RV batteries...how many?

[rcyoung3]

The wife and I are getting a Damon Intruder 2001 RV in a week (36 ft). It has a 7000W gas generator.

Here's the catch...and the reason for my post....the wife has been in an electric wheelchair (which uses qty 2 12v 35A batteries ( maybe 120V 2A for 6 hr/day to recharge) for many many years. She also uses an oxygen concentrator (uses 125V 4A basically 24x7).

I am trying to determine how many "house" batteries i will need in the RV to cover our needs. The RV comes with 2 "golf cart" batteries (6V 200AHr), of unknown "quality". However, her medical equipment demands a considerable amount of power on a daily basis as noted above.

Now we plan to spend 99,9% of the time in parks with electric power initially, but I learned many decades ago to always have backups and even backups to my backups.

If one were using the "standard" amount of electrical ( what the average RVer would use) routinely, plus the extra outlined above, does anyone have a "guesstimate" as to how many batteries i should have in the RV ( assuming they are about 200 AHr 6V) for at least one day, if not 2-3 days (just to soothe my paranoia)?

[wallynm]

Got a chuckle out of your breaking the regulator off the gas bottle story. So how safe is it to drive. In others words what is more risky driving or exploding oxygen bottles.

[time2roll]

I would probably go with four GC2 batteries. If you really get stuck the generator can run 24/7/365 until you find power or install more battery. If you do start camping off-grid for extended periods I recommend 600+ watts solar. Consider an automatic start for the generator if the battery gets low on charge.

[tropical36]

rcyoung3 wrote:
The wife and I are getting a Damon Intruder 2001 RV in a week (36 ft). It has a 7000W gas generator.

Here's the catch...and the reason for my post....the wife has been in an electric wheelchair (which uses qty 2 12v 35A batteries ( maybe 120V 2A for 6 hr/day to recharge) for many many years. She also uses an oxygen concentrator (uses 125V 4A basically 24x7).

I am trying to determine how many "house" batteries i will need in the RV to cover our needs. The RV comes with 2 "golf cart" batteries (6V 200AHr), of unknown "quality". However, her medical equipment demands a considerable amount of power on a daily basis as noted above.

Now we plan to spend 99,9% of the time in parks with electric power initially, but I learned many decades ago to always have backups and even backups to my backups.

If one were using the "standard" amount of electrical ( what the average RVer would use) routinely, plus the extra outlined above, does anyone have a "guesstimate" as to how many batteries i should have in the RV ( assuming they are about 200 AHr 6V) for at least one day, if not 2-3 days (just to soothe my paranoia)?

Basic rule of thumb, is two batteries for a 1KW inverter and four batteries for a 2KW inverter. Naturally four batteries will provide longer and direct 12vdc power, as well, so I'd go with four min.
Finding a place to put the extras, is usually the problem, with any setup.

[theoldwizard1]

Generator is a good backup to shore power. If you want a "backup to your backup" I would get FOUR 6V golf cart batteries, all new.

I would also suggest upgrading your inverter to a more modern inverter/charge/automatic transfer switch. With this setup you do not need a 12VDC converter, just a 12VDC distribution panel. Some even have an optional output to start a generator. There are several companies that make such a device, but I like Samlex because of their simple installation.

Also, with a good house battery bank, you really need a DC-DC battery charger, for charging while you are driving. READ THIS !

[Ductape]

First,look for a more energy-efficient oxygen concentrator, one that is portable battery powered will use much less power.
In general, with your loads I guesstimate 2 batteries per day, so 4 or 6 if you want 2 or 3 days. That's if you get a more efficient oxygen concentrator. With the power hog you have now, it's going to be ugly without shore power or generator.

I have family on oxy too, and I agree with your thinking. Do not depend on any single point of failure. Have two oxygen sources and two power sources.

[wa8yxm]

Well you use the generator to recharge the chair so we won't include that
Yoru two Interstate U-2200's or equal are what you need for the RV overnight.

That leaves the Concentrator.. NOTE> have a bottle on hand just in cuss.

4 amp at 125 volt is 40 at 12.5 so we will go with 40*25, why 25, simplifies the math. 1000 amp hours per day. or about half that overnight (Generator hours to generator hours) since you can only use half your battery capacity (Assumes DEEP CYCLE) we are back to 1000 amp hours

4 pair of GC-2 would likely do the job. with a bit of assist from teh existing pair.. THe downside. that's gonna make a BIG dent in the cargo carrying capacity for that RV. You might do better to use bottled O2 when traveling. Use the concentrator only when generating

[rcyoung3]

Wife is reluctant to use "bottles".....first wife uses an electric wheelchair, and her mother used oxygen too "back in the day". The wife always got tangled in the canula back when she walked, and the wheelchair has a way of tangling up with cords, canulas, etc etc.

Also, when we were in college, there was an "interesting" problem with oxygen tanks (at least the ones that are 5 ft toll + or -). Someone knocked a tank over down at the university hospital. It lacked a protective cap, so the on/off valve broke off. The tank took off, went through the hospitals basement wall, and buried itself 12 feet underground!

Both those memories are just a little too vivid 😉

[wallynm]

You can carry oxygen bottles. Some are large enough to supply 2L/min over night. What rate of oxygen flow is necessary. I always had bottle in reserve.

[rcyoung3]

I plan on going with a generator if hookup power is unavailable, but as said, I have learned to be "paranoid" over the years. I have backups to backups of my backups, so I plan on getting batteries and a larger inverter if needed as a "last resort".

The RV is used, and being prepped now. i should get it next week. The original owner added a lot of "extras" or "optional" items, so I'll have to check the inverter size when we receive it.

There is plenty of storage underneath, but reinforcing it for extra batteries is a good idea. Better safe than sorry.

If the continuous oxygen concentrator is "too much" for full time, we could get some extra batteries for her portable oxygen concentrator. They run about $400 each, and last for 8 hrs (+ or -). It takes 120V 2A to charge one of those, but you could have enough of them to run the portable during the day, then recharge at a camp overnight. The continuous stationary might then run for only 8 hrs when she is asleep in bed.

I have even thought about getting one of those small portable generators used in camping as a generator "backup" just for the oxygen.

Keep posting any thoughts or suggestions.

[Dutch_12078]

If one meets her O2 needs, a portable concentrator would reduce the power requirements, especially while underway.

[kerrlakeRoo]

Adding to what has been said, you could along with a 600 amp bank add 600-800 watts of solar. You wouldn't reach self sufficiency, but you could cut your Genny time about in half. And as you put it earlier, you would have another back up to your back up.

[wallynm]

based on my limited experience I suggest you run the generator when your are running the concentrator ans/or charging any batteries. I use a portable concentrator when driving and run the inverter to power it and the refrigerator. I have run the generator all night to power the more robust house size concentrator.

[MrWizard]

reinforce one storage bay, preferably mid-ship. use all-thread rod, or welded angle iron from the chassis/frame to below the bay floor, put angle iron and marine plywood under the bay floor supported by the new supports

stuff that with batteries i would go at least 6 (aka 3 pairs) or maybe 8
this would give 600-800 or more AmpHrs

we had 665 AmpHrs of AGM battery in our previous coach and powered a residential fridge, but it only drew 100w and a 40% duty cycle

the O2 concentrator is the biggest concern and the biggest power user

4*120v 480w, that a 40amp load using 12v battery bank to power an inverter

that only 20 hrs continuous load until dead, or 10 hours (aka overnight) until an 800Amphr bank is at 50%

you could double that to 1600 ampHrs (16*6v) and have 24hrs safety margin
but i think, you are going to need to depend on the generator if you loose power for more than 4-6 hours

traveling and short stops from inverter or genny as needed

parked/camped shore power with automatic inverter switch over when shore power drops out, then switch to genny as soon as possible, don't wait until batteries are low

i don't think you can carry enough battery for 2-3 days of powering her O2 concentrator

[Tom_Barb]

The question is how much room for batteries do you have?