Magura Throttle 3 wire...

[teklektik]

I finally finished my setup last night and have it working. Only I ran into a few issues with drive-ability.

To set the throttle off and WOT, I did not use a meter. Rather I turned the trimpot for the OFF throttle wire until the power came on...then I turned back 1/4 turn.
Then at WOT I would turn the trimpot on the WOT wire until I could hear a reduction in power...then I turned it a 1/4 turn more (back to WOT).

All is well with no dead zone at the bottom or top...but what I do have now (with 2 throttles that I converted) is low power when I start twisting the grip...then I can twist for a 1/2 turn more and the power remains the same! then at about 3/4 throttle to full it is linear (more I turn, more power I get)

Hmmm - very odd. There is no point in speculating about this - you really need to go to ebay, Harbor Freight, or Radio Shack and pick up a cheapie $10 meter so you can measure resistance and DC voltage. We need to see the voltage across the throttle sense lead and Gnd at ZERO, mid, and WOT. You should be seeing the voltage increase linearly - it looks like it's not, but we need to start there to backtrack to the cause....

BTW - Your adjustment procedure is fine...

 

[unclejemima]

Good day guys. I was side tracked on a few other projects and just got back to this one...

I took a video showing the throttle and what how it uses identical power between 1/8 and 1/2 throttle.
https://www.youtube.com/watch?v=PJhUdb-Quco

Teklektik, I have a meter. Can you tell me exactly what I'm looking for? What of the 3 wires do I hook the meter up to to test?

Also, even at very very light throttle openings the bike surges ahead like it does not recognize a very small amount of throttle input. I try to feather the gas 1/16 and it always give a big burst of power off the line. I can never just creep away.

Looking forward to any advice.

 

[teklektik]

Also, even at very very light throttle openings the bike surges ahead like it does not recognize a very small amount of throttle input. I try to feather the gas 1/16 and it always give a big burst of power off the line. I can never just creep away.

I believe you upgraded to the Magura so this sounds like a disappointing 'upgrade'...

• Did your previous throttle have a similar jerky getaway or is this new with your Magura and trimpots?
• Did the Magura have a similar jerky getaway before you added the trimpots?

...I have a meter. Can you tell me exactly what I'm looking for? What of the 3 wires do I hook the meter up to to test?

There are a couple of things that could be wrong: the trimpots may not be wired correctly, the Magura may not be a 5K unit but one of the wonky 4K/10K models, or the controller may not like the Magura and may be loading it down.

Some external measurements at the connector level are an easy place to start...

• There are a couple of ways to go after this but let's start by looking at the the actual throttle voltage being delivered to the controller. Here we really need to look at what happening while everything is hooked up so you may need to fudge a little adapter or probe the contacts from the back of the connector. Anyhow, using the DC Volts setting, look at the voltage from from Gnd (black -) lead to the throttle 'sense' lead (brown +). We want to see the voltages at ZERO, 1/4, 1/2, 3/4, and FULL throttle. These should be giving a nice linear response.
• Next let's look at the actual resistance of the throttle in these same five settings. Here you unplug the throttle and probe the throttle connector pins so the measurements include the trimpots - this shows the situation unloaded by the controller. Using the 'ohms' or 'K' setting, measure across the same two connections (Black+Brown) as above.
• Last, measure the resistance (ohms or 'K' scale) across the throttle +5v (Blue) and Gnd (blk) connections while rotating the throttle - the reading should stay the same.

Please post back the readings from the three tests.
This is a bit of fiddling about, but I think this will give a clearer picture of whether the throttle and trimpots are working as expected.

 

[unclejemima]

[*]Did your previous throttle have a similar jerky getaway or is this new with your Magura and trimpots?
[*]Did the Magura have a similar jerky getaway before you added the trimpots?[/list]

Thanks for the quick reply. I'll go and test tonight.

The unit I ordered was indeed (or its supposed to be) the 5k unit, and it came from a reputable supplier so it should be correct.

I honestly did not try before hooking up the trim post, but I believe it always had a jerky throttle response. I know the OEM throttle did and thats why I was hoping to "upgrade" to the magura. The OEM throttle also had lots of dead zone before throttle would work.

Its weird. If I use the pedal assist at its lowest setting with no throttle input, the bike can apply light power...but for some reason it does not work with the throttle. It always wants to give 1/4 throttle as its lowest setting, like the controller does not recognize anything else. I'm not sure if this is something that can be fixed. FYI, this is the Bafang BBS02 what has the controller integrated in the motor I believe...

 

[unclejemima]

There are a couple of things that could be wrong: the trimpots may not be wired correctly

\
If this was the case, then I would imagine it would not work at all...?

the Magura may not be a 5K unit but one of the wonky 4K/10K models,

Is there any way to verify this? The seller assures me its a 5K unit.

or the controller may not like the Magura and may be loading it down.

Is this a common problem? According to the guy I bought the Bafang off, any 3 wire throttle should work...so it should work with the magura you'd think

Some external measurements at the connector level are an easy place to start...

I'm assuming you mean where I connect the magura wire to the bike's harness wire. I did this by putting a probe wire in the connector for the brown and black wire, and plugging the harness in.
This is all AFTER the trip-pots.

Anyhow, using the DC Volts setting, look at the voltage from from Gnd (black -) lead to the throttle 'sense' lead (brown +). We want to see the voltages at ZERO, 1/4, 1/2, 3/4, and FULL throttle.

Sounds silly, but I don't know what the DC volt setting is on my meter? Can you tell me what one it is?


The results I got from this by using the "20k" setting on the meter was...
0: 1.65
1/4: 2.20
1/2: 2.62
3/4: 2.88
FULL: 2.66 (oddly less than 3/4 throttle)

Next let's look at the actual resistance of the throttle in these same five settings. Here you unplug the throttle and probe the throttle connector pins so the measurements include the trimpots - this shows the situation unloaded by the controller. Using the 'ohms' or 'K' setting, measure across the same two connections (Black+Brown) as above.

Ok. I used the "20k" setting on the meter for these tests.

Readings were...(I assume this was Black and Brown)
0: 2.02
1/4: 2.83
1/2: 4.03
3/4: 5.47
Full: 7.2

Does this look right? I also tried another combo (not sure what wires as I was plugging in at the harness) and got... I assume brown and blue.
0: 6.88
1/4: 6.50
1/2: 5.22
3/4: 3.7
Full: 1.68

Last, measure the resistance (ohms or 'K' scale) across the throttle +5v (Blue) and Gnd (blk) connections while rotating the throttle - the reading should stay the same.

I'm getting these reading for what should be blue and ground.
0: 8.9
1/4: 8.82
1/2: 8.83
3/4: 8.86
Full: 8.90

I used painters tape on the throttle and marked 0, 1/4, 1/2, 3/4 and Full so I would get consistent readings each time.

 

[unclejemima]

Can anyone comment on my last post? Are my readings looking right?

 

[teklektik]

hey UJ-
Sorry for the delay - a little jammed up on this end.

So for your questions:

There are a couple of things that could be wrong: the trimpots may not be wired correctly

If this was the case, then I would imagine it would not work at all...?

Sadly, absolute or catastrophic failures are rare - generally it's a case of 'not working as intended' and a lot of head scratching to figure out why...

the Magura may not be a 5K unit but one of the wonky 4K/10K models,

Is there any way to verify this? The seller assures me its a 5K unit.

Ya - the measurements confirm that it is - no problem there.

or the controller may not like the Magura and may be loading it down.

Is this a common problem? According to the guy I bought the Bafang off, any 3 wire throttle should work...so it should work with the magura you'd think

Not really. 'Any Throttle' means 'Any HALL Throttle' - here we are messing with a non-standard resistive throttle and trying to supply a voltage, but the electrical characteristics of the controller can affect our efforts.

Also - you measured in the proper place. Good.

Here's an annotated dial face for your meter and the two circled settings you should be using for these measurements:


Your resistance measurements look more or less correct although there's a little wonkiness probably due to the width of the wiper and 'landing zones' at the extremes of the rotation. Looks basically okay though, so I think it's wired properly and performing more or less as we desire - when disconnected from the controller.

That said, you need to go back and make the voltage measurements again with it hooked up. It looks like you used the wrong meter setting (20k instead of 20v). These new numbers should help resolve the linearity question.

As a side note, I did see a reference in another thread to some kind of throttle non-linearity in the programming for the BBS-02. Altering the programming may be an option (or necessary) get the desired behavior, but let's get the basic throttle hookup as good as possible before getting distracted with other possibilities.

 

[unclejemima]

Thanks again for the reply and well drawn diagram I will try this out.

Regarding the reference in another thread to some kind of throttle non-linearity in the programming for the BBS-02...do you have a link to this? I'd like to see how that thread progresses. At least I would not be the only one with an issue.

Let me know,

 

[crezzy2k1]

Did you ever figure this out. I'm having a similar issue.

 

[teklektik]

UJ never got back, but here's a link to thread on reprogramming the BBS-02 mentioned above which allows fiddling the throttle a bit.

 

[Tench]

I had a Magura throttle that had a problem, it was installed on my Bomber from new. The bike developed a surging when trying to hold constant throttle and also a lag when opening the throttle. Upon closer inspection with the throttle disassembled sideways movement of the pot shaft would start or stop the drive to the rear wheel. The gear drive in the throttle would be applying some sideways pressure to the pot shaft but maybe by a varying degree or direction depending of the gear tooth position. Anyway, I binned it and went to a hall throttle which solved all the issues.

I only mention it because it took me ages to find the problem, and checking your own if you are having issues could save some head scratching!

 

[silicium]

I tested an magura throttle: (from evdrives.com)

The potentiometer has no resistor placed in series

The linearity is good !

 

[rumme]

I purchased the Magura throttle

 

[rumme]

which would be better to use in place of the 3k resistor on the black wire of the Magura ....I have a 2.7k and a 3.2k resistor ? I don't have a 3k .

I have the 1k resistor for the blue wire.

I'm using the LYEN 18 FET sensorless controller.