CPAP on battery power issues?

[Borrego Dave]

Originally Posted by warezdog

find your local interstate battery warehouse distributor, not a retailer, and walk in and ask for a blem. I've been buying group 31's for $45 for years and smaller ones like 27s are about $35. They're basically batteries that have a blemish, dented corner, scratch across the top etc.

I have one 27 that is now pushing 5 years this November, had nothing but great luck with them.

Great info, thanks

[Paul Braun]

For used batteries try local home medical suppliers. The places that rent or sell mobility chairs. They often have gently used batteries that they have swapped out for owners. These will probably be 6 volt, which in a pair will better suit your needs.

[Roy in TO]

Originally Posted by warezdog

find your local interstate battery warehouse distributor, not a retailer, and walk in and ask for a blem.

I remember my dad doing this with GM in Oshawa that has or had a battery plant (Delco). Any autoworkers here that might know if this type of thing still exists?

I've seen "blemished" Optima's listed for sale on kijiji here in Southern Ontario. I think it is a battery distributor somewhere around Ajax.

[warezdog]

Just called my local interstate warehouse again this morning for the heck of it, they had 3 group 31's one was a deep cycle $35/$55 and a hand full of 27's for $25 all 90 day free swap warranty.

[beemerphile1]

Originally Posted by Paul Braun

For used batteries try local home medical suppliers. The places that rent or sell mobility chairs....

Good advice. My son is a wheelchair/scooter tech. On the high end units they swap out the batteries every 18 months.

He keeps me supplied with MK Battery 12v group 24 gel batteries. I can get years of service out of the used batteries. The downside is they are heavy and only 73 ah @ 20 hr.

[Paul Braun]

I have had the best luck calling locally owned places that sell or rent durable medical equipment. The big chains and hospital owned shops do not want or can not deal with a request for old batteries. I always ask for the technician who works on the units.

Your results may vary across the country as to what you find. Locally, they seem to be using dual flooded 12 volt deep cycle marine batteries in a 24 volt array. They also have smaller batteries from chair lifts. My guess a lot depends on what brand the local store sells.

It seems all their old batteries go for recycling so the friendly stores are more than willing to part with old units.

[DougOlson]

I don't have my Scamp yet, but do use a Respironics System One CPAP w/o humidifier in my tent trailer. I use a 30W solar panel to recharge an 18AH AGM battery every day and it works fine. Typically the battery voltage will go from 12.9 to 12.2 overnight and will recharge fully with 3 - 4 hours of good sun.

Sent from my SM-T310 using Fiberglass RV mobile app

[ruscal]

Welcome to the forums Doug,
That is a good solution. I have a similar battery to yours that I use to extend my stay another day when using the CPAP. I have not field charged it, I just wait until back home to re-charge. My solar is set up to charge the Scamp battery, so wouldn't work for the small AGM without some selector switches and setting changes on the controller. I use a small CTEK charger for the AGM when at home.
Russ

[Timber Wolf]

Originally Posted by ruscal

Welcome to the forums Doug,
That is a good solution. I have a similar battery to yours that I use to extend my stay another day when using the CPAP. I have not field charged it, I just wait until back home to re-charge. My solar is set up to charge the Scamp battery, so wouldn't work for the small AGM without some selector switches and setting changes on the controller. I use a small CTEK charger for the AGM when at home.
Russ

I have seen some small wattage panels advertised as no controller required. I wonder if one of those tossed on top of the tug or trailer might not at least give you a trickle charge on an AGM without hurting it. Maybe use that battery first on your trip for a night and then charge it over the next few days and squeeze out another night or two? I have a full solar setup but bought a cheap little panel just for the kid and I to play with for a fan and stuff.

[DougOlson]

I have a 5W panel that does not require a contoller that I used initially (before using a CPAP) but it was not enough to keep the battery charged up, even using it for led nights and charging cell phone.

Sent from my SM-T310 using Fiberglass RV mobile app

[ruscal]

The small panels that can be safely used without a controller wouldn't provide the correct properties to charge a 20ah battery to max. I have a small panel that runs a refrigerator coil cooling fan directly with no battery, and it could probably trickle charge a very small battery, but not optimally.
Russ

[hariph creek]

Ok, here's an update.
We went on another 4-night trip. Having charged the battery for two weeks on the converter.

Night #1= Nothing-won't even power up the CPAP, even with inverter. BAD NIGHT!

Day #2= take out the battery on the passenger side of the TV (Dodge 2500 with 2 Batteries). Replaced it with Casita Battery. Drove around for a couple hours. Scouted out new camp sites, checked on huckleberry fields, etc... Then swapped the batteries back.

Nights 2-4= ran steady on 12v supply, no need to get out the inverter.

Day #5= swap Batteries again to charge on way home. Swap back again, when home and put Casita Battery on float charger.

It would appear my converter is not charging my battery. I've looked it up, it is supposed to charge my battery. Yet another thing the PO lied about.
At least I can now make sense of why my big Marine Battery provided less capacity than a tiny starting Battery.

I don't know that I'll replace the cconverter? I don't store the battery in the trailer. I may just get a quality 3-stage or two to keep in the garage.

I've also decided to go with two Battery systems.

2x 6v DEEP CYCLE on the tongue. To be used exclusively for my CPAP. Also to be powered by TV, while in transit.

Current group 27 (to be replaced by true deep cycle 12v when necessary) in factory location. This will be for lights and fans. That way I don't have stress about the family stealing my "so I don't die in my sleep" power. It would be nice to run the MaxxFan at night, too.

[War Eagle]

Jorah, Bummer! I'm not sure I followed everything you did and then tried to do to remedy the problem, but I think each separate component of your whole battery charging system could be checked pretty quickly with a multifunction volt meter. I'm not an electrician by any stretch of the imagination, but I have one and feel pretty comfortable using it. If things get too complicated, we have a local alternator/generator shop where the proprietor, Eddie, loves to solve mysteries like that without charging an arm or a leg or trying to sell you something unless you need it. It could be something as simple as a frayed wire in the power supply cord for your charger. On one 7-pin receiver that wasn't charging the camper batteries while in tow, we found out the 12v power wire (the black wire on most models) hadn't even been connected to a power source from the tow vehicle, so no wonder the battery wasn't charging. Sometimes the problem is so simple you don't even think to look there. Best of luck....

[Timber Wolf]

Sorry for your trouble but glad you have a plan for getting it solved. As a CPAP user myself I understand the importance of the unit to a good nights sleep. I am currently modifying the tougue of my Scamp to take two 6V batteries and one propane bottle. The original configuration was one battery and two propane. I need to weigh a full propane bottle (40 poundish?) and the dual tank mount I removed but figure I am close to breaking even on tongue weight with the additional battery (62 pounds).

[hariph creek]

I need more weight up front anyway. My Casita is a standard, so no bathroom. I suspect these were configured with a bathroom in mind. Unless I put a couple hundred pounds, of gear, up front. It rocks back and forth, constantly. And I'm not even running the spare on the back (up in the TV).
ETA: I have a drop hitch, so I'm slightly nose down.

Some PO converted this from a 7-pin to a 4-pin. That'll be something I start to fix when I put batteries up front and finish when I put in a new axle, with brakes.

I'll see if I can find the fault in the converter? If it costs more than a couple bucks to fix? I'll work around it, as mentioned earlier.

[Vivian L]

I also use a CPAP and now the hubby has to use one as well. With just one, I plugged it into my 400 PowerPak and got about 1 1/2 nights from that. I have two folding 12 solar panels that run concurrent giving me close to 24 but they won't charge the power pak back up to full. So I took the power pak to the office and had them charge it over the day for me. Now with two machines, I am afraid this isn't going to work at all.
Generators are not allowed where we boondock, and the weight of an extra deep cycle battery isn't something we want to add to our boler either. What I need to know now is how much solar panel do I need to charge the powerpak or do I need a bigger powerpak, or do I plug the CPAP's into an inverter/converter and run them off the deep cycle marine battery. Then I could charge it with a solar panel?

[David B.]

Vivian, there are to many unknown variables with your questions. How large of a battery (group 24,31...etc) do you have? How many watts do your solar panels put out? How many amps do yours & your husbands CPAP machines pull per hour, and also don't forget to add the draw of other items like lights (LED or incandescents), water pump, furnace.
Dave & Paula

[Vivian L]

I'll have to check the battery but I wanted to use the 400 powerpak if possible. But Thomas says it's not big enough. The solar panels put out 20 watts. The CPAP machines need 5 to 8 amps each. We don't use the eliminator powerpak for anything else except the cpap machines. The deep cyle battery only get used to lights. Everything else is propane/electric. We don't have a furnace. I'll have to get all my figures together and then see if it's doable.
Thanks

[Jon Vermilye]

A couple of points -
Even at the lower figure of 5 amps (at 12v), 2 of them over 8 hours is going to use 80 amp hours. That is beyond the one day capacity of most single 12V house batteries without recharging. I have no idea of what the amp hour capacity of your 400 Powerpak is, but if it is portable, I doubt it is near even the smallest standard 12V battery.

If your solar panels produce 20 watts (each?) for a total of 40 watts, over a typical day you can expect to produce no more than 20 amp hours; probably less.

The combination is not going to work. In my case I use around 20 - 25 amp hours per day. I have a pair of 6V batteries with a capacity of 232 amp hours. In the summer with a roof mounted 95 watt panel I barely keep up. In the winter (low sun angle) or shade, it takes the combination of the roof panel plus a 160 watt folding panel to keep up with the normal usage.

You are going to need both more battery capacity & more solar panel(s) to put together a system that can produce enough energy to run the CPAP machines for any reasonable length of time.

One possibility - if you can run the machines without the humidifiers, it will save a considerable amount of power.

[ruscal]

On my last trip I ran my cpap 2 nights which took the group 27 deep cycle battery down to about 75% full. There was some lighting and fan draw as well. The third morning I put out one of my 100watt Renogy solar panels. By 11:30am the batt was 100%. It was very sunny, so on a cloudy day it could have taken much longer. I have 2 of the 100 watt panels for such conditions.
Russ