Greetings everyone. I have a question about camping with my CPAP that I didn't find directly answered when searching.
I have a REMstar Plus CPAP. The back of the CPAP states that it uses AC 1 amp max and DC 3 amps max. I have a pressure setting of 8 by the way.
I just went to Wal-Mart and picked up a 22 amp hour emergency jump starter battery with 12 volt outlets that I can plug the DC plug into and then power my CPAP.
In my searching I found that the REMstar uses less than the stated 1 amp when using AC power. I have also found in my searching that an inverter uses 1 amp also all by it's self. Is that true? For this example, if I use my new battery pack with the inverter to power the CPAP, will I be using about 2 amps?
My other option is to use the DC power adapter and plug directly into the battery pack - eliminating the need for the inverter. But would that mean that I would now be using closer to 3 amps of power?
Does anyone have any more information about how much DC power my CPAP uses at the power setting of 8?
I'm just trying to figure out the most efficient way to power my CPAP when I'm out camping.
Thanks everyone. I'm new with the CPAP and have found this forum to be a great source of information!
Jackie Treehorn
Another question about camping with CPAP
Hi
On DC it uses more AMPs but less Power.
Heres why...
The power used by a device is measured in Watts.
To get the Watts you multiply the Volts X Amps
So with your xPAP on AC power you have 120 Volts X 1 Amp = 120 Watts of power used
On DC you have 12 Volts X 3 Amps = 36 Watts of power used
This is of course assuming it was running at its full capacity etc.
The reason it uses over 3x more power on ac is because it is because it actually runs on DC (like most elecrtonic devices). The AC input has to go through a AC transformer to lower the voltage and then a rectifier to change the Low Voltage AC to 12 Volts DC. All of which used and wasts power.
When you use the DC input you are already providing it with the power it is made to use.
So you are much better off using the 12 Volts DC out of your Battery Pack.
Hope this helps
See Also: Thunderstorm experience... scary!
Jeff
On DC it uses more AMPs but less Power.
Heres why...
The power used by a device is measured in Watts.
To get the Watts you multiply the Volts X Amps
So with your xPAP on AC power you have 120 Volts X 1 Amp = 120 Watts of power used
On DC you have 12 Volts X 3 Amps = 36 Watts of power used
This is of course assuming it was running at its full capacity etc.
The reason it uses over 3x more power on ac is because it is because it actually runs on DC (like most elecrtonic devices). The AC input has to go through a AC transformer to lower the voltage and then a rectifier to change the Low Voltage AC to 12 Volts DC. All of which used and wasts power.
When you use the DC input you are already providing it with the power it is made to use.
So you are much better off using the 12 Volts DC out of your Battery Pack.
Hope this helps
See Also: Thunderstorm experience... scary!
Jeff
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Mr_Treehorn
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Mr_Treehorn
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thanks again Jeff for the reply!
could you tell me, given the cpaps stated amp draws (which are the max case), how long i could expect my machine to run using the direct DC power?
my battery pack is only rated at 22 aH. using the AC I would expect the cpap to use about 8 aH for a nights sleep (16 aH if the inverter uses power to work also).
you say that using the direct DC power would be far more efficient, but it looks to me that the cpap would use 21 aH in that same 8 hour period. which would be very hard on the battery pack.
I don't doubt that you are correct, but I'm just having trouble understanding how the DC power would be more efficient on the battery.
Thanks again Jeff!
could you tell me, given the cpaps stated amp draws (which are the max case), how long i could expect my machine to run using the direct DC power?
my battery pack is only rated at 22 aH. using the AC I would expect the cpap to use about 8 aH for a nights sleep (16 aH if the inverter uses power to work also).
you say that using the direct DC power would be far more efficient, but it looks to me that the cpap would use 21 aH in that same 8 hour period. which would be very hard on the battery pack.
I don't doubt that you are correct, but I'm just having trouble understanding how the DC power would be more efficient on the battery.
Thanks again Jeff!
the amp hours for the battery (22) are for 12 volts which is what the battery provides. it will (ideally) provide 22 amps of 12 volt power for 1 hour, or 1 amp of 12 volt power for 22 hours etc.my battery pack is only rated at 22 aH. using the AC I would expect the cpap to use about 8 aH for a nights sleep (16 aH if the inverter uses power to work also).
to get 1 amp of 120 volts it will take 10 amps of 12 volts
power = volts x amps
12 volts x 10 amp = 120 watts of power
120 volts x 1 amp = 120 watts of power
so with a using the AC you need 10 amps from the battery for 1 amp AC output (ignoring whatever the inverter uses) you would get just over 2 hours from the battery pack
Using DC 3 amps you would get just over 7 hours.
But this is not exact, your unit will probably draw less than the listed voltage because that is the max and people who have measured theirs have found it to be much less.
The output also will drop off as the battery gets weaker etc.
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CPAPopedia Keywords Contained In This Post (Click For Definition): CPAP, Power
Here's the deal. The REMStars actually draw less than 1 amp at 12 volts dc, so you might expect about 8 Amp-hours battery consumption per night. BUT, you shouldn't extrapolate that to expect to get 3 nights use per charge on a regular basis from a 22 A-h battery. It all depends on the type of battery.
Normal lead-acid batteries are not designed for deep discharge. They are optimized as "starter" batteries that can deliver high currents (for example, to start a car) for brief periods. They expect to be maintained in a high state of charge. Such batteries cannot take repeated deep charge-discharge cycles without a significant loss in ability to hold a charge. The marine deep-cycle batteries, on the other hand, are designed for a longer term slow discharge and are designed for several hundred charge-discharge cycles. While these are much more suitable for long term cpap use, I don't know of any smaller than 31 Amp-hours. Also, you will want to make sure you have a sealed gel or AGM battery that will not leak, and which can be operated in any position. A standard wet-cell lead acid battery is a major hazard.
The general rule, even for the marine batteries, is that you should not discharge a battery to more than half its capacity. This means that you should not use a 20 - 22 A-hr battery for more than one night between charges. Of course you can do it, but you run the risk of harming the battery.
It is much more efficient to run directly on dc, and to not use an inverter because inverters are only about 80% efficient at low power, and there are additional losses in the ac power supply in the xPAP.
Because we have had a number of short power outages at night, I am now running on a 20 A-hr battery every night with a smart charger to keep the battery topped off. The humidifier runs on ac, so if we lose power all that happens is that the humidifier is turned off. The trick with this scheme is to choose the charger so that it is able to keep up with the current draw, but does not overcharge the battery, since it is left on all the time. A "smart" three-stage charger is the way to go.
Normal lead-acid batteries are not designed for deep discharge. They are optimized as "starter" batteries that can deliver high currents (for example, to start a car) for brief periods. They expect to be maintained in a high state of charge. Such batteries cannot take repeated deep charge-discharge cycles without a significant loss in ability to hold a charge. The marine deep-cycle batteries, on the other hand, are designed for a longer term slow discharge and are designed for several hundred charge-discharge cycles. While these are much more suitable for long term cpap use, I don't know of any smaller than 31 Amp-hours. Also, you will want to make sure you have a sealed gel or AGM battery that will not leak, and which can be operated in any position. A standard wet-cell lead acid battery is a major hazard.
The general rule, even for the marine batteries, is that you should not discharge a battery to more than half its capacity. This means that you should not use a 20 - 22 A-hr battery for more than one night between charges. Of course you can do it, but you run the risk of harming the battery.
It is much more efficient to run directly on dc, and to not use an inverter because inverters are only about 80% efficient at low power, and there are additional losses in the ac power supply in the xPAP.
Because we have had a number of short power outages at night, I am now running on a 20 A-hr battery every night with a smart charger to keep the battery topped off. The humidifier runs on ac, so if we lose power all that happens is that the humidifier is turned off. The trick with this scheme is to choose the charger so that it is able to keep up with the current draw, but does not overcharge the battery, since it is left on all the time. A "smart" three-stage charger is the way to go.
Here's a good site on Battery Tutorial
http://batterystuff.com/tutorial_batter ... 7b5bd1e1#4. You may also want to consider getting a solor panal for charging the battery. They're fairly small and some come with overcharging protection. Check this site http://www.icpsolar.com/specifications. ... _article=6
Stan
http://batterystuff.com/tutorial_batter ... 7b5bd1e1#4. You may also want to consider getting a solor panal for charging the battery. They're fairly small and some come with overcharging protection. Check this site http://www.icpsolar.com/specifications. ... _article=6
Stan
After life, death is inevitable. Everything in between is negotiable.
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Mr_Treehorn
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Derek,
I'm glad to hear that the RemStar pulls less than 1 amp DC. I've emailed the company to find out exactly how much power it uses based on my power setting of 8, but I haven't heard back from them yet.
My power source (for now) is one of those emergency jump boxes from wal-mart. It's a 22 aH AGM motorcycle battery in a bright yellow box. It sounds to me that I may be better off in the long run to take that one back and grab a deep cycle marine battery. I mean after all, I'm going to be using this thing for years to come, and it doesn't sound like what I have now is going to last that long (with the amount of discharging I'll be doing to it every night).
I checked out the link to the solar panel that Stan posted after you. That seams like the ticket to me. Let's assume for a second that after 8 hours of cpap use I draw my battery down 8 aH. Would the solar charger listed at the end of that link (which states a power rating of: 6W (400 mA @ 15V)), be powerful enough to replace 8 aH of power back to my battery pack during the day?
Thanks again for the help everyone. I'm having a good time learning about the ins and outs of batteries and charging!
I'm glad to hear that the RemStar pulls less than 1 amp DC. I've emailed the company to find out exactly how much power it uses based on my power setting of 8, but I haven't heard back from them yet.
My power source (for now) is one of those emergency jump boxes from wal-mart. It's a 22 aH AGM motorcycle battery in a bright yellow box. It sounds to me that I may be better off in the long run to take that one back and grab a deep cycle marine battery. I mean after all, I'm going to be using this thing for years to come, and it doesn't sound like what I have now is going to last that long (with the amount of discharging I'll be doing to it every night).
I checked out the link to the solar panel that Stan posted after you. That seams like the ticket to me. Let's assume for a second that after 8 hours of cpap use I draw my battery down 8 aH. Would the solar charger listed at the end of that link (which states a power rating of: 6W (400 mA @ 15V)), be powerful enough to replace 8 aH of power back to my battery pack during the day?
Thanks again for the help everyone. I'm having a good time learning about the ins and outs of batteries and charging!
Another question about camping with CPAP
Mr_Treehorn,
Check this site out. The PowerFLEX panel may be ideal for camping...
http://electronics.howstuffworks.com/ces20044.htm. Follow the links for more info.
Stan
Check this site out. The PowerFLEX panel may be ideal for camping...
http://electronics.howstuffworks.com/ces20044.htm. Follow the links for more info.
Stan
After life, death is inevitable. Everything in between is negotiable.
Mr Treehorn,
You did not mention specifics about your camping situation. It can range from backpacking to "camping" in a class A diesel pusher.
If you were in an RV you would or could have lots battery power available when dry camping, meaning no electrical hookups.
I am assuming you are car camping in a tent, a wonderful way to camp by the way. Up until recently, I car camped for years and still backpack, now I have a 13ft fiberglass travel trailer for just me to travel and see this great country with occasional outings with a friend or my adult children. Some day grandchildren.
I would not bother with the jumper battery, as mentioned before they are not deep discharge batteries. Look at a larger, and heavier, AGM type battery that you could even leave in the back of car and just run the 12vdc wires pair into your tent. We are talking less than 3 amp dc so it will be a "thin" wire.
You did not mention how many nights or charging scenarios while camped. If it's a long weekend type of outing, I would get a battery with 80 to 100 amp-hr capacity ( 50 - 60 pound ) as you should not draw more than 50%, (40 - 50 amp-hour) to allow battery to last many years. That should supply you with many nights before recharging battery at home.
An AGM battery should always be charged with a 3 step charger as the regular cheapo ones will overcharge and destroy it. An AGM battery is sealed and can be left inside a car, unlike a wet lead-acid battery that can spill acid and at best emit fumes. I am installing 2 large gel batteries inside my trailer. My 420 cpap draws approximatey 0.50 amps at 13vdc and 9cm pressure. Why 2 large batteries, 1) a marine fridge that can draw up to 1.5 amp-hours x 24hrs/day = 36amps/day and 2) I go where there are no hookups, asphalt and hordes of people.
Good luck,
Kermit
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CPAPopedia Keywords Contained In This Post (Click For Definition): CPAP, Power, Travel
You did not mention specifics about your camping situation. It can range from backpacking to "camping" in a class A diesel pusher.
If you were in an RV you would or could have lots battery power available when dry camping, meaning no electrical hookups.
I am assuming you are car camping in a tent, a wonderful way to camp by the way. Up until recently, I car camped for years and still backpack, now I have a 13ft fiberglass travel trailer for just me to travel and see this great country with occasional outings with a friend or my adult children. Some day grandchildren.
I would not bother with the jumper battery, as mentioned before they are not deep discharge batteries. Look at a larger, and heavier, AGM type battery that you could even leave in the back of car and just run the 12vdc wires pair into your tent. We are talking less than 3 amp dc so it will be a "thin" wire.
You did not mention how many nights or charging scenarios while camped. If it's a long weekend type of outing, I would get a battery with 80 to 100 amp-hr capacity ( 50 - 60 pound ) as you should not draw more than 50%, (40 - 50 amp-hour) to allow battery to last many years. That should supply you with many nights before recharging battery at home.
An AGM battery should always be charged with a 3 step charger as the regular cheapo ones will overcharge and destroy it. An AGM battery is sealed and can be left inside a car, unlike a wet lead-acid battery that can spill acid and at best emit fumes. I am installing 2 large gel batteries inside my trailer. My 420 cpap draws approximatey 0.50 amps at 13vdc and 9cm pressure. Why 2 large batteries, 1) a marine fridge that can draw up to 1.5 amp-hours x 24hrs/day = 36amps/day and 2) I go where there are no hookups, asphalt and hordes of people.
Good luck,
Kermit
_________________
CPAPopedia Keywords Contained In This Post (Click For Definition): CPAP, Power, Travel
Last edited by Kermit on Thu Sep 08, 2005 9:46 am, edited 1 time in total.
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Mr_Treehorn
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- Joined: Sat Jun 11, 2005 4:24 pm
Thanks again to all who have offered their time and help.
I do indeed tent camp. Park the Jeep and I'm no more than 50' to camp. No hiking. No Class A camper. I spend anywhere from 2 to 4 nights camping at a time.
Today I took back the jumper battery and grabbed a 115 aH deep cycle battery from wally world. Got a battery box to fit, a few plugs and adapters to make the whole deal work out. Also grabbed a nice "smart" 2, 8, and 12 amp charger to charge things up when I get home.
I look forward to giving it a try in the next few weeks. My wife and I went camping this past weekend and she was ready to leave me at 4am because of my snoring. She has gotten so used to the peace and quiet now that I'm using the cpap, that she just couldn't tolerate my noise. I never could understand how she could tolerate me before the cpap anyway. But I'm glad she did!
Anyway, thanks again everyone!
Jackie
I do indeed tent camp. Park the Jeep and I'm no more than 50' to camp. No hiking. No Class A camper. I spend anywhere from 2 to 4 nights camping at a time.
Today I took back the jumper battery and grabbed a 115 aH deep cycle battery from wally world. Got a battery box to fit, a few plugs and adapters to make the whole deal work out. Also grabbed a nice "smart" 2, 8, and 12 amp charger to charge things up when I get home.
I look forward to giving it a try in the next few weeks. My wife and I went camping this past weekend and she was ready to leave me at 4am because of my snoring. She has gotten so used to the peace and quiet now that I'm using the cpap, that she just couldn't tolerate my noise. I never could understand how she could tolerate me before the cpap anyway. But I'm glad she did!
Anyway, thanks again everyone!
Jackie
I look forward to giving it a try in the next few weeks.
Anyway, thanks again everyone!
Jackie
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Hey Jackie...why wait a few weeks. Why not do a test drive at home by running the machine for 4 or 8 hrs or the # of hrs you usually sleep when camping and see how far your battery drains. You can also hookup your charger and see how long it takes to get it back up to full charge. This will tell you how many night you can run the unit w/o a charge and may help you decide what size solar panel you need if you decide to go that way. Hmmmm...I guess I would want to know what to expect before trying it in the real world. But than, that's me...full of questions
Stan
Anyway, thanks again everyone!
Jackie
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Hey Jackie...why wait a few weeks. Why not do a test drive at home by running the machine for 4 or 8 hrs or the # of hrs you usually sleep when camping and see how far your battery drains. You can also hookup your charger and see how long it takes to get it back up to full charge. This will tell you how many night you can run the unit w/o a charge and may help you decide what size solar panel you need if you decide to go that way. Hmmmm...I guess I would want to know what to expect before trying it in the real world. But than, that's me...full of questions
Stan
After life, death is inevitable. Everything in between is negotiable.
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Guest
Stan,
Will do. I'm waiting on the DC plug that I ordered from cpap.com to show up. I know I could have gone to radio shack to get the plug, but I guess the one that respironics wants you to use is a shielded plug and cord. Nothing like spending $30 for a plug I could have bought for $5 I guess. Such is the price for my fatness.
I'll report my findings to this thread as soon as I get the plug. The battery is charged and ready to go.
Plug should be delivered to my office on the 8th. I'll give it a go tomorrow night.
Will do. I'm waiting on the DC plug that I ordered from cpap.com to show up. I know I could have gone to radio shack to get the plug, but I guess the one that respironics wants you to use is a shielded plug and cord. Nothing like spending $30 for a plug I could have bought for $5 I guess. Such is the price for my fatness.
I'll report my findings to this thread as soon as I get the plug. The battery is charged and ready to go.
Plug should be delivered to my office on the 8th. I'll give it a go tomorrow night.
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Mr_Treehorn
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