IScooter i12 controller shunt mod

[Zambam]

With help from @fechter from this thread, I did the shunt mod on the controller on my iScooter i12. I am starting this thread so I don'tt further hijack @casainho 's thread.

The shunt mod made hill climbing acceptable. Before that it would bog down to 5 mph or less on hills. I hooked up a thermocouple to the controller and took it for a 9 mile ride in local park yesterday. On 8% grades, the hottest temp seen was 110F (not that hot). Battery amps went from 15A before, to 22A after the mod. Maybe I can increase power a bit more? I'll ride it more before deciding.

 

[Zambam]

This scooter is fun to ride! I've never ridden a standup scooter before. I tried it yesterday and to my surprise, it is much easier on the body on big bumps/ potholes. I guess having knee and hip joints helps a lot in shock absorption compared to sitting and having the spine take all the shock.

It'd be even more fun if I can defeat the 15.5 mph speed limiter! Here are photos of the board. Which wire/ signal do you think is the speed limiter? I did disconnect the single wire connector with the yel/gn wire (signal A3) but it didn't do anything.

 

[fechter]

The real area of interest is on the top side buried under the hall sensor wires.
I have not seen this particular board before, but many others have a 3-speed switch function with connections labeled SL and SH.
I see these on the board (but they may be something completely different).
See if the SL pad has anything connected to it. If SL is grounded on the other ones I've seen, it puts it into low speed mode. If SH is grounded, high speed. If neither of them is grounded, speed 2.
You can also measure with an ohmmeter from B- to the SL pad and see if it looks grounded. If so, see if you can unground it.

 

[glennb]

Wouldn't you rather be able to adjust phase current?

I was checking out cheap VESC controllers on Aliexpress yesterday and saw one for under fifty bucks.

 

[Zambam]

Wouldn't you rather be able to adjust phase current?

I was checking out cheap VESC controllers on Aliexpress yesterday and saw one for under fifty bucks.

My knowledge of controllers is minimal. Please tell me more about phase current. Which VESC controller do you recommend? My scooter has a 500W motor. I don't need it go go above 24 mph. Do not want to burn the motor out. Battery is 36V 7.5Ah - I have 2 or them and plan to wire them in parallel to double the capacity.

 

[glennb]

I haven't tried any, I was buying a Votol Em30, and just browsed the VESC offerings out of curiousity.

Definitely a couple of cheaper ones than last time I looked a year or two ago. Cheap and small enough you could install two, with the second wired in as a hot spare to switch to if the primary one fails.

Your motor, voltage, and power requirements are modest enough for any controller. But if you're serious about performance and motor protection you should use a programmable one, with phase limits and temperature monitoring. Particularly since you'll be exceeding 500w continuous to achieve 24mph, even on flat roads.

Cooking motors is remarkably easy ... it only takes a hill on a hot day or direct bright sun on black motor casing.

 

[fechter]

Does the white wire go to the SL pad?
If so, you might try moving to the SH pad and try grounding it and see if the top speed changes.

 

[Zambam]

Does the white wire go to the SL pad?
If so, you might try moving to the SH pad and try grounding it and see if the top speed changes.

There are 2 white wires on the SL pad (no wires on SH pad). One goes to a multi pin connector that goes up to the handle bar. The other to a multi pin connector that goes to the motor. I’ll do more measurements/ tracinglater.

 

[fechter]

I would try disconnecting both of them first and see if it makes any change. You could also measure the voltage on the SL pad with them disconnected. This may have nothing to do with the speed, but it's my best guess. Typical speed switch connections would have around 5v with nothing connected.

 

[Zambam]

I would try disconnecting both of them first and see if it makes any change. You could also measure the voltage on the SL pad with them disconnected. This may have nothing to do with the speed, but it's my best guess. Typical speed switch connections would have around 5v with nothing connected.

With both white wires disconnected from SL pad, rear wheel does not spin. Connected white wires, wheel spins.

There is 5V on SL pad with white wires disconnected or connected, does not matter.

No voltage on SH pad.

What do you suggest I try next? Standing by.

 

[fechter]

Seems like it might be the “self-learning “ function. It was worth a try.

Does the main chip have a number you can read?

Randomly putting 5v or ground on other pads might blow something up.

 

[fechter]

What does the A3 wire go to?

 

[Zambam]

What does the A3 wire go to?

A3 wire goes into the motor harness via a single wire connector, along with the 3 phase wires and a 5 wire connector (3 hall sensor wires, +5 and gnd ?).

A3 wire has 1.78V with power on, 11k ohms power off.

Yeah don't want to ground anything with 5V randomly. I'm willing to ground anything through a 10 ohm resistor though if that's useful. I have a spare controller. Ok if I blow one of them.

 

[Zambam]

Does the main chip have a number you can read?

There's numbers on the chip but it is illegible due to being abraded with something. This is on both controllers.

 

[fechter]

Pretty common practice to grind off the chip number.
A3 seems likely a temperature sensor.

 

[Zambam]

@fechter Dug out my old Tektronix scope, soldered a wire onto SL pad to probe it. The 2 white wires on SL are the brake cutouts! When I pull either brake levers, 5V on SL goes to Gnd.

Anything else you want me to try? Thanks for the help!

edit: What are the other signals on the board that we haven't looked at?

 

[fechter]

I searched around in the forum and found some other controllers where the 3-speed switch was wired to the pads marked K1 and K2. You could try grounding K2 and see if that does anything. The functions of the pads depend on the firmware and there doesn't seem to be any real standard. Even if K2 is for a speed switch, it may do nothing if the settings for all 3 speeds are programmed the same.

 

[Zambam]

Grounding K2 or K1 didn't make any difference.

I moved the shunt to give it more power and went for a ride and to my surprise, max amps dropped from 22 to 18.

I didn't touch where the shunt was soldered on the PC board, just unsoldered where it was soldered on the shunt and moved it a little further away. Is that wrong?

 

[fechter]

It should have gone up. Maybe a not-so-good solder connection on the end.

 

[Zambam]

It should have gone up. Maybe a not-so-good solder connection on the end.

I re-soldered the 1mm copper wire by bridging the shunt on the solder side of the PC board. Will test ride this afternoon.

 

[Zambam]

I re-soldered the 1mm copper wire by bridging the shunt on the solder side of the PC board. Will test ride this afternoon.

With full throttle, re-soldered shunt peaks at 30A for a split second then quickly drop to 22A. Thermocouple on the controller casing never got past 88F. The previous shunt, highest was 110F. Difference may be the cover on controller housing was off today. After the 10 mile ride, motor was warm, not hot to the touch.

Suspension is breaking in, absorbing the bumps better. I am getting used to the handling. Being able to alternate between sitting and standing is a nice feature!

Plan is more test rides. If no problem develops, will add another battery in parallel to increase range (13-15 miles when it drops to around 33V with one battery). LVC of this 36V battery is 30V.

 

[fechter]

That sounds pretty good. If you boost it too much, the battery might not handle it.
I'm out of ideas on removing the speed limit (for now) short of a new controller.

 

[Zambam]

That sounds pretty good. If you boost it too much, the battery might not handle it.
I'm out of ideas on removing the speed limit (for now) short of a new controller.

Per iScooter, the 36V 7.5 Ah battery is 10S3P with Dongci 2600mAh cells that are rated at 5C (10A) discharge. 3P is 30A. A single pack should handle the extra current. Double it gives a bigger margin.

Which controller would you recommend for better acceleration and to rid the 15 mph speed limit?

 

[Zambam]

65F outside, 5 mile ride to the grocery. With controller cover on, climbing some 8% grades, highest temp observed on the thermocouple meter was 125F.

 

[Zambam]

I've added a second battery in parallel (15Ah now). It lowered voltage sag from 4V to 2.5V. Power increased a bit. Range also increased. I can go 20 miles w/o babying it and still have 20% left.

The shunt mod really brought this scooter back to life. It has good acceleration now and can climb the hills around here w/o slowing to a crawl. Controller has not gotten hotter than 55C on a 26C (78F) day. I have around 50 miles on it since the shunt mod- no problems thus far. Riding at 15.5 mph is very relaxed compared to my much faster (34 mph) and much bigger/ heavier moped.