Battery advice

[jpaton]

Looking for advice for battery selection for a Rockwood 2506S travel trailer.
The trailer came with an AGM 12-volt battery that has proven to be insufficient for even 2-nights (fully drained in 36 hours using only lights, refer, water pump, and propane furnace fan).

We will have 4,000 watts via generator, but want to be able to run most systems (no A/C) for 1-3 days without firing up the generator to charge the batteries.

My thoughts are to install (2) 6-volt Interstate/Trojan batteries.
Does anyone know if this will be adequate?
Open to any/all suggestions and/or your experience.
Info. on charging the batteries? Do I just install them and let the on-board converter do the charging, or is there something else I need to change?

Converter/charger is a WFCO 8955PEC.

Thank you everyone.

[HONDAMAN174]

Well, two thoughts:

Heater usage uses batteries quickly. So you need to ask yourself on how comfortable you are and at what temperature. I switched to 2 6 volts this year and wifey likes it warm when camping. So we take them down to about 65% each night. We are power hogs!!

I also switched to a Progressive Dynamics converter which charged those batteries more complete each time. Not a fan of the WFCO I had.

So if you have the room, get 4 6v’s and you will have a ton of usable power. Also recommend getting a light champion 2000 instead of the 4000 you were thinking of to recharge everything. Only because most 4K generators are open frame and causes havoc for you at campgrounds

[cmysstailights]

No, your fridge is gonna consume a lot of it without running generator. Minimum 4 6v 225ah batteries or 3 lithium 100ah. You need to do a 24hr consumption to see how big you battery bank needs to be. To go 3 days with no generator your battery bank would have to be huge.

[jpaton]

OK, great advice.

BTW: Have (2) 2,000 watt Yamaha's (that you can parallel for the 4,000 watts stated).

Our Refer runs on 110 or Propane. I understand it switches automatically to Propane once you disconnect from shore power. Does it consume any appreciable power (from the battery bank) if it is running on propane?

Keep em coming...

Thanks.

[NMWildcat]

Well, you need a way to recharge the batteries, no matter how many you have. So invest in solar or get used to the idea of running your generator more often.

We boondock for weeks at a time with two 12v marine 27series. We run our EU2000s generator(s) for a couple hours in the morning during breakfast, and then a few more hours at night with TV and dinner. Easy.

[cmysstailights]

Originally Posted by jpaton

OK, great advice.

BTW: Have (2) 2,000 watt Yamaha's (that you can parallel for the 4,000 watts stated).

Our Refer runs on 110 or Propane. I understand it switches automatically to Propane once you disconnect from shore power. Does it consume any appreciable power (from the battery bank) if it is running on propane?

Keep em coming...

Thanks.

I believe it draws a lite 12v when on propane.

[ependydad]

Originally Posted by jpaton

OK, great advice.

BTW: Have (2) 2,000 watt Yamaha's (that you can parallel for the 4,000 watts stated).

Our Refer runs on 110 or Propane. I understand it switches automatically to Propane once you disconnect from shore power. Does it consume any appreciable power (from the battery bank) if it is running on propane?

Keep em coming...

Thanks.

Yes, it uses 12v to power the brains/control board and also for a door heater.

Personally, I opted for 12v lithium drop-ins because I didn't want to worry about having enough power for a length of time. But, they're expensive.

More info here: Let’s Boondock! Battery upgrade (to lithium)! | Learn To RV

[Bama Rambler]

Ependydad eluded to the door heater in the fridge, and while the controls don't use much power, the door heater uses a pretty good bit. Search around the forum on how to disconnect that and it'll help some with the power drain.

Also, if the lights in the RV aren't already LED, it would help to switch them all out.

Then that leaves the furnace. As said above, it's a power hog. You can buy propane or kerosene indoor heaters that will help keep the RV warm without using 12 volt power. Just be careful with them and keep a vent or two open when using them.

[tomkatb]

You need to be able to answer your own question.

Your battery has so many amps to deliver. If you use more than 50% you damage the battery. As you went to zero several times already your capacity, available amps, O
has gone down. So get the number you had.

P=VxI. Watts = voltage (12.5)xAmps. Get a chart of amps per item. Available everywhere. A single small 12 volt battery is not enough likely for most trailers for a day. About 50 amps.

Get the chart. That will explain it all. Leave all lights on drains the battery in 24 hours. A microwave in 30 minutes. Not rocket science. Middle school science.

More is better. In our fifth wheel I Wanted 2-3 days and have 4 6 volts. 225 amps available. More stuff more battery. Everything counts. Like LP detectors. Smoke alarms. Gas water heater and fridge. Water pump and heater. Lights.

Likely you need to run your generator like NMWildcat. Twice a day.

I assume whomever sold you your rv did not explain this.

[johnbryanpeters]

jpaton, were you running the refrigerator on propane or electricity?

[jpaton]

Running refer on Propane.

[johnbryanpeters]

Originally Posted by jpaton

Running refer on Propane.

Apologies in advance, I'm going to ask a couple more questions. What's the capacity in Ampere hours of your AGM battery?

[jpaton]

It is an Optima: specs as follows:

Model: D34M
Weight: 43.5 lb
C20 Capacity: 55 Ah
Post Type: Dual SAE & 5/16 Stainless Stud
CCA: 750 Amp

[tomkatb]

Yep, not much of a battery for an rv. Good battery thou.

You need two 6 volts. I ordered 4.

Here, Costco was selling their GC battery for $85.

It was an interstate. Apparently the same as ones sold elsewhere.

They were sold 4-5 months here in Dayton. I paid my dealer a lot more to install them on my new fifth wheel.

[cmysstailights]

55ah is more lime 25ah. As recommended upgrade to 4 6v golf cart batteries around 225ah each wired for 12v and you should be gd.

[johnbryanpeters]

Originally Posted by jpaton

It is an Optima: specs as follows:

Model: D34M
Weight: 43.5 lb
C20 Capacity: 55 Ah
Post Type: Dual SAE & 5/16 Stainless Stud
CCA: 750 Amp

OK.

1) While a quality battery, it's not a true deep cycle battery, note CCA spec - it's a car battery.
2) 55 Ah is quite a low capacity, as noted by others.
3) I have been unable to find an RV converter which is properly set up to charge AGM batteries - the converters are all designed for wet cell lead acid.
4) Your major drain is the furnace.

So, you might shoot for a capacity of about 200 Ah.

Your proposal of a couple of 200 Ah 6 V golf cart batteries in series would work if you could find batteries with that capacity and they fit in the available space.

Or, two 100 Ah 12 V deep cycle (not marine, you need to find true deep cycle batteries; they will not have a CCA rating) wired in parallel will give you 200 Ah capacity.

Physical size and the battery space you have available may become an issue.

[jpaton]

OK, thanks everyone.
I think I have the battery specs we need.
What does anyone use for a battery management system (BMS)?

[johnbryanpeters]

Bogart Engineering TM-2030RV-F TriMetric battery monitor with 50 ft. 22 gauge 4 wire twisted pair cable kit, purchased from altE.

Sort of a pain in the ass to calibrate, but works very well.