Trying to Understand the Basics

[Sunking]

I have someone from the power company coming out to the house to talk with me about rebates, credits, ect. I would relly like to find a way to work at least some solar into my life but I have allready learned that will not be because of saving money!

OK hes is going to address a Grid Tied System. Depending on where you live, if you borrow the money, and the amount of money your neighbors will pay for your system, you can get a payback in 5 years to never.

[thebrez1]

I got the manual for machine 2 and the output to the humidifier is 2 amps and the machine max is 2.5 amps. So can i figure that without the humidifier, .5 amps is more likely the voltage I need to use in this plan? That would bring it down to 55 watts X 8 = 440 watts plus the 100 watts from machine 1, I would need 540 watts per night. So with a 125 AH battery I would have 1500 watts available so I could run both machines (without humidifier) one night with about a 30% DOD. Maybe a little more than that since I would need the inverter for machine 2.

So, assuming the above is correct, a two battery, 250AH system would give me three nights in a pinch with equipment losses, assuming there is no other draw on the power and no recharge available.

Now, how long to recharge using the 210 panel once the sun comes out after 2 nights of usage or1180 watts removed? How long if I run the generator and plug in a 10, 20, or even 50 amp charger? How can I figure this? Formulas will confuse me, I just have a mental block with numbers. Words I can understand so if you talk it out, it will make better sense to me.

One last question. What if I have the panel and it is cloudy. Can I expect anything out of the panel or would it be enough to bring the battery back even a little bit and extend the three day usage window if no generator were available?

Sooo much to consider, seems like everything effects everything else like a bowl of spaghetti!

[Sunking]

I got the manual for machine 2 and the output to the humidifier is 2 amps and the machine max is 2.5 amps.

At what voltage? We need power, not current. QUIT THINKING AMPS. Think POWER & ENERGY.

Watts or power = volts x amps. Electric Energy = volts x amps x time

Amps are meaningless without voltage and time

[thebrez1]

So with my assumption that .5 amps would be realistic, would .5 amps at 110 volts not be 55 watts? 55 x 8 = 440 watts? If 1 amp at 110 volt would be 110 watts, then the above should be accurate no? Although after reading the whole booklet, it says the actual usage is 11 watts at her pressure setting without the humidifier. So 11x8=88 watts. I guess that is a significant difference from 440. Why? So I am looking at 188 watts/ 1500 watts (125 amp battery) giving me about 4 days, to 50 DOD, and two batteries would give me a week to 40% DOD (not counting loss, temp, ect.). This sounds much more realistic to me. Do I finally get it?

Sunking, thanks for the red, it really helps me get your point. And thanks for bearing with me. I can see why exact numbers are so important, they can make a huge difference!

Just a question, do you have any hair? With a forum full of people like me, I would think you would have pulled it out long ago Thanks again.

[thebrez1]

Can I get a yeah or ney on the final figures above? I need to know that I have this part down

[Sunking]

So with my assumption that .5 amps would be realistic, would .5 amps at 110 volts not be 55 watts?

Correct

55 x 8 = 440 watts?

Huh? X 8 what? 8 hours? If 8 hours then 55 watts x 8 hours = 440 watt hours.

[thebrez1]

That part was ok, just me thinking. if one amp at 110 is 110 then .5 amps must be 55 watts, 55 watts x 8 is 440 and that is what I had. Actual usage from the book was about 11 watts so 88 watts a night not counting losses. So say 90 watts pernight + 100 watts for mine gives me 190/1500 from a 125 amp battery gives me 7.8 nights to 100% DOD (theoretically) so I have about 4 nights max with one battery and one week with a two battery set up.

I have been looking at a Sunforce 1000 watt inverter that plugs into 110 and would keep the batteries charged too, but I am wondering if i would be better off going to a 1500/3000 in case I want to power something larger for a short period. I like the Sunforce 2500 but it is too expensive. Here is the other full sine wave option I was looking at:

http://cgi.ebay.com/OSP-1500W-PURE-SINE-WAVE-POWER-INVERTER-DC-AC_W0QQitemZ350267893228QQcategoryZ85805QQcmdZViewItemQQ_trksidZp4340.m8QQ_trkparmsZalgo%3DMW%26its%3DC%26itu%3DUCC%26otn%3D5%26ps%3D63%26clkid%3D7016841394919374040

I like the block lugs vs. the screw type. Efficiency and power draw do not seem to bad for the price.

Thanks again, I have been reading lots of ther posts an I have to chuckle. Some folks don't like the info you give them. Just likeme, lots of unrealistic or uneducated expectations. At least I don't argue

[Sunking]

I have been reading lots of ther posts an I have to chuckle. Some folks don't like the info you give them. Just likeme, lots of unrealistic or uneducated expectations.

It is a screwed up world today, people hate BLUNT honesty. They like political correctness and being told lies (what they want to hear).

[thebrez1]

So before I end this thread, are my calculations correct as to battery life and what do you think of the inverter, Sunking or the other? Remeber I don't need super efficient, just an emergency back-up

[thebrez1]

Bump for final answer

[Mike90250]

Bump for final answer

how about a refresh post with your final load calculations, watt hour consumptions, days of cloud you want to run through.....

[thebrez1]

2 CPAPs - Actual usage from the book was about 11 wattsfor one, so 88 watts a night not counting losses. So say 90 watts per night + 100 watts for mine (1 amp max at 12 volts x 8 hrs) gives me 190/1500 watts from a 125 amp battery gives me 7.8 nights to 100% DOD (theoretically) so I have about 4 nights max with one battery and one week with a two battery set up.

No solar at this time but I was looking at at some thing in this range:

Manufacturer: Solar Cynergy
Cells: with Q-Cells
Model Name: PV-SC190J12
Max Power: 190W
Open Circuit Voltage (Voc): 21.6V
Short Circuit Current (Isc): 12.1A
Maximum Power Voltage (Vmp): 17.2V
Maximum Power Current (Imp): 11.04A
Weight: 40 pounds
Dimensions (inches): 61 3/4" x 37 1/2" x 1 5/8"

What would work for keeping the batteries charged and how many? What would you recommend for this set up?

Thanks Mike and could you take a look at the inverter. Remeber this is for emergency backup.

I have been looking at a Sunforce 1000 watt inverter that plugs into 110 and would keep the batteries charged too, but I am wondering if i would be better off going to a 1500/3000 in case I want to power something larger for a short period. I like the Sunforce 2500 but it is too expensive. Here is the other full sine wave option I was looking at:

http://cgi.ebay.com/OSP-1500W-PURE-S...41394919374040

[Mike90250]

2 CPAPs - Actual usage from the book was about 11 wattsfor one, so 88 watts a night not counting losses. So say 90 watts per night + 100 watts for mine (1 amp max at 12 volts x 8 hrs) gives me 190/1500 watts from a 125 amp battery gives me 7.8 nights to 100% DOD (theoretically) so I have about 4 nights max with one battery and one week with a two battery set up.

88Wh rounded up to 100Wh per night #1
?? for CPAP #2


12V 125ah battery = 1500 wh

No solar at this time but I was looking at at some thing in this range:

Manufacturer: Solar Cynergy
Cells: with Q-Cells
Model Name: PV-SC190J12
Max Power: 190W
Open Circuit Voltage (Voc): 21.6V
Short Circuit Current (Isc): 12.1A
Maximum Power Voltage (Vmp): 17.2V
Maximum Power Current (Imp): 11.04A
Weight: 40 pounds
Dimensions (inches): 61 3/4" x 37 1/2" x 1 5/8"

What would work for keeping the batteries charged and how many? What would you recommend for this set up?

That panel and a PWM charger could keep the battery going for some time. I'm still not real confidant that you have your loads right.

Thanks Mike and could you take a look at the inverter. Remeber this is for emergency backup.

I have been looking at a Sunforce 1000 watt inverter that plugs into 110 and would keep the batteries charged too, but I am wondering if i would be better off going to a 1500/3000 in case I want to power something larger for a short period. I like the Sunforce 2500 but it is too expensive. Here is the other full sine wave option I was looking at:

http://cgi.ebay.com/OSP-1500W-PURE-S...41394919374040

That's likely a crap (not CPAP) inverter, the listing is pulled already.

I'd strongly suggest the Morningstar SureSine 300/600w inverter.
One CPAP based website sells a 300W mod sine inverter @ $175, but even many of them are junk, and a 1500W inverter will pull more power for it's overhead, then the CPAP consumes.

[Mike90250]

OK, I wussed out, and bought a commercial product! We have a small sleeping hut built on the ranch now, but no power in it yet. It's going to take a while to mount a panel, batteries, charge controller, wire up lights and such, and we arrive at nighttime, and no where to plug the CPAP in ! So I spent a couple days pricing out different ways to accomplish this, and settled on a portable jump start pack. Found a model with good reviews, and no air compressor (that often fails after 50 total minutes of use). Located one in stock at local autoparts store, and bought it, taking a chance it's been parked in a warehouse for a year, and then in the back room for 2 more years, resulting in a flat, sulfated battery. (fully half of the complaints at Amazon)

Other choice was to get a AGM battery, rig up a case, cigar jack outlet, charger and hope it still fits into the car.

Upon opening it up, and throwing a voltmeter on it, I was pleased to find it reading 12.85V on a warm afternoon. It's built-in indicator showed it was 4/5 charged - also good. I plugged it's wall wart (transformer, not switcher, 12V, .5A) in, and let it top it off for a couple hours, it came to quiescence at 13.37v, and I unplugged it. After an hour, it read 13.13V. Awesome! And the Respironics power cord appear to fit snugly into the lighter jack.

Using my kill-a-watt before I was shopping, I'd discovered that the CPAP consumed about 75 watt hours in a 6 hour run, and that for 2 nights, I'd consume about 12.5 ah of battery. The "450A packs" claim to have an 18AH AGM battery in them, but I figured, I may as well have a portable unit, than a hulk that will last me a month. And if I only ran it one night (6.25 AH consumed) and then recharged, it'd live a long lifetime. Well, the power brick for the CPAP is a pig. After running all night (6 hours) , the voltage in the AM, read 12.66v Whoo hooo! Internal battery indicator LEDs still showed 4/5 charge, way less drain than the power brick used (all my testing is done with humidifier OFF) so even though the brick read about 3 watts idle, it was using more with a light load.

So, this will recharge at my shop, and I think I'll get a plug in lamp timer, and set that for a 1 hour charge daily, to keep it topped off between visits. And since the shop is on solar power, now my CPAP is too!

Added benefit, the power pack has a LED lamp built in, and a USB power port, so I don't even need a cigar plug Y cord to charge my phone and PDA.

So, I've owned this less than 2 days, but I think it will do the job I need it to, and it's not DOA out of the box. It can also charge via a running car too, but I've not tried that yet, I think I can also feed it from a 3 stage charge controller set for AGM. And it can jump start the tractor too, if I need it.

And it was a lot less than the $$ soft side 14ah CPAP battery pack. I hope the AMA does not come after me!