Battery Voltage

[mnichols]

Hello,

I bought 2 new 12v deep cycle marine batteries last year. I keep the trailer on the side of my house with the battery disconnect out and a Battery Tender Plus on the batteries. Getting the trailer ready for this weekend and I put a meter on the batteries (no charger) and it read 13.6v. When I connected the battery disconnect in the trailer it droped to 12.6v with nothing on except the converter and fridge. 12.6 seems a little low to me after being on a battery tender all the time.

Anyway, does this seem low to anyone else? Could there be a short? Bad batteries? Thanks for your input.

[Dakota98]

dockmasterdave

It sounds as though you have a basic converter & not one that is a 3-4 stage charging profile.

If the batteries are fully charged & the converter is a 3-4 stage, it should read 12.8-13.2 in "float" mode.

[dockmasterdave]

Not trying to hijack this thread, just have a related question.

When you connect the shore power cable up that turns on the on-board converter/charger unit the batteries should jump up to 13.6VDC or higher up to 14.4VDC depending on what charge mode the converter is in...

I don't see my converter/charger dropping below 13.6v.
It is supposed to have 12.7, 13.6,and 14.4.
It is a wfco 45.
Is there nothing wrong with it constantly showing 13.6?

Thanks for your help.

[Dirtclods]

Don't forget to check your distilled water levels.

[4aSong]

RoyB wrote:
When you measure the battery terminals with a multimeter without the shore power or any other charging source connected they should read 12.6-7VDC when fully charged.

When you connect the shore power cable up that turns on the on-board converter/charger unit the batteries should jump up to 13.6VDC or higher up to 14.4VDC depending on what charge mode the converter is in...

This tells you your converter/charger is charging the batteries...

Roy Ken

Very good information.

[Dirtclods]

I have one of these:

http://www.walmart.com/ip/Everstart-932W-Everstart-Battery-Monitor/16139506

[RoyB]

When you measure the battery terminals with a multimeter without the shore power or any other charging source connected they should read 12.6-7VDC when fully charged.

When you connect the shore power cable up that turns on the on-board converter/charger unit the batteries should jump up to 13.6VDC or higher up to 14.4VDC depending on what charge mode the converter is in...

This tells you your converter/charger is charging the batteries...

It is important to know what your disconnect switch does in regards to charging the batteries.

Best way to tell is just read the DC VOLTAGE at the batter terminals. Then you know for sure.

The chart posted above is good info to have available to you. I watch my batteries real close when camping off the power grid and when I notice the battery bank is down to 12.0VDC this tells me they are approximately at their 50% charge state and it is time for me to start re-charging or shutting down using them. I follow the golden rule real close here to not go below 50% charge status to not do any harm to the battery bank.

Has kept my original batteries I got with my trailer in 2008 still working fine. Just now starting to fall off on performance.

Roy Ken

[Dirtclods]

mnichols Yep I printed that chart and posted it in my trailer so.... I wouldn't forget either!!

[mnichols]

Thanks. Been searching and came across that chart. First two camping trips this year I had full hookups... guess I forgot what the batteries were supposed to read

[Dirtclods]

Great info:

http://www.marxrv.com/12volt/voltchart1.gif

http://www.marxrv.com/12volt/12volt.htm

[TucsonJim]

12.6 VDC is a fully charged battery.

[Dakota98]

12.6 + = fully charged battery

At 13.6 you probably had some surface charge & when the switch was engaged a load occurred & dropped the reading to 12.6