installing 2 batteries

[dog_soldier]

im thinking of installing a 2nd battery in our rig. its a 12v system. my question is do i hook up + to + and so on or + to - ?
we boon dock camp mostly and i would like the extra power.

[nailit]

If you already have a 12v marine battery, + to +, - to -. I have used #4 cables between batteries, which I purchased at the local auto parts store.

[dog_soldier]

yes i have 1 deep cycle battery.
thanks , that is what i was thinking but wanted to make sure.

[jimbo16720]

Should use the same type battery too they say...agm, wet cell, whatever you already have.

[Tha_Rooster]

Use they same type and your battery bank will only be as good as the weakest battery

[missle_man]

Originally Posted by dog_soldier

im thinking of installing a 2nd battery in our rig. its a 12v system. my question is do i hook up + to + and so on or + to - ?
we boon dock camp mostly and i would like the extra power.

I just added a second 12v battery and found this site very helpful. The advice on using the same type battery is good. Also you want to be sure both batteries are strong (see this site):

The 12volt Side of Life (Part 1)

[dog_soldier]

thanks for the link missle_man
i was planning on getting a new battery. i did some measuring and may have to rework the battery tray a bit but not much and i may luck out and it will fit just right. if all else fails i have a really big hammer

[CD]

Careful now! Batterys don't stand up well to a hammer.

[missle_man]

Originally Posted by dog_soldier

thanks for the link missle_man
i was planning on getting a new battery. i did some measuring and may have to rework the battery tray a bit but not much and i may luck out and it will fit just right. if all else fails i have a really big hammer

I have a class C Four Winds with pull out battery tray and 2 Group 27 batteries (a bit longer than the Group 24 you usually see in automotive applications) just fit. The battery tray (on mine) has two sets of slots in the sides which accept the hold-down straps but the MH only came with 1 battery and 1 strap. I had a dickens of a time finding another strap that would work with the slots. Finally found one at an RV dealer in Indiana.

[ksg5000]

If you do a lot of boon docking then I suggest you look at getting the most amp hrs that you can afford/fit into your rig. During my recent review of battery prices in the Portland Oregon area I noted that two type 29 twelve volt batteries from Walmart ($170 for 250 amp hrs) gave me the lowest cost per amp hr - followed closely by two six volt Costco golf cart batteries ( $158 for 230 amp hrs).

[wa8yxm]

Originally Posted by Tha_Rooster

Use they same type and your battery bank will only be as good as the weakest battery

Sorry for the militant tone of this but....

JUSTIFY THAT STATEMENT.

I keep hearing how batteries in parallel need to be identical, however so long as neither of them (none of them) are SHORTED, I do not believe your statement.

True, if the "Weakest battery" is shorted, then it's true, else, You are going to have to prove it.