I am a tent camper and have just started to having use a Bi-Pap to sleep. Much of my camping are at sites with no electic. I can run the Bi-Pap with a 12 v battery and inverter, but I have a question about charging:
1) Is there a problem with charging the battery using jumper cables from the battery in my truck?
2) If not, any idea on how long it would take to achieve a full charge (how do I know when a full charge is achieved?)
3) I guess I could also plug the inverter in the cigarette lighter, then plug a standard battery charger to the inverted and charge the battery that way. It seems this would take much longer than the more direct method of jumper cables.
Yes you can run a CPAP machine with an inverter. I have run one on two inverter RV's to test that out. However I have 4 batteries, and a 8 amp draw for 10 hours only Starts to deplete my batteries. Most group 27 atteries will hold 100 amp hours of power while they are new, and when they stay full of water. But . . .
A pair of golf cart batteries will last longer. They have thicker battery plates, larger water capacity, and more space below the plates for minerials to collect before the plates become clogged, and short out, requiring battery replacement.
It would help to use warmer water if you do use the humidifier, because the warmer water will evaperate with less power usage.
To get a full charge, one way is to hook up a 500 watt inverter directly to your battery, and run the truck engine (it can draw 50 amps or so) and plug in your trailer's battery charger, and this will work. The trailer charger should put out 13.5 to 14 volts to the battery.
Another way is to use jumper cables, and the truck battery will reach 13.5 volts, and might transfer 20 amps to the trailer battery - if it is a short distance with good connections, but loose connections mean less amperage transferred.
The most fuel efficient way is to connect a small generator to the trailer and run it about 1 hour in the morning and evening. Running it for 2 hours will provide less charge than two runs of 1 hour each, because the charger slows it's charge rate after the first hour or so. (do to internal resistance in the battery) You might require two or more hours to recharge in the morning and you should have 12.5 to 12.6 volts when done charging.
While charging you can not use battery voltage to know how full the battery is, but after charging and the battery has sat for about 5 minutes, then has a small load on it, say a couple of lights (or the CPAP) then you can measure the voltage and determine how full it is. If it reads about 12.7 - 12.8 with one light on, then it is full or at least 95% full.
If it reads about 12.6, then about 80% full
12.5 70%
12.4 60% and you should keep charging the battery (or sulfur can develop on the battery plates)
12.3 50%
12.2 40%
12.0 30%
11.8 20%
11.5 10%
The worst thing to do to a battery is let the plates go dry, because they can warp, requiring replacement.
Second is leaving the battery in a discharged state for more than a day or two. Leaving it discharged allows the chemicals to harden on the battery plates.
Third is overheating the batteries. Kinda explains itself. But charging at a really fast rate, or discharging at a fast rate can overheat the battery, warping the plates would then be possible.
Fred.
Money can't buy happiness but somehow it's more comfortable to cry in a Porsche or Country Coach!
My Remstar will run directly from 12 volts if I would buy the adapter. The heater in the humidifier will not work with the voltage out of most inverters but if they did your battery would die quickly. You can still use the humidifier but just not in HEAT mode.
Thanks Guys. Golden- You sound very knowledgeable. I pan on using one Deep Cycle Marine Battery (Marine Cranking Amps: 875 - Cold Cranking:675 amps) with a Black & Decker 400 Watt Power Inverter w/Alligator Clips and Cigarette Plug. At night I would use hope to run the Bi-Pap directly 5-6 hrs from the Marine Battery. (Gale - Good tip to turn the humidifier heater off to conserve power).
Using one battery I understand I would need to recharge the battery every day. I have a standard 12 v battery charger. For charging I could attached the inverter clips directly to the truck battery (instead of the cigarette lighter w/wimpy little cord), with truck running,and re-charge.
Do you have any idea how long the truck would have to run at idle to achieve a full charge on the marine battery?
I could also get another battery and hook them together in parallel.
Not dumb questions at all!
You can get as expensive as you want with the setup, but if you want to stay just basic then here's what you NEED:
A cheap digital volt meter, available for ~$5-10
Jumper cables
A TRUE deep cycle battery (Not a marine battery)
You can charge the deep cycle from your truck via the jumper cables, and as long as the truck battery isn't getting over charged neither will the deep cycle. The chart posted above is fairly accurate for state of charge. Try not to let the deep cycle get below 12.0V (12.3V would be better). When the truck is running you'll see about 13.6-14V. How long it takes to charge depends on how discharged it is, and what your alternator puts out. Probably safe to assume a couple hours each day. Probably cheaper in the long run to get a decent small generator, but not required right away.
Now, can you go for more gadgets to make it easier? Absolutely. Just depends on how fat your wallet is!
I'm not an expert, but I play one on the internet
"Never drive faster than your guardian angel can fly"
98 Chevy 3500 CC 4X4
Back to tent camping, and looking forward to no RV related issues. (Take that RV industry!)
dondford wrote: ..... I pan on using one Deep Cycle Marine Battery (Marine Cranking Amps: 875 - Cold Cranking:675 amps).....D
Just want to second another poster --- you want a good deep cycle battery, not a marine. For your usage, 'cranking' is a totally useless number. That's for starting something. Your battery is going to be used to continually run something and a true deep cycle battery is made to be discharged (up to 50%) over and over. I use an inverter and deep cycle battery for 'dry camping'. I also have a solar panel for charging but of course, you need to be in a sunny place for that.
Pup: 2007 Jayco 1206 w/slide-out + shower
surge brakes, 54w solar panel
TV: 2005 Nissan Xterra 4X4, manual trans
25 years tent camping, 4000+ miles of hiking, lots of biking
Marine / Deep Cycle / Trolling etc. are just words of marketing.
Look for amp hours. Group 24 about 80/85, Group 27 110/115, & Group 29 130 amp hours. If it is in that range it is a good deep cycle battery.
A low battery takes two to five hours to recharge to 80/90%. Eight+ hours to get 100% charged. Jumper cables are your best bet but may take longer. A small generator such as a Honda 1000 and a 30 to 40 amp smart battery charger such as Black & Decker would be much faster.
2001 F150 SuperCrew 5.4 Lariat Offroad 4x4 Tow Package 4.10 Truetrac
2006 Keystone Springdale 249FWBHLS
12K SuperGlide, KGE3000Ti 2.3kw rated 2.6kw max
Frank's voltage booster, Prosine 1800 powered by 4 GC2 batteries
Everyone needs to keep in mind the term Deep Cycle carries many different meanings as there are people using the term.
As far as I know there is only one true deep cycle battery for RV use sold in the US. It may be a Rollins, Concord or some other name and I am not sure if they have dealerships or not. Most will not pay the price and I have never seen one. A electric tow motor/forklift with quarter inch lead plates is a true deep cycle battery. The Optima D-31 AGM battery is physically the same battery except for the post configuration be it red, blue or yellow top.
Most often the term deep cycle does not actually apply to any battery that ships in most any RV. There are some good threads here with all of the specifics if one is interested in doing a search.
Gale Hawkins wrote: Everyone needs to keep in mind the term Deep Cycle carries many different meanings as there are people using the term.
As far as I know there is only one true deep cycle battery for RV use sold in the US. ...
I agree on the term "deep cycle". The basic technology is:
"Normal" vehicle starter battery=thin plates for high draw/minimal time
"Marine" battery=thicker plates still suitable for high draw, but OK for low draw/longer time
"Deep cycle" batteries have the thickest plates, which are best suited for steady deep discharges found in industrial and RV applications.
Trojan brand batteries have a good reputation in the golf car and RV worlds. Like another poster said though, "look for Amp hour ratings", not "CCA" or crank ratings. The higher the Amp hour rating the more "juice" you can put in/take out of the battery.
(I don't think I could have used any more quotes!)
Offline
Online
