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[GMCnet] House batteries [message #274649] Tue, 31 March 2015 10:24
glwgmc is currently offline  glwgmc   United States
Messages: 1014
Registered: June 2004
Karma:
Senior Member
Hi Bob,

I agree with your decision. I did the four 6vdc golf cat house battery set up in the Royale (460 amp hour) several years ago, and a single 4D 12vdc AGM house battery (200 ah) plus red top Optiima starting battery in the Clasco when we picked it up in Florida a couple of years ago. Both set ups work well but I am now sold on the AGMs. They can be installed anywhere in any orientation and require no maintenance. In our coaches I find the AGMs tolerate high discharge rates (ie: heavy inverter loads) better than the golf cart batteries. According to the manufacturers representatives, AGMs also tolerate overall lower discharge rates and higher recharge rates without shortening life better than the wet chemistry batteries. Two different AGM battery manufacturer factory reps independently said we could safely take the AGMs to 80% discharge in our application without shortening their useful life. If that proves to be true, then they are no more expensive than the 6vdc golf car
t wet chemistry units which will only tolerate 50% discharge before recharge. Taking those any lower than that will quickly shorten overall life.

There is a significant build up of white powder residue around the golf cart batteries and on the terminal posts all the time that I have to clean a couple of times a year while checking water levels. There is a discharge of hydrogen gas during recharge on the wet chemistry batteries that can be corrosive and/or potentially explosive if any other electronics are near by. With the AGMs I can mount other things near by without the corrosion issue. AGMs will pop their sealed vents if they are charged at too high a rate (above around 15.5 volts) so a combiner/battery charger with a multi-step charge profile appropriate for AGMs is certainly recommended.

The golf cart batteries in the Royale are now several years old and I sense they do not have the working capacity they did when new. I had them checked by the battery manufacturer at the FMCA national rally in Redmond, OR, last year. They measured about 80% of working capacity left. When those go south I plan to replace them with 12vdc AGMs mounted closer to the coach centerline for much better weight distribution. Since I don't need to get to them for periodic maintenance, and since they do not outgas, there are a lot more mounting options. The four 6vdc golf cart batteries are now located in the PS rear compartment where the propane tank is on a GMC finished coach. On the Royale, the propane tank is under the rear seat in the dinette just forward of the entry door. I had to move a bunch of other stuff in the Royale to equalize the weight with this set up.

Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR

glwork@mac.com
http://jerrywork.com
==============
Message: 11
Date: Mon, 30 Mar 2015 22:39:48 -0600
From: Bob de Kruyff
To: gmclist@temp.gmcnet.org
Subject: [GMCnet] House batteries
Message-ID:
Content-Type: text/plain; charset="utf-8"

I've decided to go against the general house battery suggestions. I replaced all four of my 6V golf batteries with 4 Optima Yellow tops. When I first
got my coach it had a giant 12V truck battery that was almost impossible to run down. When it finally died after about 5 years, I went with the
popular GMC Net advice and went with 6V golf cart batteries in series. Even with total disconnects, they would lose voltage while sitting while my
chassis cranking battery never lost any detectable charge while sitting. After lots of googling I realized I was not alone and the purist viewpoint
was very questionable. After a one week trip, I have to say that I see a dramatic improvement with the Optimas during prolonged discharge usage with
my 2 electric refrigerators. Time will tell of course but the warranty is 3 full replacement vs 3 months on the golf cart units. BTW I took very good
care of the 6V batteries and they still have seviceabale life after 6 years. They were just never very good to begin with.

http://www.gmcmhphotos.com/photos/march-2015-upgades/p57668-img-23603.html


--
Bob de Kruyff
78 Eleganza
Chandler, AZ
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Jerry & Sharon Work
78 Royale
Kerby, OR
 
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