Solar Power?

Hi John,Val thanks.
The only details that I can find are,
CPAP 200.
240v sup freq 50-60hz
it also has 240~0.60amp
Don't know if that helps but that's all that is in the book.
My X power rates at 20 ah
mod sine wave
output 50hz + _ 4hz.
Thanks

Bushy,

The current drain ( 0.6 amps) of the cpap 200 seems pretty high, but it does include a humidifier which probably accounts for a fair bit of that power. At 240 volts that's about 150 watts. If this power is drawn continuously for say 8 hours, that's about 1200 watthours required overnight. To supply this much power using an inverter (probably about 80% efficient) from a 12 volt battery will require from the battery a current of about 15 amps. That 1200 watthours is equivalent to about 120 amphours at 12V.

Your Xpower pack is rated at only 1/6 of that, but it gets worse - although the power pack is rated at 20 Ah, that will assume using all the energy in a perfect fully charged battery. No battery is perfect, they are rarely 100% charged, and have a very short life if repeatedly 100% discharged.

IF (and this is the critical if) the 0.6 amps at 240 volts is correct and IF it is a continuous drain, then you will require much more battery capacity than the Xpower unit. If all the above is valid, you will need about 120 Ah each night. To get reasonable life from the battery it shouldn't be discharged beyond about 2/3 of its capacity, and should be recharged fully each day.

Consequently, you will need about 200 Ah of battery capacity. That's about the size of two of the batteries you'll find under the bonnet of a big 4WD. The other problem is charging them. Putting 150 Ah in every day (120Ah plus margin for inefficiency) will call for a fair amount of driving, probably a special charger (eg Arrid or better) and/or a lot of solar capacity. (150 Ah from say 6 hours of good sunshine will require 25 amps - that's a lot of expensive solar capacity, probably about 400W of panels, and of course the sun doesn't always shine.

It's not good news. As already suggested, you might find an alternative machine, one that is intended to run from 12V a more viable option. Any machine though is going to be pretty heavy on power requirements.

A final point to dampen any remaining enthusiasm! - The machine may not like the modified sine wave from the inverter. I would expect it to be a bit noisey and this will indicate inefficiency resulting in heating.

Not good news but I hope that helps. You might find our blog Electricity for Camping interesting as it discusses power requirements and solutions, though not on your scale.

John

Bushy, John has given you a very good break down of what you require. Many deep cycle batteries will require long charging times. I have the same problem with the AGMs in the Karavan so have installed a Ranox that allows me to tailor the charge that goes to a particular battery set. I had that in the Karavan but am just installing it in the car now to better charge the additional batteries I have for non-trailer trips. It has given me a capacity to fill to 100% according to my meters. Never before the Ranox could I approach that.

John has given you a good picture of the battery power require and perhaps a 300 watt quality inverter if you aren't looking for a 12v CPAP with humidifier.

The Ranox has a range of charging capabilities up over 14.6v charging and up to 25amphours at that voltage. All decided by two switches on the face panel. Good for AGM batteries for a bulk rate charging, and drops right away for float. When I was looking at Arrid, I couldn't get enough information as to performance to decide to go that way. You really do need a three stage charger with high charging capabilities, to charge from a car.

Just a point on the car - you don't say what it is. Some cars drop their charging capacity quickly after reaching temperature to minimise fuel consumption. That often will not charge additional batteries. That is where the Ranox can output a completely different charge rate to what it takes in. Take in at 11.6v and charge at, say, 14.2v. Nothing is simple in charging additional batteries.

Have done the search in the directory but does not explain everything.
Just trying to find what members might have done.
Thanks.

No new cpap on the horizon yet so have to make do with what she has.
Solar is something that I would like to set the van for self supply with the 3 way fridge on gas and the rest solar.
Thanks for your idea's.
Bushy.

Bushy,
Maybe make your long term decision to set up for solar power, start with 1 x large capacity panel now, with the knowledge you can add a few more at some other time, so you have to use a solar regulator and panel fixing system that will be suitable for the future expansion of your solar system.

Maîneÿ . . .

Good idea Mainey , will work on that it's a good idea.
Bushy