Solar Panels

grandpabeard

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Hi I am Looking for a bit of advice would like to do more wild camping my only problem is that I suffer from sleep apnoea.This means I must have a CPAP machine on at night all the time I am asleep. I have now found I can get a 12v/230/240v machine. I Have a demountable motor home so recharging the battery while running about is a bit tricky so I thought getting solar panel's would like to know how to caculate the size of the panels to recharge the battery. Can they be fitted easily? Are there specialist firms out there that can advise and fit. Where is the best place to have them positioned. Thanks
 
Hi grandpabeard.
Snap, I also suffer from sleep apnoea. I now have a 12v CPAP machine, but the previous one was mains powered which I ran from a 300w inverter. I’ve fitted a 130w solar panel connected to 3 x 125amp batteries + the normal multi stage chargers. No problems at all.

Cheers Big Trev.
 
Practicality of running the machine often comes down to whether you need the humidifier on as well as the blower because it adds a lot to the power consumption.
 
Thanks for saying that Tony but I do not use a humidifier just the damned blower.
 
No humidifier certainly makes a huge difference to the size of the system you will need.Fitting solar panels is not a difficult job but the first thing is to find out how many amps the unit uses, multiply that by the number of hours you use it and that will give you the Ah you need just for the CPAP. Add what Ah you are likely to use every late afternoon and evening on lights, tv etc to give your normal power requirements each day.

Then it gets tricky.

If you could guarantee good sunshine each day, then you need a battery having a capacity double what you calculated above (because it is kinder to the battery to only discharge them half-way each cycle) and enough panel area to replace that amount of charge in one day. If a panel claims to be an 80Watt panel then it is safer to regard it as little more than half the rating giving say 4 Amps output. Multiply that by say 5 (hours of good sunshine each day) gives you 20 Ah back into your battery. Two such panels will give you 40Ah back into the battery

The tricky part comes because if you want to spend two nights free-camping and it rains all the second day, then you are going to need double the battery capacity and extra panel area to replace the power used when the sun does shine.

For this reason many CPAP users who do want to spend more than one night camping before moving on, often have a small generator and a 20Amp charger to use when power gets tight and you must have enough to run overnight.


Bigtrev will have some good info but you need to check what his free-camping pattern is and relate that to how you want to go. Obviously if you free camp for one night and move on the next day, your problems are far fewer than if you want to camp for a week.
 
Another user!!

I have used CPAP off grid for five nights this summer on an 85ah battery - reserved for the machine. New MH will have 110ah and 85w panel allied with LED lights and I'm hoping to get similar performance without the separate battery (although for festivals i'll probably bring it along at first till i'm sure) I'm hoping when we're touring that the panel will do the trick.
 
grandpabeard said:
Hi I am Looking for a bit of advice would like to do more wild camping my only problem is that I suffer from sleep apnoea.This means I must have a CPAP machine on at night all the time I am asleep. I have now found I can get a 12v/230/240v machine. I Have a demountable motor home so recharging the battery while running about is a bit tricky so I thought getting solar panel's would like to know how to caculate the size of the panels to recharge the battery. Can they be fitted easily? Are there specialist firms out there that can advise and fit. Where is the best place to have them positioned. Thanks
Click to expand...

There's a solar calcualtor here at Solar Amp and Watt Hour Calculator which is a handy little tool for looking at battery sizing and solar panel sizing. If the CPAP is life critical then you need to consider what risk level you are prepared to put on getting a flat battery and then size the battery to meet your risk level; eg if the CPAP draws 30Amp hours overnight you might want to consider a leisure battery of at least 100Amp Hour capacity. Then size your panels to put back at least double the draw down.

Fitting solar panels maybe an issue on a demountable as the only sensible place is on the roof - BUT demountables usually struggle with weight distribution - too much over the rear axle already and adding a couple of panels up high may make handling a tad unpredictable :(

You can buy "suitcase panels" which you just put out pointing at the sun, but security is then a bit of an issue.

The other thing to consider is fitting another leisure battery into your vehicle so that driving around during the day will charge it up, just wire it up so that only your CPAP is hooked up to it. Another leisure battery and some wiring will be about 30% of the cost of solar panels, regulators, etc.

But, I think this is one of those situations when a small generator that has a 12V battery charger connection might be the way to go. Kick the genny up when you get back after a day out, give the battery an hour or two or three and then turn it off for the night.
 
I recently looked at this problem for a caravaner, I would not recommend solar panels as they are limited to having suffiecient solar gain to guarantee your needs are met. I would recommend an EFOY fuel cell which will work 24/7 to keep your batteries topped up fully.

Bob
 
jennyp19 said:
I'm pleased this cropped up, I have same problem, but need the humidifier.
Click to expand...


Staerting point Jenny is to tell us what the machine is rated at as far as power consumption goes.
This will be either on the label or in the instruction book and will probably look like - Rating - blower ?? Watts, Humidifier ??? Watts.

I assume the humidifying heater doesn't run at full power all the time and maybe there is a manual control so you can adjust it??? If so, then you would need to get someone to measure the actual power drawn. I would expect the humidifier would double or triple the power consumption.

Give us those figures Jenny, and we can see what is possible.
Also I would assume that it is a 240V only machine?

Then we need to know what the risks are if the machine stops. Is your life in actual danger, or do you just snore the place down and wake up feeling lousy. No need to get too personal, but it is essential to be able to work out what you need.

In complete ignorance, I would say you will probably need at least two reasonable batteries - AGM if possible to allow a greater depth of discharge - say 120Ah each PLUS a small quiet generator coupled to say a 40 Amp charger.

This combination allows you to run the generator for say 2 hours in the mid-morning to get a reasonable charge into the battery ASAP, followed by say two or three hours in the late afternoon to make sure the batteries are fully charged ready for the night.

Having say 160Watts of solar would help keep things topped right up and could reduce the run time of the generator.

All depends on the rating of the machine. The manufacturer should be able to give you precise figures as well.

LOTS of people rely on these machines and there is no reason why you shouldn't enjoy at least a few days wild-camping, even if you still feel reliant on EHU for most of the time.

Also need a sign to hang on your door letting people know the run times of the generator and that it is running for medical equipment will prevent a bit of aggro.

So basic info needed is

Rating of machine.
Importance of the machine
What rig have you got (weight and space may be critical)
Budgetary constraints.

BTW an EFOY fuel cell is a BIG expense so you would need even deeper pockets than the system I think will do the job.
 
Hi,

As per Tony's request, if I have the ratings of the CPAP, there are a few things that could easily do the job.

Have completed an install based on a nice piece of 12v CPAP kit, problem is that he's off to some serious cold clomate and will be without hook-up for 80% of the trip.

Recent email was that he's going fine in -30deg C and all is working as it should!!
 
And did that machine include a humidifier? I'd imagine that users who didn't normally need extra humidity would at those freezing temperatures because the air is extra dry.
 
Tony Lee said:
And did that machine include a humidifier? I'd imagine that users who didn't normally need extra humidity would at those freezing temperatures because the air is extra dry.
Click to expand...

He has it as a plug in option, but from what I can gather doesn't use it that much. The humidifier is a clip-on attachment, which increases the current consumption by 3-4amps. I will try and find the link the customer sent over and post it here when I can.
 
Hmmm. 4 Amps extra isn't as much as I thought it would be. Total of say 6 Amps is only 50Ah per day. Aim to stay on one site for two nights at a time in-between access to shore power and a couple of 100Ah batteries would just about do the job including supplying a modest amount of power for normal living.
1KW quiet generator and a decent charger (essential to save having to run the generator for hours) would extend that indefinitely without even having to annoy the neighbours.

Normally I would suggest adding enough solar and doing away with the generator, but since this is - or may be - a critical application, solar isn't going to be reliable enough so the generator becomes essential. In Spain or Morocco yes, but not in the higher latitudes.

Yes, a fuel cell would also do the job but unless the user were full time on the road, the cost of that or adequate solar might not be able to be justified.
 
As promised, but have ful PDF spec if needed (please email me nickj@vanbitz.com);

DC Power Consumption: 12 VDC, 3.0 A max.
Type of Protection Against Electric Shock: Class II Equipment
Degree of Protection Against Electric Shock: Type BF Applied Part
Degree of Protection against Ingress of Water: Device: Drip Proof, IPX1
AC Power Supply: (Reorder number 1015642):
Drip Proof, IPX1
Mode of Operation: Continuous
Electromagnetic Compatibility: The device meets the requirements of EN 60601-
1-2, 2nd edition.
Fuses: There are no user-replaceable fuses.

TEMPERATURE 41° F (5° C) to 95° F (35° C)
RELATIVE HUMIDITY 15 to 95% (non-condensing)
ATMOSPHERIC PRESSURE 77 to 101kPa (0 - 7500 ft)

Medical info;

PRESSURE
Pressure Increments: 4.0 to 20.0 cm H2O (in 0.5 cm H2O increments)
Pressure Stability: <10.0 cm H2O (±0.5 cm H2O) ≥10.0 to 20.0 cm H2O (±1.0 cm H2O)
Measured in accordance with EN ISO 17510-1 @ 1/3, 2/3, and Pmax with BPM set to 10, 15 and 20 BPM @ 20° C (±5° C), 50% RH (±5%), and an atmospheric pressure of 101.54 kPascals.
Maximum Flow: 35 LPM Measured in accordance with EN ISO 17510-1 @ 1/3, 2/3, and Pmax with BPM set to 10, 15 and 20 BPM @ 23° C (±2° C), 50% RH (±5%), and an atmospheric pressure of 101.54 kPascals.

There is other alternatives to lugging a generator around, believe me!! The gent that ownes the "Z" motorhome with this equipment has a 220AH Leisure Battery, with a 100A Battery to Battery charger which weighs 6kg and uses his alternator on just "tick over" speed to recharge the leisure battery. He has confirmed that his "run time" on the engine is approx 1 hr's worth to deal with his overall total demand of the motorcaravan in normal use. He still has the back-up of the Efoy fuel cell just in case his heating demand increases due to extreme cold climate. He has done all of this because he wants to use the van as and when he wants, without any restrictions.

Rgs

Nick
 
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