Recently the Thumb Throttle With Battery Gauge, The yellow light turn off

[Abe]

Hello Alan,
Recently the Thumb Throttle With Battery Gauge, The yellow light turn off after about a minute, even though the battery is charged to full status.
** Importantly, light, green color and the red color stays on all the time.
Should I be concerned or is it normal?
I use a 16-cell battery type High Quality 3.2V 15Ah LifePO4 (48v).

**
I must explain what the process:
1. When I turn the key to start the motor three lights on.
2. After about a minute yellow LED going out.
3. Now I'm turning the key to close the motor three lights are lit for one second, ie the yellow lights on, coming back for a second.
Thank you,
Abe

[Bikemad]

Hi Abe,

Check the battery voltage with a voltmeter immediately after a full charge, and again when the yellow LED goes out and see what the difference in voltage is.

If I understand you correctly (and your yellow LED is coming on momentarily as you turn the key switch off) I suspect you may have a poor connection on the key switch contacts which is causing a slight voltage drop.

Alan
 

[Abe]

Hello again,
Unfortunately I built a battery pack which makes it difficult for me to test the battery system at this stage.
Next week I will check the battery system and the connection between the batteries controller BMS.
More to the point, I use two 24V relays of which are connected in series, starting the Motor performed through an external key that actually activates the contacts of the two relays.
Contacts of the two relays are connected in parallel of course, with the flow capacity of 80A each (five months of daily use only).
** What do you suggest me to check now, what could be the problem from your experience?
Thank you,
Abe

[Bikemad]

Hi Abe, I have some additional questions for you:

• Has anything been changed recently on your bike that may have affected the recent drop in the battery gauge reading?
• Are you able to check the battery voltage at the charger connector?
• Do you have any high wattage lights on your bike powered by the lighting switch on the throttle? If so, check to see if the yellow LED goes out when the lights are turned on.
• Have you noticed a reduction in your range?
• Does your motor feel less powerful?
• Is your maximum speed slower than it used to be?

In addition to the battery itself, there are several other things that can affect the actual voltage being monitored by the LED battery gauge, and these include dirty or arc damaged switch (or relay) contacts, poor connections on the battery power cables or the throttle connector, and thin harness wires with excessive current loads (high wattage lights etc.)
 
Low ambient temperatures can affect the efficiency of the cells and damp conditions (or water ingress) can sometimes make the battery's BMS misbehave.

In order to pinpoint the exact cause of your problem you really need to start by measuring the voltage at the battery/BMS output. If the output voltage is correct and the gauge is still reading low, there must be a voltage drop somewhere along the wiring between the battery and the gauge (unless the gauge itself is faulty).
A voltage drop on the thin feed wire supplying battery voltage to the gauge and/or the thin ground return wire coming from it can significantly reduce the reading shown on the battery gauge LEDs in comparison to the true battery voltage.

Alan
 

[Abe]

Hello Alan,
I'll try to answer some of the questions, some of the questions I will answer later:
1. It is important for me to explain that the event also appears when I'm not riding a bicycle, the bicycle is standing still.
2. I performed measurements of voltage charging points, before and after the yellow LED is off and the voltage remains the same 55v.
3. In addition, I performed measurements on voltage relay (contacts), again before and after the LED is off, and voltage was and remains the same ie 54v.
4. I finally I made a a bypass on the relays and the event remains, ie the yellow LED is turned off after a minute.
5. In addition, I conducted a number of tests directly at the entrance of voltage motors, the yellow LED switch off after a minute and the battery voltage remains constant, meaning that there was no drop in voltage.
6. I think this may not be the BMS but the internal controller in the Motor.

** I did not make any change on the bike including the battery system.
** I have a lighting consumes about 15 Watt on the main lighting, but the main lighting has been used for ages now (yellow LED's event is also when the main lighting off)
** I do not feel that the engine is not working properly or is  less powerful.
** Since I ride short distances is difficult for me to answer whether a shorter driving distance.

*** I'm not sure, but:
Three weeks ago, pretty close to the yellow LED's event, the nuts of the axis motor loose and I strengthened them perhaps too hard.
Is it a possibility that caused the problem?

Thanks,
Abe

[Bikemad]

Hi Abe,

If the voltage at the battery does not change when the yellow LED is on or off, it looks like you must be getting some voltage drop at the gauge when the key switch is operated. I have no way of knowing how your relays have been wired, but I suspect the power used to energise the two relay solenoids (windings) may be affecting the gauge operation, which might also explain why the light comes on for a second after the key switch is turned off (fed briefly by the residual battery voltage stored in the controller's capacitors).

Does the battery feed going to the key switch come directly from the battery power connector, or could the key switch feed wire (or relay ground wire) be connected somewhere to the wiring harness itself?

If the key switch and relay solenoid (windings) circuit is not on the battery side of the battery connector, it should be wired totally separate from the main wiring harness and should not utilise any of the thin harness wires to carry either the battery feed or the ground return. The relay and key switch wiring should connect directly to the battery power connector in parallel with the thick Red and Black battery power cables coming from the motor harness.

I'm pretty sure that having the 15 watts of lighting turned on will also affect the operation of the battery gauge as the ~270mA of current will definitely cause a slight voltage drop along the shared thin wires. The simple LED battery gauges were originally intended for use with lead acid batteries and are not much good for monitoring the higher voltage LiFePo₄ and LiPo batteries, so if you are very lucky, you might even find that having the lights on will reduce the voltage at the LED battery gauge enough to make it work more a little bit more realistically.

This basic LED battery gauge was originally designed for lead acid type batteries which have a more pronounced voltage drop throughout their discharge, but the LiFePO₄ batteries in use today have a higher voltage which drops very little in comparison as they discharge, and the LEDs would probably remain fully lit for 90-95% of the battery's use.



Take a look at this post to find out how a resistor can be used to adjust the gauge operation to better suit the battery type being used. As your cable has already been chopped it should be relatively easy to solder a variable resistor into the battery gauge power supply wire.

Incidentally, 55V seems a little bit low for a fully charged LiFePO₄ battery, as I would have expected be nearer 56~58.4V (dependant upon the set charger voltage).
LiFePo₄ batteries have a very similar discharge characteristics to LiPo, and my LiPo cells would have to be ~25% discharged to achieve the same percentage of voltage drop from fully charged.
I would expect my GM 48V LiFePO4 battery to take a few weeks before for the residual drain of the BMS alone could cause it to drop from 58.4V to 55V.

I can at least put your mind at ease regarding your concerns about it being a problem with the internal controller. The controller could not cause the gauge problem unless it was very heavily loading the battery and causing the battery voltage to drop excessively, which it obviously isn't doing (this has already been confirmed by the constant 54V voltage reading).

Alan
 

[Abe]

Hi Alan,
You focus on the key and relays, I think I have mentioned that I connected the battery directly to motors, which means I made bypass and relays + key is not used now.,
** Still fault appears after about a minute.
** Tomorrow I'm going to make another change, I'm going to try another option (Method of elimination) I will remove the batteries BMS controller and connect the battery directly to the motor.
What do you think ?
** I have to take a step by step to find the problem.
** Maybe you can offer me a number of steps I can take to find the problem?
Thank you,
Avi

[Bikemad]

I have tested three different throttles using a variable voltage power supply to try and determine the working voltages of the three LEDs on the battery gauge and here are the actual results:

LED	24V throttle	36V throttle	48V throttle
Green	24.1V and over	36.2V and over	48.2V and over
Yellow	21.7V and over	31.6V and over	42.5V and over
Red	12V and over	21V and over	30V and over

(The above measured voltage readings were taken at the battery end of the thick Red and Black power cables on the motor harness.)

According to the above empirical results, the yellow LED on your 48V throttle should only go off if the voltage drops below ~42.5V.
As your battery output remains at a constant 54V the yellow LED should stay on, and bypassing the BMS should not be necessary.

I can see three main reasons why the yellow LED might not remain on with the battery voltage output reading 54V:

• The battery gauge is faulty
• The voltmeter you are using to measure the voltage with is inaccurate and giving a false voltage reading
• The actual voltage at the battery gauge is less than 42.5V

I suggest that you measure the voltage at the lighting connection with the lights turned on to see if the voltage is below 42.5V. If the voltage measured at the light connection is greater than 50V (and your voltmeter is reasonably accurate) I would say that the battery gauge in the throttle unit is probably faulty.

However, if the measured voltage is below 42.5V, there is obviously a severe voltage drop problem with either the thin lighting feed wire going to the light switch, or the thin common ground return wire somewhere within the harness.
If this is the case, you can use your voltmeter to measure the actual voltage drop across each of the two wires (battery feed and ground return) by measuring the voltage at the two ends of each of the wires in turn:

Connect your Red meter probe on the thick Red battery cable connection and then connect the Black meter probe on the thin lighting feed connection and measure the voltage. I would expect the reading to be less than 0.5V with the light switch turned off and probably a bit higher with the lights switched on.

Perform the same test on the thin ground wire by connecting the Black meter probe to the thick Black battery cable and then connect your Red meter probe on the lighting ground connection and measure the voltage, which should also be less than 0.5V with the light switch turned off and probably a bit higher with the lights switched on.

Let's hope that something obvious can be found by carrying out the above checks.



Alan
 

EDIT: Actual readings entered (instead of the original estimated figures) for the 36V throttle.

[Abe]

Hi Alan,
First of all thank you, of course I will replace the voltmeter.
I'm going to perform the tests that you recommend, (where I can check the voltages of the throttle?).
** By the way, I connected the battery directly to motor and the result was the same as before, namely yellow LED switch off after a minute, without the BMS.
If the throttle is defective, can I continue to ride a bike?
I myself can correct the throttle?
Of course I will inform you later
Thank you,
Abe

Further:
1. I made measurements the voltages with another voltmeter and the results were completely identical.
2. Also, I opened the thumb throttle, I think is 36V for the reason: motherboard gets very hot, nowhere on the throttle does not say 48V.
3. I charged the battery and at the end the voltage was 58 volts.
4. In addition, do you think, I can damage internal controller if I will continue to ride that bike In this state?

[Bikemad]

The 24V and 48V throttles usually have their voltage clearly marked on the casing like this:



But the 36V throttles are not visibly marked.

If it is a 36V throttle, I think the battery gauge unit has most probably failed due to being overloaded with too high a voltage.

I don't think it is going to be easily repairable and it is probably easier to fit an additional voltmeter or battery gauge to monitor the capacity of the battery.

It is extremely unlikely that the faulty battery gauge will cause any damage to the motor controller as it is connected to the battery feed wires and only shares a common ground connection with the throttle and lighting circuit.

If you are worried about using the throttle as it is, I would suggest disconnecting and insulating one (or both) of the two wires connected to the LED circuit board inside the throttle enclosure:


This would definitely ensure that there would be no way that it could cause a problem even if the circuit board was completely shorted out.

Alan
 

[Abe]

Hi Alan,
Many thanks to extensive assistance.

I'm going to disconnect one of the wires from the motherboard.
I think we found the problem, I purchased the same throttle from Ebay of 48 volts.
I'm going to replace only the circuit board, ie to take the new circuit board from a new throttle and install to the old one, so I do not have to touch any wiring.
Thank you,
Abe
** Only in the case of continued failure I will inform you..

[Bikemad]

Be careful that you don't accidentally mix them up, as the circuit boards on the throttles I've had apart had identical part numbers, even though the battery voltages (and several of the resistors on the boards) were different.

Alan

[GM Canada]

That is odd as I am still using the same wire harness and controls that were already on my 29er bike from my MP5 setup. The Edge controls are still in the box. Everything has been working great for quite a while now.

Gary.

[Abe]

Hello Alan,
I decided to inform you:
In the old throttle I replaced to a new LED circuit board inside the throttle which supports a voltage of 48V, the LED indicator is now works great.
** I would like to take this opportunity to consult with you, every time the rear wheel spokes are released in which the motor is installed, what can I do to prevent this?
which
Thanks,
Abe

[Bikemad]

Hi Abe,

It's good to hear that your battery gauge is now working again but not so good to hear that your spokes keep coming loose.

Check out this post to find out how to refit the spokes so that they are much better supported at the elbow. This will help to reduce the unwanted stretching of the spokes which causes them to become loose, and will also reduce the flexing of the elbow which can lead to broken spokes caused by metal fatigue.

If you don't want to spend time removing the wheel and tyre and swapping the spokes around, I would suggest simply retightening the spokes so they are all at a similar tension (but reasonably tight) whilst trying to keep the wheel rim as true as possible.
This will hopefully reduce the likelihood of the spokes working loose again.

Alan