We have a 2000 4 seater GEM. We upgraded the controller in 8-3-09 to a Delta-Q. We just replaced 2 batteries that wouldn’t take a charge to 100% anymore but have not replaced the other 4 because they would charge up to 100%.
We are in an area with big hills to climb.
When the battery charge level gets to 80% or below and we are climbing a big hill on road mode, we start to hear a humming noise coming from under the dash. Then the GEM will click off and will read -15. After waiting about 1 min. the GEM will restart and will go a ways again. The green light over the battery symbol also appears to be flickering right before it clicks off and then there is a light that flickers above the wrench symbol.
Delta-Q makes chargers, not controllers. The controller was made by GE. These are generally reliable. Code -15 indicates low battery voltage. Check all of the batteries. “Taking a charge” does not always indicate a good battery. Is the new charger set for the battery type you are using? Charge the batteries and take an accurate voltage reading. The results should be within a few tenths on a volt. Drive the car until the batteries are low. Check the batteries again. Compare the results. If one test lower than the others, it is bad. If they all test the same, charge them again and have them load tested by a shop with a large load tester. The handheld load testers sold at auto parts stores are only rated at about 75 amps and will give a false positive on these large deep cycle batteries. Be sure your batteries are actually bad before replacing them.