Repairing an electric bike battery can be dangerous & requires technical knowledge.
Big lithium batteries are not just one single battery but they are multiple individual cells.
The most common ones are the 18650 battery cells.
Each big battery has a certain structure of battery cells which determines the capacity, voltage and amperage.
Batteries, besides all the cells have a piece of electronic circuit called a BMS.
If your e-bike battery isn’t working, try these common issues and possible repairs.
Safety Must Come First.
NEVER open the battery unless you are competent at what you are doing. Lithium-ion batteries can be dangerous.
ALWAYS wear safety goggles.
DISCONNECT from your electric bike before starting.
NEVER short circuit or puncture the battery.
Basic Troubleshooting.
Make sure the charger is working by trying it on another battery.
Is your charging port clean and dirt free. Is there any damage, have a thorough inspection.
Check the Battery Connections.
Loose and corroded terminals can stop the battery from its charging process.
Use rubbing alcohol and a cotton swab to clean the contacts.
Try resetting the Battery Management System otherwise known as the BMS.
Has your bike battery got a reset button. If so, press and hold it a few seconds.
If no reset button disconnect the battery for up to 10 minutes and then try a recconect.
Fixing Common Battery Issues.
Battery Will Not Charge. Possible Reasons & Fixes:
Dead cells. Battery needs a recondition or possible replacement.
BMS fault. You possibly need a reset or replacement.
Loose wiring. Open the case and check but only if you are competent
Blown fuse. Some EBike batteries have fuses, check these and replace if neccessary.
Battery Drains Quickly.
Possible Reasons & Fixes.
Battery cells. You may need a full cell replacement if yours are ageing.
Parasitic drain. Have a look for faulty components in your ebike’s electrical system.
Extreme temperatures. Always store and charge your battery at room temperature.
Battery Not Delivering Power.
Possible Reasons & Fixes.
Faulty BMS. Replace or bypass the fault which is considered an advanced repair. PLEASE take note.
Damaged wiring. Inspect the bikes internal connections.
Failed cells. Check the voltage and replace ones as neccessary.
Advanced Repairs BUT For Experts Only.
Only attempt this if you have previous experience with lithium battery packs. DANGER
Cell Replacement. Open your pack and find bad cells by using a multimeter and then proceede to replace them.
BMS Replacement. Change the battery management system if you know it is faulty.
Rebuilding the Pack. Completely take apart and replace all cells. This requires spot welding so ask a professional.
When to Replace the Battery.
If you see the battery is actually swollen or you can see damage.
If the voltage is too low to recover, say under 2.5V per cell.
The battery will not hold a charge even after cell replacement.
In many cases replacing the battery is much safer and cost-effective than spending money and time trying to repairing it.
