Hi there, I'm a newbie to this site and I was hoping to gain some advice from all the experts here. I have an ebike conversion kit that's probably 5-6 years old now. I bought it used and I know the original owner. The whole kit including the battery probably has 3,000-3,500 miles on it. My issue I'm having is that after a short ride, I'm talking a mile or less the motor shuts off and when I feel the hub it is quite warm to the touch. I can disconnect the cable from the controller to the battery and then I'm able to ride again, but once it heats up it shuts down again. Otherwise once it cools down (about 10-15 minutes) it works again. I'm contemplating getting a new kit at this point considering the age and amount of use it already has, but if I could get a cheaper fix then I'd rather due that. Any help would be appreciated.
motor heats up and shuts down
- Thread starter NGU
- Start date
are teh wires from motor to controller hooked up in exactly the same order they were originally?
If not there is an article on the ES wiki that will help you determine the correct combination for the hall and phase wires.
If not there is an article on the ES wiki that will help you determine the correct combination for the hall and phase wires.
nutnspecial
10 MW
It could verywell be bad timing (halls/phases) if wiring is switched around OP, but all the info you can include about the situation/conditions it's being used and what exactly is the system (motor, controller, battery, bike) would really help. Instead of playing guessing games.
Pictures are good too esp if you have no idea what the beast is.
Pictures are good too esp if you have no idea what the beast is.
dogman dan
1 PW
Pure guess, but I think maybe your motor heat is normal. Motors do get warm, If it's scalding your hand in 15min, that is not usually normal.
I think your battery is no good by now, and it can run again briefly after a rest. Battery is my guess as to the problem.
But we do need a ton more info what you have. Pictures of everything, including any labels on the battery and controller.
I think your battery is no good by now, and it can run again briefly after a rest. Battery is my guess as to the problem.
But we do need a ton more info what you have. Pictures of everything, including any labels on the battery and controller.
Wow thanks for all the quick responses. I realize now I should have mentioned what I have. The hub/motor is a Crystalyte Road Runner # X-408R (on the hub-rear wheel) with a Crystalyte CT4825 controller. Not sure about the battery beside it being a lithium ion one. I haven't got into that part of the kit before, but I have measured the voltage after charging it fully and it reads between 54-56 volts (if that helps anyone). All the wiring that I can see is attached properly and is in good condition. No modifications have been done to the entire kit except I replaced the throttle assembly w/cable a year ago and I fabricated some torque arms on the axle to prevent it from spinning out of the frame. It's strange, but right before it shuts down I can anticipate is shutting off because of the feeling that occurs from the wheel. It's almost like a "dragging" feeling occurs and then it shuts off.
dogman dan
1 PW
Ok,, I'm pretty confident you don't have mismatched wiring, or other problems that happen with poorly matched motor and controller.
But I can be 99% sure your battery is toast, just by the age of it. It works, it charges, so no cell is dead. But some if not all cells are very very weak, and cannot support the motor anymore.
That dragging feeling, is the battery voltage dropping drastically, just before the bms shuts off the battery.
New battery time. I often say when people are buying a used e bike, the battery is worth zero dollars, until tested and proved otherwise. Even a fully functional battery that is more than a year old could be in its last few cycles before failure. Typical lifespan is about three years use. An older battery can test fine, yet fail almost immediately once actually used.
Again, the hot motor is normal, unless it actually burns your hand after less than 10 miles of flat riding. It can get very hot normally, when doing a lot of hills, or a long enough hill.
But I can be 99% sure your battery is toast, just by the age of it. It works, it charges, so no cell is dead. But some if not all cells are very very weak, and cannot support the motor anymore.
That dragging feeling, is the battery voltage dropping drastically, just before the bms shuts off the battery.
New battery time. I often say when people are buying a used e bike, the battery is worth zero dollars, until tested and proved otherwise. Even a fully functional battery that is more than a year old could be in its last few cycles before failure. Typical lifespan is about three years use. An older battery can test fine, yet fail almost immediately once actually used.
Again, the hot motor is normal, unless it actually burns your hand after less than 10 miles of flat riding. It can get very hot normally, when doing a lot of hills, or a long enough hill.
Thanks Dogman, I think you are correct here, but unfortunately I don't have the funds for a new battery, but I'll "drive it 'til the wheels fall off" 
I noticed last Friday when I got back from work and charged the battery back up it didn't take nearly as long as it normally does, so at this point I agree with you the battery is done.
Thanks again everyone for weighing in on my problem.
I noticed last Friday when I got back from work and charged the battery back up it didn't take nearly as long as it normally does, so at this point I agree with you the battery is done.Thanks again everyone for weighing in on my problem.
dogman dan
1 PW
Confirmed then, short to recharge definitely indicates capacity is low.
Hi there, I thought I would try one last attempt to continue to use the battery I have and somehow by-pass the BMS. I know what the BMS does and why it's on the battery but I'm asking the group here if it's possible to remove it and direct wire the battery with the motor. The battery still gets to 56-57 volts when fully charged so I know there is some "juice" left and I only have a 5 mile commute to work. I went to my local battery shop and the guy wouldn't touch it because it's a lithium ion one. Is this a bad/dangerous idea to remove the BMS? I've read other posts where some have don't have one on there battery and it works great as long as they monitor charging of it. Could I just unplug the white wire harness that monitors the cells and still have power to the motor? Again any comments on this would be helpful. I tried to send some pictures to help you see what I'm working with but the file was too big apparently. Anyone know how to send pictures as well? Thanks
There is a thread called Adding Pictures with many methods of doing that, stickied near the top of every forum section.
Bypassing the BMS is usually easy, but it's different for different ones. some possible searches
https://endless-sphere.com/forums/search.php?keywords=bypass*+BMS&terms=all&author=&sc=1&sf=titleonly&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search
https://endless-sphere.com/forums/search.php?keywords=bypass*+BMS&terms=all&author=&sc=1&sf=firstpost&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search
Properly designed ones will shut the pack off if the sense wires to the cells are disconnected, but most are not properly designed, and will simply never perform any part of their function if the sense wires are disconnected, and be "always on".
Those that are powered by only a few cells near the negative end will probably not operate at all, or not as designed, without the sense wires connected.
In any case where disconnecting the sense wires doesn't bypass it, you'd need to physically connect the main output + and - wires of the BMS to those of the battery itself (presently on the main input of the BMS).
Side effects of bypassing the BMS are that you no longer have any monitoring of the cells, so they can be:
--discharged so low that they have a risk of fire when charging them up again, any time after doing so.
--charged up so high that they have a risk of fire at any time after that.
--if a cell group is really low, then it not only gets discharged down to zero, it can actually be negatively charged (reversed), which increases the risk of fire both at that moment and when recharging.
--more and more unbalanced on every charge cycle, making all of the above more likely each time.
Fire might never happen, but it can, and you won't have warning of it until it does. Normally with known-good cells the risk is small, but if you already have a known-problem-battery pack, the risk has already increased. By how much, it is impossible to say, as the internal reasons for the cell(s) problem(s) are not visible, and some of the failure mechanisms are more likely to result in fires than others, and different conditions affect those mechanisms in different ways.
A BMS is no guarantee that a fire won't happen, but if it's properly designed and not defective then it's better than no monitoring or management at all. There are no "safe" batteries that don't have any fire risk--every kind of rechargeable I've ever seen has had a fire or even explosion at some point in history. (even some non-rechargeables)
There are a lot of fire discussions here on ES, including prevention, management, containment, and results of actual fires, if you would like a few days (or more) of reading. One possible search (for the word "fire", in any post, displayed by topic:
https://endless-sphere.com/forums/search.php?keywords=fire&terms=all&author=&sc=1&sf=all&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search
Another only in thread titles
https://endless-sphere.com/forums/search.php?keywords=fire&terms=all&author=&sc=1&sf=titleonly&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search
another in first post only
https://endless-sphere.com/forums/search.php?keywords=fire&terms=all&author=&sc=1&sf=firstpost&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search
Bypassing the BMS is usually easy, but it's different for different ones. some possible searches
https://endless-sphere.com/forums/search.php?keywords=bypass*+BMS&terms=all&author=&sc=1&sf=titleonly&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search
https://endless-sphere.com/forums/search.php?keywords=bypass*+BMS&terms=all&author=&sc=1&sf=firstpost&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search
Properly designed ones will shut the pack off if the sense wires to the cells are disconnected, but most are not properly designed, and will simply never perform any part of their function if the sense wires are disconnected, and be "always on".
Those that are powered by only a few cells near the negative end will probably not operate at all, or not as designed, without the sense wires connected.
In any case where disconnecting the sense wires doesn't bypass it, you'd need to physically connect the main output + and - wires of the BMS to those of the battery itself (presently on the main input of the BMS).
Side effects of bypassing the BMS are that you no longer have any monitoring of the cells, so they can be:
--discharged so low that they have a risk of fire when charging them up again, any time after doing so.
--charged up so high that they have a risk of fire at any time after that.
--if a cell group is really low, then it not only gets discharged down to zero, it can actually be negatively charged (reversed), which increases the risk of fire both at that moment and when recharging.
--more and more unbalanced on every charge cycle, making all of the above more likely each time.
Fire might never happen, but it can, and you won't have warning of it until it does. Normally with known-good cells the risk is small, but if you already have a known-problem-battery pack, the risk has already increased. By how much, it is impossible to say, as the internal reasons for the cell(s) problem(s) are not visible, and some of the failure mechanisms are more likely to result in fires than others, and different conditions affect those mechanisms in different ways.
A BMS is no guarantee that a fire won't happen, but if it's properly designed and not defective then it's better than no monitoring or management at all. There are no "safe" batteries that don't have any fire risk--every kind of rechargeable I've ever seen has had a fire or even explosion at some point in history. (even some non-rechargeables)
There are a lot of fire discussions here on ES, including prevention, management, containment, and results of actual fires, if you would like a few days (or more) of reading. One possible search (for the word "fire", in any post, displayed by topic:
https://endless-sphere.com/forums/search.php?keywords=fire&terms=all&author=&sc=1&sf=all&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search
Another only in thread titles
https://endless-sphere.com/forums/search.php?keywords=fire&terms=all&author=&sc=1&sf=titleonly&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search
another in first post only
https://endless-sphere.com/forums/search.php?keywords=fire&terms=all&author=&sc=1&sf=firstpost&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search
Wow thanks Amberwolf for all this useful (and somewhat scary) information. So it's possible then to by-pass the BMS w/ the sense wires disconnected then? I'll give it a shot. Obviously the threat of a fire is ever-present like you said and I'm totally aware of that risk!
Don't bypass the BMS. It's a very dangerous thing to do. next time you charge the battery, it probably won't charge at all, and if it does, there's a chance that it could catch fire.
if you want to be really sure about your problem, fit a voltmeter so that you can see the voltage while you ride. Almost certainly, you'll see the voltage go right down as soon as you open the throttle. Another thing you can do is measure the voltage of the battery when it cuts out. Fully charged it's 54.6v. It will cut off round about 40v when empty, though it'll normally bounce back a few volts afterwards.
if you want to be really sure about your problem, fit a voltmeter so that you can see the voltage while you ride. Almost certainly, you'll see the voltage go right down as soon as you open the throttle. Another thing you can do is measure the voltage of the battery when it cuts out. Fully charged it's 54.6v. It will cut off round about 40v when empty, though it'll normally bounce back a few volts afterwards.
Thanks d8veh. Interesting #s you gave me here, because when mine is fully charged it is around 57.1v and when I ride it for about 2-3 miles it drops to around 51volts. It has never come close to 40volts??? Either way I think it's best I do not try and by-pass the BMS. Thanks for your comment.
