ZEV Tips and Troubleshooting

TROUBLESHOOTING CASE STUDIES

SQUAWK CASE 1 | SQUAWK CASE 2



The customer reported that the bike would not run.  Attempts to charge the bike repeatedly blew out the fuses in the charger.

Inspection of the bike charger showed that it was not just the fuse that was blown.  Even if the charger was not plugged into the bike, it would throw and arc when plugged into the wall connection.

Inspection of the bike with a voltmeter showed that the bike had only .2 volts to .8 volts on each cell group of 4 which should have shown approximately 14 volts.  Total voltage was only 28 volts.



The bike had been admittedly run down the road until it died after grinding along at very low speed.   Because the bike had been run continuously without being slowed down or stopped, the battery protection was defeated or tricked. 

The batteries were so low that when the charger was plugged in, the minimum voltage requirement of the MOSFET was not met creating a dead short, burning out the transistors.

Each 4 battery in a group in the bike should have 3.2 volts each or 12.8 volts per the 4 as the minimum, max will be 14 volts.  This is the same as a lead battery charger puts out.  So a 12 volt lead battery charger for a car with a minimum of 55 amps rating can be used to charge the lithium battery – BUT – only 4 at a time.  Trying to connect across the entire battery pack will create a blown battery charger and probably a fire due to the huge difference in voltage and the fact that the full pack will try to draw over 180 amps.  Attempts to use a car charger with less than 55 amps capacity will cause the car charger to shut down to protect itself or burn up.

A typical car charger has small clamps about 3 inches long.  These will fit on the battery with no contact to the frame. 
Remove the little door in the between the legs V and start charging groups of 4 battery.

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Move back one battery pack of 4 battery at a time.  Charge each and every battery pack to at least 12.5 volts.   This typically takes about 40 minutes per group of 4 battery. 


After charging all groups of 4, check the voltage at the charging plug to make sure it is high enough to use the standard bike charger – assuming that it has not been destroyed by the low voltage.

When the voltage at the charging plug is 12 volts less than the nominal rating for the bike, the standard charger can be used to charge the bike. 

IE – 62 volts for a 72 volt bike (ZEV6100)
       74 volts for a 84 volt bike (ZEV7100)

If you attempt to drive the bike after only charging with the lead battery charger, the BMS will shut the bike down as the battery will not be equalized.

It will take the standard charger about 4 hours working with the BMS to equalize the battery. 

If the bike does not run without a stutter or momentary shutdown, then in all probability a cell has been destroyed.  You will need to isolate that bad cell.

If the bike does not run when the battery are fully charged, then it is highly likely that the controller MOSFET have been destroyed by the low voltage use of the bike.

In this case, the deliberate running of the bike into the ground, long past the point where the needle on the battery capacity swings down to the red, and long past the warnings built into the shift down in the gears and the clearly apparent speed and power drop constitutes abuse and callous indifference to the operation of the bike.  All repairs and the two $500 chargers are not covered under warranty.