Battery charging issue

[927palmetto]

I have a 2005 MADP with a Magnum inverter/charger. About a year ago, I installed 4 6v Lifeline AGM batteries. I set the charger for AGM batteries. I just noticed that in "float charging" mode, the charger displays 12.3 volts, at least when connected on shore power. I have not checked the voltage when charging from the generator. The volt meter in the coach indicates voltage at 12.0. Since my ability to use the inverter is extremely limited before the auto gen start is activated, and since I recall the voltmeter indicating 12.6 volts when fully charged, I am thinking that the batteries are not charging fully, at least when on shore power. This would explain my limited battery capacity when boondocking. Any ideas?

[harleyman134]

Originally Posted by 927palmetto

I have a 2005 MADP with a Magnum inverter/charger. About a year ago, I installed 4 6v Lifeline AGM batteries. I set the charger for AGM batteries. I just noticed that in "float charging" mode, the charger displays 12.3 volts, at least when connected on shore power. I have not checked the voltage when charging from the generator. The volt meter in the coach indicates voltage at 12.0. Since my ability to use the inverter is extremely limited before the auto gen start is activated, and since I recall the voltmeter indicating 12.6 volts when fully charged, I am thinking that the batteries are not charging fully, at least when on shore power. This would explain my limited battery capacity when boondocking. Any ideas?

I would think that you should be charging at a rate over 13 volts in the "float" stage, 12.3 volts seems awfully low. Go thru the setup menu on your remote unit for your inverter and make sure you have your inverter/charger set up properly. As far as the AGS, when I had set mine to start the generator to come on at 12 volts and the generator kept coming on, I dropped this setting to 11.5 volts and this has been better for me, I don't know what this lower setting does to the life of the battery though.

[racer0624]

Just a WAG on my part but it's possible the battery installer may not have hooked up the thermostat in the battery compartment. To perform a quick check call Magnam and ask them which connector to pull on the back of the charger. I thinks it's yellow but not sure. When our coach was new I had the same voltage as you now have and it was a bad thermostat.

[GaryKD]

Hi 927palmetto,
My assumption is the batteries are all good. If racer0624's post produces no joy, consider the charger is not working. If you can, take a reading on the charger's output for charging the batteries. If that is not within spec. check the reset button(s) on the charger. Check to see that the circuit breaker is not tripped.

The charger should be outputting 13.6 to 13.8 VDC in float mode. In charge mode it will output over 14 VDC.

Try calling the charger manufacturer.

If all this fails to produce results, consider getting all the batteries load tested. The batteries will need to be fully charged to be load tested. Put a portable charger on the batteries until the problem is closed. The portable charger should be placed on the batteries immediately. Leaving the batteries at 12 VDC or less is not good.

[JVR]

I had a similar problem and the settings on the control center which includes the inverter and charger were set incorrectly, the problem is it's been too long for me to remember the exact setting that I probably messed up.

[927palmetto]

Thanks to all for your input. I unplugged the coach from shore power and started the gen set. The charger immediately began the absorb charge at 13.4 volts. I charged the batteries for about an hour. They were still absorb charging when I shut down the gen set and restored shore power. Once on shore power, the display continued to show an absorb charge at 13.4 volts, and I was hoping all was well.
The next morning, the charger had returned to float mode, again at only 12.3 volts. The voltmeter in the coach still says the batteries are at 12.0 or 12.1 volts.
I am thinking that the charger is not working properly in float mode. My next test will be to run the gen set long enough to get to float mode under gen set power. I don't think the source of the A/C power to the charger should make any difference, but I still want to test it. I also plan to check the charger output in float mode as suggested...I expect it will be low at 12.3 volts.
Any ideas, or do I need to be looking for a replacement charger/inverter. If so, any recommendations?

[harleyman134]

I wish I had an answer for you, but unless you have a bad battery (which I doubt since they are only a year old) this sounds like it's above my pay grade. Please keep us updated. I have the same unit as you and will follow this thread.

Sonny

[GaryKD]

Hi 927palmetto,
Consider purchasing a portable smart battery charger. They come in handy in a lot of different situations. Gut feel says getting the batteries to full charge will take about 48+ hours with a smart charger. With the price of diesel, the smart battery charger will pay for itself the first time you use it.

[alan1]

927palmetto:

Do you have the manual for setting the remote up?

[927palmetto]

Yes, I have the manual. I am still experimenting with the resolution to the problem. Here is what I have discovered so far. I unplugged the battery temperature sensor wire from the inverter, and charging performance improved dramatically. The Magnum owner's manual lists the BTS as an "option," so I don't know what the impact will be from leaving it disconnected. I am boondocking this week in Daytona, so I will not be able to test shore power performance until next week.

[harleyman134]

Where are you staying in Daytona? I'm riding down on the bike this morning and coming back home Saturday.

[Iron Man]

Originally Posted by 927palmetto

Yes, I have the manual. I am still experimenting with the resolution to the problem. Here is what I have discovered so far. I unplugged the battery temperature sensor wire from the inverter, and charging performance improved dramatically. The Magnum owner's manual lists the BTS as an "option," so I don't know what the impact will be from leaving it disconnected. I am boondocking this week in Daytona, so I will not be able to test shore power performance until next week.

The charger will "throttle" charging amperage based on battery temps. Since the batteries are near the engine and exhaust the temp probe will show the batteries get hot while traveling. When we stop I notice the charging amps are down until the batteries cool.

[racer0624]

927 palmetto,
Leave the temp sensor disconnected. All it will happen is make the charger "think" the ambient temp is 68 degrees and charge at a higher amperage. I had the same failure and left the sensor disconnected per Magnum until I received a replacement from them. No harm will be done while you're waiting.

[Perry White]

Here's a manual if you need it