GoldenMotor.com Forum
General Category => Magic Pie & Smart Pie Discussions => Topic started by: Jbwiden on July 26, 2019, 05:34:03 PM
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If the bike is left on for some time, seen when bike is accidentally left on after a ride for example, the top green light on the throttle often will turn off and flicker when the battery voltage is still high while at lower voltages afterwards the green light will often come back on. Anybody have seen similar or have an idea what could be going on?
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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.)
If your green LED is going off/flickering and the battery voltage is above the figure shown above for your particular 24/36/48V throttle unit, then it is probably a faulty battery gauge/LED.
Using a 36V throttle with a 48V battery (or a 24V throttle with a 36/48V battery) will greatly overload the battery gauge, which will get very warm, making it more susceptible to eventual failure.
(https://i.imgur.com/flWvYEn.png)
(http://www.goldenmotor.com/accessories/images/zoom_tt2.jpg)
24V and 48V throttles have their voltage printed on the casings as shown above, but the 36V throttles are usually unmarked. ::)
Alan
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https://imgur.com/a/vR9Q9qa
Here is an example. The green led should be on.
The battery is 14 cell lion so it can get to 58.8 volts but I almost never charge past 57.4. the throttle is 48v.
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After watching your video, I would say it is probably the green LED itself that is faulty, because (with a 14 cell Li Ion pack) I would expect the green light to stay on continually throughout the entire discharge cycle.
Ideally, a 14S Li Ion battery pack should never be discharged below 49V (3.5V per cell) so the LED battery gauge (if it was working correctly) should always have all three LEDs continuously lit.
To make the battery gauge useable with a Li Ion pack you would need to add a variable resistor in the supply to the gauge PCB and adjust it to suit your preferred voltage warning levels
Alan
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I'd start by looking for a poor connection... something that may be getting hot when over-volted.
Some internal pictures...
(https://i.imgur.com/yhbmPbi.jpg?1)
(https://i.imgur.com/1nXoCne.jpg)
(https://i.imgur.com/rg1N2j3.jpg)
Information about how to add a mini pot for better accuracy... (spoiler alert... you can get closer, but never satisfied...)
https://electricbike.com/forum/forum/builds/ebike-building-directions/48457-1st-build-e-bike-rider-magic-pie-v5-rear-bottle-batt-52v-11-5ah-huffy-parkside?p=58677#post58677 (https://electricbike.com/forum/forum/builds/ebike-building-directions/48457-1st-build-e-bike-rider-magic-pie-v5-rear-bottle-batt-52v-11-5ah-huffy-parkside?p=58677#post58677)
How to get at the internals...
https://electricbike.com/forum/forum/builds/ebike-building-directions/48457-1st-build-e-bike-rider-magic-pie-v5-rear-bottle-batt-52v-11-5ah-huffy-parkside?p=57489#post57489 (https://electricbike.com/forum/forum/builds/ebike-building-directions/48457-1st-build-e-bike-rider-magic-pie-v5-rear-bottle-batt-52v-11-5ah-huffy-parkside?p=57489#post57489)
As I mention, IMHO nothing beats a good accurate voltage indicator.
(https://i.imgur.com/3siWKdu.jpg)
Regards,
T.C.
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> Ideally, a 14S Li Ion battery pack should never be discharged below 49V (3.5V per cell) so the LED battery gauge (if it was working correctly) should always have all three LEDs continuously
For the cells I have NCR18650PF, 3.5v under load still has like half charge remaining, so seeing the led to off does occur with what I consider near ideal battery usage. I generally stay within 35 to 75% SOC.
> I'd start by looking for a poor connection... something that may be getting hot when over-volted.
Yeah, I think I will open it up. Thanks for the instruction links.
> IMHO nothing beats a good accurate voltage indicator.
The battery pack itself has Bluetooth so I can monitor voltage, it also has a soc meter that is coulomb counted so it's actually pretty accurate though does have some drift over time as I don't fully cycle the pack.