Community Forums

shepd · 04-21-2015, 11:58 AM

I'm trying to wrap my head around adding some batteries and other modifications to my TT. Just got it brand new, but I can't wait to mod it. LOL. I'm trying to avoid adding LP to it (yep, it came from the factory without propane). I want to run a compact residential fridge and possibly a very compact (~1.3 cu ft) freezer overnight, along with the wife's CPAP mask. I plan to dry camp for a few days at a time and to use a 1000 watt inverter generator to charge the batteries each day. I'll have to test the unit in the camper, but based on testing what I have I figure on an average draw of 50 watts per fridge/freezer, or about 5 amps each @ 12 volts through the inverter.

The trailer came with a group 24 battery (mounted on the tongue, probably 55 Ah), and two golf cart batteries (about 220 Ah each). I plan to run a circuit off the inverter to the fridge, freezer, and add a convenience outlet by the dinette.

The tongue is already heavy, and I'm towing with a Class II hitch, so I *really* don't want to add more weight to it--especially not 130 lbs of batteries! I want to put the two golf cart batteries inside and move the one that's on the hitch now with them. I know that means a risk of hydrogen and so they have to be vented, so I'm going to build an airtight wooden box (lined with some decently thick plastic) with an intake vent to inside near the bottom, and an exhaust vent at the very top to outside (uphill run only). I know it's safest that they're outside, but being unable to do that, I want to keep it as safe as possible anyways.

I bought a new converter (progressive dynamics PD9245) because I was unhappy with the quality of the factory WFCO converter and plan to install that---I hear it should charge the batteries quickly?

Well, this brings me to my question: How should I hook up the batteries? The two GC batteries will be in series, of course. I was planning to use a 2+1 battery switch so I could select between the OEM battery and the ones I'm adding. Is the right way to use it to select one individual battery bank at a time for charging, wait for it to charge up, then switch to the other and charge it up separately? When I am not connected to the generator, can I set the switch to combine the batteries and use them overnight without damaging batteries, or should I use each one separately?

I know most people wouldn't go buy a brand new trailer and start hacking it up before even taking a trip in it, but I managed to get this thing for the deal of a lifetime so I don't feel bad... "improving" it.

brulaz · 04-22-2015, 08:13 AM

Quote:

Originally Posted by shepd

...
The trailer came with a group 24 battery (mounted on the tongue, probably 55 Ah), and two golf cart batteries (about 220 Ah each). I plan to run a circuit off the inverter to the fridge, freezer, and add a convenience outlet by the dinette.
...
I bought a new converter (progressive dynamics PD9245) because I was unhappy with the quality of the factory WFCO converter and plan to install that---I hear it should charge the batteries quickly?

Well, this brings me to my question: How should I hook up the batteries? The two GC batteries will be in series, of course. I was planning to use a 2+1 battery switch so I could select between the OEM battery and the ones I'm adding. Is the right way to use it to select one individual battery bank at a time for charging, wait for it to charge up, then switch to the other and charge it up separately? When I am not connected to the generator, can I set the switch to combine the batteries and use them overnight without damaging batteries, or should I use each one separately?
...

PD charger should definitely be better than WFCO.

But I think you might want to keep the 2 golf carts separate from the 24 all the time, definitely when charging but also when discharging. Not sure though, have heard conflicting reports.

That would mean you would only have 55 Ah sometimes, until you switched back to the GCs, which probably would not be too useful. Maybe if weight is a concern you could just toss the 24. No switching and easier wiring then.

shepd · 04-22-2015, 10:57 AM

Quote:

Originally Posted by brulaz

PD charger should definitely be better than WFCO.

But I think you might want to keep the 2 golf carts separate from the 24 all the time, definitely when charging but also when discharging. Not sure though, have heard conflicting reports.

That would mean you would only have 55 Ah sometimes, until you switched back to the GCs, which probably would not be too useful. Maybe if weight is a concern you could just toss the 24. No switching and easier wiring then.

I'm seriously considering not using the small battery at all. But I have this nagging feeling the first time I don't bring it will be the first time I wished I had it. LOL. It does give me an idea, though. Just leave it on the hitch for now, use the manual battery disconnects you can fit to the battery cables, and leave the small battery at home if I know I won't be dry camping that trip.

Decisions, decisions.

wa8yxm · 04-22-2015, 01:15 PM

Group 24 is 75 amp hour less it is an optima then your estimate is rather close..(Why I recommend AGAINST Optima) that is most likley your emergency brake battery.

House batteries are the pair of GC-2 and yes there is no reason you can not parallel them.

THey contain about 1KWH of usable energy at the 20 hour rate so you should be able to run a 100 Watt Fridge about 8=10 hours with both batteries (THink of the pair of Six Volt as a single 4D) with the proper (1KW-2KW inverter)

Xantrex suggests one pair GC-2 for each Kilowatt of inverter. That is a MINIMUM.. More is better.

Both Dometic and Norcold make compressor driven RV Fridges in the under 50 watt rang. You might consider these.. thats 3-4 amps at 12 volt and you do NOT need to use an inverter.. I have an Engel Chest freezer beside me.. Same technology I do not even have it pluggd into 120 Run it on 12 all the time.