Troubleshooting - Electric Drive System

Check Battery Pack Voltage

Verify battery voltage is between 50-58vdc.

Without power, nothing happens. The first place to start troubleshooting is the battery pack. Using a digital multimeter (VOM), measure the voltage at the battery connector. Fully charged, it should be 57-58vdc, but if it's below 50vdc that could be a problem.

In order to measure the battery voltage, you will need to disconnect the main battery supply connector. Be aware that when connecting or disconnecting the battery connector, the conductors can arc. This is normal, but be careful and don't short the battery conductors.

Locate Main Battery Supply Connector

The main battery supply connector is located in the same connector bundle as the 'P11' connector. It's the biggest cable in the bunch. There is also a smaller battery charger cable that comes out of the battery pack, so don't confuse the two.

  • Is the battery voltage greater than 50vdc?
Yes - (Normal) Click Here
No - (Abnormal)  Continue Below

Check Battery Charger

Check the voltage output from the battery charger.

The battery charger is pretty much the work horse of the e-bike system. It is also one of those items on the short list of 'common failures'. It should have a 58vdc output voltage. Again, you'll have to disconnect its connector to measure its output.

⚠️  Make sure you plug in your e-bike 120v charge port, or you won't see any voltage output.

If it's doing its job, your battery pack should be charged. If your battery charge is low, the battery charger is the most likely culprit. The battery charger itself is located on the right side of the top tube. To gain access to it, you need to remove the right tank clam. It does have a small LED on the side of its case, but that doesn't always provide useful information.

Replacing the Battery Charger

While not shown in the photo, the 2 amp battery charger has a 120v cable that plugs into the side. When replacing the battery charger on your Fat Woody cruiser, discard the 120v cable that comes with the new charger and use the one already installed on your bike.

Note: To replace the 120v cable on the bike, you need to disassemble the lower unit. That's a lot of unnecessary work. If you suspect the cable is bad, check the voltage at the 120 plug (w/charge port plugged in).

Replacement battery chargers are available in our parts shop.


Replacing the Battery Pack

If you verify the charger is operating properly and the battery pack does not appear to be charging, it's best to replace the battery pack rather than open it and attempt repair.

In order to replace the battery pack, you will need to disassemble the lower unit. Please visit the 'disassembly' section if you have not done this before.

Replacement battery packs are available in our parts shop.