Accessories Wiring Help!

[huntervh]

Hey there!

I am in the process of putting together my first ebike and have hit a wall when it comes to the final stages of the wiring. I am trying to wire up accessories such as a headlight, brake light, etc. which are all rated at 12 volts. My battery is a 72volt 20Ah. In order to get the accessories to work I bought a 72v to 12v - 10amp step down converter. The converter works great and powers all the accessories when it is the only thing wired directly to the battery, but when I wire the converter into the battery leads going to the controller, the converter doesn't really work and gets super freaking hot to the touch within a minute. Is it not getting enough power when plugged into the chain that the controller is plugged into? Not enough Amperage? Any help would be greatly appreciated!

Thanks!

 

[harryS]

That's a puzzle. Maybe the converter needs its 12 volt output to have a floating ground. When you plug in the controller, is there any connection, like a headlight signal, that connects to your accessories? Maybe that's affecting the converter ground. A relay would fix that, or an optoisolator,

With converter not plugged in, you might want to see if there's continuity between battery negative input and the 12Volt negative output. .

 

[tomjasz]

72v to 12v - 10amp step down converter.

Brand and model specs?

 

[PedalUma]

My first builds had a dog's breakfast of wired accessories. There were wires everywhere. I do not do that anymore. USB accessories work better and you don't need to wire them. You might want to reconsider and go with the simple clean solution.

 

[Gionnirocket]

Brand and model specs?

I concur

 

[Gionnirocket]

That's a puzzle. Maybe the converter needs its 12 volt output to have a floating ground. When you plug in the controller, is there any connection, like a headlight signal, that connects to your accessories? Maybe that's affecting the converter ground. A relay would fix that, or an optoisolator,

With converter not plugged in, you might want to see if there's continuity between battery negative input and the 12Volt negative output. .

I'm wondering the voltage range of input on the converter... It may be too narrow.
Was the bike motor running?

 

[PedalUma]

If it is heating up, it is just wrong. And there really is no need for it. Guess which of these two electric bikes is one of mine; Orange or Red.

 

[huntervh]

Brand and model specs?

I bought the controller and battery from NBPOWER off of Amazon. There isn't a brand name on them. They were made to order. The controller looks pretty typical and the battery is a 72volt 20amp. There isn't any wiring for accessories coming off of the controller. There is also no usb connection for anything either.

 

[tomjasz]

Buck converter details?

 

[Slaphappygamer]

Could you have gotten the polarity reversed? That’s usually one of the things I check first.

 

[harryS]

No wiring between accessories and motor-controller-display. All that is shared is the +/- power leads from the battery. Does the step down still work if you re-connect to battery with the controller not attached? Did it work with the controller plugged in, but controller not turned on?

Maybe the stepdown blew up. Is your 72V the nominal or peak battery voltage? If it's a 20S li-ion battery, you have 80V at full charge.

 

[huntervh]

No wiring between accessories and motor-controller-display. All that is shared is the +/- power leads from the battery. Does the step down still work if you re-connect to battery with the controller not attached? Did it work with the controller plugged in, but controller not turned on?

Maybe the stepdown blew up. Is your 72V the nominal or peak battery voltage? If it's a 20S li-ion battery, you have 80V at full charge.

The step down still works with no problems when it is the only thing plugged into the battery. I have problems when I turn on the controller with it. I was thinking it could have gone bad so I purchased a second identical step down, and it is doing the same thing. STill works perfectly when taking the controller out of the mix. I believe it is 72 Peak, but I haven't fully charged the battery. It's only been charged about half the whole time.

 

[huntervh]

Buck converter details?

This is the converter I bought. Has no problems when it is connected directly to the accessories and the controller is taken out of the line.

 

[huntervh]

Could you have gotten the polarity reversed? That’s usually one of the things I check first.

No I rechecked a million times, I'm pretty shure the polarity is correct, b/c the bike is powering up. The accessories will work for a second and it's almost as if they aren't getting enough juice or something b/c the horn will only make a clicking noise when I push the lever. Here are the accessories that I am running. Headlamp is 60 watts, just fyi, but they are all 12 volts. Thinking the converter can't handle the amperage, maybe? Or it's not enough to offset the controller? I really don't understand all of it, it's my first bike build.

 

[Slaphappygamer]

Glad to know it's not the polarity. I always feel lame when I find that that is my issue.

You can also try to remove devices from your circuit, one at a time. To isolate the problem. I'd start with the headlight. If it is the headlight, then you know that your suspicion is correct. With the horn acting like that, it seems likely that too much is being drawn from the converter. You can prove this by removing devices. You can also measure the voltage at each device, to see if they are getting the proper voltage.

 

[Gionnirocket]

Sorry if this is obvious... But...
Are you sure you are not wiring the controller through the converter?
The controller should be in parallel, not series with the converter

Then... Is the problem with the controller under load... Motor running? Or not.

Then I would check voltages before and after the converter and at the controller and see what you have when the problem is occurring

 

[huntervh]

Glad to know it's not the polarity. I always feel lame when I find that that is my issue.

You can also try to remove devices from your circuit, one at a time. To isolate the problem. I'd start with the headlight. If it is the headlight, then you know that your suspicion is correct. With the horn acting like that, it seems likely that too much is being drawn from the converter. You can prove this by removing devices. You can also measure the voltage at each device, to see if they are getting the proper voltage.

When I remove the headlight, I'm still not getting any of the accessories to work. If they aren't getting the proper voltage, any recommendations on the proper converter I should be using?

 

[huntervh]

Sorry if this is obvious... But...
Are you sure you are not wiring the controller through the converter?
The controller should be in parallel, not series with the converter

Then... Is the problem with the controller under load... Motor running? Or not.

Then I would check voltages before and after the converter and at the controller and see what you have when the problem is occurring

I'm wiring the converter straight off of the battery leads before it gets to the controller. Here is a drawing of the signal flow and how I have things wired up. Please excuse the terrible drawing. And the motor will still power up and run, the converter just gets super hot when the bike is powered on.

 

[Gionnirocket]

I'm wiring the converter straight off of the battery leads before it gets to the controller. Here is a drawing of the signal flow and how I have things wired up. Please excuse the terrible drawing. And the motor will still power up and run, the converter just gets super hot when the bike is powered on.

Looks good.... As long as you have the direction of the converter correct. Input and output.
Check your voltages with the problem occurring... I can't see how a controller not under motor load would cause a great enough voltage sag especially since the unit should be fine under load with a 60v - 80v range.
Is the controller and motor working properly?

 

[huntervh]

Looks good.... As long as you have the direction of the converter correct. Input and output.
Check your voltages with the problem occurring... I can't see how a controller not under motor load would cause a great enough voltage sag especially since the unit should be fine under load with a 60v - 80v range.
Is the controller and motor working properly?

I will check the voltages. The input and output is correct, all my accessories work perfectly when I take the controller out of the mix and it is only the battery running directly to the 12v converter.