Throttle response changed after increasing battery voltage

[Zambam]

My Fly 7 moped/motorcycle came with a 60V 20 Ah SLA battery (around 64 V fully charged). Since building a 22S 30 Ah LFP battery for it (around 73 V fully charged), it has become a different animal with much better acceleration, higher top speed and longer range. That's all good!

However, the throttle does not respond sometimes from a standstill (like at a stop light) unless I turn the throttle cw then ccw (full twist throttle). This never happened before with the SLA battery. What's strange is this does not always happen, I'd say about 30% of the time. I have not done any diagnosis such as looking at the throttle voltages yet. What do you think is the problem and what troubleshooting steps would you recommend?

 

[TommyCat]

My first knee jerk reaction from your description would be that...

Your throttle is not returning correctly back to the home position due to mechanical interference.
If in the case of a hall sensor throttle, a magnet has shifted out of place, or possible resistance to ground.
(Both of these tripping controller's throttle lock out safety due to voltage above allowed start position.)

Or possibly a change to the throttle's output with the higher voltage driving the system.

I have not done any diagnosis such as looking at the throttle voltages yet.

This is where to start.
Check the incoming supply and the output signal to verify where you stand, home position to WOT.

Use this as a guide to help...
Guide to Hall Sensor Throttle operation, testing, and modification. - Electricbike.com Ebike Forum
It will explain solutions to the examples above as well as testing tips.

Looking forward to your readings, as well as any other information you have about your particular throttle and controller.


Regards,
T.C.

 

[Zambam]

Use this as a guide to help...
Guide to Hall Sensor Throttle operation, testing, and modification. - Electricbike.com Ebike Forum
It will explain solutions to the examples above as well as testing tips.

Looking forward to your readings, as well as any other information you have about your particular throttle and controller.

That's an amazing guide! A lot of work went into that. Thanks! I'll try to check voltages tomorrow.

Pics of a spare controller:

 

[TommyCat]

Jackpot!

Product description for your controller... (well just a bit off, but perhaps similar enough. )
http://www.lingbo-mc.com/en/upload/file/20210207/16126782042462934.pdf

The throttle protection error code of 14 might be handy.
Pin-outs a must!

Have a good look, lots of great information. Verify, just to be sure...

 

[Zambam]

Interesting find! In the past, I've searched for my controller p/n LBMC0601220HO2A-M23 (different than the one you posted) but never found anything. Assuming they are similar, where is the LED indicator located?

I'll look but I don't think it is on the controller. The only other place would be on the Instrument Panel and I am not aware of one there. I will check.

edit: No LED on the controller (under the seat). No LED on the Instrument Panel (from left to right: battery, controller power setting, speedometer, odometer)

 

[TommyCat]

I've searched for my controller p/n LBMC0601220HO2A-M23

Might be the extra 0 before the H in your model number above….

With a dedicated display, one would expect the error codes to be shown there.
That said, from your bottom picture of your controller. I’d look carefully at the “small round dot” at the top right corner next to the connector, tucked up next to the plastic case rise.

Do you have communication available for programming?

Looking forward to your voltage readings.


Here’s an 060 model…
http://www.lingbo-mc.com/en/upload/file/20210207/16126790123451841.pdf

You sure it can handle the extra voltage?

 

[Zambam]

Might be the extra 0 before the H in your model number above….

With a dedicated display, one would expect the error codes to be shown there.
That said, from your bottom picture of your controller. I’d look carefully at the “small round dot” at the top right corner next to the connector, tucked up next to the plastic case rise.

Do you have communication available for programming?

Looking forward to your voltage readings.


Here’s an 060 model…
http://www.lingbo-mc.com/en/upload/file/20210207/16126790123451841.pdf

You sure it can handle the extra voltage?

The moped came with no documentation or user manual. It's difficult to get info since the mechanics at the dealer do not speak English.

I didn't know the controller is programmable. To do that, isn't a bluetooth app or a serial port required? I am not aware of either.

I took the spare controller cover off to look for an LED and there is one! It's not apparent from the outside unless you know it's there- a small 1/16" plastic dot lens flush with the case (same color). When the seat was off and power was on, if the LED was flashing, I would have seen it. I will check again tomorrow to make sure.

I tried to get the cover plate off the throttle (2 small phillips) to probe voltages. Cover wouldn't come off! I tried removing the throttle from the handlebar to make access easier but that also failed. There's a hole on the bottom which I thought would be an Allen set screw but none of the metric wrenches in the set I have fits. Maybe it's not a set screw? There must be a trick to it. Tomorrow I'll take a ride to the dealer and ask the mechanic how it comes off to save me from breaking something.

No problem with the throttle today while doing errands.

 

[Zambam]

You sure it can handle the extra voltage?

The electrolytics caps inside the controller is rated @ 100V, not sure about the FETS (p/n not visible). It's been running fine for a few hundred miles at 73V so far, except for the intermittent throttle problem.

 

[fechter]

One thing that comes to mind is there may be a significant voltage drop in the ground wire going to the throttle. You could try measuring voltage between the throttle gound (at the throttle connector or inside the throttle) and the battery negative when it's turned on. This should be zero volts. If there was a high resistance in the wiring someplace, it might read a few tenths of a volt, which would be enough to nudge the throttle signal.

 

[offGridDownUnder]

what troubleshooting steps would you recommend?

Put the original battery back in place and do the same measurements with your multimeter.

Compare the range produced by your throttle with each.

 

[amberwolf]

The electrolytics caps inside the controller is rated @ 100V, not sure about the FETS (p/n not visible). It's been running fine for a few hundred miles at 73V so far, except for the intermittent throttle problem.

Keep in mind that not just the FETs and big electrolytics sit on the battery bus. At minimum, there are smaller caps (often non-electrolytic) usually used for damping on the phase FETs that sit across that bus, and there is the LVPS that creates 5v, 12v, etc from battery voltage, and there is the "voltmeter" circuitry that buffers battery voltage to an analog input pin of hte MCU so it can read BV and know when to implement HVC and LVC.

 

[Zambam]

Thanks for the different ideas. I am wondering if the throttle is not the issue after all and the problem lies elsewhere? Maybe it's a sticky brake lever cutout switch?

 

[TommyCat]

I didn't know the controller is programmable. To do that, isn't a bluetooth app or a serial port required? I am not aware of either.

The communication pins are on the main connector. So possibly there could be a connector hiding in the harness somewhere.
Or for access, sometimes the display is disconnected, and then the communication ties into there...
As you will need the software and a dongle to do this. The manufacturer would likely be your best source If you desire to go this route.

No problem with the throttle today while doing errands.

Perhaps you've used enough of the battery to lower the voltage enough to stop tripping the controller's safety.

I am wondering if the throttle is not the issue after all and the problem lies elsewhere?

Agreed.

Since the throttle's voltage readings are difficult to obtain. (but recommended if you can do so...)

I would recommend that you suspend the drive wheel off the ground. Charge the battery to FULL capacity and voltage reading. Then pop the seat up with the machine immobile and keep an eye on the controller's troubleshooting LED for any flashing whist trying the throttle. May give a clue.

 

[Zambam]

Since the throttle's voltage readings are difficult to obtain. (but recommended if you can do so...)

Finally got the throttle off. I removed the 2 screws on the cover plate and tried to pry it off. Didn't work. What's the trick? Seems like the twist handle has to come out first but how do I get it off w/o breaking anything?

 

[Zambam]

Tried to get throttle apart:

There's a thin plastic washer between the twist handle and the throttle housing mechanism, the gap there is too small to get a 0.25 mm thick plastic in there, so a thicker metal tool to push on the 3 tabs is out of the question unless the gap can be increased.

photo from your writeup:

 

[TommyCat]

The 3 tabs are accessed up through the hole the handle bar goes into…
This may help explain further…
Need access to wiring of Luna full twist throttle. - Electricbike.com Ebike Forum

And even when you get it open, that would seem to me to be a difficult place to get readings… Have you considered back probing the main connector? Or perhaps a junction in between the throttle and controller?

Have you done the easier testing for the flashing trouble-code light as recommended earlier?

 

[Zambam]

The 3 tabs are accessed up through the hole the handle bar goes into…
This may help explain further…
Need access to wiring of Luna full twist throttle. - Electricbike.com Ebike Forum

And even when you get it open, that would seem to me to be a difficult place to get readings… Have you considered back probing the main connector? Or perhaps a junction in between the throttle and controller?

Have you done the easier testing for the flashing trouble-code light as recommended earlier?

I thought probing voltages at the hall sensor is the best spot, but not if it is so difficult. Probing between throttle and controller is not simple either. The 2 mirrors have to come off first (they go though the instrument panel cover fairing). Then a bunch of screws and bolts have to be removed from the fairing, then the fairing snaps off which can break some the the plastic locking tabs if I am not lucky.

The next test I will do is the LED error code. I am not ready to charge the battery up just yet. I'm at 43 miles on a range test. I want to see how much beyond 50 miles it'll do before having to charge.

 

[Zambam]

The next test I will do is the LED error code. I am not ready to charge the battery up just yet. I'm at 43 miles on a range test. I want to see how much beyond 50 miles it'll do before having to charge.

Went out for a ride, got to 60 miles and battery indicator still show 3 green bars, runs with full power and can keep going if I wanted to. I ended the range test, battery is on charger. Will check if there are error codes tomorrow.

 

[Zambam]

I went to do an errand this morning (battery fully charged) and forgot to look at the controller LED. After the 5 mile round trip (battery was at 72.9V) I checked the LED and it was not flashing. I did notice the throttle was extra sensitive where the tiniest twist would launch the bike forward. I think the throttle needs taming (remapping with resistors)? Maybe that will also help with the intermittent no throttle response?

I will take off the instrument panel to access the throttle connector and take some voltage measurements.