Battery life over night

[tennlady]

While we are talking batteries, was wondering if anyone knows if it is possible to put a battery charger on a set (two) of batteries at the same time.

[camaraderie]

Yeah really. Your reply makes it clear that you don't understand what a real battery monitor measures and it has nothing to do with 8Ga wire OR measuring voltage at the battery vs. the monitor.
I can guarantee you that without a true monitor IF YOU BOONDOCK a lot, you are getting significantly less battery life over time by using a Voltmeter. If you don't boondock it doesn't matter.
You get significantly less battery life because:
1. You have no idea when you are 100% charged. Less than 100% charging degrades battery life.
2. You have no idea when you actually go below 50% state of charge.
3. You have no idea of the actual present capacity of your batteries as they age.

There are a number of other things a monitor can tell you that are not directly related to battery life but are helpful....like how many amps does my CPAP draw or how long at my present amp usage do I have before I need to recharge or how many amps is my battery charger putting in RIGHT now.
If you're happy with what you have...fine. Others may wish to have the real ability to save & monitor their batteries in a more proactive way.

[camaraderie]

Originally Posted by tennlady

While we are talking batteries, was wondering if anyone knows if it is possible to put a battery charger on a set (two) of batteries at the same time.

YES. But they should be the same age and type and the charger will work best if it is at least 10% of their combined amp hour rating.
Assuming they are 12V...connect the batteries positive to positive and negativve to negative....then connect the charger to the first battery positive and the second battery negative.

[ependydad]

Originally Posted by 2ramblers

We have a Georgetown Motor Home and have been unable to overnight without shore power because my CPAP requires either 110 or a cigarette lighter plug in. Do I have to convert the 110 outlet next to our bed to a 12V then get an inverter to plug the CPAP into?

I only have a 110 cord for my CPAP and very limited 12v cigarette lighter outlets in the camper (like 2 in the middle of the camper in the kitchen). I plugged a cheap inverter into one of my 12v outlets and just ran an extension cord up to the bedroom.

Originally Posted by John McClain

You do know Cpap are 12 volt and you can buy a 12 plug, that well run them.

The plug from the wall goes to a coverter box the converts 110 to 12 volt. You can save yourself a lot of battery by not running the inverter

I do know that but these 2 overnights were literally the first non-hookups "camping" (well, parking) I've ever done with a camper. If we keep doing it, I'll consider proper alternatives.

[camaraderie]

So...Ependydad... how many 12V amps or 120V amps does your CPAP use...it should be printed in small letters on the wall wart or AC box....that would be helpful to know to advise others how much battery power they need for that device in addition to whatever else they need.

[1l243]

I boondock about 8 weeks a year and my monitor does just fine. But I am sure you could tell me how to do it better!

Originally Posted by camaraderie

Yeah really. Your reply makes it clear that you don't understand what a real battery monitor measures and it has nothing to do with 8Ga wire OR measuring voltage at the battery vs. the monitor.
I can guarantee you that without a true monitor IF YOU BOONDOCK a lot, you are getting significantly less battery life over time by using a Voltmeter. If you don't boondock it doesn't matter.
You get significantly less battery life because:
1. You have no idea when you are 100% charged. Less than 100% charging degrades battery life.
2. You have no idea when you actually go below 50% state of charge.
3. You have no idea of the actual present capacity of your batteries as they age.

There are a number of other things a monitor can tell you that are not directly related to battery life but are helpful....like how many amps does my CPAP draw or how long at my present amp usage do I have before I need to recharge or how many amps is my battery charger putting in RIGHT now.
If you're happy with what you have...fine. Others may wish to have the real ability to save & monitor their batteries in a more proactive way.

[Herk7769]

Originally Posted by camaraderie

So...Ependydad... how many 12V amps or 120V amps does your CPAP use...it should be printed in small letters on the wall wart or AC box....that would be helpful to know to advise others how much battery power they need for that device in addition to whatever else they need.

My DW's CPAP has 120 volt watts listed. Divide the watts by 12 to get DC amps.

[ependydad]

Originally Posted by camaraderie

So...Ependydad... how many 12V amps or 120V amps does your CPAP use...it should be printed in small letters on the wall wart or AC box....that would be helpful to know to advise others how much battery power they need for that device in addition to whatever else they need.

I'll look and will report back... if I remember!

[camaraderie]

I've always heard that a triceratops never forgets!

[ependydad]

Originally Posted by camaraderie

I've always heard that a triceratops never forgets!

P

Perfect timing, I'm sitting right next to it!

That said, I don't know if those power requirements are with the humidifier or without. The humidifier generally used 3 times the amount of power as the blower only.

[camaraderie]

Well...if they both work off the same plug...then the spec is WITH the humidifier.. Looks like it has a step up transformer for DC that works at 24V and 2.5 amps. So that would translate into 5 amps at 12V + some loss in conversion...so lets call it 6 amps.
So 8 hours of sleep with a CPAP will run about 50 amp hours out of your batts. This is essentially taking a single group 27 or 31 large 12V battery to half charged. Or a pair of group 24's which a lot of folks have to 66% charged.
If one has to run the furnace in cold weather and a Cpap...you are probably gonna want the basic 2 battery set up + another one.
Assuming your setup is pretty typical...that is a good rule of thumb for people I think..."Add a CPAP... add a 12V battery."
Thanks for the data & have a great Xmas in the warm!

[billb800si]

Note to the OP, be careful boondocking behind a Cracker Barrel restaurant. It's much darker back there and when they close up at night no one can observe your RV from the front. You're on your own. Always felt much safer in rest stops or truck stops.

[elind]

I'm thinking that I will use a jump start battery pack that has a 12 volt or 120 inverter for my CPAP when overnighting at Walmart. That way if the CPAP draws down the battery it's only the battery pack dead. It also moves around with the CPAP where it's needed.

[ependydad]

Originally Posted by elind

I'm thinking that I will use a jump start battery pack that has a 12 volt or 120 inverter for my CPAP when overnighting at Walmart. That way if the CPAP draws down the battery it's only the battery pack dead. It also moves around with the CPAP where it's needed.

Just remember, if you can go without the humidifier, it uses a lot less power.

[rockfordroo]

Also I will not be un hitching for the night but should I un plug the electric hook up from my TV?

I installed a relay in my engine compartment and a switch in the cab so I can turn the power to the trailer on and off. Probably not a big concern, but I'm always worried that if we stop for the day somewhere, I'll come out and find the trailers drained the TV battery somehow. Pretty cheap insurance. The relay's about $8, I had the switch from an old Mr. Coffee coffee pot, and a few feet of wire.

[garbonz]

Originally Posted by 1l243

"Once again I remind everyone" Really?

Actually I am pretty happy with they way my cheap battery monitor is setup. I wired my cheap monitor directly to the batteries and ran multi stand 8 GA wire. When I compare the reading with the cheap monitor and battery bank direct the reading is the same with no measurable voltage drop.

Your explanation is to assume your tying to get a accurate reading when running alot of amps at the same time. I get my most accurate reading in the morning when the system as been at rest.

YES he did need to remind everyone (maybe not you) because the alarm monitor is a very crude method and nobody mentioned "12.2 volts at rest". You obviously know that but the OP didn't.

For the OP's situation, the "yes you can" was the only appropriate answer and every other post just complexitizes the situation, which then needs to be clarified la,da dada. Then others post bit and pieces which need to be corrected etc etc.

Kinda fun to read these tho.


Sent from my iPad using Forest River Forums

[camaraderie]

Originally Posted by elind

I'm thinking that I will use a jump start battery pack that has a 12 volt or 120 inverter for my CPAP when overnighting at Walmart. That way if the CPAP draws down the battery it's only the battery pack dead. It also moves around with the CPAP where it's needed.

Well... I think you are going to be EXTREMELY disappointed over time with that approach despite its' attractiveness.
1. The quick start battery packs are made to deliver SHORT jolts of high current to start a car. This means lots of thin plates .. and not much DEEP CYCLE capacity.
2. Using a "starting " battery continuously in deep cycle application will cut battery life by OVER 50%... most likely by 2/3.
3. The run time you get per charge on the pack...will not take you though the night AND you risk going below 12.2V ...or going flat which is really damaging to a battery.
4. Using the inverter mode rather than the 12V mode costs at least 15% of your battery power in conversion loss in a small inverter.
5. You need a conventional true deep cycle battery (wet or AGM) with amp hours of close to 100 which means a group 27 or 31 and around 60-65 lbs in a wet battery. That's a lot to carry around!

Anyway...good luck & think it through ...or at least buy it somewhere you can take it back to for a while if unhappy.

[fasthauler]

Originally Posted by Tomgky

I'm looking for your thoughts. In a few weeks We will be heading south with our TT. Plan on staying in a Crackle Barrel parking lot for the first night. I checked with them and they said "come on you are welcome to stay" It looks to be in the 30's over night and I was wondering if my batteries would last the night with the furnace cycling on and off. I have two deep cell batteries wired in parallel. Also I will not be un hitching for the night but should I un plug the electric hook up from my TV?

Any thoughts or advice would be appreciated. This will be our first time with no electric hook up.

It is very important to check the reserve capacity of a battery not the CCA when choosing a battery to use in an RV. A 12-volt marine battery with a 221-minute reserve would run a furnace continuously for 14 plus hours. Your one night stay wouldn’t be a problem if you had a single 12-volt battery like this. I use to dry camp at Quartzsite for four nights on two 6 volt Trojan 105’s in series before a recharge was needed.