Axis Battery Charging Issue

[Oneilkeys]

I’ve got an issue with the charging system in my 2016 Axis that I don’t understand. I have installed a PD4655 converter/charger and it has worked well for a year. All three modes - boost, normal and maintenance work as programmed at 14.1, 13.6 and 13.1v. For the past year when the PD4655 is on, the voltage measured at the batteries has registered at those voltages depending which mode the charger was in. The other day, when I plugged into shore power to charge up the house batteries (batteries down to 11.4v), the voltage at the house batteries read 13v even though the charger said it was in boost mode and the voltage at the batteries should have read 14.1. Voltage at the chassis battery also read 13v so the Trombetta was open. After a few hours, the voltage at the batteries had slowly climbed to 13.5 and the batteries seemed to be charging normally.

My first thought was that there was something wrong with the PD4655. However, when I unplugged from shore power and turned on the engine, I got the same 13v at the batteries with the alternator running. I cleaned all the battery posts of corrosion and replace a cable and a few cable ends to make sure all connections were OK.

I left the coach plugged into shore power over night to charge the batteries. After I disconnected from shore power, I waited an hour to let the batteries stabilize and they did at 12.7v - OK for 3 Year old batteries. I then turned on the Max fan and let it run for four hours. The house batteries seemed to degrade normally to about 12.3v during that time.

When I turned off the fan and plugged back in to shore power, I got the same 13v reading at the house batteries, even thought the PD4655 said it was in Normal mode and should have read 13.5v. After an hour, the reading at the batteries had climbed to 13.23v.

I do not understand why the voltage at the batteries does not read 14.1, 13.5 or 13.1v depending on which mode the PD4655 is in. It alway has before? Something has changed and I do not know what it is? Anyone have any ideas?

[scrubjaysnest]

What current are you reading going into the house batteries? Even though the PD is rated for 55 amps it may not supply that current at 14.1 volts.

Also your original battery reading of 11.4 indicates the batteries were dead.
If you have the dangle try setting it to the 14.4 volt setting and see what happens.

[Oneilkeys]

For the last year the PD4655 has been able to charge a more than 50% discharged battery at 14.1v so there is enough amperage there. After charging for several hours, I went and put the PD4655 on boost mode and it this time the voltage at the batteries did go up to 14.1v. So it may be that the batteries were so discharged that they had to be charged sufficiently before the voltage would show the full 14.1v or 13.5v at the battery when under charge. I think these batteries may be in poorer shape than I thought and if I replace them, my issues may go away. These batteries were charged b6 the old Thor charger for a couple of years before I bought the PD4655 so they very well may have been damaged then. Thanks.