Noob trying to check voltage on a battery

[HK12K]

Personally I'd replace the fuse and see if you can get those Anderson's to kick on first. Once they do I'd look into the motor issue before connecting the Anderson's to the bike, or at the very least before applying any throttle. You don't want that fuse to pop again.

As far as the motor is concerned, again I'm not too familiar with exactly which one is on the bike, but I believe it's a 500w direct drive hub motor meaning no gears inside to cause problems. I'd flip the bike over and try spinning it manually in both directions to see how it behaves. If it makes scraping or grinding noises, has an ususual amount of resistance, or doesn't seem right let us know what it's doing and we can try to help. Maybe post some pics of the motor itself, both sides, so we can see if it can be opened without unlacing the wheel if that's what it comes down to. Could have overheated and thrown a magnet, could be wiring, could be bearings. We shall hopefully find out.

Not to disagree with Amber as he is a much better authority on this stuff than I am, but I wouldn't bother reconnecting the speed limiter at the moment. You could, but I don't think it's necessarily the root cause of this issue. (Unless it being disconnected allowed the motor to overheat and damage itself, in which case you'll probably be upgrading to something more robust in the future anyway.)

 

[Singularo]

Hey everyone, I badly soldered on a new fuse (this is my first time soldering) and now I have a different issue. I measured the voltage again after soldering and now it reads 0.6 volts (it used to read 0 volts). Any ideas on how I can get the full voltage out? What could be causing this? Could it be that I just soldered it badly?
One interesting thing is, I plugged the XT30 connector back into the power button on the bike, and now the light doesn't come on when I press the power button (despite there being voltage coming from the XT30 connector)
I tested each cell and they all seem fine, putting B+ to B- still gives full voltage.

 

[Singularo]

Another update: Turns out I was wrong about the XT30 connector being for the power button, it's actually for the charger, and the black square cable from the battery is for the power button. I plugged the battery up to the power button and turned it on, and it turned on (I tested the battery, and its getting full voltage now, 41.6v).
I connected the anderson cables and the display powered on. I plugged in the motor cable and as soon as I did it, a spark came out of motor wire, and the fuse that I just put in the battery blew. What could be causing my motor to blow the fuse on my battery? Should I try opening the motor now?

 

[amberwolf]

The fuse is probably on the output.

Usually it will blow whenever there is a short or high enough current draw, and that could be anything that is connected to the output.

But it's usually the controller that fails in a way that draws that much current. The motor doesn't usually fail in that kind of way, without blowing up the controller first.

So either way, the controller is your first bet.

However, the best way to troubleshoot things is to start unplugging things until stuff starts working. Since you don't want to keep blowing fuses just to test, then instead disconnect the battery from the bike, and set your multimeter to Ohms, on the lowest number range it has if it doesnt' have an Auto(range) setting.

First, on the bike, (NOT the battery!), connect a wire from the positive to the negative of the input connector (the one you would plug the battery into). This will drain any voltage left in the system (there shouldn't be any becuase it's a short, but this is to ensure no chance of damage to your meter).

After a few seconds, take that out, and then connect your meter red wire to positive and black to negative.

If everything is operating normally, then after a while you'll see the reading increasing from zero up to eventually reading OL or whatever your meter does when it's not connected to anything.

If it's shorted, you'll eventually see a low ohms reading of some steady value.

If this is the case, then start unplugging things. First, the motor from the controller. If the reading doesn't change back to the "normal" description, then the motor isn't this problem.

Next, unplug any display the controller has. If no change, then each othe rthing that is plugged into the controller directly.

If it never goes back to normal, the controller itself is likely the issue.

If so, you can open it up and post pics, to see if there's anything obvious we can tell you about it. Most likely a short circuit type failure is going to be blown FETs in boht halves of a bridge, making a complete short from power to ground. This may not be visibly obvious, but there's further testing that can be done to find out, if needed.

FWIW, blown FETs could also cause a grinding sound as the motor "cogs" past each magnet set, becuase it's shorting out the motro coils making it harder to turn than usual. The faster you try to turn it, the harder it will be to do.

 

[Singularo]

The fuse is probably on the output.

Usually it will blow whenever there is a short or high enough current draw, and that could be anything that is connected to the output.

But it's usually the controller that fails in a way that draws that much current. The motor doesn't usually fail in that kind of way, without blowing up the controller first.

So either way, the controller is your first bet.

However, the best way to troubleshoot things is to start unplugging things until stuff starts working. Since you don't want to keep blowing fuses just to test, then instead disconnect the battery from the bike, and set your multimeter to Ohms, on the lowest number range it has if it doesnt' have an Auto(range) setting.

First, on the bike, (NOT the battery!), connect a wire from the positive to the negative of the input connector (the one you would plug the battery into). This will drain any voltage left in the system (there shouldn't be any becuase it's a short, but this is to ensure no chance of damage to your meter).

After a few seconds, take that out, and then connect your meter red wire to positive and black to negative.

If everything is operating normally, then after a while you'll see the reading increasing from zero up to eventually reading OL or whatever your meter does when it's not connected to anything.

If it's shorted, you'll eventually see a low ohms reading of some steady value.

If this is the case, then start unplugging things. First, the motor from the controller. If the reading doesn't change back to the "normal" description, then the motor isn't this problem.

Next, unplug any display the controller has. If no change, then each othe rthing that is plugged into the controller directly.

If it never goes back to normal, the controller itself is likely the issue.

If so, you can open it up and post pics, to see if there's anything obvious we can tell you about it. Most likely a short circuit type failure is going to be blown FETs in boht halves of a bridge, making a complete short from power to ground. This may not be visibly obvious, but there's further testing that can be done to find out, if needed.

FWIW, blown FETs could also cause a grinding sound as the motor "cogs" past each magnet set, becuase it's shorting out the motro coils making it harder to turn than usual. The faster you try to turn it, the harder it will be to do.

I followed the instructions and once I put my multimeter into the controller anderson connector, I started getting a steady 0.2. I then unplugged the motor, and it went to OL. Does this mean the motor is the problem?

 

[amberwolf]

That means, most likely, that something is wrong in the controller FETs but not all in the same bridge, so the top half of one bridge is shorted, and the bottom half of another. The wires in the motor connect them, so that makes a short.

Normally the controller turns off all bridges except when it's turning the motor, and then it does them sequentially with top of one phase and bottom of another.

In this kind of failure, some of them are stuck "on".


So the next test is to find out if i'ts the motor or controller.

Does the motor turn smoothly in both directions, when off ground, and not connected to the controller?

If so, the motor is probably fine.

If it is hard to turn in either direction, it is probably internally shorted, or the cable to it is shorted.

If it turns normally when disconnected from the cotnroler, then reconnect it, with no battery, and if it becomes hard to turn, then the controller is damaged, usually shorted FETs.

 

[Singularo]

The wheel turns fine without the controller plugged in. Whenever I plug the controller in, it becomes much harder to turn (almost very similar to the "grinding" I felt when it first messed up). I found a video and I'll watch it and see if I can figure something out
https://www.youtube.com/watch?v=lTssCn5YyTw
Thanks for helping me figure this stuff out! It's very exciting.

 

[amberwolf]

Whenever I plug the controller in, it becomes much harder to turn (almost very similar to the "grinding" I felt when it first messed up).

Then the controller has shorted FETs, and needs to be repaired or replaced.

http://ebikes.ca has a Learn tab, Troubleshooting link, that will show you some ways to test various things, including controller FETs. That video is one of the series.

Often it's easier to just replace all the FETs at the same time, in case somethign "tests" fine but then fails right after you just replaced the other ones.

Controllers can be so cheap that its' frequently cheaper to replace than repair, unless there are specifics about yours that your bike needs, or it has custom wiring or display or whatever, that a generic controller won't be compatible with.


Then when youv'e got it fixed or replaced, put that limiter back on, or it's probably going to fail again.

Moving the controller out where it has some airflow might help, instead of boxed up where all the heat stays inside it.

 

[HK12K]

Glad you were able to get the BMS to kick on. Sorry to hear you popped the fuse again. Good soldering practice though I guess.

As usual, Amber is dead on. Redo the fuse and fix or swap out that controller and with any luck you should be back in business. Make sure to carefully check the phase and hall wires going from controller to motor to ensure no intermittent shorts too, as shorting them while riding is a good way to kill controllers. :thumb: