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Swollen Battery

I was wondering if the battery is swollen if you could still use the bike? i am scared it will explode.

If an electric bike's battery is swollen that is a sign that it overheated while being used or recharged.

If it is a Lead Acid battery or battery pack then the swelling is usually caused by the battery being old and having depleted electrolyte levels which causes it to overheat while it is being recharged. With Lead Acid batteries there is no chance of them exploding or catching on fire if they are swollen, however the swelling is a sure sign that they need to be replaced. If they are continued to be used then there is a chance that they will swell even more which could cause them to wedge themselves inside the battery box making them difficult or impossible to remove, or the battery's outer plastic case could break open and spill highly acidic electrolyte paste inside of the battery case which would need to be carefully cleaned up before installing the new battery.

If it is a Lithium battery then stop using it immediately and remove it from the bike. Swollen Lithium batteries are a sign that the battery has been overcharged, overheated, or has a manufacturing defect. Lithium batteries can explode due to these reasons so anytime that a Lithium battery has swollen then it should not be used anymore and replaced with a new battery.

No matter which type of battery it is it should be removed from the bike and replaced with a new battery.

Please let us know if you have any questions.

Thanks so much for replying . very helpful 

Hi there I now have a new problem . About 2 weeks ago i changed my batteries for the bike and installed 4 Batteries. the bike was running fine for about a week and a half. last week my bike just shut down, when i checked the main toggle switch had gone off. so i turned it back on and everything was fine. the next day it happened again. do you have any idea what the problem may be. could the batteries be sending out to much power for the toggle switch.when it trips the toggle is warmer than it usually is. Any insight would really help, I have a TaoTao electric bike. 

Those type of toggle switch circuit breakers wear out over time and every time that they trip they get a little weaker. So eventually they will trip during a situation that they did not trip during before.

The new battery pack could very well be outputting more power than the old battery pack did which is causing this to happen now. I recommend to replace the old circuit breaker with a new one.

We sell TaoTao toggle switch circuit breakers on the TaoTao 501 and TaoTao 502 parts pages.

how would i know which one to get 

All TaoTao electric scooter use the same circuit breaker so it does not matter which page you purchase it from.

sorry to keep bugging you. on your site it says there is a 32amp and a 63 amp. which one do i purchace.and it says shipping is 1-6 week is it actually that long if i pick that option. i live in toronto and i am not sure where else i can get the part from . the other shipping options is coming to alot more than the actual part. 

TaoTao electric scooters use the 32 Amp circuit breaker. The 1-6 week shipping time estimate is there because some countries are halfway around the world and have slow post offices so they take a long time for delivery. USPS First Class international shipments to Canada usually only take around 5 to 10 days to be delivered though.


sometimes you have to check the motor phase wires. start from the controller to the connectors and make sure they are clean and not burnt looking. check any area in the motor wire loom that bends. look for melted insulation and wires sticking to each other. these are things that tripped the circuit breaker on my panterra

I just bought a used scooter for my son yesterday. We were both aware that the battery life has been cut from approx 30-40 km per charge to approx 20-30 km. We charged it for the first time last night fully confident that the charger would stop once full. This was not the case. This morning it was super stinky, opened the container and the batteries were swollen. Any idea as to why the charger never cut out? And are these batteries now garbage?
Once the batteries have overheated and swollen then they are no good and need to be replaced.

The cause of the battery failure could be due to old, worn out, or faulty batteries. If the batteries are old or have a lot of discharge and recharge cycles then a significant amount of the electrolyte inside of them may have evaporated which caused them to overheat. The electrolyte helps keep the batteries cool during recharging and when it has been used up the batteries can overheat. It is also possible that the batteries have an internal short circuit due to a previous accident or rough handling which has caused them to overheat while recharging.

Less likely although possible is that the charger has malfunctioned and is outputting too high of a Voltage level. The output Voltage of the battery charger can be tested to determine if it is within specifications. The output Voltage of the battery charger should be around 13.8 Volts per battery that it is charging. If the charger's float cycle did not work and the charger stayed on charge cycle after the batteries were fully charged that should not cause the batteries to overheat because the Voltage of the battery pack would equalize with the output Voltage of the charger and both would remain at a safe level.
Ok. So now than likely... The cause of the overcharge is due to old batteries. And the batteries still read over 12 volts. They cannot be used anymore even though they are lead batteries?
No matter what the Voltage of the lead batteries are if they have melted and swollen then we recommend to discontinue using them because they could continue to swell and lock themselves into the battery box or frame of the scooter or they could burst open and leak which may damage other components.

Hope I can get an answer here.  I have an Emmo Max and love it.  It has 5 12v 20ah batteries.  The original batteries that came with the bike were awesome.  They really went the distance and I got a lot of kms out of them before I needed to replace them.  Their total life span was over 5000km spanning over two years.  When I replaced the batteries, I replaced them all at the same time.  The mileage I was getting with the new batteries wasn't much better than with the old ones before I replaced them.  I was thinking I might have had a bad bearing or something causing drag.  Disconnected the back brake and kept checking for signs of a bad bearing but everything seemed fine other than my travel distance.  My speed was fine, it wasn't running any slower, just not going anywhere near as far as when the bike was new.  Went out the other day to use it for a small trip and it had no power at all.  Turning on the headlight caused the needle to drop way down on  my power gauge and the motor had zero push at all.  Plugged in charger and green light came on indicating a full charge.  Removed seat bucket to access the batteries and all of the batteries are swollen.  Not just a little either, these things look awful.  I can understand an old battery swelling but all of them?  They were bought new and put in just a year ago.  Did I get a bad batch of batteries?  Do I have a short somewhere?  When I plug in the charger the bike does power up and the lights work and the motor spins just off of the power from the charger but when run just off of the batteries the lights will come on and using the brights will make them flicker as they are under powered.  Any advise you could offer would be an immense help.

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