Bike doesn't fully charge? Charger turns green @ 83%

[Howie]

One problem after another on this damn thing....

It's a stealth bomber clone from China. Panasonic battery 72v. 8000w. Sabvoton mqcon 72150 controller with ukc-01 display.

For some reason, my throttles keep burning out. I'm on my third one. This time after replacing it, the bike won't charge to 100%. The light turns green on the charger and it stops charging the bike at 83.7%. I don't want to risk (further?) damage to the battery or short anything out. HELP! What could be the issue? What should I do and in what order should I do it?

 

[K PierreR]

True Panasonic battery cells are good cells but you battery capacity is likely not high enough.. Got to cut costs somewhere. I also suspect that you are using high power for too long at a time. The Chinese version is likely not duty rated and you are experiencing overheating problems in the controller or motor and getting some breakdown of insulation in the system that is giving you higher current through the throttle.
As far as charging: You are showing a reading on your display. Displays are notorious for being inaccurate. Check the actual voltage on the battery. 84 volts would be a full charge. Its possible you have a battery issue but more likely a reading error.
It is not really practical to buy a Chinese knock off version unless you ware well versed in performing you own diagnostics and maintenance. A warranty is really an insurance policy and is priced into the product. The Chinese typically offer warranties but make it especially hard to collect on the policy. That puts them technically not lying with little cost to offer the warranty.

 

[Gionnirocket]

I concur... Check voltage on the battery directly for an accurate reading. Also check that your charger is putting out the proper full charge voltage which should be listed on the back of its case.
As for the throttle... I suspect that it's just not rated for 72v

 

[K PierreR]

I concur... Check voltage on the battery directly for an accurate reading. Also check that your charger is putting out the proper full charge voltage which should be listed on the back of its case.
As for the throttle... I suspect that it's just not rated for 72v

Bingo, I somehow overlooked the obvious with the throttle voltage.

 

[Howie]

True Panasonic battery cells are good cells but you battery capacity is likely not high enough.. Got to cut costs somewhere. I also suspect that you are using high power for too long at a time. The Chinese version is likely not duty rated and you are experiencing overheating problems in the controller or motor and getting some breakdown of insulation in the system that is giving you higher current through the throttle.
As far as charging: You are showing a reading on your display. Displays are notorious for being inaccurate. Check the actual voltage on the battery. 84 volts would be a full charge. Its possible you have a battery issue but more likely a reading error.
It is not really practical to buy a Chinese knock off version unless you ware well versed in performing you own diagnostics and maintenance. A warranty is really an insurance policy and is priced into the product. The Chinese typically offer warranties but make it especially hard to collect on the policy. That puts them technically not lying with little cost to offer the warranty.

Thank you. Really appreciate your response. That sounds like it's exactly on the money. But when I bought my bike, I shopped around for other bikes that are available in the US, and they all seemed to use the same Chinese parts. Including the actual Stealth Bomber branded bike from Australia. Some of these companies are selling their bikes for upwards of $15k (Cab motorworks) and most of the bike is just pre-fabbed stuff from China that they assembled here. And from my research, I've found that there isn't much in the ebike world that isn't manufactured in China. Perhaps you could enlighten me? Furthermore, I have yet to find a company that offers a serious warranty on their product. Most of the important parts on the bike aren't covered outside of 45 days and if it's an out of state or even worse out of county company, then it's very difficult to collect on the warranty if you have an issue. Until more people are riding ebikes and there are more shops that work on them, I think if you own one, you're almost obligated to learn how to care for it technically/mechanically. And you gotta start somewhere.

 

[hoggdoc]

One problem after another on this damn thing....

It's a stealth bomber clone from China. Panasonic battery 72v. 8000w. Sabvoton mqcon 72150 controller with ukc-01 display.

For some reason, my throttles keep burning out. I'm on my third one. This time after replacing it, the bike won't charge to 100%. The light turns green on the charger and it stops charging the bike at 83.7%. I don't want to risk (further?) damage to the battery or short anything out. HELP! What could be the issue? What should I do and in what order should I do it?

Wait back in June and early July you were having issues with no power to the motor after removing the rear wheel for a tire repair. What ever happened with that? At that time you never mentioned having issues with throttles "burning out". The only way the throttle could burn out is if the design of the bike is trying to past all the voltage and current through the throttle. The proper design sound use the throttle to control a low voltage signal and the high voltage should be handled in the controller circuits.

Back to your battery issues, have you checked to voltage at the terminals on the battery itself, as there could be a problem with calibration of the battery display on the head display unit.

 

[Howie]

It's fixed. For the most part. And for now. It is the throttle that keeps burning out. I'm being told it's because there's no bms on this bike and the throttle is burning out from just hammering down on it on hot (southern Californian) days. Basically, I'm over-heating according to my sources...

 

[hoggdoc]

It's fixed. For the most part. And for now. It is the throttle that keeps burning out. I'm being told it's because there's no bms on this bike and the throttle is burning out from just hammering down on it on hot (southern Californian) days. Basically, I'm over-heating according to my sources...

I can't believe anyone would make a large battery pack like that without a BMS. Do you have any way to contact the manufacturer or the people that sold it to you to ask them?

 

[Howie]

Even if I did, I'd need to learn Chinese first. And to be quite honest, I've taken this thing completely apart and put it back together several times. I can see where they cut corners on the build and I've done many upgrades to correct the things that they could have made better. Although it sucks when I'm stranded or can't ride for a while, I value learning the ins and outs of these bikes. Which aren't very complicated actually and all use relatively the same parts. Yeah, no bms but actually not the end of the world. If I was in a cooler climate I probably wouldn't even be having an issue, considering my riding habits. Really not looking forward to rebuilding a battery, but I guess that too is just part of owning one of these bikes. And at least when the time comes, I can make it better than it was previously. The more I rebuild this thing, the more badass it's gets honestly. Similar spec'd bikes are selling for a lot more than what I paid for mine

 

[harryS]

Beats me why your throttle blows up. Ebike Throttles are just a magnet and a Hall sensor chip that detects the magnet as it rolls past. The chip runs on 5 volts DC and the throttle signals varied from .70 to 4.5 volt. The 5V comes out of the controller, and never changes, as long as you don't exceed controller's working voltage. If you do, the internal DC-DC voltage converters probably blew up and you don't have 5 volts anymore.

You should never see battery voltage at the throttle, unless it's the type that has a voltage display or an on/off button built into them.



The battery has to have a BMS for safety. Otherwise there is nothing to stop overcharging it. Improperly used BMS is why there were dozens of hoverboard fires five years ago. I bought a couple of those packs on a "fire sale". Turned out they bypassed the circuit protection on the charger port.

 

[harryS]

As for the charger stopping at 83%, that's the BMS in the battery stopping the charging. All the charger knows is that the battery stops taking current so it goes green. It goes green when you unplug the charger too.

The BMS is detecting that one or more of the series groups is at full charge, so it stops the charge for safety. Otherwise, the fully charged cells get overcharged. In other words, the battery is unbalanced. You got some groups at full charge, 4.20 V, and others somewhere below it. Add them all up, and it's 83%.

How do you fix that? It's involved and no guarantee you can fix it. The first thing you do is open the battery, find the balance leads, and check the voltages of all the series groups. I believe there's 20 groups in series for a nominal 72V pack (84V max). The 20 voltages will be a measure of the health of the cells. You proceed from there.

 

[Gionnirocket]

@harryS makes some excellent points.
You say "It's fixed. For the most part. And for now."... what was your repair/conclusion on the 83% chaging?

And on the throttle he's right about operating at a lower control voltage. I mis'assumed that the controller and throttle for a 72v system might be operating at a slightly higher control voltage like 12v... But from a quick search of your controller that doesn't seem to be the case and it appears to still be in the 5v department... my bad.
Is it possible that they are just supplying poorly built throttles? Have you tried another type/brand. Have you checked the voltage either at the controller or throttle? Your source stating no BMS is the problem is more than likely incorrect as the throttle is connected to the controller and the issue is between there and the throttle and beyond the battery in that part of the circuit
Excellent attitude on making the repairs... If anything this experience though frustrating because of the lack of technical information available is still an excellent learning experience and a great way to build on your troubleshooting skills.