Jumpstarter to power CPAP for camping – problems

A few months ago I spent a lot of time researching different ways to power my CPAP while camping. This was for a week long photography trip in which I would be wandering about in my Jeep so that I would always have the vehicle ready to recharge the battery. My goal was to be able to get away from hotels (and electrical power) for at least 2 days in a row. Since I was going to be doing a great deal of driving, I hoped that I would be able to recharge the jumpstarter every day while driving, potentially allowing me to camp every day of my trip (although in reality I planned to take the easy hotel route a couple times at least).

Based on discussions here, I decided to go with a car jumpstarter as my power source. Although perhaps not ideal, it seemed a convenient solution for my purposes. Here is an example of what i am talking about (but not the same model):

http://www.walmart.com/catalog/product. ... id=5679656

Anyway, I have been very disappointed for two major reasons:

1) I am only able to get one full night out of the thing. The consensus here seemed to be that a jumpstarter should be able to power my CPAP for 2-3 nights before needing a recharge. For reference, I have a RESMED auto with C-flex, and 90% of my pressures are under 10. My particular jumpstarter has a 22 amp-hour rating. Testing it at home to I was able to confirm that it will only deliver about 8-10 hours of power before needing a charge.

2) The second problem is that I could not seem to get the unit to charge in the car at all. This was with it hooked up to one of the 12V "cigarette lighter" power outputs in my car, via a somewhat home-made adapter, but with the car being operated for several hours during the day.

Any ideas? Is there something I am doing wrong here? Is it possible that the jumpstarter is just defective? And what about charging? Is there some kind of battery charger I need to interface between the car's power and the jumpstarter to make it work? Or should it charge by just being plugged in to the car's 12V outlet?

I should add that if I could just get the unit to charge with the car, I wouldn't be so concerned about the one-night use because I could just charge it every day. Conversely, if it would last for 2-3 days, then I wouldn't be so concerned that I can't charge it from the car since I typically will be staying in a hotel every few days anyway.

Any help would be appreciated! Thanks.

Denverdad wrote:I am only able to get one full night out of the thing. The consensus here seemed to be that a jumpstarter should be able to power my CPAP for 2-3 nights before needing a recharge.

It depends on how big (in capacity terms) the battery is in the jump start unit. The SLA (Sealed lead Acid) batteries used in these things genrally run from 12AH up up to 22AH capaciity in the same form factor (physical size).

A 12 AH battery will do one night with an S8 while a 22AH battery will do two.

I haven't had time to look up the detail on the B&D unit in your link, but as it says "450 Amps" for the cranking capacity, I'd guess its probably a 12AH battery.

2) The second problem is that I could not seem to get the unit to charge in the car at all. This was with it hooked up to one of the 12V "cigarette lighter" power outputs in my car, via a somewhat home-made adapter, but with the car being operated for several hours during the day.

I can't comment specifically on the B&D unit, but in generally you wont get a full charge into a jump start unit from a automobile cigarette lighter socket... you need a mains power source to achieve full charge. I don't know if this is related to your problem or not.

Is it possible that the jumpstarter is just defective? And what about charging?

That is a possibility.

Cheers,

Bill

I went thru almost the same problems as you mentioned.

I bought a battery pack from cpap.com to run my Respironics M-series Auto Bipap. https://www.cpap.com/productpage/respir ... -pack.html
. I also have a 1600 watt battery jumpstarter I bought at Napa.http://www.napaonline.com/MasterPages/N ... ac+Charger

I also bought a 12v power cord https://www.cpap.com/productpage/respir ... -cord.html from cpap.com.

I can use the 12v cord in my RV I also need to use it with the battery pack from Respironics, and it will also work with the battery booster pack I bought from Napa.
Also the link I showed is not the booster pack I have from Napa but one that they are selling now. the unit I have will jumpstar a 24 volt system.

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CPAPopedia Keywords Contained In This Post (Click For Definition): respironics, bipap, cpap.com, Power, auto
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CPAPopedia Keywords Contained In This Post (Click For Definition): respironics, bipap, cpap.com, Power, auto

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CPAPopedia Keywords Contained In This Post (Click For Definition): respironics, bipap, cpap.com, Power, auto

My experences sound very similar to yours. My jumpstart is listed as having a 700 amp battery and I get about 8 to 10 hours as well. Additionally I was having problems getting it charged via the 12 volt source, either through the cigeratte adapter or the jumper cable. My next step was to try an inverter and charge it using 120 volts power, however the camping season ended.

If you do try the inverter, please post your results.

Chris

I forgot to post how long my jump starter will power my Bipap Auto......I can use it up to 36hours. On my battery pack from Respironics I can use it for 2 nights. About 18 hrs. With my RV coach batteries I have 6 6v. in series I can use it almost 2 weeks before the batteries go down. On the chasis battery I can use it for about three days before I need to charge the battery.

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CPAPopedia Keywords Contained In This Post (Click For Definition): respironics, bipap, Power, auto

Thanks for the feedback so far.

Bill, my particular jumpstarter is rated at 22Ah (in fact I chose it for this rating) and is supposed to be of the AGM (absorbed glass mat) type. The link I provided is NOT for my particular unit - I couldn't find a link to it, so I just posted this one as an example for those who might not know what a jumpstarter is. Sorry for the confusion! Patrick, yours are the kind of results I was expecting! I'm just not sure what I'm doing wrong.

There are two factors which lead me to believe I should be able to get 2-3 nights on a charge:

1) people have made this claim on the forum before
2) a while back somone posted numbers they measured for the current draw of the RESMED auto C-flex CPAP for different conditions. If I recall correctly the value was at or below 1 amp at 10cm pressure. So this would indicate I should be able to get at least 22 hours.

I can say that the unit charges as it is supposed to with the AC adapter. Or at least it seems to - it takes most of a day to recharge from completely drained. Maybe the Car's 12V outlets just can't provide enough current to charge the jumpstarter in a reasonable time (?). Chris, the inverter is an interesting idea. But I would suspect that if the 12V DC isn't working, then the inefficiency of converting to AC then back to DC again would make it even less do-able. But what do I know? Clearly I need to learn a little more about charging batteries if I want to solve this issue.


Jeff

I wonder, Are you plugging your cpap machine in using a standard electrical plug, or are you using the DC converter that Resmed sells? I have a Resmed S8 Escape and have the DC Converter from Resmed. At 10cm pressure, I can get a full night out of a 9AH jumpstarter battery. If I were to plug the cpap in using the regular cord, so that would mean I was using the battery power with an inverter, the battery won't last as long because using an inverter is not as efficient. Although, I would think you would still get close to 2 nights with a 22AH battery.

Jeff

Denverdad wrote:Bill, my particular jumpstarter is rated at 22Ah (in fact I chose it for this rating) and is supposed to be of the AGM (absorbed glass mat) type.

That's a good overall spec Jeff!

If I recall correctly the value was at or below 1 amp at 10cm pressure. So this would indicate I should be able to get at least 22 hours.

Well, you wont get 22 hours. The battery terminal voltage will not remain constant over the discharge period and will definitely dip below 12V towards the end of battery capacity. However, you could resonably expect to get 20 hours or so before the voltage from a fully charged battery dropped low enough to start creating problems with your flow generator. I don't know what a DC input voltage tolerance a Respironics generator has, or what it does does when the DC input voltage drops below specification, but at some point below 12V it will stop functioning as expected.

Chris, the inverter is an interesting idea. But I would suspect that if the 12V DC isn't working, then the inefficiency of converting to AC then back to DC again would make it even less do-able. But what do I know?

You'll have an efficency loss of about 10% with a good inverter, so there's really not any benefit if all you are going to do is run your flow generator off it.

Cheers,

Bill

jmurkve wrote:I wonder, Are you plugging your cpap machine in using a standard electrical plug, or are you using the DC converter that Resmed sells?

It seems we are talking here about a Respironics flow generator, not a Resmed one, so a Resmed DC-12 is probably not appropriate (at least without some modification).

I have a Resmed S8 Escape and have the DC Converter from Resmed. At 10cm pressure, I can get a full night out of a 9AH jumpstarter battery.

Yes, that would be quite adequate at sea level.

Keep in mind that if you ever need to set the altitude adjustment for a higher altitude, the S8 Escape (aka Lightweight) will use more energy and you may find 9AH is not quite enough for a full night.

Cheers,

Bill

Doh! Please ignore all the instances where I said "Resmed". I meant to say REMstar! The machine is a REMstar c-flex Auto (which is of course by Respironics). Sorry about the confusion. I'm not well rested, can you tell? Oh, and I looked up the jumpstarter and it is an AutoPower Dynamite, which is rated at 22Ahr, if anyone was interested. Its wall plug adapter says it puts out 13.5 volts DC, 500mA.

My REMstar does in fact provide a warning beep when it senses that the supply voltage is too low, and then just turns off. And no, I am not using the "official" power cord. As I said before I basically built my own, (a Radio Shack special, along with the correct size plug, which I had to purchase).

Here's the history of that cord, in case anyone thinks IT may be the reason I am not getting very many hours out of the jumpstarter. Basically I tested the cord out briefly before my trip to verify it worked and I was able to power the cpap. Everything seemed to work fine. Unfortunately, shortly after I hooked it up the next time (which, as Murphy would predict, was late at night out in the woods!), everything suddenly shut down. Further inspection revealed that the cigarette lighter portion had a 2-amp fuse, and this had blown. After putzing around trying to find a suitable piece of metal to bridge over the fuse, I eventually ended up tearing the end off and connecting the bare wires directly to the jumper cables of the jumpstarter. Not very pretty, but it worked! Subsequent tests I did with the jumpstarter have all been with that cord, so you might very well think that is the root of the problem. I don't really see how, but I'm willing to entertain suggestions. In any event I will probably be purchasing the official cord soon just so I know I have a reliable one.

Thanks for all the input so far. Maybe I can actually figure this thing out!

Jeff

Denverdad wrote:Further inspection revealed that the cigarette lighter portion had a 2-amp fuse, and this had blown.

This may be a clue as to your unexpected low duration on the 22AH battery.

While there is probably some "inrush" curremt when your flow generator is plugged in, I would be surprised if it was enough to blow a 2A fuse! Now the fuse may just have failed from simple fuse fatigue, but if your flow generator is drawing ~2 Amps instead of "at or below 1 amp", then that would explain why you were only getting one night from a 22AH battery,

If you have any way of measuring the actual current draw of the flow generator, now might be a good time to do it!

Cheers,

Bill

The RemStar Auto when on 12vdc power has a max current draw of 3 amps. It is only 1 amp on 120vac. Based on that a 22 amp hr battery will give you at best 7 hours at full current. Your time would increase depending on the pressure level it runs at. The lower the pressure the longer run time you could expect. I would think that about 13 hours would be the most I would expect to get from it. JMHO.

RemStar auto needs 1-amp-hour on CPAP machine AC, and the humidifier needs 1.7 amp-hours, so combined 2.7-3 amp-hours on AC.

Unplug humidifier and use Remstar only at 1-amp-hour with humidifier kinder like passover it will last more then enough!!!!

Rich03079

Yep, if I could a basic measurement of the current draw that would answer a lot of questions in short order. I don't have a decent meter, but I will see if I can borrow one from work. For what its worth, the fuse didn't blow right away. I don't remember the circumstances exactly, but it was maybe 20 minutes after I put the mask on.

In the mean time, I found the posting I was referring to earlier. It indicates a typical current draw for the REMstar auto w/c-flex of about 0.6 amps at 10cm pressure. The poster speculates that the 3-amp rating of the device is mearly a maximum or "worst case" value. The link is here (if I did it right!):

viewtopic.php?t=4590&highlight=remstar+current+amps

And here is a post where a Remstar user (UKnowWhatInSeattle) claims to get 3 nights with a 22Ahr jumpstarter:

viewtopic.php?t=289&highlight=remstar+jumpstarter


Jeff

Yep, I had the humidifier off. Actually I kept the air hose connected hoping to get at least be getting SOME (albeit minimal) passover humidification.

Jeff