running two batteries parallel?

[captbanjo]

Hi. For those who have done it (or know about it) can you tell me how to set up to run two batteries in parallel? I have a deep cycle. Would one more deep cycle do the trick? Also, what exactly happens when it's 'parallel'? Does that mean it runs simultaneously with the first battery? So many questions...so little time...

[Flastro]

Actually I think you want to run them is series....parallel on a 12 volt system will give you 24 volts with two batteries, this might be a little tough on our 12 volt rv systems

Add your second battery, then run a battery cable jumper from the positive terminal to the positive terminal of your additional battery and then another jumper from negative to negative. Make sure you use the same gauge battery cable and ensure a good connection, they will charge and discharge at the same rates providing both batteries are of equal capacity. Hope this helps

[Montana_657]

Wrong guys...parallel is positive to positive,thats the right way. Positive to negative is series that's the wrong way.

Look at my post under technical, I answerd Captbanjo there, and I went into some of the perils of adding batteries.

[mobrownies]

Couldn't find the post Guffy referred to, but agree with his wiring. It is my understanding that you don't gain much by putting 2 12v in parallel. They don't charge and discharge the same so they are always fighting each other, even if you could find a matched pair. You can run them one at a time and switch when one gets low or run 2 6v in series.

[palebluedot]

When you connect two 12v batteries in parallel (pos. to pos. & neg. to neg.) the voltage is still 12v, but the amp hours (run time) is doubled. Another way of putting it is, if you could run 50 light bulbs for an hour with one battery, you could run the same 50 bulbs for two hours - or run 100 bulbs for one hour with two batteries in parallel. Another example would be replacing a one gallon jug of water with a two gallon jug - same water but double the amount. Some folks who need extend run times will connect two golf cart (6v Trojans) in series (pos. to neg.) to give 12v, but the amp hour rating on these batteries is very high. (WARNING: Do not connect two 12v batteries in series as this will produce 24 volts and do mucho damage to your converter unit). JMHO

[Searchers]

Wayne,
Try the following link for useful information. Let us know what you dedcide to do.
http://www.uuhome.de/william.darden/

[Montana_657]

Go to "dry camping battery" questions in this forum... read about matching your batteries...

[Flastro]

sorry about the terminology mix up goys..got in too big of a hurry fact remains , .i think my hook up is correct, just called it wrong. as stated....positive to positive and neg to neg on on a 12 volt system maintains the 12 volts, when you hook positive to neg you start increasing voltage. as for adding additional batteries, you will increase useful time, thats called reserve capacity ,and they will charge and discharge close to the same rates...your standard group 31 series deep cycle battery has approx 160 to 190 reserve capacity minutes at 25 amp output at 80 deg F , Even though its not a deep cycle battery, when mine goes i will not be adding additional batteries, in the past i have been more successful using a single 8D battery at 465 reserve capacity minutes. dont let it go stone dead too many times and it will last several years. A single 8D takes up no more room than two or three group 31 batteries and you will have less battery connections to corrode. JMO

[jerryb]

I wonder how many amps my bat charger uses, I could plug it in to my inverter and have perpetual electricity.

[Merv]

Hello Captbanjo,
I run three deep cycle batteries in parallel.
I have 3 of the largest deep cycle batteries wal-mart stocks. I have them hooked together with 3 foot battery cables that they sell there also. One end of the cable has the post clamp and the other end of the cable has an eyelet. I hook them up positive to positive. And negative to negative.
The batteries will last all weekend with plenty to spare.
To give you an idea of the usage we get, we usually run the TV,s about 6 hours, a few lights about 4 hours, we both take showers each morning, the furnace runs some at night (lately), and my bag phone(cellular)runs off the battery all weekend. Not to mention the usual slides and jacks and dish water. Also the kitchen fan and bath fan run occasionaly.
This is a very good setup for us. I have never had any problems with batterys fighting each other or any of the other things that have been mentioned here. They charge just like normal. We plug the camper in on Sunday night when we get home and Friday we take off again. I have not run out of battery power yet.
Hope this helps out.
Merv