I am confused

[Tim5055]

Well this week I replaced the group 24 battery that came with the new Niagara with to two 6v golf cart batteries. We went out camping Friday for the weekend to test the new batteries. While we were camped at a site with electric we did not plug in.

I used my multimeter to check the batteries when I arrived and it registered 14.4v DC. I assumed the high reading was because I had just disconnected from the tow vehicle and the reading would drop into the 13.5 +/- area quickly. It never did.

When we were packing up to leave I totally disconnected the batteries and let them rest for about 2 hours and the reading never went below 14.2v DC

Now we used these batteries all weekend for lights, fans and the water pump - the furnace wasn't needed yet. Now, I admit for the most part we used LED lights rather than incandescent, but what gives - why over 14v??

[tlhdoc]

What are the golf cart batteries supposed to charge to?  Could your multimeter be out of wasck? :confused:

[Tim5055]

What are the golf cart batteries supposed to charge to?  Could your multimeter be out of wasck? :confused:

Nope, I thought of that I tried two different meters. :confused:

[P-MAN]

Tim,

I have no experience with the 6v Golf Cart Batteries, but based on what I do know about batteries, the 14.4v they held in your case and the supposed strength of Golf Cart batteries, I think that that your truck did a great job of keeping them charged on the way to the cg, and that you just did not draw a lot from the batteries so as a result, they held their charge real well.

As you said, the 14.4v represents the approximate output of an alternator, especially a powerful alternator like your F-250 Diesel has.  I have the same truck and engine combo myself.

[mike4947]

Well since 2 six volt batteries in series output exactly the same voltage as one 12 volt battery and even that is nothing more than 6 individual cells in a single case. Where as the twin 6 volt batteries are just two cases with 3 cells in each.

Each cell produces apx 2.14 volts for a total of apx 12.6 to 12.8 volts.
 
Since you've check the batteries with two meters here's a site with a couple of other ways to test batteries. http://www.ibsa.com/www_2001/content/faqs/tech_talk/maintenance/faq_tech_maint.htm

[topcat7736]

I'm not an expert on batteries, but I believe you were measuring surface charge both times. After driving to the campsite, there was a high surface charge because of the charging. Once the batteries had been used, and left alone, the plate mass changed causing a surface charge to reappear.

You must either rid the batteries of their surface charge, before using your meter, or take readings when the batteries are under load. Meters have such a high internal resistance that their loading effect will not do the discharging very quickly. But, with the meter constantly connected to the battery, you should see the voltage slowly drop to a typically expected level (which would indicate that the false reading was the result of the surface charge).