Need help with diagnosis of dead Riding Times Z8!

[drobins9]

Hello- I bought my son a Riding Times Z8 electric bike for Christmas. It lasted 100 or so miles before it went dead and, shockingly, the support has been virtually nonexistent. I have been trying to make my way through resources to understand what is going on and what I need to do. I would greatly appreciate any help or guidance.

The bike does not power up. It is completely dead.

Batteries: The two 48V batteries are fully charged, the electronic gauges work on them, and they output about 50V.

Battery Equalizer: Both batteries are wired into a unit that merges the power. The output on the unit is also about 50V, so power is making it to the system.

Controller: The controller is labelled KCHQ RD-Z8, and seems to be a pretty standard one.

• When I connect a negative multi-meter terminal to the negative battery input, the positive multi-meter terminal reads 8.58-8.59 kOhms of resistance on each of the 3 motor phase wires.
• When I connect a negative multi-meter terminal to the positive battery input, the positive multi-meter terminal reads no resistance/continuity on each of the 3 motor phase wires.
• When I connect a positive multi-meter terminal to the positive battery input, the negative multi-meter terminal shows overload resistance on each of the 3 motor phase wires.
• When I connect a positive multi-meter terminal to the negative battery input, the negative multi-meter terminal reads 8.58-8.59 kOhms of resistance on each of the 3 motor phases.

I've searched around a lot, and I am not clear why the order of the multi-meter terminals matters (it seems to be continuity is continuity, regardless of the order of the terminals), or whether this suggests have a problem.

Motor: There is complete continuity / 0.00 resistance across any combination of the 3 motor terminals. The bicycle moves smoothly. If I connect two of the unpowered motor terminals, it gets more difficult to move.

I contacted the company, and after a few weeks, they sent me a new controller. I hooked it up and when I turned it on, there was a "pop" where the controller connects to the battery equalizer. There is some noticeable black marking on the negative input cable of the controller. With everything connected (after that), the bike was completely dead.

I have tried connecting only power to the controller and the 5-wire connector to the digital display to see if it would power on (thinking if there are issues or shorts in other places, at least the display might turn on if it is the only thing connected), and it does not.

At this point, I am unsure if my controller was "blown" from whatever problem might be in the bike and made have made it pop when I connected the new one. I am unsure what to check next. The company (Riding Times) has not responded to my inquiries for the last few weeks. I have been looking through online resources, but am confused on where to go next.

Could anyone possible provide a little guidance?

Thank you so much!

 

[amberwolf]

The bike does not power up. It is completely dead.

That simplifies things greatly. This is almost always a battery problem, or a connection failure between the battery and the rest of the system. So it's easy to troubleshoot first steps.

Batteries: The two 48V batteries are fully charged, the electronic gauges work on them, and they output about 50V.

Battery Equalizer: Both batteries are wired into a unit that merges the power. The output on the unit is also about 50V, so power is making it to the system.

Do they still read that voltage when you turn the system on with the batteries connected? If not, they are probably powering off when a load is applied. That usually happens when something is wrong in the battery and the BMS has turned off the output, so you only see a "ghost" voltage. The battery gauge on there may be connected before the BMS, or on the charger side instead of the bike side, and so works anyway.

50V isn't full for a 48v battery (54v would be for a 13s, and 58v for a 14s, often called a 52v battery instead). What voltage does the charger have listed on it's label?

Controller: The controller is labelled KCHQ RD-Z8, and seems to be a pretty standard one.

• When I connect a negative multi-meter terminal to the negative battery input, the positive multi-meter terminal reads 8.58-8.59 kOhms of resistance on each of the 3 motor phase wires

If this means at the controller, without the motor connected, then those are normal.

• .
• When I connect a negative multi-meter terminal to the positive battery input, the positive multi-meter terminal reads no resistance/continuity on each of the 3 motor phase wires.

If this means on the actual motor itself, then that's normal, as they are all connected inside the motor, which is just a bunch of wire, so only a special meter can read the very low resistance of the wire.

If this means at the controller without the motor connected, it's probably sdtill normal as you're probably reading the diode in each FET; many meters have enough voltage on the ohms output to turn it on and make it read a "short". If you have a diode test mode, it will probably beep once then show a reading between 300 and 800 depending on how your specific meter works.

• When I connect a positive multi-meter terminal to the positive battery input, the negative multi-meter terminal shows overload resistance on each of the 3 motor phase wires.
• When I connect a positive multi-meter terminal to the negative battery input, the negative multi-meter terminal reads 8.58-8.59 kOhms of resistance on each of the 3 motor phases.

if this meanso n the controller without motor connected, thy sound normal.

Motor: There is complete continuity / 0.00 resistance across any combination of the 3 motor terminals. The bicycle moves smoothly. If I connect two of the unpowered motor terminals, it gets more difficult to move.

This is normal for the reasons stated above.

contacted the company, and after a few weeks, they sent me a new controller.

Was this because of this same no power situiation, or was there a previous problem not mentioned here that this was intended to resolve? If the latter, what was the problem, and what happened to the bike before this problem?

I hooked it up and when I turned it on, there was a "pop" where the controller connects to the battery equalizer. There is some noticeable black marking on the negative input cable of the controller. With everything connected (after that), the bike was completely dead.

That usually means that the battery connector is wired backwards on one of the items, or there is a broken wire at the back of one of the connnectors, or poor solder or bad crimp, or a contact that is spread out so much that it arced across as power was drawn.



Can you post good clear well-lit images of the connectors in question, of all of their contacts, and if possible of the back of the conectors where the wires come out? Taking them in direct sunlight makes most cameras and phones focus better.

 

[drobins9]

Hello- Thank you for the responses.

Everything I listed under controller were probes into the controller voltage. I was surprised that there was complete continuity with the negative multimeter probe on the positive battery terminal, and probed the positive multimeter probe to each of the 3 motor output wires. But when I reversed the multimeter probes, there was infinite resistance/no continuity. I can only wonder if capacitors are tricking the multimeter into thinking there is a complete circuit, but I'm not that talented in electrical stuff.

Anyway, a little more precise measurements on the battery: The batteries haven't been charged in a month or so, and were used a little bit. The digital gauges indicate they are "full," but obviously there is a range there. The charger says it is 54.6V. When a turn on only one battery, the splitter has 51.9V, with the other battery, it has 52.5V, and with both batteries, it has 52.5V. The fuse on the battery equalizer is obviously good, or it would not have any current.

The reason I was given the replacement controller was the dead bike. The original controller has a pink water-detection sticker. The controller was well-protected under the seat, and I can imagine that was due to humidity. There is no black marking on the battery connection of the original controller. One of the videos I watched last night said it is normal to have a loud "pop" when connecting a new controller, which is caused by the energy needed to charge the capacitors. For what it's worth, I had the battery switched on (so instant power) when I connected the new controller, instead of connecting the controller and then switching the battery on.

The second controller has the black marking on the negative plug that matches the black mark on the negative plug of the battery equalizer.

I tried connecting the controller directly to one of the batteries. From what I read last night, I think I should be able to get 5V of power from the red and black wires on the 5-pin display connector with nothing else connected. I am not getting any power. So, is that right, and is that confirmation the controller is bad?

I do have one more (larger) controller the company sent me by mistake before getting the proper replacement controller. The specs on it are the same (except it has a higher maximum current), but the power and motor wiring connections are different. I feel like the right next step might be to swap out the connections on the controller and the bike using some connectors I have laying around (picture of bag attached), hook up the new larger controller, and see if I can get the 5V on the display connectors, and then work from there. I guess maybe I would connect one thing at a time and see what blows the new controller unless there is a better option?

Does that sound like the right next step?

Thank you again!

 

[amberwolf]

Everything I listed under controller were probes into the controller voltage. I was surprised that there was complete continuity with the negative multimeter probe on the positive battery terminal, and probed the positive multimeter probe to each of the 3 motor output wires. But when I reversed the multimeter probes, there was infinite resistance/no continuity. I can only wonder if capacitors are tricking the multimeter into thinking there is a complete circuit, but I'm not that talented in electrical stuff.

This is because of the way FETs work inside. You can see the results you should get and ways to do the test in various places, such as ebikes.ca Learn - Troubleshoot pages, and various threads here on ES and elsewhere, but the results you see appear normal to me for non-damaged controller phase FETs.

If power is applied to the controller during the tests, aside from damaging the meter, the results may not be valid.

If the capacitors are still charged up after power was removed, they can affect the test the same way, but most controllers will drain them rapidly when disconnected. You can verify this with your voltmeter by meausuring the votlage on the B+ and B- input wires of the controller before doing the test. If there's a voltage, wait until it's gone.

Anyway, a little more precise measurements on the battery: The batteries haven't been charged in a month or so, and were used a little bit. The digital gauges indicate they are "full," but obviously there is a range there. The charger says it is 54.6V. When a turn on only one battery, the splitter has 51.9V, with the other battery, it has 52.5V, and with both batteries, it has 52.5V. The fuse on the battery equalizer is obviously good, or it would not have any current.

FWIW, "equalizer" is a terrible term for them to use; they don't equalize anything, they just allow you to connect two in parallel without feeding a lower voltage battery from the higher one. If they actually equalized things, they couldn't do that job and broken batteries at lower voltages could then be damaged or start fires.

While the fuse could be good, it is possible for the FETs in either the BMS or the battery merger to be "off" and still show you a ghost voltage.

If you do not test them with a load on them, the test doesn't tell you whether this is a problem, and so you don't know if the batteries are good or not.

A load can be as simple as a resistance across the + and -, any ghost voltage will go away with even a tiny load, including the bike's controller/etc (wired as a normal system) directly connected to the battery (without the battery merger), and trying to turn the controller on via the display just like normal. As soon as battery is connected, the controlelr capacitors and dsicharge circult and the display's internal regulator will use up enough power to zero any ghost voltage, so you c an then be reading the real battery output voltage while the battery is still connected to the system. (measuring at the back of the connector on boht the battery side *and* the *controller* side to ensure you are testing the connector as well).


For a thorough test ideally you'd use an operating bike running a motor, but that's not an option here. There are other tests that can be done, but this one needs to be done to verify the batteries' BMS outputs are actually working.

The reason I was given the replacement controller was the dead bike. The original controller has a pink water-detection sticker. The controller was well-protected under the seat, and I can imagine that was due to humidity. There is no black marking on the battery connection of the original controller. One of the videos I watched last night said it is normal to have a loud "pop" when connecting a new controller, which is caused by the energy needed to charge the capacitors. For what it's worth, I had the battery switched on (so instant power) when I connected the new controller, instead of connecting the controller and then switching the battery on.

Then the spark could have simply been the high current needed to cahrge the capacitors in the controller. You don't show the requested images of the backs of the connectors where the wires go in, so I can't see if they are all wired correctly, or soldered or crimped correctly, etc., but the contact sides all look ok except the plasma-arced burned ones, and even those don't look very damaged and would probably still work fine.

I tried connecting the controller directly to one of the batteries. From what I read last night, I think I should be able to get 5V of power from the red and black wires on the 5-pin display connector with nothing else connected. I am not getting any power. So, is that right, and is that confirmation the controller is bad?

If you have a display, then you'd have to check the wiring diagram for that specific controller and display to know what to expect for certain.

If they don't come with a diagram that tells you what each wire is for, you would have to open up the units to trace where the wires go on the board inside, and if there are no clear markings explaining what voltages or signals to expect, you'd ahve to trace where these lead to on the circuit board inside and what should be at each of those points based on the electronics design in there.

But most display-capable systems use five wires:
--battery + (from controller to display)
--battery - (from controller to display)
--KeySwitch / Ignition (battery + sent back to controller only when display is turned on at it's power button)
--tx data(a 0-5v signal)
--rx data (a 0-5v signal)
There is no 5v or any other output from the controller until the display is on, because the LVPS that makes 5v/etc gets it's power from the KSI wire.

So if you measure all those wires (and do the battery test as well) and post the results, we can make a better guess.