12V battery question

[Danmccuan]

Newbie battery question here.

I have two group 29 batteries which do not fit end to end on the battery rack between the tongue. We are going dry camping for a week and I am wondering if I should build a battery box that sits atop the tongue and wire the batteries together or if I should just switch out the first battery when it gets low.

Is there a benefit to having the two batteries wired in parallel rather than switching them out mid week other than a little less work?

Thanks for the advice

Dan

[Bumpyroad]

westend wrote:

Two 6v's wired in parallel will make one large 6V battery.
Everybody with more than one 12V battery has them wired in parallel.

yep, that's how all of my MHs have been wired. two 12 volters in parallel.
bumpy

[westend]

wwest wrote:

Danmccuan wrote:
Newbie battery question here.

I have two group 29 batteries which do not fit end to end on the battery rack between the tongue. We are going dry camping for a week and I am wondering if I should build a battery box that sits atop the tongue and wire the batteries together or if I should just switch out the first battery when it gets low.

Is there a benefit to having the two batteries wired in parallel rather than switching them out mid week other than a little less work?

Thanks for the advice

Dan

It is NEVER a good idea to connect 2 lead/acid batteries in parallel.

1.) The weaker battery (there will ALWAYS be one) will (slowly?) draw down the other.

2.) A shorted cell (common failure mode) in one will QUICKLY draw down the other.

3.) in a few cases of the above (2) you will be risking an explosion due to rapid outgassing from the boiling electrolyte.

Much better to use two 6 volt batteries in parallel.

But since you already have two 12 volts batteries and place to mount both I would suggest keeping the spare on a SOLAR charger ready for a quick swap.

Need more coffee?
Two 6v's wired in parallel will make one large 6V battery.
Everybody with more than one 12V battery has them wired in parallel.

[wwest]

Danmccuan wrote:
Newbie battery question here.

I have two group 29 batteries which do not fit end to end on the battery rack between the tongue. We are going dry camping for a week and I am wondering if I should build a battery box that sits atop the tongue and wire the batteries together or if I should just switch out the first battery when it gets low.

Is there a benefit to having the two batteries wired in parallel rather than switching them out mid week other than a little less work?

Thanks for the advice

Dan

It is NEVER a good idea to connect 2 lead/acid batteries in parallel.

1.) The weaker battery (there will ALWAYS be one) will (slowly?) draw down the other.

2.) A shorted cell (common failure mode) in one will QUICKLY draw down the other.

3.) in a few cases of the above (2) you will be risking an explosion due to rapid outgassing from the boiling electrolyte.

Much better to use two 6 volt batteries in parallel.

But since you already have two 12 volts batteries and place to mount both I would suggest keeping the spare on a SOLAR charger ready for a quick swap.

[wa8yxm]

The first reply nailed it, By sharing the load they can provide power longer.

And a suggestion.. When they eventually go bad.. Try a pair of GC-2 Golf car batteries, these are six volt so you wire them in series, after that you treat them as though they were a single 12 volt battery. (Which they are).

[mbopp]

I had the same issue. But having a welder and some angle iron laying around I made a dual battery rack that goes across the top of the frame rails:

http://i1114.photobucket.com/albums/k530/starmaster1953/North%20Trail%2021FBS/100_1324_zps3f9dba20.j...

[da_bees]

If I drove the tv from time to time while camped I would leave one on trailer while other sat in bed of tv to be charged through 7 pin. If I were charging with genny,I would put battries in parallel.

[landyacht318]

Peukert effect.

2 batteries in parallel to spread the load means more total capacity.

The higher the loads, the greater this effect