Install Voltage Meter on ebike

[LukeMike88]

Hello, Gentlemen, I have an ebike bought from China and you know, it has an LCD screen with a battery indicator but it is inaccurate, there is no option to show how much V the battery has in the settings.

I want to install something like this:

Digital Display 12 100v Voltmeter With Lock/Shifter Universal for Electric Bike Scooter Tricycle ATV Battery Capacity Indicator|display digital|display for electric bikedisplay locks - AliExpress

Cheap Electric Bicycle Accessories, Buy Quality Sports & Entertainment Directly from China Suppliers:Digital Display 12 100v Voltmeter With Lock/Shifter Universal for Electric Bike Scooter Tricycle ATV Battery Capacity Indicator Enjoy ✓Free Shipping Worldwide! ✓Limited Time Sale ✓Easy Return.

aliexpress.com

Is it hard to do? I have never installed it, and on the internet I did not find any simple manual ...

 

[harryS]

No, there are no instructions, You shouldn't do this if you don't know the wiring, It's just like using a voltmeter, You need to know whereto put the probes, On an ebike, you always have battery and ground going to the LCD.

Most LCD's have 5 wires, One is battery. One is ground. There is a third wire that is raised to battery voltage when the LCD turns on. I hooked my voltmeter to this wire and ground, so it turns on with the LCD. Mine did not have the keyswitch,

I did get another one with the keyswitch because they don't sell the simple ones any more. For that one, you could wire the keyswitch to turn on the battery power to the LCD, and wire the meter so it would turn on when you turned the key. You would still have to start the LCD.

 

[LukeMike88]

in my display this is what it looks like




I will find one without a key, only a voltmeter

 

[harryS]

There you are! I have the same connector and I use the blue and black wires. Blue gets battery voltage when the LCD is turned on. I would attach it on the main cable before the two green connectors.

You could use the key switch version. Just don't wire up the keyswitch. If you have your keys dangling on the handlebars, nothing good can happen with the extra weight. Probably have the keys fall off.

 

[LukeMike88]

do you have any photo? seriously, I don't know anything about it, all I can do is solder

 

[harryS]

Just cut the insulation carefully off the cable, without damaging the 5 internal wires. Finf the blue and black. Attach the voltmeter. Or go all the way back to the controller, and run the wires from the voltmeter to the blue/black.

The cover photo is the kind of wire connection you will be doing.

 

[jsonjson1]

in my display this is what it looks like


View attachment 92446

I will find one without a key, only a voltmeter

Luke, my wires coming off my display are, green, blue,yellow, red, white and brown. Want to duplicate your installation. How can I identity the controller power control line and the ground? Thanks Jim ([email protected])

 

[indianajo]

You know, many controllers have a red block female pin connector with red & white wires for alarm power. These are ever-hot. Mating connectors can be bought on e-bay (but not red). red is plus, black is minus.
When I had a digital voltage display built into the throttle, it was powered up all the time. It didn't drop the voltage even a tenth of a volt in a month of not riding (dead of winter).

 

[teskow]

A little trick I have used over the years for testing and tapping into wires without damaging them is to carefully stick the wire with a small pin on the end of my tester wires to test for voltage etc.
You will just have to prick the wire a bit to get contact with the copper in the wire to get a reading. When I don't want to strip the wire midway to make a connection I have stuck the pin into the wire parallel into the wire and then soldered to the pin. Some sewing common pins are brass which carries power quite well and take to soldering well. They will be non-magnetic if brass.