dean_and_monica
Colorado
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Joined: 08/27/2007
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I want to add a second 12 volt battery to my 2008 roo 23ss. What's the best way to do this? I was thinking of adding the second battery in series and installing a master switch. By doing this will my TV be able to charge both of these batteries or do I need to do something different to keep these charged up.
Thanks
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bldrbuck
Boulder, Colorado
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Joined: 02/11/2001
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12 volt batteries must be in parallel. You can add a switch to use one or the other or both.
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Chuck_S
Broadview Hts, OH, USA
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A pair of 12v batteries needs to be in parallel as Jim notes, otherwise you get 24 volts rather than 12. 
Batteries do not like to be deeply discharged, not even deep cycle batteries. For this reason it's better to keep them paralleled and use them as one big battery. By the time you deplete them to the 50% point you'd have super deep discharged one if you're running them separately. Use -- and charge -- as one big battery.
Depending on your LP tanks are mounted there should be room for a pair of batteries on the Roo 23SS tongue. There are on mine.
These are actually a pair of Trojan T125 6v batteries connected in series to produce 12v, but they're the same footprint as the Group 24 you probably have there now.
There is a minor problem with 12v batteries in parallel: The lower voltage, weaker battery will constantly siphon power from the higher voltage, stronger battery. Recall that batteries charge by voltage differential. Current will flow anytime the voltages are different, even by a fraction of a volt.
Based on many years experience in sailboats needing lots of battery power without the engine running I chose a pair of 6v batteries to get the amp hours I needed. Single ON/OFF switch manages them as a single battery. To use a pair of 12v batteries as one big battery but prevent the parasitic effect you just need a different switch.
A pair of closely matched 12v batteries can be managed with an OFF-1-BOTH-2 marine battery switch. You can mount it externally like my swtich. You're going to want to put the switch in the BOTH position to charge and use as one big battery and OFF the other times to eliminate the parasitic effect. Since these are connected separately to the switch the batteries are kept separate when the trailer is not in use. The 1 and 2 positions can be used if needed but will be rare, the switch is really just there to isolate them from each other.
-- Chuck
'06 Roo 23SS behind '07 Expedition out of Cleveland
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nny12972
NY
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Joined: 10/25/2006
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Google "The 12 Volt Side of Life." All you need to know is there----explanation and diagrams.
J
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Leaf-Peeper
Small Town, USA
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What Chuck & nny12972 said. Here’s what our ’08 Roo looks like with a pair of 6v golf cart batteries.
A pair of 6v battery boxes and my old golf cart batteries from the popup. Blue Sea battery switch. Can't get the switch that Chuck's got no more, the one with the visual green/red inicator when you turn the knob.
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toolmantr
MA
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Leaf-Peeper wrote:What Chuck & nny12972 said. Here’s what our ’08 Roo looks like with a pair of 6v golf cart batteries.
A pair of 6v battery boxes and my old golf cart batteries from the popup. Blue Sea battery switch. Can't get the switch that Chuck's got no more, the one with the visual green/red inicator when you turn the knob.
I just bought this switch at BoatersWorld.com.
They have a few others there similar to Chuck's. It is a solid switch and I am ver happy with it so far.
Tom, Jenn, Mitchell and Steeie the cat
North Andover, MA
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smkettner
Southern California
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Up to four in parallel will charge fine. Although it will take longer to charge.
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risingsun
Prescott, AZ
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I have a pair of 12V batteries mounted in boxes like Chuck's. I only use a couple El Cheapo Wal-Mart EverStart deep cycle batteries. I put a Blue Sea Systems switch on that's wired into the positive lead. The switch is designed to be on battery 1 or battery 2. So, if I need to charge both, I flip the switch to the other during charging to direct the TV power to the other (like if I have a long day of travel, I run switched to battery 1 in the morning, and flip it to 2 in the afternoon). Works fine, and the pair of batteries keep us up and running with power for at least a week with no hookups. As we like National Parks and other out of the way campgrounds, this is important for us. Rarely do we stay somewhere with hookups.
Yes, we do conserve power to make this work, but nothing out of the ordinary. Probably, the main thing my wife and I do to save some battery power is read by our high quality LED headlamps in the evening after the kids are in bed. No need to light up the whole trailer when you only need a book or magazine lit, and the lighting is better for reading anyway. If we're playing a game or something at the table, then we burn the overhead lights.
2006 Rockwood Roo 23SS
2001 GMC Yukon SLT
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dean_and_monica
Colorado
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Thanks for all of the info.
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squirescampers
Derry, NH
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We are going to try dry camping next week for the first time in 5 yrs.
Couple questions:
I am thinking of adding either a 2nd battery, or replacing the 5yr old group 24 with a 27 or 29-- would I get substantialy more battery life- or should I get 2 less expensive 24 group batteries?
Do I need to add a switch? I am not of an electrical engineer mind.
How long would it take to recharge by using the TV in idle?
Thank for the help
Families who camp together, stay together...
Dad
Mom
11yr old son- knows everything now...
5 yr old son- still sweet...
4 yr old daugher- turning me grey already...
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