Display turn off immediately

[hab]

Hi,
First time poster here.
We have an older boxbike with 36V battery. There is a KT36SVPR-SY02D controller and a KT-LCD3 display.
Battery is new (I bought a new) and fully charged. I also replaced the rearwheel including motor.

Before these replacements, the problem began when one day nothing would turn on. I’m now at the point where only the controller and harness hasn’t been replaced.

When I turn on the battery and press the “on” button on the little assistance controller, the display will light up under a second and then be completely dead.

I have disassembled the controller and measured that none of the mosfets are completely shorted. I haven’t unsoldered anything though.
Any tips on what I can try before also replacing the controller? As you can see I already poured some money into this thing - would really like to get it working again.
Thank you anyone for any tips

 

[E-HP]

Where did you buy the battery and what are the specs? Can you measure the voltage when the problem occurs?

 

[hab]

I bought the battery here in Denmark - I believe it fits. I measure app 39,9v before and after pressing the on button.

 

[E-HP]

A fully charged 36v lithium ion pack would be 42v, so again, can you provide the specs on the battery or possibly a link to more info about it? Is it lead acid?

 

[hab]

Hi again,
I bought this one:

Elcykel Batteri Ebike 36V 10.4Ah eller 14Ah - passer til Ansmann, Jensen, X-Zite, El ladcykler, E-fly

Elcykel Batteri Ebike 36V - Kan vælges i to forskellige størrelser: 10,4Ah eller 14Ah. OBS! Der følger ikke oplader med - men denne kan købes separat - se vores udvalg af opladere til elcykel her.

batteriservice.dk

This project has been on standby during the winter.

I put it back in the charger now - is 40V a problem? Lets see if it goes to 42V. The 4 LEDS on the pack indicates that it is fully charged but that is obviously not very precise.

Specs:

Volt	36V
Kapacitet	10.4Ah
Celle kombination	10S4P
Vægt	2.15Kg
Energi	375Wh
Gennemsnitsholdbarhed	1000+ opladninger
Celler	Grade A 18650 celler (High power 2600)
32,0 x 14,8 x 5,5 (LxBxH i cm)

 

[E-HP]

Thanks. As long as the battery can be charged fully, then it’s less likely to be the issue.
Does you LCD3 use a julet/higo or JST connector? If JST, then when it goes dead, measure the voltage of the red conductor to ground. It should be battery voltage. That will let you know if it’s getting power, and possibly a faulty display, or something upstream.

 

[hab]

Thanks. The display has JULET connector near the display.
Connectors from the controller:

 

[docw009]

When the battery is not in the bike, you can switch it on and measure the voltage. The LED's will light? I have that same battery case, but mine does not have an LED that shows it is powered up, I have to look at the switch, It does have the LED gauge.

When you put the new battery in the bike cradle, the battery will not stay on? Have you checked that the positive and negative pins are set up like the old battery? Do you still have the old battery to compare?

If I misread your answer, and it is the LCD3 display that turns off immediately, follow E-HP's advice. Check the voltage to the LCD3. Do it at the white connector. Red to black. Should be same as the battery voltage,

 

[hab]

I measure voltage on the battery when powered on outside the case. I can measure the battery voltage on the input side on the controller board.
+ is the connector near the centerline of the cradle.
The old battery was dead and recycled.

 

[docw009]

Sounds good. So you can insert the battery, turn it on and the battery lights still come on.

Now you can measure at the red/black on the display JST connector, per E-Hp.

 

[hab]

Hi again,
Thank you for replying. Which of the connectors do you reckon is the display one? I have a 5-pin and a 6-pin JST (please see above for picture).
I can't seem to find a replacement controller anywhere, it seems they all have different type connectors now, and I don't know what each wire does except battery input and the 3 phases for the motor.
I found some videos on youtube on how to measure if the MOSFETs are shorted (cont. measurements between battery +/- input and the 3 phases for the motor), that doesn't seem to be the case. Any other obvious things I should check?
I'll try to get the black/red measurements from the JST connectors tomorrow (the disassembled bike is out in the black cold night now )

 

[E-HP]

KT uses a 5 conductor display cable. You can verify by unplugging it, since the display won’t respond at all.