# Interest group forums > Energy and Resource Conservation Forum > [Question] Best solution for portable power

## henny

I am not an expert in the field (I actually know very little  I know how to connect a plug). I have sleep apnoea and have to sleep with a CPAP (Continuous Pressurised Air Pump) machine. My problem is I cannot go on holiday to places where there is no electricity available (and that is the places I would like to go to). Can anyone suggest an affordable solution to this for me? 
I want to be able to charge the device using either Solar or from my car cigarette lighter socket.
The following is the information I find on the documentation of the CPAP machine I am using with respect to electricity usage 
(Please note I do not have the 12V DC adapter and I am not sure if it is available in South Africa)

Electrical Rating	115 V  230V AC +10/-15%, 50-60 Hz with power supply unit WM 24480 or
12V  24V DC +25/-15% with DC adapter WM 24469

Power consumption in operation at:
230V    0.1A                                                0.23A
115V    0.2A                                                0.45A
24V      0.9A                                                2.0A
12V      1.8A	Without Humidifier               4.0A With Humidifier

Power consumption on standby at:
230V    0.02A
115V    0.04A
24V      0.2A
12V	   0.4A

Please ask if you need more information

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## HR Solutions

You need some sort of battery pack to charge from solar or your electric charger.  You then plug this battery pack into your cpap and switch to 12v-24v Dc. (You cannot "charge the device")
Very similar to a battery that you can buy for cell phones - You charge it before hand and keep it in case you need to use it to charge your phone.
I know that Sleepnet in Cape town had them at one stage


Or I suppose you could run a cable directly from your cigarette lighter to your 12v input on the machine

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## Justloadit

The issue here is more of how long do you wish to run the unit for on battery power?

Your data shows that at 12V it draws 4Amps. This is a total of 50Watts. If you run for 24 hours, you need a reservoir of 1152Watts. 
If you use lead acid battery, and wish to get a decent life span out of the battery, then a 100Amp deep cycle battery will give you 600W of energy, so you will need 2 off 100Amp batteries. Quite a load to carry around, since they weight about 22 to 25Kgs each. Next if you use solar, and my experience has shown that you will need 2 off 250W solar panels and a charger to get the batteries properly charged in the time the sun shines, and that includes cloud cover, which have quite a large physical size, approximately 1.6 meters by 1m and weight about 23Kgs(each).

So the solution will be quite expensive and possibly a problem to carry around and setup in a rural area for a few days or so.
Yes you can charge the battery up from your car, for the required maximum charge for the batteries, the alternator will only give a usable charge of about 20amps at about 1000rpm, and would require to run your car for about 5 hours. The cost in fuel would be prohibitive.

One of our other members may offer a better solution.

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## PlatinumWealth.co.za

Deep cycle batteries and a ac converter

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## Justloadit

> Deep cycle batteries and a ac converter


Yes and what about charging the batteries on site?
Sine wave or square wave?
What about the losses in the AC invertor, then the SMPS back down to 12V DC. This all reduces battery life.

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## PlatinumWealth.co.za

> Yes and what about charging the batteries on site?
> Sine wave or square wave?
> What about the losses in the AC invertor, then the SMPS back down to 12V DC. This all reduces battery life.


I'm not Google. 

I guide you in the right direction, the nitty gritty is your job.

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## AndyD

> I want to be able to charge the device using either Solar or from my car cigarette lighter socket.


 You say you want to charge it......does it already have its own batteries?





> Power consumption in operation at:
> 230V    0.1A                                                0.23A
> 115V    0.2A                                                0.45A
> 24V      0.9A                                                2.0A
> 12V      1.8A	Without Humidifier               4.0A With Humidifier
> 
> Power consumption on standby at:
> 230V    0.02A
> 115V    0.04A
> ...


 Do you need the humidifier to be on? There's a big difference in power consumption, it uses less than half the power if the humidifier isn't needed.

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## henny

Thank you for all the answers so far.
I have tried the deep cycle battery (105ah) with a 800w inverter (which has now packed up) with a Optimate6 charger but as stated it is a heavy solution and only last 1 and a half nights and the charger work off mains so camping in remote places will not work. I am looking for a much simpler solution but all my investigations work out to be very expensive and big. 
And
No I do not have to use the humidifier.

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## henny

"The issue here is more of how long do you wish to run the unit for on battery power?"

I want to be able to sleep at night (1 night) and then be able to charge the battery again during the day using solar or preferably, from the car as I do drive around a lot.

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## henny

Sorry, no, it runs of mains

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## AndyD

I would look at a scalable lithium ion battery. These seem to be one of the popular ones and they have an agent in SA. https://www.ultrabatt.com/batteries They're not cheap but they're life expectancy is 3 or 4 times that of a lead acid battery and they're about 1/5th of the weight so you kinda get what you pay for.

Then you'd need to decide whether to use a solar panel and charge controller or the alternator on your vehicle to recharge it.

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## Gerald Schaffer

> Sorry, no, it runs of mains


I know it is a long time since your query but I had the same problem and had a battery system made to suit me. *No inverter*. You say that your machine can run on 12V so why invert?  During load shedding I have a 12V battery running my cpap machine (Phillips Respironics) for over 6 hours (tested). I did try and buy a commercial battery unit but was not satisfied that it was what I needed and the cost was high.

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## Gerald Schaffer

This is my setup.  The battery pack was made in Cape Town and does not use an inverter. I have tested the battery pack and it runs my Phillips Respironics CPAP machine for over 6 hours before the drop in battery voltage causes it to cut out. This is more than enough for use during power outages which have been 2 to 3 hours. 
There is no noise as with a UPS. 
It is comparatively small and the cost is reasonable.

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