I have a 29' 5Th Wheel with a single battery. I am guessing (and will have the battery tested to confirm) that it is probably no longer reliable. I went dry camping this past weekend, for only the second time with this camper in 4 years. We were extremely conservative with power usage and by the beginning of the second night, the battery was drained enough to not even have enough power to light the fridge. Thank god for generators. Can a second battery be added, and if so how is it wired to the trailer and tow vehicle (for charging)?

The original converter was a piece of crap, which I finally had replaced a couple of months ago. The new converter manages the charging of the trailer battery. My guess is the old converter probably over charged the battery numerous times and cooked it.

The current set up obviously charges the battery when the trailer is connected to the tow vehicle with the engine running. Again, how would a second battery be installed?

 

What's easiest is to replace the original battery with two identical batteries. Wire them together - to - and + to + (to keep the original 12v and just add longevity, the other way doubles voltage. I can't remember which is series and which is parallel... I think what you want to do is parallel.).

You don't want to keep your old battery in the mix without isolating the new battery, and that's way too much effort for what you need.

 

If you want reliable batteries that last longer and give you better power go to two of the golf cart 6 volt batteries. They are more expensive but come out cheaper on a year to year basis. I had my last set for 9 years and they still held a reasonable charge. Also remember to top the cells up with distilled water once or twice a year and if you are in a cold climate pull the batteries and store them using a trickle charge once a month or plug you unit in to AC once a month or every 2 weeks during cold weather.

 

wire them in parallel and in fact, most coaches will have the wiring there. however, from the charger 'in' there is typically a large diode on each charge line to prevent draining back in the event of some failure. (in addition to the reverse blockage from the rectifier)

purists might even put diodes on the battery output to prevent a strong battery from draining into a bad one.

use deep cycle batteries. unless you primitive camp it a lot, you wont drain them down nearly fully which deep cycle batteries like, so they start to sulfate. some of the smart chargers today have a DES phase to alleviate this.

 

With 2 batteries wired in parallel, is the battery charging as efficient as a single battery whether being charged from shore power or the vehicle (i.e.: will it take as long/longer)? I assume that with 2 batteries I will have more capacity for longer stays without the need to "plug-in"? Will the trucks alternator be "overworked" while trying to charge 3 batteries - truck and trailer (it already has a heavy duty alternator as part of the towing package)?

 

It should draw the same amount of power, just for a lot longer. The alternator shouldn't work any harder than trying to charge an empty battery. You probably won't see a DOUBLE capacity as far as minutes of light, but you will definately see a huge advantage to having two or more batts.

 

I run dual 6 volt batteries on my 32' TT. They are far better than dual 12 volts. I had dual 12 volts on the trailer before this one & when I bought this one the dealer recommended I go this route & I'm really glad I did. I have Trojan Batteries. Not that expensive.

 

Check out this article about replacing an RV 12-volt battery with 6-volt batteries:

Mod #1: 6-Volt Batteries | ModMyRV

 

I use the two 6 volt golf cart battery set up wired to produce 12 volts. I am big into boondock camping, and I can go for 6 days with my batteries before I use my generator. I use power very conservativley. Now when it starts getting cold, the batteries only last about 3 to 4 days because the fan for the furnace runs. I have had this set up for three years, and the batteries seem to be real strong. I do have to add distilled water about twice a year.

 

Another vote for two 6 volt batteries in series.
The six volt batteries are a LOT heavier = more lead plating = last a lot longer.

 

another vote for 6V batteries in series.

 

Another vote for the 6 volt batteries. What ever you do, be sure to get 2 batteries that are the SAME. And when useing 2 batteries if one goes bad you really should replace both. Happy trailes.

 

That site ROCKS - thanks for the link...

 

No problem man. That's my site so thanks for the props. Just trying to share the mod love...

 

My vote also for 2, 6 volt deep cycle batteries. You'll be much happier with the result.