp relays to make the change would be kind of expensive.
Doing it from a high amp switch/breaker or an Anderson Powerpole connector set would be more cost effective, if not quite as simple.

[vanilla ice]

Curious what controllers are you using on this? Whats the amp delivery curve like? I'm surprised the motors are overheating in the low 20's mph. Are you sure its not some drivetrain snag?

I've been wanting a moped to cruise the hood. Got a street reg XR200 roller, you and Frank started the rusty gears in my head spinning. After seeing your results I'm not so sure my pair of 48v 28a ecrazy controlled Kolls would reach the 30-35mph I am after.

[captainslug]

Bike is running great. Temperature sensor is indicating that the motors are not getting above 120F, even at top speed.


Next I need to change the front sprocket so I can increase the top speed from 29mph to 35mph, and I would like to make a storage box for the charger cord that will fit in the upper most slot in the battery rack.

Curious what controllers are you using on this? Whats the amp delivery curve like?

I'm using a YiYun YC43 which is rated for 60 volts & 1000watts (but I'm running it at 48 volts). I don't have the amperage measured at the moment, but the controller is capable of surge outputs of up to 100 amps. Acceleration can easily draw 50 amps for a short period.
The motors are currently wired to the controller in parallel, so they both receive 48 volts.

At 60 volts I was not experiencing overheated below 20mph, it was only becoming an issue above 25mph. I'm under the assumption that the motors cannot handle such an increase in voltage and the resulting increase in peak RPM was causing excessive arcing on between the brushes and stator plates. I have not had the issue running the motors at 48 volts.

[only1jake]

hey captainslug,
i have been following your porject for a while now and i have been very interested in it. Its awesome and a great idea, but i have some questions;
Have you made it road legal, or plan to?
How much has it cost you so far?
keep up the good work.

[vanilla ice]

Ah you are using a single controller. Great news that you figured out the problem!

Since it is already designed in to your layout, I guess you could leave the 5th battery as the accessory battery. If you wanted to.

[captainslug]

hey captainslug,
i have been following your porject for a while now and i have been very interested in it. Its awesome and a great idea, but i have some questions;
Have you made it road legal, or plan to?
How much has it cost you so far?
keep up the good work.

The DMV code for this state considers this to be a moped, so I do not have to insure, license, or title it so long as it doesn't go over 40MPH.
Cost-to-date is $1700

Since it is already designed in to your layout, I guess you could leave the 5th battery as the accessory battery. If you wanted to.

I don't really need to have a 5th battery since I'm using a DC-DC converter to step the pack voltage down to 5v and 12v for all of the gauges and lights.

[vanilla ice]

Right I have those things too. I guess it wouldn't help range a noticeable amount unless you had a ton of accessories.

That is pretty lucky about the 40mph law in your state. Here the reg/insurance is also not required, but its 30mph max. A lot of the gas moped guys seem ok going faster. I guess its not a big deal.

[captainslug]

I've ordered the relays I need to make the motor wiring adjustable from a toggle switch on the handle bars that will control a pair of relays.

Doing this will give me a 2-speed manual electric speed selection.
Series wiring will be used for acceleration. Parallel will be used for top speed.
Doing this should also GREATLY reduce the power consumption during acceleration without sacrificing any performance (since it will in fact give me more available torque).
I will have to do practical tests once the relays are installed to determine what positive effect the configuration has on range. I'm hopeful that it should be a noticeable increase of 20 to 40%.

[captainslug]

With the motors wired in parallel, unless I really yank the throttle back when going up hill, it never really manages to deliver more than 50 amps. 40 amps is more typical.
I will be running at 48 volts from now on to keep the motors from overheating.

Practical tests will tell me if the setup functions the way I need it to or not. The difference in voltage drop between using series or parallel for acceleration should give me some indication of any reduced consumption.
I have not yet bothered to buy a shunt ammeter in order to get real-time current readings.

[vanilla ice]

Will be a good test. I think it will at least be a useful feature for extending range on slower cruises if nothing else.