I have just purchased a second battery for my travel trailer. I am getting comflicting reports on how to hook them both together. It is a 12 volt system.
Posted 2005-07-08 5:28 PM (#27805 - in reply to #27796) Subject: RE: Batteries
Expert
Posts: 2689
You DEFINITELY want to hook pos to pos and neg to neg.
As this is a SECOND battery and though you didn't ask;
a) It should be same/similar type and capacity to your FIRST battery.
b) It should be similar age. This implies that a good time to add a second battery is when you are replacing the old first battery anyway.
c) If you can't bring yourself to chucking out the existing first battery, or find another use for it, you should probably use isolation switches in such a way that the two batteries are only ever connected to each other when both are being charged. Some folk recommend this regardless of battery relative age.
BTW, deep cycle batteries require about 14.7 aiming volts to charge properly vs about 14.3 for regular auto/truck batteries.
Posted 2005-07-09 9:13 PM (#27852 - in reply to #27843) Subject: RE: Batteries
Expert
Posts: 2689
Originally written by geebsmith on 2005-07-09 2:36 PM
thnak you very much for your help. both batteries were purchased at the same time. There sure are alot of conflicting veiews from so called experts.
The only "conflicts" I have come across (so far) have been due to folk taking small pieces of information out of context and misapplying them.
If you read enough on the subject I think you will find the info from the "experts" to be quite consistent. Ignore the self proclaimed experts, read the tech articles on the battery manufacturers' web sites.
Posted 2005-07-10 7:11 AM (#27859 - in reply to #27852) Subject: RE: Batteries
Veteran
Posts: 216 Location: Chillicothe, Ohio
I would like to throw my 2 cents in here. After researching some on the internet RV sites, I decided to purchase two 6 volt golf cart batteries for my trailer. These type batteries are true deep discharge batteries and with 2 of them you have more amp hours of capacity than most "marine" deep cyle batteries. For some information check out phrannie.org this site has a lot of information re RV solar and battery setups. The two 6 volt batteries of course must be wired in series ei neg to pos and pos to neg so the combined voltage is 12 volts.
Posted 2005-07-10 10:18 AM (#27863 - in reply to #27859) Subject: RE: Batteries
Expert
Posts: 2953 Location: North Carolina
Originally written by martyg on 2005-07-10 6:11 AM
...I decided to purchase two 6 volt golf cart batteries for my trailer. These type batteries are true deep discharge batteries and with 2 of them you have more amp hours of capacity than most "marine" deep cyle batteries. For some information check out phrannie.org this site has a lot of information re RV solar and battery setups. The two 6 volt batteries of course must be wired in series ei neg to pos and pos to neg so the combined voltage is 12 volts. Marty.
Good solution ... I will add Martyg's set-up avoids the whole issue of self-discharge and matching of parallel 12 volt batteries.
Posted 2005-07-10 10:22 AM (#27864 - in reply to #27859) Subject: RE: Batteries
Veteran
Posts: 140 Location: Colorado
Some years ago when I lived in a solar schoolbus (think very poor college student), the premium golf course in our area would throw out their cart batteries once a year. I forgot about checking with them for batteries. The batteries they tossed out were perfectly usable and lasted several years.
Thanks for reminding me, I still love a good bargain and will check into that possibility.
Posted 2005-07-10 7:09 PM (#27873 - in reply to #27859) Subject: RE: Batteries
Expert
Posts: 2689
Originally written by martyg on 2005-07-10 7:11 AM
I would like to throw my 2 cents in here. After researching some on the internet RV sites, I decided to purchase two 6 volt golf cart batteries for my trailer. These type batteries are true deep discharge batteries and with 2 of them you have more amp hours of capacity than most "marine" deep cyle batteries. For some information check out phrannie.org this site has a lot of information re RV solar and battery setups. The two 6 volt batteries of course must be wired in series ei neg to pos and pos to neg so the combined voltage is 12 volts.
Marty.
I'm close to buying a pair of U2200s for similar reasons, plus I want to put them parallel once in a while. For ONLY 12 Volt apps the Walmart Maxx Marine 29 is probably the best deal amp-hour dollar wise, 125 AH for about $65. They're 13 inches by 7, so you need some space. A pair of U2200s are 10 1/4 by 7 - EACH, but you get about 225 amp-hours. Two of 'em will cost about what two Maxx MArine 29s cost, similar cost per amp-hour.
Do you NEED 225 AH ? (rhetorical)
Batteries
