Good Sam Club Open Roads Forum: Downsizing to smaller rig, battery capacity
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 > Downsizing to smaller rig, battery capacity

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~DJ~

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Posted: 04/22/19 07:18am Link  |  Quote  |  Print  |  Notify Moderator

The one I'm looking at holds two standard size 12 volt batteries. I have to run a CPAP @ 3.75 amps and an oxygen concentrator @ 7.9 amps for about 8 hours. I don't know if two standard size batteries could handle this and hoping someone could help me out. Thanks so much, DJ


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SoundGuy

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Posted: 04/22/19 07:26am Link  |  Quote  |  Print  |  Notify Moderator

Have no idea what you mean by "standard size batteries". Deep cycle 12 volt batteries are Group 24, Group 27, Group 31, sometimes also a Group 29. The greater the Group number the larger the battery is but also the greater is it's capacity. Since a CPAP draws quite a bit of power, especially if you need it's humidifier running also, I'd go with the larger Group 31 if there's sufficient space to mount them. Otherwise you might want to switch to a pair of 6 volt GC-2 batteries which in series will offer about the same capacity as a pair of Group 31 12 volt batteries wired in parallel, and although taller will have a much smaller footprint, about the same as a Group 24 12 volt battery.


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valhalla360

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Posted: 04/22/19 07:26am Link  |  Quote  |  Print  |  Notify Moderator

Are those amps at 12V-DC?

I'm guess yes. If they are 120v-AC, not a chance.

Assuming 8hr use between charges...that's around 96amp-hr...assuming nothing else is drawing a couple golf cart batteries should do the trick but that assumes you have a means to completely recharge the next day.


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wanderingaimlessly

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Posted: 04/22/19 07:27am Link  |  Quote  |  Print  |  Notify Moderator

Looking at your old setup, a pair of GC=2 and solar, how did that do?
If you were not drawing that down to less than 60% of a full charge, then cutting it in half is about your minimum.

Two GC-2 batteries with 210-230 amps will allow for the needed 64 amp hrs for the O2 concentrator and the 32 amphrs for the CPAP but you will need to top off daily, not getting back over 90% with that will leave you lacking after only a day or two.

azrving

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Posted: 04/22/19 07:50am Link  |  Quote  |  Print  |  Notify Moderator

If you add in what the rig is using for the fridge etc you will most likely be pulling 13 amps. Mulitply that by say 10 hours equals 130 AH down. You need more like three group 27 or four GC2 6 volts. You also need to consider your draw between no sun and bedtime if on solar.

If topping off 100% on generator at bedtime then go back to about 130 ah draw down. As mentioned, if you are drawing them down far it takes a considerable amount of time to completely charge so you go into the next night full. If not they will start dropping more and more.

As you do this check the specific gravity at times to be sure you aren't walking them down by not fully charging.

You don't need to dip them constantly, you just need to dip enough to be sure your energy management program is working.

MEXICOWANDERER

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Posted: 04/22/19 11:09am Link  |  Quote  |  Print  |  Notify Moderator

The QUACKS had me on an O2 concentrator that sucked 520 watts at 1.2 liters. Is a 12 volt concentrator -The New Miracle-? Flapping and whirring through the night?

I just cannot imagine a 12 volt concentrator. Would be like a 12 volt microwave.

The humidifier uses four times the power of the CPAP blower. So that's a factor.

Methinks you are on the wrong trail. Two 24's will allow around 85 amp hours total With standard gizmos online after dark you will be taxing group24 batteries to the max. I suspect the O2 unit is 120vac. A pipe dream.

Might want to start thinking about a 1500 watt generator that can run 8 hours.

MrWizard

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Posted: 04/22/19 02:07pm Link  |  Quote  |  Print  |  Notify Moderator

Two for the house?
Or one each for two total?
If only one house battery, then no way, even with two for the house going to 50% discharge every night is going to be hard on them , still need a full total recharge, each day


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Blackdiamond

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Posted: 04/22/19 02:20pm Link  |  Quote  |  Print  |  Notify Moderator

I run 2 CPAPs with the built in humidifiers off of 2 6V batteries and will run the heat as needed, generally it doesn't get below 40 here most times.


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Posted: 04/22/19 02:54pm Link  |  Quote  |  Print  |  Notify Moderator

Blackdiamond wrote:

I run 2 CPAPs with the built in humidifiers off of 2 6V batteries and will run the heat as needed, generally it doesn't get below 40 here most times.


Are you counting AH down? What's your morning voltage? How are you recharging. Two 6's would hold up better than two group.

theoldwizard1

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Posted: 04/22/19 03:43pm Link  |  Quote  |  Print  |  Notify Moderator

wanderingaimlessly wrote:

Looking at your old setup, a pair of GC=2 and solar, how did that do?

Stick with your 2 GC2 batteries !

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