Zamp Solar Cell Purchase

geospectrum

We purchased a T@B CS-S this year and would like to do a lot of dry camping in British Columbia. We would like to get a Zamp Solar Cell (ZS-200-P) but wonder if this is overkill. The main electrical draw is the Norcold refrigerator (model NR 740 BB, 2 way [AC/DC],DC 12V/24V - 5.5 Amp, total input 75W) and a ResMed CPAP S9 (2 way AC/DC, 70W, 80VA) that is run at night. Can I get away with a smaller unit to keep the trailer battery charged every day we are dry camping? Zamp has not been as helpful as I would have thought so I hope a fellow T@Ber can help me. Thanks in advance.

Geospecrum

Verna

Actually, the Zamp 120 Watt Solar Panel is the lowest amount of solar recommended for a T@B, but with the fridge and the CPAP, you are actually closer to needing the Zamp 200 Watt Solar Panel.  Don't forget you'll probably be using the water pump for water, the lights for seeing after dark, the fan in the fridge, and the parasitic draw of the Jensen sound system, the CO detector, the smoke alarm, and whatever else there is.  Yes, the 200 Watt would be best for your case. 

Nomad

Verna - Wouldn't the CPAP be running off the battery at night so the battery capacity/longevity would be the limiting factor as long as the solar managed to charge the battery during the day. If so, wouldn't a better investment be more battery and just 120w on solar.

T@Buhura

PXLated's right about the CPAP running on battery... although depending on how late into the summer and how far north in BC, Geospectrum may still get at least a supplemental trickle off the midnight twilight. From the sounds of it 120W may suffice to power the fridge and maintain the battery. Figure 120W should be good for about 8 - 9amps. Remember, Power = Voltage * Current, so if  you have a 120W system at 14.8v the current should be 8.1A. BUT, I'm not familiar with Zamp and quality of the panels although I've heard a lot of great things about them in this forum. By comparison, I've seen 100W Renogy panels compared to 90W German made Bosch and the Renogy only put out 1A while the 90W put out 5.7A. Do the math and the Renogy is really only putting out like a 15W system while the Bosch was a 84W system under comparable sunlight conditions.

In fact we just got back from a 1 month Alaskan adventure and used 60W Bosch panels to keep us going. The only draw we when setup was the fridge (running on propane which still draws electricity to power the fan periodically), run the CD/radio, 50W ham radio occasionally, and charging up iPhones and iPads. I'm not sure what the draw is in propane mode so the 3.8-4amps the 60W put out was plenty to keep our battery in top shape.

We dry camped all but 1 night and go figure, the one night we plug in to 30A the battery got depleted completely. I just checked and the converter is not putting out 13.6v and thus while it was plugged in I thought it would be running the roof fan, lights and I also may have inadvertently run the fridge on 12v instead of 120. Needless to say our battery was beyond dead and unrecoverable.

Lisa33

The battery is always the primary limiting factor since it can only "get so full" during the day.  For best results, it's important to have the solar panels match the battery capacity (roughly 1w of solar per amp hour of battery).  I'd recommend a second battery and 200 watts of solar.  Check the weight and dimensions on those panels, though.  They are going to be big.  

Verna

PXLated said:

Verna - Wouldn't the CPAP be running off the battery at night so the battery capacity/longevity would be the limiting factor as long as the solar managed to charge the battery during the day. If so, wouldn't a better investment be more battery and just 120w on solar.

Not all CPAP machines are 12V. According to what I have read about Mike's CPAP, most are 110V, which would then take an inverter to work. 

Verna

Lisa33 said:

The battery is always the primary limiting factor since it can only "get so full" during the day.  For best results, it's important to have the solar panels match the battery capacity (roughly 1w of solar per amp hour of battery).  I'd recommend a second battery and 200 watts of solar.  Check the weight and dimensions on those panels, though.  They are going to be big.  

Thanks, Lisa. I forgot about the battery...always one thing

jkjenn

You can get CPAPs that are lower power draw. It might be worth the investment.

geospectrum

My CPAP came with an AC/DC converter with a 110 V plug. With the T@B in mind I also purchased a DC/DC converter 24/90W with a cigarette plug for the trailer. I only plug the CPAP in before I go to sleep and pull the plug first thing in the morning to prevent excess draw. Thanks for all the suggestions. I haven't found a dealer that has a 200W Zamp unit so I don't know the actual size Zamp has them (back ordered until August/September).

Nomad

Don't know the actual size Zamp...
The Zamp site has dimensions/weights of each (bottom of page) - Surprised the LG shop doesn't.
http://www.zampsolar.com/product/200-watt-portable-solar-charging-system-zs-200-p/

RuthieB

Verna said:

PXLated said:

Verna - Wouldn't the CPAP be running off the battery at night so the battery capacity/longevity would be the limiting factor as long as the solar managed to charge the battery during the day. If so, wouldn't a better investment be more battery and just 120w on solar.

Not all CPAP machines are 12V. According to what I have read about Mike's CPAP, most are 110V, which would then take an inverter to work. 

How do you use the invertor? We got our T@b in late June and are still figuring things out (and not doing a very good job). We bought generators and are going to buy the zamp solar 120's. I use a cpap and want to use the 110v off the battery.

Verna

Ruthie, you would need to buy an inverter that would either wire directly to the battery or plug into the 12V accessory plug (formerly known as the cigarette lighter plug). You'll need to find out how many watts of power your CPAP takes and buy your inverter according to that size. And you will need to buy a Pure Sine Wave inverter. This is a better inverter that will not ruin the electronics in your CPAP machine.  (do a search on Anazon to see various choices of 

For instance, I had a 300 watt inverter last winter that would give me 300 watts of power IF I wired it directly to the battery with the appropriately sized wires (see the directions when you buy it). Since I plugged the inverter into the 12V plug, it only gave me 100 watts of power. My laptop needed 90 watts to charge the battery, but the 100 was not enough to charge the laptop. So, be sure to get a larger size than you actually need. 

If you use a generator, I am not sure if that is pure sine wave coming out of the generator. You'll need to read the generator's paperwork to figure that one out. But, if it is pure sine wave, you can run the CPAP off of the generator. But, only if you are where you can run the generator all night. 

Yes. This can get complicated, but you need your CPAP, so you'll need to figure all of this out.  So, now ask your questions that I'm sure came up from this info. Not trying to built your intelligence, just trying to help. 

jcfaber1

I have the Resmed S9 autoset and purchased their 12V power supply.  It works great.  I second the larger battery 225 AH golf cart batteries along with 200 Watts solar.  Here's a picture of my Renogy  setup

jkjenn

You will use less battery if you can get a 12v power supply for your CPAP. I echo the support to increase your battery capacity. I switched to 2 golf batteries this summer. Huge difference. Also, watch your fridge use on battery. If you have a 3  way, you would deplete very fast on battery.

jcfaber1

geospectrum, the below link is the 12V power supply for your CPAP ($89).

http://www.cpap.com/productpage/DC-Converter-For-S9-Machines.html

It is way more efficient to use the 12V power supply than to use an inverter.  I use my humidifier with the heat level turned down some (68-70deg) but I am significantly more comfortable with the humidifier than without.  I require 5-10lbs of air pressure.  Resmed has charts on estimated amps used for 8 hours sleep with differing pressure settings.  These charts are very conservative(overstated) in their power consumption.  I also talked to some of their engineers and found them to be very helpful.  We have 225AH batteries.  Our usage is with the 12V fridge, lights, CPAP, fan resulting in use 10% of battery capacity per day.  With the 200 watts solar we get back to 100% of charge each day if there is sun.  Happy sleeping while boondocking!  Boondocking is the best camping in my opinion.

John

RuthieB

Verna said:

Ruthie, you would need to buy an inverter that would either wire directly to the battery or plug into the 12V accessory plug (formerly known as the cigarette lighter plug). You'll need to find out how many watts of power your CPAP takes and buy your inverter according to that size. And you will need to buy a Pure Sine Wave inverter. This is a better inverter that will not ruin the electronics in your CPAP machine.  (do a search on Anazon to see various choices of 

For instance, I had a 300 watt inverter last winter that would give me 300 watts of power IF I wired it directly to the battery with the appropriately sized wires (see the directions when you buy it). Since I plugged the inverter into the 12V plug, it only gave me 100 watts of power. My laptop needed 90 watts to charge the battery, but the 100 was not enough to charge the laptop. So, be sure to get a larger size than you actually need. 

If you use a generator, I am not sure if that is pure sine wave coming out of the generator. You'll need to read the generator's paperwork to figure that one out. But, if it is pure sine wave, you can run the CPAP off of the generator. But, only if you are where you can run the generator all night. 

Yes. This can get complicated, but you need your CPAP, so you'll need to figure all of this out.  So, now ask your questions that I'm sure came up from this info. Not trying to built your intelligence, just trying to help. 

ok starting to make sense. I'm headed out to read manuals talk to cpap people etc. thanks so much

Verna

RuthieB said:

  ok starting to make sense. I'm headed out to read manuals talk to cpap people etc. thanks so much

Good.  We can "talk" when you've talked to the cpap people.