Help with electrical issue? (Resolved)

barboma

100 mW
Joined
Jul 13, 2018
Messages
44
Location
Southern Idaho
Hello,

I have a geared rear hub motor (350w), dolphin style battery pack (36v/11ah with integrated controller) and a KTLCD3 display. At random times the system will shut itself down, the display goes blank and doesn't come on right away, it takes a few times of pressing the on button for it to come back to life. So far I have checked all the connections and there does not appear to be any corrosion or bent pins on any of the connectors. I also tightened the battery case screws and checked the discharge port and wires on the battery and controller. This seemed to help a bit but when I thought I had it figured out, the same issue appeared today.

I am hoping someone has any additional ideas of what I can check (without voiding the warranty, IE opening the battery) or provide some pointers on how I can track this problem down and get warranty replacement items if needed.

Thanks.
 
It sounds like a loose connection somewhere. The most common fail point is between the battery and the battery holder if you have the removable pack style. Otherwise somewhere between the battery and the controller on the main power wires. Unplug any connections and look carefully at the contacts. If it's cutting out while riding, it will make a little burn mark on the contact.

About the only other suggestion would be to try measuring the battery voltage at the controller connection when it goes out and see if it is present.

You could also possibly have a problem inside the battery that is tripping the BMS. Generally this would happen under heavy load but not at light load.
 
Hi fechter,

Yeah, that is what its look like, a connection problem. My problem is trying to find out where. Whats interesting is that if I tap along the body of the battery the system will usually come on. So I am wondering if there is a loose spot weld on a cell(s). It could also be an issue with the discharge port on the battery and the wires that goes to the controller. If I can take some pictures of the port, would you mind giving them a once over?

Thanks,
 
it is most likley something inside the battery, if it is not the contacts at the mounting or between there and controller.

It could be anything in there, but you would have to open it up to find out.

I've seen:

bad solder joints (or *no* solder, just wire looped thru and forgotten),

wires pulled almost cmpletely out of a connection, held by one strand that later breaks, so the connection becomes intermittent under vibration,

wires broken inside insulation,

sense wires broken off the cells, so the BMS triggers shutdown

etc.



If you're worried about voiding the warranty, you'd have to contact the seller or manufacturer (whoever the warranty is thru) and service it via their procedures, which probably involves you paying to ship it to them, and after however many weeks it takes for shipping, handling, and testing, them finding no problem with it (if it's intermittent, murphy's law says it wont' fail while the techs are looking at it), they then charge you again to ship the (unfixed) pack back to you. :(

But they might find and fix the problem, without creating any new ones. :)
 
amberwolf said:
it is most likley something inside the battery, if it is not the contacts at the mounting or between there and controller.

It could be anything in there, but you would have to open it up to find out.

I've seen:

bad solder joints (or *no* solder, just wire looped thru and forgotten),

wires pulled almost cmpletely out of a connection, held by one strand that later breaks, so the connection becomes intermittent under vibration,

wires broken inside insulation,

sense wires broken off the cells, so the BMS triggers shutdown

etc.

Hi amberwolf,

Thanks for the response and information.

What you say makes sense. The kit, purchased from an outfit in Denver, CO called Electric Bike Outfitters. They use Higo (they call them JULET) connectors that are supposed to water tight. What gives me hope that it is not the battery is that those connectors are pretty sensitive. So much so I have thought about changing them. But I did speak to the owner of the company and he gave me some good tips. For example I am using zip ties to the frame to route the cables but something like Cobra flexroute might be better.

But back to the battery for sec, on that dolphin case, I tightened all the screws that seemed to rattle loose over time. Never seeing inside of one of those, might it be possible that something was getting jostled? Do you think it might be wise to order a new cable that runs from the front peripherals (display, e-brakes, etc) to the controller? The owner seems to think this is a good way to go but I am not 100% sold on the idea of putting money is replacement parts when the problem is intermittent and the direct cause is unclear to me.

I seem to have stable connections at the moment after pushing in the connectors hard and tightening the battery case screws. I am also going to the check all the programmable parameters on the controller, though I doubt that alone was causing my problems.
 
The problem you are having indicates power is disconnecting between battery cells and controller, either from a direct disconnection problem, or from the BMS turning off power due to an indirect disconnection problem.

The most likely sources for those problems are listed in previous posts.
 
amberwolf said:
The problem you are having indicates power is disconnecting between battery cells and controller, either from a direct disconnection problem, or from the BMS turning off power due to an indirect disconnection problem.

The most likely sources for those problems are listed in previous posts.

Definitely. i am going to do some more testing but i suspect you are right even though i would prefer not for the battery or some component therein not to be malfunctioning. The company seems to be alright with small warranty stuff but does not have a lot of my confidence otherwise. You summed it with what will likely happen with a battery. Thanks again, i will post more info if i can find anything else. I might just open the battery.
 
The hex bolt on the two pin connector for my Dolphin battery fell off. So when I slid it into the cradle, the connector just pushed back inside the battery and soon lost contact. Was on a group ride, couldn't quit, and had to pedal over 20 miles w/o power wondering what was wrong. WHen I came home, I finally saw what happened and was lucky because the hex bolt was on my garage floor.

I still have to fix that battery. The packing inside it shrunk and the cells now rattle. Otherwise, everything on mine is solidly soldered up.
 
amberwolf said:
The problem you are having indicates power is disconnecting between battery cells and controller, either from a direct disconnection problem, or from the BMS turning off power due to an indirect disconnection problem.

The most likely sources for those problems are listed in previous posts.

i believe i have definitively found the issue. It is the connector between the battery and the controller. unfortunately it looks like the female side is the culprit because i have two known good controllers and i can break the connection by lightly tapping on the connectors when coupled (took battery apart). The solder joints look okay too. Now I need to figure out what to do next. Any advice on a solid connector type i can find in a hardware store? I would like to still be able to remove the battery.
 
Only thing in a hardware store will be a wire nut, which will work temporarily.

Once they come in the mail, replace with crimp on anderson power pole 45 amp connectors, or solder on 4 mm gold plated bullet connectors. Both can be bought on line.
 
dogman dan said:
Only thing in a hardware store will be a wire nut, which will work temporarily.

Once they come in the mail, replace with crimp on anderson power pole 45 amp connectors, or solder on 4 mm gold plated bullet connectors. Both can be bought on line.

Much appreciated!

Any problems with using XT60 connectors? I have a pair left over from a Luna Cycle battery charger.
 
Thanks everyone for the help, I believe its all sorted out. Ended up replacing the battery to controller power connector with an extra XT60 I had laying around. I also put some more Styrofoam in the battery case so that the block of cells would not move around.

One more thing, the company, Electric Bike Outfitters did not shrink rap the block, instead they built some cheap housing out of heavy paper and tape. Would it be worth it, in the future, to go back in there and do that?
 
I doubt they built the battery themselves--like most people/places, they almost certainly buy everything as-is from whatever vendors in China they can get them cheapest from.

If the cells are held in place and don't rattle around, and all the wiring is secure, then it's good enough--shrinkwrap won't do anything more than that, and may make it less serviceable. (plus some people use too much heat to shrink the wrap and may damage stuff just inside it ;) ).
 
amberwolf said:
I doubt they built the battery themselves--like most people/places, they almost certainly buy everything as-is from whatever vendors in China they can get them cheapest from.

If the cells are held in place and don't rattle around, and all the wiring is secure, then it's good enough--shrinkwrap won't do anything more than that, and may make it less serviceable. (plus some people use too much heat to shrink the wrap and may damage stuff just inside it ;) ).

Yeah, probably best to leave well enough alone. Thanks again!
 
amberwolf said:
I doubt they built the battery themselves--like most people/places, they almost certainly buy everything as-is from whatever vendors in China they can get them cheapest from.

If the cells are held in place and don't rattle around, and all the wiring is secure, then it's good enough--shrinkwrap won't do anything more than that, and may make it less serviceable. (plus some people use too much heat to shrink the wrap and may damage stuff just inside it ;) ).

Just a curiosity question on li-ion battery packs. Brand new, my pack would charge to 41.8-9 volts. Now it charges to 41.7. I am sure this is normal as the cycle count goes up. But could it be the BMS is not balacing them correctly, prematurly stopping charging? Or a cell that might be starting to go? I still get great range and power output on this 6 month old pack. So I am not concerned at all, just curious. I do try to charge often to 80% or 40 volts and do a 100% charge at least once a week.
 
Could be age; could be imbalance.

If the former, that's just how they work.

If the latter, you could leave it on the 100% charge setting for at least a day or two (whenever you aren't using it) and see if it goes back to normal.

Also, check your multimeter battery, if that's what you're measuring with. (or just use a new battery)
 
One pack I have has a cheap BMS that just stops the charge when the highest group hit 4.2, and didn't do any noticable balancing, with the end result being the pack voltage kept going lower as the imbalance got worse. Cutting into the pack and manually balancing thru the BMS plug fixed it.
 
amberwolf said:
Could be age; could be imbalance.

If the former, that's just how they work.

If the latter, you could leave it on the 100% charge setting for at least a day or two (whenever you aren't using it) and see if it goes back to normal.

Also, check your multimeter battery, if that's what you're measuring with. (or just use a new battery)

Will try that, thanks!

Voltron said:
One pack I have has a cheap BMS that just stops the charge when the highest group hit 4.2, and didn't do any noticable balancing, with the end result being the pack voltage kept going lower as the imbalance got worse. Cutting into the pack and manually balancing thru the BMS plug fixed it.

Interesting idea but I am afraid I don't know enough about batteries and BMS's to give that a try (willing to learn though). I am not even sure how many series and parallel groups my pack has, I only know its 36v, 11 ah. So how would you check and balance each group? I know there is single connector with lots of white wires, I am assuming that go to each group. Are they the positive wires? I have a picture of the BMS I can dig up. Please forgive my ignorance, this is all somewhat new to me.
 
docw009 said:
The hex bolt on the two pin connector for my Dolphin battery fell off. So when I slid it into the cradle, the connector just pushed back inside the battery and soon lost contact. Was on a group ride, couldn't quit, and had to pedal over 20 miles w/o power wondering what was wrong. WHen I came home, I finally saw what happened and was lucky because the hex bolt was on my garage floor.

I still have to fix that battery. The packing inside it shrunk and the cells now rattle. Otherwise, everything on mine is solidly soldered up.

You were spot on, after reading about your experience, I checked the connector and sure enough that was it. Although I had to wire in a new connector (XT60) that is less convenient, I think the new connector is more sturdy and less susceptible to damage and vibration.
 
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