Two battery set-up

Just put a 2 battery setup in my Outback 25RSS yesterday, planning a boondocking trip later today to RMNP to Glacier Basin CG. Interested to see how they perform.

Everlast Maxx 29DC, hooked up in parallel. 1 of them replaced a 24 on a straight across swap (defective battery under warranty) and I bought the 2nd one. Did a lot of reading here about batteries and figured for my purposes, this would work fine for us. They were slightly larger than the battery trays, but I've got them bungee'd down real tight, so they are not moving.

I have a new Palomino bunkhouse and switched to 2 each 6V 235amp/hour batteries in series. They use group 27 cases and I purchased some longer cables so the tops seal. I get about 3-4 days of use out of them and keep a small generator at the site to charge them when dry camping at the race track. Gets me everything but my 120V switches, A/C and microwave.

If you are charging from a generator you also need to review the charging system.
Or go with some solar if you are parked in the sun.

Otherwise I would drop another battery on the tongue and go.

My trailer came with only 1 battery but the tray was big enough for 2.... kind of. I had to cut the handle off one side of the battery box so they would fit on the tray together.

As you shop for batteries be sure you know the terminology and get the right one(s). I learned the hard way that all batteries aren't created equal. You ultimately was a true deep cycle. There are hybrids that are cheaper but aren't nearly as good. The junk that came with my 2013 TT failed after about 1.5 years. I replaced with the two Heavy duty full deep cycle and it's awesome. I think they were around $100 each at Walmart.

Thanks for all the great info!!!

kgarrett9999 wrote:

valhalla360 wrote:

kgarrett9999 wrote:
I bought a switch that allows me to choose either battery or both or neither. Since my batteries are of two different sizes, I don't intend to ever use them at the same time, but the switch allows it if/when I replace them. My idea is to use my primary (larger), but always keep the 2nd battery as a spare in order to be able to run the slides, tongue jack and emergency brakes should I run the primary down too far.

This is an OK system but you need more than a single switch or you need to always be keeping an eye on the switch.

If you want to do it manually, you have to remember to move the switch to "both" once hooked up and then back to one battery once parked. If you forget you get one of two conditions:
- It's always on both and you always use both battery banks, so you've only added complication for no benefit.
- It's always on 1 bank and the other is dead when find out you need it because you haven't been charging it.

There are options using battery combiners that bypass the switch when a charge current is available but you just added cost and complication.

With a trailer, a second bank is usually not needed anyway. You always have the truck battery available in a pinch. Simply plug in the truck while it's running and it should give you enough juice to get the slide in (if the plug doesn't move enough juice, a set of jumper cables certainly will).

I don't bring the second battery at all unless I intend to be dry camping and when I do it has a full charge from the charger in the garage. As I stated I never intend to use both at the same time either.

Bottomline is this setup works for my needs.

That's key point you left out. Most people don't keep spare deep cycle batteries lying around and they usually don't prefer to install them and leave them in place because they are heavy.

If it works for you have at it.

valhalla360 wrote:

kgarrett9999 wrote:
I bought a switch that allows me to choose either battery or both or neither. Since my batteries are of two different sizes, I don't intend to ever use them at the same time, but the switch allows it if/when I replace them. My idea is to use my primary (larger), but always keep the 2nd battery as a spare in order to be able to run the slides, tongue jack and emergency brakes should I run the primary down too far.

This is an OK system but you need more than a single switch or you need to always be keeping an eye on the switch.

If you want to do it manually, you have to remember to move the switch to "both" once hooked up and then back to one battery once parked. If you forget you get one of two conditions:
- It's always on both and you always use both battery banks, so you've only added complication for no benefit.
- It's always on 1 bank and the other is dead when find out you need it because you haven't been charging it.

There are options using battery combiners that bypass the switch when a charge current is available but you just added cost and complication.

With a trailer, a second bank is usually not needed anyway. You always have the truck battery available in a pinch. Simply plug in the truck while it's running and it should give you enough juice to get the slide in (if the plug doesn't move enough juice, a set of jumper cables certainly will).

I don't bring the second battery at all unless I intend to be dry camping and when I do it has a full charge from the charger in the garage. As I stated I never intend to use both at the same time either.

Bottomline is this setup works for my needs.

kgarrett9999 wrote:
I bought a switch that allows me to choose either battery or both or neither. Since my batteries are of two different sizes, I don't intend to ever use them at the same time, but the switch allows it if/when I replace them. My idea is to use my primary (larger), but always keep the 2nd battery as a spare in order to be able to run the slides, tongue jack and emergency brakes should I run the primary down too far.

This is an OK system but you need more than a single switch or you need to always be keeping an eye on the switch.

If you want to do it manually, you have to remember to move the switch to "both" once hooked up and then back to one battery once parked. If you forget you get one of two conditions:
- It's always on both and you always use both battery banks, so you've only added complication for no benefit.
- It's always on 1 bank and the other is dead when find out you need it because you haven't been charging it.

There are options using battery combiners that bypass the switch when a charge current is available but you just added cost and complication.

With a trailer, a second bank is usually not needed anyway. You always have the truck battery available in a pinch. Simply plug in the truck while it's running and it should give you enough juice to get the slide in (if the plug doesn't move enough juice, a set of jumper cables certainly will).

My old camper had 2 - Group 27 RV deep cycle batteries and it was always a struggle to keep them topped up with the portable solar panel that I have.

First thing I did when I bought my new camper was ditch the single 12V and put in two 6V with the solar panel to keep them topped up.

We've never run out of 12V power when we dry camp since we switched to the 6Vs.

Valhalla's right. Sams or Costco is the best battery route. Batteries work MUCH better wired in series than in parallel. The problem with wiring them in parallel (especially reusing an older battery) is the weaker battery will 'pull' the voltage of the stronger one down. This will cause the charging system to try to charge the weaker battery while the stronger one tends to be overcharged. I.e., if you have a battery that puts out 13 volts when fully charged and an older one that puts out 11.5 volts, there will be continuous current movement from the higher to the lower voltage battery. Batteries wired in series do not have this self-discharge problem.