[Bafang + Nuvinci] Cargo bike seizes up in hills

[Shohreh]

Hello,

Remotely, I'm trying to help a non-techie who bought a Dutch-made used cargo trike in good condition from a bike shop.

1. It has a Bafang M400 mid-drive (MM G33.250, 36V 250W 14A; It's in Europe, hence the 250W motor)), and a Nuvinci Optimized 330 gear hub with an automatic shifter + H3 controller.

She intends to ride her handicapped 30kg kid to school on 4-6% grade hills — so, not really steep, but not flat either.

The issue is that, when climbing, the motor just stops: The pedals won't go forward, but she can backpedal.

FWIW, she chooses the one dot mode on the H3 because the bike barely moves in hills when using the other two modes, especially the three dot mode (where you spin the most).

Could it be the 80Nm torque of the Bafang is fine, but a 36V battery isn't up to the task, and the controller shuts it off to preserve it? And/or something to do with the electric Nuvinci shifter?

2. As a lesser issue, when she recharges the battery — after letting it cool off as recommended —, the charger gets quite hot, although it came with the bike.

Thank you.

 

[E-HP]

Hello,

Remotely, I'm trying to help a non-techie who bought a Dutch-made used cargo trike in good condition from a bike shop.

1. It has a Bafang M400 mid-drive (MM G33.250, 36V 250W 14A; It's in Europe, hence the 250W motor)), and a Nuvinci Optimized 330 gear hub with an automatic shifter + H3 controller.

She intends to ride her handicapped 30kg kid to school on 4-6% grade hills — so, not really steep, but not flat either.

The issue is that, when climbing, the motor just stops: The pedals won't go forward, but she can backpedal.

FWIW, she chooses the one dot mode on the H3 because the bike barely moves in hills when using the other two modes, especially the three dot mode (where you spin the most).

Could it be the 80Nm torque of the Bafang is fine, but a 36V battery isn't up to the task, and the controller shuts it off to preserve it? And/or something to do with the electric Nuvinci shifter?

2. As a lesser issue, when she recharges the battery — after letting it cool off as recommended —, the charger gets quite hot, although it came with the bike.

Thank you.

Urban.Wheels.cargo.trike_Nuvinci.Bafang.png
Chargeur.png
Battery.png

When you say the motor just stops and pedals won't move forward, do you mean the cranks lock up, or that the motor just stops assisting?
On the battery, it looks like a 10S5P pack, possibly constructed using LG cells (by the info on the label; (I believe INR cells are LG). A 10S5P pack of decent cells should be a bottleneck. The charger getting hot is odd, given the relatively low charge rate, but as long as it's getting the pack to full charge, probably not an issue.

 

[Shohreh]

The cranks lock up: They won't spin forward, but she can go backwards.

"A 10S5P pack of decent cells should be a bottleneck."

You meant "should not be", I guess?

Is there a way to investigate, see if it's the Bafang+battery, or the Nuvinci?

 

[Chalo]

I don't think there's any possible electrical failure that would prevent the cranks from turning. It sounds like a mechanical issue to me. If you disassemble and inspect the drive unit, you may be able to identify the problem.

 

[Shohreh]

What do you mean with "drive unit"?

If it's the Nuvinci, is there a simple way to remove its electric shifter from the equation, or does it require buying a manual shifter + couple of cables?

--
Edit: What does "calibration" do on an electric Nuvinci ? What happens if it hasn't been done (correctly) at the shop?

https://support.enviolo.com/hc/en-us/articles/360028287112-Automatic-3-button-H3-controller-calibration

 

[Chalo]

What do you mean with "drive unit"?

If it's the Nuvinci, is there a simple way to remove its electric shifter from the equation, or does it require buying a manual shifter + couple of cables?

By drive unit I mean the crank motor and its gearbox. Not the rear hub. I'd be very surprised if it had anything to do with the rear hub.

 

[Shohreh]

That means opening the Bafang M400… which only the bike shop could possibly do — and even then, I'm really not sure they have the expertise for open heart surgery on a e-bike motor.

It doesn't look good :-/

 

[Chalo]

That means opening the Bafang M400… which only the bike shop could possibly do — and even then, I'm really not sure they have the expertise for open heart surgery on a e-bike motor.

It ain't rocket surgery.

[youtube]nm6UTwLRays[/youtube]

 

[Shohreh]

I'll pass on the info, and see what the shop (and the bike manufacturer) does with it.

Thank you.

 

[99t4]

Remotely, I'm trying to help a non-techie who bought a Dutch-made used cargo trike in good condition from a bike shop.

"...good condition from a bike shop." Very possible the bike shop offers a guarantee? Couldn't hurt to check.

Regarding the suggestions to open up the mid drive unit: This forum is full of extreme DIY-ers, unafraid of opening things up and digging in. It's totally OK if you're averse to that, but good to know the crowd you are amongst here.

 

[Shohreh]

Morning thought: Since…

1) that cargo trike is made in the Netherlands, so rather meant for flat terrain,

2) the issue occurs in hills but not on the flat, and the Nuvinci N330 dates from before mid-drive motors, and

3) the user has to dial the motor to its maximum power (5) because of the grade + weight…

could it be that the Bafang M400 provides too much torque (80Nm even for that 250W version) for the Nuvinci to handle, and the hub simply gets stuck?

I've read of users having problems with mid-drives and older Nuvinci/Enviolo (ie. not meant to handle as much power + torque).

Too bad there's no LBS around so she could have the Harmony electric shifter removed from the equation, and use a mechanical shifter + pair of cables to see if changes anything.

 

[Chalo]

Too bad there's no LBS around so she could have the Harmony electric shifter removed from the equation, and use a mechanical shifter + pair of cables to see if changes anything.

The shifter isn't a factor. NuVinci and Enviolo hubs are always "in gear", and the shifter can only change the ratio. So even if the problem is in the hub, which I don't think it is, there's nothing the shift mechanism can do to make the hub malfunction (unless you count being in the wrong ratio as a malfunction).

 

[Shohreh]

Good to know.