Help needed with <span class="highlight">CPAP</span> machine
Submitted: Sunday, Jul 19, 2009 at 17:22
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Homebrewer
G'day all , I am seeking advice , for a friend , on the best way to run a 240 volt
CPAP blower and heated humidifer when 240 volt power is not available.
The unit is a Fisher and Paykel HC 200.
The instructions state , electrical ratings , 220-240 V .. 0.8 A max.
Heater plate power 85 W.
It needs to be used for two nights, so approx. 18 hours.
Is this possible using a car starter battery and an inverter? If so what size battery or batteries , and what size and type of inverter would be required?
We have a 600 watt inverter , would this be suitable?
Would a car starter battery do the job , or is a deep cycle battery essential?
Or is our only option to use a generator? We are trying to avoid the generater option as the
campsite is space restricted , so we will be camping close to others.
Cheers Pete.
Reply By: Peter_n_Margaret - Sunday, Jul 19, 2009 at 17:39
Sunday, Jul 19, 2009 at 17:39
0.8A @ 240V = 200W = 17A @ 12V x 18 hrs = 216Ahrs @ 12V + 20% losses = 250Ahrs.
Allowing 50% max discharge you will need 4 deep cycle batteries @ 120Ahrs each.
If the 'real' power requirement is 100W (not 200W) as is more likely, then you will ONLY need 2 batteries!
It is the humidifier that uses most of the power.
The inverter is plenty big enough for th job, just
check if it is Modified sine wave or pure sine wave. If it is MSW,
check with the manufacturer of the
CPAP machine that it won't damage the machine. PSW will be OK.
Cheers,
Peter
ps...did I do the sums right?
AnswerID:
375217
Reply By: Maîneÿ . . .- Sunday, Jul 19, 2009 at 19:50
Sunday, Jul 19, 2009 at 19:50
I was camping near a woman using a white Fisher and Paykel with humidifier about 2 months ago, it was run from a DC battery, looked about normal size (80ah) was on it for two nights (weekend away) it also run a few lights too.
They had no means of charging other than the Alternator, they did drive around sight-seeing during the day.
I would NOT use your Cranking battery, *unless* it had a "low Voltage disconnect" attached or you were in a group where you could rely on a jump start if it failed.
Maîneÿ . . .
AnswerID:
375242
Follow Up By: Member - JohnR (Vic) - Monday, Jul 20, 2009 at 00:13
Monday, Jul 20, 2009 at 00:13
That sized battery without a low voltage cut out over two nights without recharging would really shorten the life of the battery. A couple of 120s being recharged every day is a better guarantee. The humidifier can use a lot of power, depending on the amount of moisture to be driven off.
I would agree with the latter statement Mainey. Asking for trouble otherwise on a remote trip.
FollowupID:
642535
Reply By: Maîneÿ . . .- Monday, Jul 20, 2009 at 01:11
Monday, Jul 20, 2009 at 01:11
I recently bought a RemstarPro M series, it's paperwork states it draws <1 Amp with-out humidifier and ~3 Amps with humidifier working.
Haven't used it on the 12v system yet, but will be using a 300 watt PSW Inverter.
With
Inverters, I would recommend use of an Inverter rated as close to the total requirement of the powered device as is possible.
(example only) no value using a 600 watt Inverter to charge a mobile phone.
Reason being, there is too much power 'wasted' running the Inverter compared to amount sent to mobile phone, if other items are charged simultaneously it saves
battery power.
You definitely won't require a generator.
Maîneÿ . . .
AnswerID:
375315
Reply By: kend88 - Monday, Jul 20, 2009 at 09:48
Monday, Jul 20, 2009 at 09:48
I have a F & P 220, much the same as a 200. F&P assure me that a modified sw inverter is ok. (Wouldn't try to use it with humidifier turned on). You can leave it attached but off. I have only used
mine the once overnight as a trial.
7 hours took my 100ah AGM from 12.8 to 12.5 so on that basis 2 nights would probably be the max. My inverter is only 300watt so the 600 is probably going to have some wastage.
KenD
bris
AnswerID:
375345
Reply By: Homebrewer - Monday, Jul 20, 2009 at 15:51
Monday, Jul 20, 2009 at 15:51
G'day all ...Thanks very much for the replies , the info is much appreciated.
A couple of decent batteries and a 300 watt inverter might do the job.
Unfortunately the humidifier needs to be used , and that is what is going to eat the power. The heater is used at the half way setting.
Cheers Pete
AnswerID:
375393
Follow Up By: Member - Vince M (NSW) - Monday, Jul 20, 2009 at 19:06
Monday, Jul 20, 2009 at 19:06
Is the humidifier used to stop the dry throat feeling or some other reason?. I do not use my humidifier when camping but I do a couple of things to stop the morning sore dry throat
1)I have found just by having a in-line water
dam this helps (but is hard in winter) but have made a Thermos type wish is great (fill it up with warm water & off to bed by morning its cold when I get up but other than the cold air I have no problems
2) before going to bed have a strong lime drink or the old code liver oil (this helps a lot)
regards Vince
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