Help with LCD SW900

markkg

Finding my (electric) wheels
Aug 13, 2020
20
0
Hi guys after all the great help in my previous thread I though I would ask again before doing something wrong.
I’m running voilamart 1000w rear drive, the kit came with a twist throttle with nasty little built in display, I have a SW900 LCD to fit and thumb throttle but wiring not looking straight forward so any guidance appreciated.
to make it easier I’ve attached some photos.
Photo 1; Plug from controller to throttle
Photo 2: Plugs from LCD
Photo 3: Thumb throttle
Do I just connect like for like colours if so what are the brown and white wires on the second LCD plug for and what about thumb throttle.
Thanks for looking.
 

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vfr400

Esteemed Pedelecer
Jun 12, 2011
9,822
3,986
Basildon
You can't plug in the LCD because it has a 5-pin connector, while as the controller has a 6-pin That's just as well because if you had connected them, you would have wiped out both, as the wires are in the wrong sequence. You can see that on one, the blue (switched battery voltage) is next to the red (battery voltage. On the other, the ground is next to the red.

The new LCD has:
red battery volts
blue switched battery volts
black ground
green Rx
yellow Tx
The other two are for the lights, but I wouldn't risk using them for that.

The old LCD has unusual colours. You'd have to follow them into the controller to see which is which other than the red and black, which are almost certainly battery supply. Hopefully, the controller is marked on its PCB. It's important also that you get the Tx and Rx the right way round - Tx from the LCD connects to Rx from the controller.

You need to show the throttle connector for advice on that, but if it's a normal 3-pin connector, it should be red to red, black to black and green to whatever the third wire colour is on the controller.
 

markkg

Finding my (electric) wheels
Aug 13, 2020
20
0
You can't plug in the LCD because it has a 5-pin connector, while as the controller has a 6-pin That's just as well because if you had connected them, you would have wiped out both, as the wires are in the wrong sequence. You can see that on one, the blue (switched battery voltage) is next to the red (battery voltage. On the other, the ground is next to the red.

The new LCD has:
red battery volts
blue switched battery volts
black ground
green Rx
yellow Tx
The other two are for the lights, but I wouldn't risk using them for that.

The old LCD has unusual colours. You'd have to follow them into the controller to see which is which other than the red and black, which are almost certainly battery supply. Hopefully, the controller is marked on its PCB. It's important also that you get the Tx and Rx the right way round - Tx from the LCD connects to Rx from the controller.

You need to show the throttle connector for advice on that, but if it's a normal 3-pin connector, it should be red to red, black to black and green to whatever the third wire colour is on the controller.
Thanks for the information I’ve just seen another controller which has the correct plugs so maybe this is a better option than risking getting it wrong.
 

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vfr400

Esteemed Pedelecer
Jun 12, 2011
9,822
3,986
Basildon
Sorry wrong photo thats the current controller should have been this one, if anyone knows where to get one.
Controllers have to match the LCD with their software, not just connections. They have to have the right protocols (language) and the right instructions. It can be like you asking me what to do next and I reply, "go afore and unclip the bob-stay from the dolphin striker". It might sound like nonsense to you, so you reject it, though it might be a valid reply to a different person in different circumstances asking a different question.
 

Walks

Just Joined
May 6, 2021
1
0
Hi Mark, where did you buy your lcd with 5 wire plug with brown & white wire, Alan
 

felbutss

Just Joined
Jun 24, 2023
1
0
Hey guys. First post.

YOU can use a not for SW900 controller with the SW900.

I purchased a not for sw900 controller with a 6pin (voltage and throttle plug).

I had to solder two cables to the TX and RX pads. Works fine. (The yellow and white cable at the bottom right on the pic)

Im an industrial electrician. From my work experience, most Chinese stuff is mass made generic with minimum mods to change the product to different versions.

To create tooling for different products is expensive.
 

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saneagle

Esteemed Pedelecer
Oct 10, 2010
4,143
2,059
Telford
Hey guys. First post.

YOU can use a not for SW900 controller with the SW900.

I purchased a not for sw900 controller with a 6pin (voltage and throttle plug).

I had to solder two cables to the TX and RX pads. Works fine. (The yellow and white cable at the bottom right on the pic)

Im an industrial electrician. From my work experience, most Chinese stuff is mass made generic with minimum mods to change the product to different versions.

To create tooling for different products is expensive.
You were just lucky that your controller uses the same protocols and has the right software to interpret them. Maybe some functions are working, but not all.