How should I connect the ignition switch cum voltmeter to the controller?

seba240698

100 mW
Joined
May 10, 2019
Messages
42
Hi all,
I have a few questions and had been searching for answers in the internet and in this forum in particular, but I'm still not able to get any answer. I've written to sellers in Aliexpress too but till date there is no response.

My question are :
1) I have a ignition switch cum voltmeter, similar to the one listed in Aliexpress, shown in photo 1. The wiring instructions (photo 2) are : green wire to battery's positive terminal, black to battery's negative terminal and red wire to ignition wire. So far so good. However, I'm going to get a new controller which has a 2-terminal ignition switch. See photos 3 and 4. It has a red and purple wire. Can I just treat the red wire and as the ignition wire and ignore the purple wire? Means I leave the purple wire unconnected? I can try it but I'm just worry it might burn my controller or ignition switch or voltmeter.

2) There is a wire (in fact it is a bunch of 6 wires) coming out of the controller labeled as Cycle Analyst. See photos 3 and 4. I presume it is for a cyclometer and I don't have one. Can I just leave the wires unconnected? Will my controller able to work with no connection to a Cycle Analyst? I know it probably will work but I just worry because I had a bad experience with another controller which has a connection to a display unit and without a display unit, the controller just didn't power up!

3) This will be a difficult question to answer but I'll still try to ask. I know battery voltage dictates top speed and controller's maximum current dictates power (how well the motor can accelerate and climb hills), but is there a rough guide on how many volts (of battery) and how many watts (of controller) one can attain top speeds of how many kph or mph on flat roads? I know all these depend on many factors such as weight, headwinds/tailwinds, weather, conditions of roads etc, but I just need estimates. Currently I have a 48V, 20Ah battery.

One more last thing, I read that the power rating of motor does not really matter, so we can pretty much connect controllers of any power ratings to motors of any power ratings? Is it true?

Thank you in advance!

Have a nice evening.

It is 7.48 am here in Singapore. :wink:
 

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1. The red and black wire on the controller would normally be shorted via an ignition switch to turn the controller on. You should measure for voltage the two wires to determine which is at battery voltage (usually red, but not always). The battery positive wire can go to the green (Battery+) of your switch, and the other wire would go to the Red (ignition wire) of your switch. The black wire on the switch should go to ground/battery negative, which allows the volt meter to display the battery voltage.

2. You shouldn't need to connect a Cycle Analyst for the controller to work, since you can connect your throttle directly to your controller (rather than to the CA, which would send the throttle signal through the CA connector).

3. You could try using the Grin simulator to get a feel for the relationship of voltage to speed, and changing the controller parameters, grade of hills, rider weight, etc, so see what the effect is as you change the parameters.
https://ebikes.ca/tools/simulator.html

Power Rating: You can provide substantially more power that the rating of a motor, but at some point, the motor won't be able to dissipate the excess heat and could burn up the motor. Short bursts would usually be OK, but running above the rating for long periods could result in a meltdown.

seba240698 said:
1) I have a ignition switch cum voltmeter, similar to the one listed in Aliexpress, shown in photo 1. The wiring instructions (photo 2) are : green wire to battery's positive terminal, black to battery's negative terminal and red wire to ignition wire. So far so good. However, I'm going to get a new controller which has a 2-terminal ignition switch. See photos 3 and 4. It has a red and purple wire. Can I just treat the red wire and as the ignition wire and ignore the purple wire? Means I leave the purple wire unconnected? I can try it but I'm just worry it might burn my controller or ignition switch or voltmeter.

2) There is a wire (in fact it is a bunch of 6 wires) coming out of the controller labeled as Cycle Analyst. See photos 3 and 4. I presume it is for a cyclometer and I don't have one. Can I just leave the wires unconnected? Will my controller able to work with no connection to a Cycle Analyst? I know it probably will work but I just worry because I had a bad experience with another controller which has a connection to a display unit and without a display unit, the controller just didn't power up!

3) This will be a difficult question to answer but I'll still try to ask. I know battery voltage dictates top speed and controller's maximum current dictates power (how well the motor can accelerate and climb hills), but is there a rough guide on how many volts (of battery) and how many watts (of controller) one can attain top speeds of how many kph or mph on flat roads? I know all these depend on many factors such as weight, headwinds/tailwinds, weather, conditions of roads etc, but I just need estimates. Currently I have a 48V, 20Ah battery.

One more last thing, I read that the power rating of motor does not really matter, so we can pretty much connect controllers of any power ratings to motors of any power ratings? Is it true?

Thank you in advance!

Have a nice evening.

It is 7.48 am here in Singapore. :wink:
 
Hi E-HP, thank you so much for your valuable information and the simulation, the Grin simulator is so cool, wow! It helps a lot!

But I still don't get the followings points:
1) I know the green wire from the voltmeter/ignition switch should be connected to the positive terminal of the battery, black wire to the negative terminal and the red wire to ignition wire, but that is provided the controller has ONLY 1 ignition wire. For the controller I am going to buy, there are TWO ignition wires, one red and one purple, shown in photos 2 and 3 of my previous post, my question is, what should I connect the purple wire to? Should I leave it unconnected, or should I connect it to the negative terminal of the battery?

2) Throttles are not allowed in my country, I do not possess one. Only pedal assist is allowed. So I just leave the throttle wire UNCONNECTED? I think it should work, shouldn't it?

Thanks in advance!
 
E-HP said:
1. The red and black wire on the controller would normally be shorted via an ignition switch to turn the controller on. You should measure for voltage the two wires to determine which is at battery voltage (usually red, but not always). The battery positive wire can go to the green (Battery+) of your switch, and the other wire would go to the Red (ignition wire) of your switch. The black wire on the switch should go to ground/battery negative, which allows the volt meter to display the battery voltage.

Sorry, I was eyeballing the colors. It would normally be the red and purple wires on the controller connection that you would normally short via a switch to turn on the controller.
 
seba240698 said:
1) I know the green wire from the voltmeter/ignition switch should be connected to the positive terminal of the battery, black wire to the negative terminal and the red wire to ignition wire, but that is provided the controller has ONLY 1 ignition wire. For the controller I am going to buy, there are TWO ignition wires, one red and one purple, shown in photos 2 and 3 of my previous post, my question is, what should I connect the purple wire to? Should I leave it unconnected, or should I connect it to the negative terminal of the battery?

2) Throttles are not allowed in my country, I do not possess one. Only pedal assist is allowed. So I just leave the throttle wire UNCONNECTED? I think it should work, shouldn't it?

Thanks in advance!

1. Your switch requires a BAT(+), and BAT(-) and has an ignition output. Your controller ignition connection has a
BAT(+) and an ignition input. If you test the controller ignition connector to determine which wire is BAT(+), then you know the other wire is the ignition input,

So, you have TWO of the connections for your switch, BAT(+) and ignition that can come from the ignition connector, so you only need to run a BAT(-) to complete your connections.

2. Don't need it.

FYI - for a future upgrade, you could add a cycle analyst, and at that point your can connect the PAS through the CA which would provide a lot more options with respect to how PAS functions.
 
Hi, thank you for your quick reply.

Now I undersrand how the ignition work.

So the purple wire from the controller has a low, maybe +5V potential typically to be connected to a switch to activate the ignition.

I am thinking, if I were to connect this purple wire directly to the negative terminal of the battery, as advised by you, wouldn't it create a short circuit and melt the purple wire as there is no resistor in between the +5V and ground?

Would it be better to leave the purple wire unconnected and insulate it so that it would not accidentally touch any ground?
 
seba240698 said:
Hi, thank you for your quick reply.

Now I undersrand how the ignition work.

So the purple wire from the controller has a low, maybe +5V potential typically to be connected to a switch to activate the ignition.

I am thinking, if I were to connect this purple wire directly to the negative terminal of the battery, as advised by you, wouldn't it create a short circuit and melt the purple wire as there is no resistor in between the +5V and ground?

Would it be better to leave the purple wire unconnected and insulate it so that it would not accidentally touch any ground?
Don't connect anything yet. What measurement do you get between BAT(-) and the purple wire, and what do you get between BAT(-) and the red wire?
 
I've not bought the controller yet. :|

I'll update you one once I bought and received it.
 
Hi E-HP,
The controller has arrived.
When I measure the voltage between the purple and red wire, the red wire is 48V, purple wire 0 V.
My battery is 48V.
Please explain to me how to connect it.
Thank you.
I don't dare to connect my ignition switch cum voltmeter to the controller yet as I worry it might blow up my controller.
 
Hi E-HP,

Just to close the case and let everyone knows, I followed what you said plus reading the instructions.

I connected the ignition wire from the ignition cum voltmeter switch to the thin red wire of the controller. I left the purple wire from the controller free, that's, I didn't connect anything to it (I connected it to a plastic connector and left it hanging there, I insulated the plastic connector with black tape though).

It worked fine.

Thanks for advice.
 
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