Motor Stops Working After Hill Climb

[David Spangenberg]

I have an original A2B and replaced its battery two years ago. If I go up a steep hill that lugs the motor the motor will stop working while the red and yellow lights remain lit. It has done this three times now and it seems to be a function of lugging the motor. The situation does not correct itself over time. I need to charge that battery and then the motor will start to work again. Any idea what may be causing this? I live a long way from anyone who could service it. Thank you for any help. David

 

[JRA]

This can be caused by the low voltage cutoff being reached which will shut you down. If you take off your battery and put it back on (without the charge cycle) will it work again that way? If so then it is probably a low voltage situation. If you can check the voltage of the battery fresh off the charger to see if you are getting a full charge to begin with.

In general it is not good practice to lug a hub motor up hills btw. Try pedaling in a complimentary gear ratio and going a bit slower.

 

[David Spangenberg]

This can be caused by the low voltage cutoff being reached which will shut you down. If you take off your battery and put it back on (without the charge cycle) will it work again that way? If so then it is probably a low voltage situation. If you can check the voltage of the battery fresh off the charger to see if you are getting a full charge to begin with.

In general it is not good practice to lug a hub motor up hills btw. Try pedaling in a complimentary gear ratio and going a bit slower.

Thank you very much. I have tried to peddle harder each time and one time it worked and the motor did not shut off but I'm still a little weak from a surgery. When you say "if you take off the battery and put it back on" what do you mean as this is the internal battery? I like your ideas. I will put a volt meter on the plugs sockets and see what I get. I am have trouble accepting the fact that the new factory battery at $800 crapped out after just two years.

 

[JRA]

Batteries have life spans which get shortened when they are either used too much or not enough. If you didn't use it for a long period for instance it will degenerate. Batteries with Lithium chemistry like to be stored about 3/4 charged which is not always done.

If you have a volt meter and aren't afraid to use it for sure check it when "fully" charged and then again when it conks out on you. I never trust the battery "lights" on a readout as they are not reliable.

I am not all that familiar with the A2B system but I would suppose it is 36v which should read more than that hot off the charger. And by undoing the battery and plugging it back in sometimes will reset the controller and the low voltage cutoff will reset also. As yours is internal and thus you charge it while in the bike that is not an option I guess.

 

[David Spangenberg]

Thank you again. I'll follow your suggestions and see where it leads me. I see that it is possible to have the battery rebuilt. So, that may be my best option at this point. Thank you again.

 

[J.R.]

Lugging the motor can also cause overheating, which can result in a shutdown. My first ebike had that happen in winter! Riding uphill on snow covered roads was hard on the bike and the motor would slow to a crawl. I resolved the issue with less/lower assist and spinning the cranks at higher rpm in a low gear. This way the motor does less and rider more. Never happened again.

 

[Ann M.]

@JRA & @David Spangenberg, the A2B Metro with the internal battery cannot easily be uninstalled & remounted; it's inside the frame, pushed in from the bottom of the bike after removing part of the controller; not a quick process! It's possible that the battery you got sat on a shelf for a while before you received it and was built with older style cells that lack the capacity that current ones have. Even with maintenance charging it still ages. If you let that battery sit for a few months it starts to degenerate. When new in good condition, it should read approximately 41.5 Volts; if it's much below that then you're more likely to experience the motor bogging down or cutting out due to low voltage, particularly on hills. Better to choose a smaller or easier to pedal gear; you can damage the motor or controller from overheating & low voltage.

Getting the battery rebuilt is a reasonable option; you'll have better range and maybe a little more speed depending upon how the pack is built.

 

[David Spangenberg]

Lugging the motor can also cause overheating, which can result in a shutdown. My first ebike had that happen in winter! Riding uphill on snow covered roads was hard on the bike and the motor would slow to a crawl. I resolved the issue with less/lower assist and spinning the cranks at higher rpm in a low gear. This way the motor does less and rider more. Never happened again.

Thank you so much for that story. I am going to try less epower and more mepower today and see what happens. If it continues I may just need to walk the bike up the hill if I cannot overcome the shut down. Now I am afraid to take it on my last year's one hour ride as there are some tall hills on the far end with no cell service to be had which would create an interesting problem for me getting home.

 

[David Spangenberg]

@JRA & @David Spangenberg, the A2B Metro with the internal battery cannot easily be uninstalled & remounted; it's inside the frame, pushed in from the bottom of the bike after removing part of the controller; not a quick process! It's possible that the battery you got sat on a shelf for a while before you received it and was built with older style cells that lack the capacity that current ones have. Even with maintenance charging it still ages. If you let that battery sit for a few months it starts to degenerate. When new in good condition, it should read approximately 41.5 Volts; if it's much below that then you're more likely to experience the motor bogging down or cutting out due to low voltage, particularly on hills. Better to choose a smaller or easier to pedal gear; you can damage the motor or controller from overheating & low voltage.

Getting the battery rebuilt is a reasonable option; you'll have better range and maybe a little more speed depending upon how the pack is built.

I got a price yesterday of $530 plus shipping to rebuild the battery from a place in Las Vegas. She said to see if I could not juice out the battery this year and send it in the winter and I am going to give that a try. I need to track down my volt meter and give that reading a try. Thank you for the correct number - very helpful.

Do you know if there is an after market external battery that will attach to the back of that bike and does that also need its own controller?

 

[David Spangenberg]

@JRA & @David Spangenberg, the A2B Metro with the internal battery cannot easily be uninstalled & remounted; it's inside the frame, pushed in from the bottom of the bike after removing part of the controller; not a quick process! It's possible that the battery you got sat on a shelf for a while before you received it and was built with older style cells that lack the capacity that current ones have. Even with maintenance charging it still ages. If you let that battery sit for a few months it starts to degenerate. When new in good condition, it should read approximately 41.5 Volts; if it's much below that then you're more likely to experience the motor bogging down or cutting out due to low voltage, particularly on hills. Better to choose a smaller or easier to pedal gear; you can damage the motor or controller from overheating & low voltage.

Getting the battery rebuilt is a reasonable option; you'll have better range and maybe a little more speed depending upon how the pack is built.

I put a volt meter on a fully charged battery and it read 41.7 volts. What do you think of that reading? Does that sound like a bad cell? Also, do you know if there is an after market battery pack I can attach to the external battery port? Thank you for all your help on this.

 

[Ann M.]

David, that voltage reading doesn't sound bad. You may have an issue with the controller or secondary electronics connected to the controller that are located just below the battery. Depending upon the version of Metro you may have a motor with the controller inside the motor which would be more vulnerable to overheat issues during climbs, especially if you're not pedaling enough. Have you spoken with the tech staff at A2B in San Francisco? Kyle and his team are quite knowledgeable.

Technically, you could add a rear rack battery; your bike should already be wired for that. The challenge is the unique connector coming from the bike to the battery. A2B has one that is designed to slide onto the rear rack and lock in.

 

[David Spangenberg]

David, that voltage reading doesn't sound bad. You may have an issue with the controller or secondary electronics connected to the controller that are located just below the battery. Depending upon the version of Metro you may have a motor with the controller inside the motor which would be more vulnerable to overheat issues during climbs, especially if you're not pedaling enough. Have you spoken with the tech staff at A2B in San Francisco? Kyle and his team are quite knowledgeable.

Technically, you could add a rear rack battery; your bike should already be wired for that. The challenge is the unique connector coming from the bike to the battery. A2B has one that is designed to slide onto the rear rack and lock in.

Ann, Thank you! That is great news about the voltage. I called A2B in San Francisco before I posted and got a disconnect for the showroom number. Do you know how to get in touch with Kyle in S? I'm in Healdsburg, about an hour or so north of SF.

 

[Ann M.]

Hmmm, I've heard the same response from some of my customers; let me check this out. The company has been having money issues.

It may also be possible with the help of a good electronics tech to convert the original connectors to the 2nd battery unit to other more universal connectors.
@Thomas Jaszewski, what's your thoughts on this?