Dual Batteries

[Marauderer]

If adding a 2nd battery does it need to be identical to the 1st battery?

[wowchad]

It shouldn't matter what batteries you use if you just run an isolator between them.

[Lowsuv]

I had one of my conventional group 24 batteries that kept corroding badly and quickly .
I replaced it with an agm .
I am a detail guy .
I wash my trailer after every outing .
It drove me nuts having to clean that battery so frequently .
So I went AGM .
A year later I got another to match .

[retiredcamper20]

Lowsuv - Just curious - for my own learning curve. If you say that 2 6v batteries in series is the best solution, why did you go with exide edge agm 12 volt?

[retiredcamper20]

Lowsuv wrote:
NO
they do not have to be identical .
IT IS BEST to be identical .
Before you flame me I was an industrial electrician before becoming a lumber company owner .
it is agreed on this forum that 2 6 volt batteries in series is the best solution .
I make the argument that AGM batteries , typically 12 volt in parallel are the next best solution .
I further make the argument that an exide edge agm battery is compatible in charge rate as a conventional battery .
I ran a conventional battery in parallel with my new upgrade edge AGM battery until I got an identical AGM battery to be its mate .
I had no issues .
I paid $ 140 each for my exide edge agm batteries at BiMart .
They charge faster , do not corrode , have a 4 year guaranty , typically last 7 to 11 years , and are made in the USA .
Over time I converted to edge AGM in my TT , Boat , duramax , Porsche , and Mercedes ( agm standard , I just replaced with edge AGM group 49 ).

[Jayco23FB]

I use a group 24 and a group 72 battery connected in parralel because thats whats fits on the tongue of my TT. Both are deep cycles. If I could I would have 2 group 72s.
Never had an issue.

[thomasmnile]

pianotuna wrote:
Hi,

Best practise is that they be identical. Wiring matters.


This is what is balanced and best for twin twelve volt batteries.

What Pianotuna says!

[pianotuna]

Hi,

Best practise is that they be identical. Wiring matters.


This is what is balanced and best for twin twelve volt batteries.

[westend]

The batteries should be of the same make, type, and size. Since the OP's battery is new, that covers the same age rule.

[Lowsuv]

We camp without hookups , mostly .
If I only had one battery , I would consider buying the second battery and case in the largest amp-hour capacity that would fit .
If I had one group 24 and only had space for an additional battery in group 27 size I would go that route .
As my Dad said "There is no substitute for cubic inches " .
That applies to batteries just like a 454 vs a 396 .

[Lowsuv]

NO
they do not have to be identical .
IT IS BEST to be identical .
Before you flame me I was an industrial electrician before becoming a lumber company owner .
it is agreed on this forum that 2 6 volt batteries in series is the best solution .
I make the argument that AGM batteries , typically 12 volt in parallel are the next best solution .
I further make the argument that an exide edge agm battery is compatible in charge rate as a conventional battery .
I ran a conventional battery in parallel with my new upgrade edge AGM battery until I got an identical AGM battery to be its mate .
I had no issues .
I paid $ 140 each for my exide edge agm batteries at BiMart .
They charge faster , do not corrode , have a 4 year guaranty , typically last 7 to 11 years , and are made in the USA .
Over time I converted to edge AGM in my TT , Boat , duramax , Porsche , and Mercedes ( agm standard , I just replaced with edge AGM group 49 ).

[Marauderer]

I have one new battery that came with the TT when I bought it a month ago. It is an excide???? and I will have to open the batt box and see which one it is. I was thinking of two of the large marine deep cycle batts. Comments and suggestions are always welcome.

[prichardson]

When wired together they should be the same capacity and age as they essentially become multiple cells of one battery. As such if one is weaker than the other; the weaker will draw down the stronger.

[Lynnmor]

If your batteries are considerably different, you might want to use just one at a time. Same amount of capacity, just not as convenient.

[RoyB]

The ideal situation would be both batteries would be the same make and same age.

Then they should charge and discharge at the same rate.

just my thoughts here...

Roy Ken