Charger Blinking Red

I am getting a red blinking charging light and audible alarm when charging my 2002 GEM car has a Zivan charger that has worked well since I bought the car in 2008 with new sealed lead acid batteries. Last year I replaced all batteries with AGM batteries and changed the setting to “D” on the charger and all has worked fine. I recently charged the batteries and drove the car to have it inspected for new tag and noticed the batteries drained quicker than normal. I checked voltage on each battery and found one battery at 10.5 volts so I replaced that battery and then charged again. I began receiving the red blinking light and alarm so I checked the new/used battery and found it was abut 11.5 volts and 85% charge on the range meter so I replaced that battery with battery that had 12.5 volts and installed and tried to charge but still received the red blinking light and alarm. The batteries indicate 95 % charge on indicator and each battery indicates about 12.6 volts using hand held volt meter. With 95% charge on start up, when I plug the charger cord in to charge to 100%, I receive the red blinking light and audible alarm. Does anyone know why I am getting the red blinking lights and alarm? I thought red blinking lights meant battery voltage was not correct or equal between all batteries. One time after receiving blinking light and alarm, I tried turning the key switch off and on and depressing the accelerator petal and then tried charging and it charged OK. But the next time I tried to charge, after replacing the low voltage battery, the red light started blinking again even though it is showing 95% charge on gauge.

I would suggest confirming that the series voltage of the batteries is within range instead of relying on the display. If it is in range, be sure that all of the battery cables and connections to the charger are clean and tight. If so, the charger may need to be serviced. All four of ours have now been out for service. There is a factory update to the charging software. If it has been serviced, there will be a label saying “micro upgraded”. Over the years, I have found the Zivan chargers to be reliable. Electric Conversions, the Zivan dealer in the US, has good customer service and a reasonable turnaround time on repairs.