Questions on Adding a Second Battery

[poodlepeople]

I just got my 2010 Sabre 31REDS and have already decided I want to add a second battery for more extended dry camping but I have questions.

1. How do I tell if the existing converter will handle two 12 v batteries hooked in parallel?

2. Should I have an arrangement to charge one battery separately with a generator while the other is supplying the "house" or can I just run the generator to supply "shore" power and let the converter charge them both?

3. Should I wire these so I can select A, B, Both, or Disconnect or just hook them all in permanently to be removed when I want to charge off-line (there is no disconnect in the stock trailer)?

4. Will I have any problems charging two batteries in parallel from my tow vehicle (2010 Ram 2550HD diesel) while underway?

5. Is there any site that discusses all of this or do I just have to keep asking until I get all the answers (and then post them for the next guy)?

Thanks.

[bsmall]

I changed my 12 volt batteries out of 4 6 volts batteries for extended dry camping. With my past trailers I have had better luck with the 6 volts lasting longer by both charging and time. My last 6 volts batteries on my last trailer lasted almost 6 years.

My dealer was the one who installed the four six volt batteries when I took delivery...

[milzat]

The 12 volt side of life explains quite a bit.

More info HERE.

[NWJeeper]

Originally Posted by poodlepeople

I just got my 2010 Sabre 31REDS and have already decided I want to add a second battery for more extended dry camping but I have questions.

1. How do I tell if the existing converter will handle two 12 v batteries hooked in parallel?

2. Should I have an arrangement to charge one battery separately with a generator while the other is supplying the "house" or can I just run the generator to supply "shore" power and let the converter charge them both?

3. Should I wire these so I can select A, B, Both, or Disconnect or just hook them all in permanently to be removed when I want to charge off-line (there is no disconnect in the stock trailer)?

4. Will I have any problems charging two batteries in parallel from my tow vehicle (2010 Ram 2550HD diesel) while underway?

5. Is there any site that discusses all of this or do I just have to keep asking until I get all the answers (and then post them for the next guy)?

Thanks.

Here are your answers,

1. The converter doesn't care how many batteries are connectd to it.
2. Only the converther charges the batteries, the generator supplies power in lieu of shore power to the converter
3. All house batteries should be connected together. Unlike boats, RVs do not use an A,B,Both selector setup.
4. No
5. Just as Milzat said. The 12volt side of life has a lot of good info.

[Big Vic]

Best way is to use two 6 volt batteries in series. If adding another 12 volt battery in parallel, try to use an identical battery, as one will "drain" into the other if different voltages.

[poodlepeople]

Thanks to all for these quick, useful replies. It sounds like I should use my available space for two 6 volt batteries. Since this is easy to do in this trailer, I can think about how to double that up later if I discover I really need it.

I was especially interested to see the information on "The 12 Volt Side of Life" on issues with converters vs. proper chargers. It sounds like having the ability to disconnect the batteries and use a charger when shore power (or generator) is available might not be a bad idea either.

[kvtaylor]

When we towed a Montana 5th wheel, I added a second battery along with a marine A B Both switch. I occasionally switched batteries so the onboard charger would keep both charged full for extended camping. It worked great.

[KyDan]

Originally Posted by poodlepeople

4. Will I have any problems charging two batteries in parallel from my tow vehicle (2010 Ram 2550HD diesel) while underway?

Most folks find that their trailer batteries receive little
charge from the tow vehicle while underway.
The reason seems to be that the truck alternator/voltage
regulator sees the engine battery as being charged and
drops the voltage pretty quickly after start up.
The trailer batteries are several feet "down stream" and
the wire between is not big enough to let the regulator
"see" the low charge state in the trailer batteries.
Some have added much larger gauge wire between the
engine and the trailer batteries to help over come this.
(The difference between a charged battery and one
that needs a charge is measured in tenths of a volt.
The wire needs to be really heavy or it will have a few
tenths of a volt drop along it's length.)
The wire that typically comes in a pre-wired truck/trailer
plug is not
large enough to prevent this tiny voltage loss.

The rest of us just use some other means to re-charge
the trailer such as generator, shore power and the trailer built in power center and or separate charger just for the trailer.

My 2¢

[poodlepeople]

I wondered about how much charge I got from the alternator while towing and now I know. I think I have a series of steps to follow to get to the ultimate solution but at least now I think I can miss most of the potholes. Thanks.

[NWJeeper]

Originally Posted by poodlepeople

Thanks to all for these quick, useful replies. It sounds like I should use my available space for two 6 volt batteries. Since this is easy to do in this trailer, I can think about how to double that up later if I discover I really need it.

6 volt batteries are the absolute best way to go if you do a lot of dry camping. Much more amp hours available. Our last motorhome had 4 6volt batteries. With our new one I cut out the battery box that held the 2 12v batteries and welded up a new one that holds 4, then put 2 more up behind the front grill for 6 total. We also added 260w of solar panels for charging.

Your power needs will dictate how many batteries you need and how to re-charge them.