A large complaint from electric golf cart owners is when a golf car has been unused for several months and the owner goes to plug in the automatic charger and finds it will not come on.  They did not feel comfortable leaving the charger plugged in for the entire time since, they used the car last. But now they find out that the battery charger won’t come on.

This is one of the most common problems with electric golf cars left sitting for several months without a charger connected to it.

They appear to be dead; next a technician is called to check it out. The typical technician will check the car over and tell customers the batteries or the charger is the problem, transport the car back to the shop where they have a method of charging batteries that are under the critical 80% discharge level (70% nominal voltage level), and or checking the charger.

There are still many automatic chargers in use today that will not come on until there is at least 70% nominal charge voltage in the battery pack. That is how they were designed; this keeps them from working if there are major issues within the system. That is why they need to have a 70% nominal charge voltage to start; it was a designed safety feature. The nominal pack voltage of a 36 volt system fully charged is around 38 volts. A 48 volt battery pack fully charged would be around 52 volts. On the low end 70% (voltage) of a 36 volt pack would be close to 25 volts and a 48 volt pack at 70% (voltage) would be close to 33 volts.

The good news is that in the last five years charger technology has improved to the point where most automatic chargers only need to detect one or two volts to start a charge cycle. Also many chargers are now built with multiple fail-safe systems. Now, if the relay fails the charger will not continue to run until unplugged as some older chargers did. The problem with wet cell lead acid batteries is they discharge at a rate of 4% per week. In higher temperatures the discharge rate is even quicker. That means 16% per month. If you do the math it will only take two months and you are below the 70% nominal voltage. Newer charger technology also allows maintenance charging for storage.