• Howdy! we're looking for donations to finish custom knowledgebase software for this forum. Please see our Funding drive thread

More KT LCD8H display problems

Joined
Aug 6, 2022
Messages
62
I was able to resolve one problem thanks to answers I received on another post. However, I still have three issues, one new and two I have not been able to correct.

New issue: The battery usage bar is not displaying correctly. Yesterday it was displaying 50% battery left, but is now showing 100% left. The display is showing voltage at 44.2v on a 48v system. Actual battery has about 50% capacity left.
  • P5 setting is 0 (default)
    Setting P5 to 15 for 48v makes no difference in display, not does any other setting.
    Prior to changing P1 and P2 settings, display was showing 50% battery capacity left. After setting P1 and P2 back to previous setting, battery display did not change
Without an accurate way to measure battery usage it is difficult to know how much battery you have left.

Old issue 1: I have never been able to get throttle to work
  • No combination of settings for throttle works
    Throttle indication on display does not show when throttle lever is pressed
    Seems like signal is not getting to the display or controller
    Triple checked all connectors, and all were tight
    Throttle has a male connector, and so does the 4-1 wire it plugs into. Using a female to female extension wire to complete the connection
I would like to be able to use the throttle as it can be very useful in certain situations.

Old issue 2: I have never been able to get the brake cutoff to work
  • Brake indication on display does not show when the brakes are applied
    Seems like signal is not getting to the display or controller
    Triple checked all connectors, and all were tight
    The brake levers have a female connector, and so does the 4-1 wire they plug into. I am using a male to male extension wire to complete the connection 

Since the motor stops running when I stop pedaling, this is not too big of a deal, unless I use the cruise function. It is not safe to use the cruise function without the brake cutoff.

How do I determine if I have a controller problem, a display problem, or if perhaps the 1-4 wire is faulty?
 
Here are my current KT-LCD8H settings:

P1 80
P2 6
P3 1
P4 0
P5 0

C1 3
C2 0
C3 1
C4 0
C5 10
C6 3
C7 0
C8 0
C8 0
C10 N
C11 0
C12 4
C13 0
C14 2

L1 0
L2 0
L3 1
L4 5
 
Others may be able to decipher what you have going on, but without knowing exactly what the battery voltage actually is, the following info is virtually useless:
New issue: The battery usage bar is not displaying correctly. Yesterday it was displaying 50% battery left, but is now showing 100% left. The display is showing voltage at 44.2v on a 48v system. Actual battery has about 50% capacity left.

Would also be nice to know if you're playing with a 48v or 52v battery, and if it's been fully charged.

It sounds like you are going to have to do some closer checking on the throttle and brake. Because you have 3 wire connectors that plug in together, (assuming no bent pins or connector damage), there is no guarantee of functionality. You need to assure yourself that the positive, negative, and sensor wires all line up with each other on both sides. This especially important if all of your stuff wasn't all purchased together as a package.
 
No idea on your voltage display problem. I have noticed mine does not update voltage right away. It could be down to 50% and when charged needs for me to use power before it changes. Figured that is the nature of the beast.
Have you checked to make sure you have 5v? The KT22A I used had a small capacitor inside that was floating on long leads and shorted 5v out. The symptom was brake switches and thumb throttle did not work. I lucked out and was able to move the capacitor over and epoxy it to the board and have been using it since.
 
I installed the new display, controller and 1T4 cable last week. The 48v battery was fully charged. I was road the setup for a few days with the incorrect P1 and P2 settings. The speedometer worked ok unless you were coasting. The battery is a 49v 17Ah unit. After riding last week, the display showed 50% battery life left and less than 48v. (With a fully charged battery, the display showed over 50v). Today I corrected the P1 and P2 settings. Now the Speed works perfect, even when coasting. During my short test ride I noticed the display now showed 100% battery life and 44.2v. I know the battery has about a 50% charge left right now. I will be fully charging the battery before Saturday when I have a 35 mile ride. I typically will use about 30% of a fully charged battery. It will be interesting to see what the display reads.

Have you checked to make sure you have 5v? The KT22A I used had a small capacitor inside that was floating on long leads and shorted 5v out. The symptom was brake switches and thumb throttle did not work. I lucked out and was able to move the capacitor over and epoxy it to the board and have been using it since.

This is interesting. I do have the option of returning/exchanging the controller. Perhaps I should do this.
 
So I am returning the controller and getting a replacement. Maybe this will solve the brake/throttle problem. I will be trying something else this morning regarding the battery issue, hopefully that will resolve that problem.
 
I have an LCD8 and tested what it shows at different voltages against a calibrated Fluke.

So for the display to show 35V, 35.24V was needed. It's reading low throughout the range.

Code:
	Voltage Accuracy Test	
		
Target Volts	Input	Difference
20		20.28	0.280000000000001
25		25.24	0.239999999999998
30		30.32	0.32
35		35.24	0.240000000000002
40		40.32	0.32
45		45.34	0.340000000000003
50		50.41	0.409999999999997
55		55.42	0.420000000000002

This will probably vary unit to unit since I suspected it's just a voltage divider using some cheap SMD resistors.

You need to figure out what the actual battery voltage is, and what the display shows. That's step 1. Step 2 is brush up on how batteries work. The battery charge level meter is just an estimate. It doesn't count energy in-out. There are meters out there that do count. They are not expensive. Maybe you need a coulomb counting meter. That will show an actual charge, not make a guess like the LCD8 does.
 
It probably would be a good idea to get a meter to test.

My concern was not what the display was showing in regard to estimated voltage, as I know that is just an estimate. The battery level indicator (battery symbol) is also just an estimate. The battery symbol on the display shows 4 green LEDs when the battery is fully charged. The LEDs turn off one at a time as the battery is discharged while riding. This was all working fine, and the LEDs were down to only two lights which corresponded to my estimate of the remaining battery life. The display showed the battery had an estimated charge of around 42v when I shut down the system.

The next day with the battery about half discharged, I changed some of the settings on the display. When I turned the system back on on, the battery symbol on the display showed 4 green LEDs, even though the voltage still showed about 42v. This is what I found strange. I shut everything off and fully charged the battery. This morning I reconnected the battery and turned everything on. The battery symbol still shows 4 green LEDs (which it should now), and the voltage on the display shows 54.2v. This is what the system has been showing with a full charge since I put it together. I plan to do a couple of long test rides to see if everything is working OK again, or if still have a problem.

The new controller arrives Monday. I will install it after I complete this test.
 
rocketman58 said:
The next day with the battery about half discharged, I changed some of the settings on the display. When I turned the system back on on, the battery symbol on the display showed 4 green LEDs, even though the voltage still showed about 42v.

There is a micro controller inside the LCD8 which has a bunch of human written computer code on it. There is more than likely an if-else statement that decides if a 36V or 48V battery is connected. Something like... at boot up, if voltage is <= 42V then the battery is 36V (which would be 42V at full charge), and then the displays thinks you have a fully charged 10 cell 36V battery, not a half discharged 13 cell 48V battery.
 
Comrade said:
There is a micro controller inside the LCD8 which has a bunch of human written computer code on it. There is more than likely an if-else statement that decides if a 36V or 48V battery is connected. Something like... at boot up, if voltage is <= 42V then the battery is 36V (which would be 42V at full charge), and then the displays thinks you have a fully charged 10 cell 36V battery, not a half discharged 13 cell 48V battery.

I was wondering if the cause was something like that. It would make sense. I am assuming that since I reset everything with a fully charged battery, all should return to normal. We will see after a few days of riding.

Thanks for the information Comrade
 
So the new controller made no difference regarding brake cutoff and throttle operation. Since the KT controller has the same plugs as the old Bafang brake levers and throttle, you cannot plug them together. (Throttle has a female plug, and so does the controller. Brakes are male, and so is the controller.) What I did is to order a male to male extender cable as a go between for the throttle. (Throttle female plug connects to the male end of extender, and the female controller throttle cable plugs into the other male end of the extender cable.) Evidently this does not work as the display receives no signal.

Just for the heck of it I plugged the female throttle cable into one of the male brake cables coming from the controller. This lights up the brake symbol on the display. While this does not resolve anything, it is interesting.

I ordered a new KT specific throttle with a male connector. This will plug directly into the controller. I am hoping this will resolve the problem. As far as the brakes go, I really do not need the cut offs as the motor stops when I stop pedaling.
 
My experiences with the KT LCD8H are bad.
The first issue started when regen brake on a mountain.
The new display couldn't manage the brake energy/voltage and broke down. Black screen.
New display with LCD3. No problems anymore.
Second issue with another ebike. The display LCD8H didn't react on the buttons.
I opened and checked the buttons but everything looked ok.
New display with LCD3. Again: no problems anymore.
My conclusion and advise: don't use a LCD8H but choose the LCD3.
 
Albert_01 said:
The new display couldn't manage the brake energy/voltage and broke down. Black screen.

Are you suggesting regen kicked your system voltage so high it burned out the display?

As to the issue above, it apparently can be easily solved by changing L1 setting from 0, which is auto-detect of number of cells in the battery, to 2 or 3, which would would 36V and 48V batteries respectively.
 
There is a micro controller inside the LCD8 which has a bunch of human written computer code on it. There is more than likely an if-else statement that decides if a 36V or 48V battery is connected. Something like... at boot up, if voltage is <= 42V then the battery is 36V (which would be 42V at full charge), and then the displays thinks you have a fully charged 10 cell 36V battery, not a half discharged 13 cell 48V battery.
Hi, I have the same problem. If only there was a P setting for nominal battery voltage, rather than a coder's what-if algorithm. I was assured that the KT-22A and LCD8H system would work fine with a 52V battery. It does seem to work ok, (apart from the PAS, but that's another story) however, the battery display is all over the place. Shows full charge until just before the current limit for a discharged battery kicks in.
 
Maybe you didn’t ask the right question. The KT-22A and LCD8H system does work fine with a 52V battery. But what doesn’t work fine is the controller low voltage cut off.

I also use a 52v battery with a KT controller and as I can’t rely upon the controller lvc, my BMS is the safety cut off, but I try not to get the battery depleted enough for that to kick in.

That’s my only gripe. Other than that I’m very pleased with my controller. And I’m glad I opted for the LCD03 rather than the LCD08.
 
Maybe you didn’t ask the right question. The KT-22A and LCD8H system does work fine with a 52V battery. But what doesn’t work fine is the controller low voltage cut off.

I also use a 52v battery with a KT controller and as I can’t rely upon the controller lvc, my BMS is the safety cut off, but I try not to get the battery depleted enough for that to kick in.

That’s my only gripe. Other than that I’m very pleased with my controller. And I’m glad I opted for the LCD03 rather than the LCD08.
I can live with the battery display, though the lvc cut-off makes me anxious. What voltage does your BMS kick in at? I lose power when the display is showing just under 50V. The indicator on the battery shows 1/4- 1/2 full.

My big bugbear is the PAS. I have never been able to get it working. After trying four different sensors I must assume the controller or some part of the wiring is faulty. I have posted a question about this.

Can you say why you prefer the LCD03? The LCD08 seems to have about the same functionality.

Thanks
 
My BMS has never kicked in I always recharge when I get down to 2 bars on the display. That’s when I start to lose performance from the motor.

I have responded to your other post.

I read posts about people preferring the LCD display because it was easier to read, especially in bright sunlight. It’s also cheaper and does everything it needs to. The only thing it doesn’t do is let you set up the P, C and L parameters on the same screen without cycling through the menu, but I can live with that.
 
Back
Top