jrejr2345 - The identical charger is available from Quick Charge, the OEM, for less than $500. RFF just puts their sticker on and marks up the price. Error code 15 is low battery voltage. A complete list of error codes can be found here: http://www.electricforum.com/cars/neighborhood-electric-vehicles-hev/2486-complete-list-gem-error-codes.html I will need to know what size and type batteries you are using? I’ll give you a step by step tests to help find the problem without replacing unnecessary parts. Do this before spending big money on a set of batteries.
First, turn off the master switch, then clean and tighten all battery cable connections. Use a commercial battery cleaner such as NAPA part number 1072. Hose off the batteries and let dry. Replace any damaged or badly corroded cables. GEM uses good quality cables. I have never replaced one on four vehicles.
Second, Turn the switch back on and charge the batteries to a green light. Record the elapsed time. If you have flooded batteries, check the water level in each cell. Add distilled water if needed. With the key off, check and record the voltage across each battery. If one is even slightly less than the others, it is suspect. Another reason for voltage variance is using different batteries in the same vehicle.
Third, double check that your charger is set for the type of batteries you are using. Every charger manufacturer I have dealt with has had good technical support.
Fourth, drive the GEM under normal conditions until it feels weak. Record the mileage driven. Check the voltage across each battery as before and check again for variance. Sometimes, a weak battery will reach full voltage quickly, fooling the charger into believing the charge is complete. This will result in a shorter than usual charge time and a GEM that needs frequent charging. The other possibility is that one of the batteries is not reaching full voltage. This is more easy to find as the voltage will not rise regardless of charge. This will result in hot batteries, long charge time, charger errors, and frequent need to charge. If one or more of the batteries has lost considerably more voltage than the others, it is suspect. Now would be a good time to do a load test. Before charging the batteries, a hand held load tester, such as NAPA part number 7001112 can check voltage and battery performance under load. Observing polarity, connect the tester to each battery and engage the load switch no more than ten seconds. Wait five minutes between tests. Record the reading after ten seconds. If one or more batteries show weaker results, they are suspect. Compare these readings to the voltage tests taken earlier. If one battery lags behind the others, replace it.
Fifth, If a battery was replaced, charge the GEM regardless of how recently the GEM was driven. Drive the GEM and record the mileage again and compare to previous. Then, charge the GEM and compare the time elapsed. Knowing the correct values for your GEM will alert you when something goes wrong.
Sixth, If you have gotten this far and can’t find anything wrong with your batteries, contact the charger manufacturer and find out what the finishing voltage is for your battery type. Charge the GEM, take the voltage reading across all the batteries near the end of the charge cycle and compare. This will be somewhere around 80 volts. This will tell you if your charger is over or under charging the batteries.
Seventh, look for current draw. This occurs when something electrical in the GEM is not turning off with the key. Charge the batteries. Wait an hour. As before, read the voltage across all of the batteries. Let the gem sit for 48 hours. Read the voltage again and compare. The temperature should be fairly level during this test. If the voltage is still about the same, you should not have a current draw.
Eighth, If the voltage dropped, charge the GEM again. Open the master switch. Wait an hour. Read the voltage. Let the GEM sit for 48 hours. Read the voltage again and compare. As before, the temperature should be fairly level during this test. The voltage should be about the same because the GEM electrical system has been disconnected. If the voltage did not drop with the master switch open, but did drop before with the switch closed, you have a current draw and must investigate.
If you get this far, I’ll tell you how to go through each circuit. I know all this is time consuming. Just consider the cost of a complete set of batteries. Even worse would be to replace them and the problem is still there.
Daniel