I’ve changed the name of this series to reflect the now-higher level of expertise appearing on this thread. Continued from here
Part 7
Part 6
Part 5
Part 4
Part 3
Part 2
Part 1
ANON-YYZ at 11:42
Dennis in Colorado at 20:48
I will defer to Professor Eccles for the technical assessment.
Otherwise there are few main considerations relating to generators for pandemic preparedness:
1. noise
2. fuel storage, maintenance and sustainability.
3. DC or AC appliances, or usually both
4. installed transfer switch or portable
With these in mind, it is easy to see there are really two options:
1. whole house large generator with installed transfer switch
2. portable generators that has native DC output and sinewave AC output.
Finally, fuel storage is a serious problem for pandemic preparedness. You may wish to consider propane instead of gasoline or diesel.
I have given up on whole house generator - too expensive and burns too much fuel too quickly. If its pandemic, my life style has to change.
On portable generators, the two main players are Honda and Yamaha. Yamaha is a bit quieter and also has a 6200W propane model in Canada
This is available from Northern Tool Canada (but not on U.S. website)
Then there is a small company that is authorized by Yamaha to sell a tri-fuel models (i.e. warranty intact)
This company also sells propane conversion kits for small generators made by Honda, Coleman, etc. A bought a kit for my Kipor 2000 and it works, but there was a lot of delay in delivery (their phone lines are hard to get through). If I were to do it again, I probably would have bought the Yamaha EF2400is trifuel model.
The Honda, Yamaha, Kipor digital sinewave models are relatively quiet and also have smart throttle which idles at very low fuel usage and automatically adjust throttle based on electrical load.
Hope this helps.
dbg at 00:36 Consumer Reports didnt list a Best Buy in the 28003600 watts group
What was their top-rated generator in the lower-power group, even if it is not a Best Buy? Ill get a copy of the magazine as soon as it is available here; right now my store still has the September issue.
perusing the last few threads, I didn’t see this:
low cost, very low power, solar powered refrigerator: http://www.fieldlines.com/story/2006/1/11/22240/6609
and aren’t diesel generators more reliable?
I’d feel better about that freezer if the author had measured the power consumption instead of writing, “Assuming a 100W current draw…” I’d feel even better if he or she knew the difference between current and power.
Pfwag at 18:53
‘arent diesel generators more reliable? ‘’
My concerns about diesel (please correct if I am wrong):
1. cold weather
2. fuel storage - not sure if diesel can be kept for long period
3. don’t believe small/quiet/digital/efficient diesel generators are available - see fuel storage problem
Dennis in Colorado
Consumer Reports issue gave top marks to the small Honda generator with a tested output of 3000W, but it is almost four times as expensive as the other two. Midsized they gave a best buy to the Briggs and Stratton Elite 30242.
BB at 14:49. Does that mean we dummies must post elsewhere now? ‘Bungled Preps that Failed’ or whatver the name of the thread is …. ? :-)
The experise is certainly here, to the immense gratitude of those of us much lower in the learning curve.
When we lived in the frigid Northeast (Connecticut), we used fuel oil to heat our house and get hot water(along with a woodstove later). My neighbor, who at one time worked for the local fuel oil company, mentioned on more than one occasion that instead of diesel oil for their trucks, the company would just pump in fuel oil and add a bit of kerosene to it to thin it. The argument was that in the cold months of winter, diesel tended to gel, and not be very efficient, whereas heating oil didn’t have the same problem.
Could the same be used for diesel generators, considering heating oil is still a bit cheaper than diesel at the pumps?
blackbird at 19:24 --- The experise is certainly here, to the immense gratitude of those of us much lower in the learning curve.
That’s why I don’t post on this series very often…”lack of expertise”. I just read and learn… :-)
I have used solar power and back up generators for years. There is a good reson why Honda generators are more expensive. You get the value that you pay for, just like with any tool. Home Power mag ran tests some years back and found that cheap( read Briggs and Stratton) engines last an average of 350 to 500 hours. If your life depends on it don’t buy cheap weapons or cheap generators. Kelly
Hi all, quiet would seem to be a factor in selecting a generator, especially during a pandemic when keeping a low profile is a good thing. How do y’all experts rate quiet vs reliability/quality? I’d think they are related.
bttt
Eccles or others - do you have any experience with solar-powered battery re-chargers? I came across one the other day and thought that might be VERY useful. It was one of those universal kinds that can re-charge all sizes, the larger ones taking longer to fuel back up. Thanks.
On generators: if you have a trusted electrician, pick his brain. Mine uses several different portable ones for job sites and said there definitely is a difference in quailty, noise, etc. He’s helping me out in sharing his reserach for a larger portable for his own house.
LauraB-
I have been using a Solar Walk light as a charger for AA cells for several months now. Depending on how large the solar cell that associates with the charger, it definitely can recharge batteries using the sun. You especially need to be aware of where the charger is pointed during the day to keep it looking at the sun for the best performance.
Again, depending on the size of the cell, it can possibly charge a few batteries per day. This also depends on the day length. In my location, things charge fairly well if it gets all day on a clear day in mid summer. Even now, as the days are shortening, there is insuficient charging time to completely fill the AA cells that it was filling just a few weeks ago. In mid-winter, this will be a very difficult device to get substantial productivity from.
Just realize that a solar charger is what it is. It charges batteries from the sun. it will provide you with a little bit of battery power. If you expect it to provide unlimited charging for an unlimited number of batteries, you will be very disappointed.
A different approach that I can also use here is to connect a larger (15 watt) solar panel up to run a battery charger designed to run from the cigarette lighter in a car. Because of the (much, much) larger size of the solar panel, it provides sufficient power to charge a whole pile of batteries in a day. But then, I can’t carry it around easily.
Presently have a gasoline driven genset. Air cooled 18 hp B&S engine, it has about 100 hours on it, and is reliable. Rated for 7.5 KW continuous 13.5 peak.
I am currently buying and installing a 20 hp slow speed diesel which will run on WVO, waste motor oil, kerosene, diesel, HHo; basically anything that’s oil. These engines are known to run 40,000 hours between rebuilds; service is easy and parts are readily available. It’s married to a 15 KW marathon genset. Longer term, I plan for a steam engine to run my genset; that burns anything combustible.
Diesel or HHO will last for over 10 years in storage if treated; kero lasts longer; gas may go a year or two with treatment; past that it gets pretty pukey. Propane is not something I have any experience with, but since it runs rich, like a gas engine, it will not be as efficient per btu as diesel. Also, you need propane to run a propane genset. In my judgement, the preferred order for longterm use is-
Steam;
diesel;
Propane;
Gasoline;
LMWatBullRun at 10:10
Interesting comment about ‘large’ diesel generator. What is your estimate of how much diesel you need per KWh? I know it’s apples to oranges, but just to get a sense. In ROI terms, how does diesel compare to solar or wind?
This looks neat, but costly, just to charge 4 AA batteries-and I don’t know if another gadget is necessary also, because all that shows is the foldable panel. tempting, in a sorry, I-just lost-my-mind-for-a-minute-and-bought-it, way.
LauraB at 07:05
Several months ago I bought a little solar battery recharger. It will accomodate 4 AA batteries at a time. It takes about 3 full days of sun to recharge 1200mAh batteries. After finding that out, I’m glad I didn’t pay too much for it. It works, and I will use it, but anything I would power with those batteries would drain them a LOT faster than it will charge them back up.
I’m doing what Eccles said. I’ve got several of those 15W panels and I’m finding the best places to use them, both inside and outside the house. They do the job a lot faster!
Jane- the items your link shows are just foldable solar panels. Since their outputs are on the low side, they call them solar battery chargers. The prices shown on the page you linked to made me gag when I saw them. Without editorializing too much, I will just say that you ought to be able to do a whole lot better on the price.
Eccles at 07:30
Are you going: solar panel → battery charger
Or: solar panel → 12V battery → battery charger?
Eccles - Can you list a few sites that have the stuff we need? Can you recommend a quiet generator? We do have a back up heating scource secured now we need to work on the electricity.
This is my last area to prep for…I left it to the end because it may as well be rocket science because I know nothing about any of this stuff. I ran around buying all sorts of batteries, lamps, clear oil for lamps…lots of it…but I don’t know what I am doing. I just wanted to have it in the house in case things popped quicker than I thought.
You are one of the heros of this site and you have come to my rescue before and I thank you!
Eccles at 12:43
What is your favorite SW/AM/FM receiver?
Eccles and HBB - thanks! I figured it sounded a little too good to be true. We are thinking about something like you described Eccles - would that be sufficient to run a lap top for awhile?
Right now I have one of my solar panels hanging inside of a southern-facing window and it is charging a 12 volt deep-cycle battery. Once the battery is fully charged I plan to use it to power a laptop for a few hours. Then I will see how long it takes to get the battery back up to full charge again using just the panel. I expect to be disappointed from previous experiences. I do enjoy doing these field tests to see how well what I have on hand will work in an SIP situation.
Eccles - I have been reading past threads and now have some ideas. You are probably sick to death of people asking you the same questions for the past year, but in our defense, I found it easier to just jump in and learn enough of the science to get the gist of what is going on, but this stuff I have not gone near.
Anon-
I have calculated that I can run my entire household including AC during the summer for about 8 gallons of diesel or equivalent per day; I am also using a large solar panel array (~2000 watts). Since I plan on a large storage tank, I expect to have at least 100 days of run time continuously available. If I need to reduce consumption I will at least have the solar to fall back upon.
Seacoast-
I’m not sick to death of people trying to create a backup capability. I figure every person I help is that many fewer that will be out roaming the countryside hungry and afraid later.
Some of this stuff is contagious. Some of the folks I help can then go and help a few more. it’s like a giant pyramid scheme. (Except I don’t get to collect on the part where you put $5 in an envelope to me and then send the list to ten friends…)
I am happy to inform you all, that me and girlie will move to the countryside for a year or two :) Its not a pandmic panic thingie ( I still belive sentral urban living is ok all considered, safty is comunity, not guns), but we got evicted by the landlord due to a burning hot real estate marked here in the downtown. So we say f***k you, we will live the rabbits and carrot life :D
We will rent a old nice small house in a Pipi Longstocking like valley 30 minuts from the city. Since we are renting I can not build my solarheated dreamhouse, but we have a wood oven (of course) and have a well in the basement!! with electric pump. (need a handpump as backup) and I will invest in a kerosene stove http://tinyurl.com/py6l6 to use in my new workshop. We got a garden and I will grow beans, jerusalem artichokes and potatoes next spring ;)
Will keep you updated on the kerosene experiense. I am also wondering if i can feed my entire 230v AC net system with 12 volt DC for light in a emergency. Just by killing the main svitch, and plug a carbattery into one of the sockets after unplugging any 230 apparatus.. Got alot of 12v LED lamps with ordinary lampsockets.
Urdar -
1) Lots of luck in your new place. I hope you and your yoing lady are very happy there.
2) I hope you will continue to have access to the internet so that we can continue to get the benefit of your inputs.
3) be very, very careful about using the 230V wiring for 12V operations. One single mistake and your entire emergency capability can go up in a puff of smoke.
Take care of yourself.
th:D a ADSL line is essential, and is taken care of. I know the puffs and the poofs. But idea is instead of putting cables around the house in a blackout, I would instead turn of the main saftey switch. Then I guess im completly off grid.. If the differnet internal house parts grid is still conected together, and I have made sure that there is not a single 230v apparatus conected in their sockets or have been turned of, I guess I can use the wire and sockets system for 12v. The ledlamps is mixed polar, so + - dont matter. I know that 12v is not suited for long stretches of cabel, but the lamps uses so litle amps I think it will work all over the house.
The smallest problem would be to register that the grid power is back, a look in the window will tell me that.
let me specify.. there is three types of atomatic safty swithses her in Norway. Tha main one (that I guess disconeckts the grid) The ground switsch ( I guess it does the same) And then there is the singe parts of the house switch (like kitchen, water heater, living romm etc. If I use a voltmeter with the “piiip” function I can safly find out if the different parts are still conected when main is of. If so, this is the simplest emergency light solution. Most have a full car battyery, and a number of 12v ledlamps can go for weeks on one battery. Of course a more simple way would be to use your ordinary extension cords around the house .Tehn you would know for sure what is conected or not.
this is great with an 230 v ac inverter for solar/car battery
http://www.dotlight.de/shop/product_info.php/cPath/203_213/products_id/669
this is for simple 12v dc
http://www.dotlight.de/shop/product_info.php/cPath/203_210_248/products_id/676
and this are cool but not very landfill friendly… for AAA! batteries
Eccles, thanks for the reality check on those folding solar panels. That company has battery chargers which demand much larger panels than those, another warning sign.
For everyone, here’s a site for finding out if your state has incentives for adding/switching to alternative power www.dsireusa.org Illinois has a minimum requirement of 700W system, and there’s a finite amount of money available, not sure if it’s possible to find out if there’s any left before putting in a system.
For those looking for solar panels, you might want to take a look at this one.
OK, it’s only a 15 watt panel, but it is easily portable, comes with a lot of handy accessories, is completely waterproof and does perform well even on cloudy days. A few of these and a deep-cycle battery for atorage would give you a way to collect energy and use it for recharging lanterns and batteries and powering laptops and small TV’s.
We had the remenents of the Hurrican pass through NY last week. We lost power for 4 hours from 4pm to 7pm. I finally tried my inverter off my Jeeps battery while it was running and it worked great for the little ones to watch tv on.
Okidokie, were you driving around? If not, I thought it didn’t help if the motor was running, if the vehicle was sitting still. If the car is moving, it’s recharging, but if it’s just sitting, it’s draining whether the engine is turned on or not. If I’m remembering the lessons correctly, that is.
The fan belt turns when the engine runs, the fan belt turns the alternator keeping the battery charged. The battery only discharges when loads (electric usage) are present. Loads can be the radio, headlights, interior lights and miscellaneous engine draws. You can run the inverter, but the battery drains. The inverter has an alarm at 10.6 volts and automatically shuts down at 10.2 volts so not to ruin the battery.
Okidokie- Just a warning. if you run a car battery down to 10.2 volts a few times, you will find that you are, indeed ruining it. they’re not built to take a whole lot of discharging to that depth.
The engine draws on the electrical system are pretty large. Most gasoline powered cars these days have electronic fuel injection systems with electric fuel pumps, typically fused for around 30 amps. The engine controls are fused for another 20 amps or so. Now, they don’t draw that all the time, but it still makes that 75 amp alternator look a lot smaller. Also, the alternator typically needs about 1500 engine RPM to produce its full rated output. At idle, the amount of surplus electricity is rather limited.
SIPCT at 18:23
“At idle, the amount of surplus electricity is rather limited.”
It sounded like he was powering a TV only. Maybe 150 watts? So the question is:
How much is the limited surplus? 150 watts worth of limited surplus?
“OK, its only a 15 watt panel, but it is easily portable”
On a hot summer night, it would be nice to have a small 12 volt fan to move the air a little to get to sleep. Does anyone have any fans in mind that would work well with limited watts?
Seacoast et al,
I’ve compiled [[http://pandemic-plans.com/Files/Page2.html|webpages] of items that will be useful in a pandemic, including some of the items you asked about.
we’re updating our gridtied solar (sma sunnyboy inverter goes down if the grid goes down) to a grid intertie (offgrid on demand with batteries).
anyone have experience with the sma sunny island? this would be the easiest way to go but im wondering if anyones had problems (beside sma’s atrocious customer service).
thanks
http://itsgettinghotinhere.org/443 - a blog about campuses moving towards clean energy, with a set of instructions to build your own windmill.
We need to reach out to them and suggest that some of those ideas might be placed in an “open repository for global-resilience” (“org”?).
We might work for each other.
If you’re shy, you may not want to contact the blog as such, but rather individuals there.
spok at 19:31
Try Kansas Wind Power. They don’t have online ordering, and you have to be patient to get through on the phone, but they will take plenty of time with you and make sure you are buying the right thing. Let them know your power will be limited.
Incidentally, if you throw the “main power switch” on a standard electrical panel, you are NOT “off the grid”. It is indeed very possible to back feed the system through the return feed. This can cause many unpleasantries for your local hydro company, and is traceable to your residence. You may be on the hook for repair costs (YIKES!).
If your intention is to use your existing wiring to distribute off-grid electricity, talk to an electrician about installing an isolation switch, which will make you completely “off-grid”. These are very expensive (a few hundred bucks) and probably not in the rental picture?
Hillbilly Bill at 08:16
Great site! I looked at the DC fans that take 5 to 15 watts to run. And I looked at the DC Evaporative Air cooler that takes 35 to 50 watts to run. We have pool water so that might be an option.
Thank you.
spok at 12:17
You are most welcome. Just to give an example of how fast power goes out of a storage battery bank as opposed to getting put back in, please note the following. I used the solar energy collected by 4 of the 15W panels to run the air pump and lights on our fish tanks. The pump draws 5 watts and the lights use 45 watts. We only have the lights on for 1 hour a day but run the air pump continuosly. I found that even with a stretch of good weather, I slowly “fell behind”. Ocassionally I would need to put the fish tanks back on house power and let the battery bank build back up. To my further dismay, it took at least two good days of sun to get the bank back to fully charged from a reading of 70% full.
Good info - Thank you
If you assume 4 hours per day of sun - your 4 panels should generate theoretically 240 Watt-Hours.
Your fish tank consumes 5×24 + 1×45 = 165 Watt-Hours
So either you had a bad stretch of weather (3 hours of “usable” sun, or your panels are grossly under-efficient.
RPh at 13:10
I wouldn’t blame the panels. I did not see where you took into account losses due to storage in the batteries, conversion to AC by the inverter, and power usage by the inverter, not to mention loss due to resistance in the wiring. It all factors in.
Real Life situations are always different. There’s all kinds of inefficiencies.
Inverter power loss Battery power loss and during charging, as the batteries get full, they will only take so much from the solar panels. etc.
RPh at 13:10 Solar panels are most efficient at lower temps; the hotter they get the poorer they perform. 100 watts into a battery and you can, at best , get 80 watts out( in the long run, lead acid batteries are not very efficient)convert this to 120 volt and with most cheap inverters you lose another 10%. Lets not even talk about wiring lose.
Hillbilly Bill at 12:27: your experience is not unsual, but try not to get that battery down below 70%. I have run my homestead for years on solar. My solution has been 1) conserve 2) build a big enought system. It take time to become even slightly self sufficent. Kelly
Really is food for thought when looking for power alternatives. Solar is great for heating stuff up (read air, water), but really sucks when generating electricity.
My personal view is money is better spent in solar heat, and gasoline (or propane - my preference) electrical generation.
btw, solar doesn’t work very well at all in winter…. at least here
RPh at 14:44
Initially, I was resistant to the idea of solar panels. I first bought a generator and have been storing gasoline for it. However. after some field trials with my battery bank and a battery charger, I found that I would need to run the genny MUCH more than I wanted to every day to get my batteries recharged. Then, I saw a good deal on some small panels that would fit the only roof space I have that gets decent sunlight, so I bought them. Still, using both a battery charger and the panels, I will need to be very conservative to keep from depleting my battery bank.
I don’t understand the need to run a generator to charge batteries. Your gennie can provide your needs much more efficiently, without the losses associated with storage/inversion/etc. That is, of course, assuming that you are using a variable output generator. I currently use a Honda 2000i portable. I can use it at the cottage, at my house, out hunting, wherever I like. At full load, a tank of gas (about a gallon) lasts over 4 hours. At minimal draw, fully 12 hours (I’ve left it on overnight one day of heavy storm weather for my sump). It’s also very quiet.
RPh at 15:52
I’m not running a generator JUST to charge batteries. I plan to run the generator to keep a a rudimentary form of refrigeration going, and depending on the season to provide and circulate heat through the house.
The battery bank and inverter are for sensitive electronics and timed appliances that don’t fare well on the power supplied by the generator.
Everybody’s situation is different. I have found what will work best for me.
Fair enough, but btw, the Honda puts out a beautiful sine wave (I actually tested it on my bro’s equipment). Perfect for electronics.
Do you use 12V electronics, or do you invert to 120 from your bank?
I would love to find another generation alternative, but I haven’t found the right product for the investment yet.
RPh at 16:11
I envy your generator, I could not afford that model. I have purchased an Aims pure sine wave inverter to run my electronics and have a few cheaper models for backup.
That’s my main purpose for juice too - circulationg of heat in my house. Unfortunately, my heat right now depends heavily on oil, and I can only store about 6 weeks in the dead of winter.
Has anyone actually tried a diy solar air or indirect water heater (I’m in a northern clime subject to extended freezing)? Asthetics are modestly important, as the wife won’t want the house to look like crap.
RPh at 16:11
That generator and Yamaha’s version are my two favorite gens but even quiet generators would probably attract attention at night when there is no other noise. Having some batteries, for night use, seems like a good idea.
I have a Xantrex 60Ah unit that comes with a 120W AC Input-5A 12V output charger. It says 20 hours to fully charge the battery. This means I am getting 30% efficiency in AC sourced charging, and it’s too slow for charging from a portable generator.
Is there a faster and more energy efficient way of charging batteries from portable genset. I do have a DC output on the genset but it’s only rated 8.3A at 12V. I would like to use the AC output from the genset so I can charge several batteries at the same time.
I agree with spok. I don’t want to turn on the genset at night.
The very short answer to your question is NO, Kinda. There ARE more sophisticated chargers that can cnarge batteries with a higher efficiency than the one that is built into your Xantrex, but most of the problem lies in the chemistry of a lead-acid cell. When the cell is heavily discharged, its intrinsic voltage is very low, and so applying a charging source with a safe voltage produces a large charging current. This brings the early part of the charge cycle up pretty quickly. But, as the voltage of the cell rises due to the charging process, the current that the charging voltage produces falls off. If everything else were even, if you increased the charging voltage, then you could maintain the charging rate and have done with it fairly quickly.
Unfortunately, charging a lead-acid cell at anything higher than the manufacturer’s safe charging voltage will result in the breakdown of the battery electrolyte solution by hydrolysis, produce hydrogen and oxygen gasses where you really don’t want them, and cause permanent damage to the inner structures of the battery.
That’s why Edison and Ford developed the Nickle-Iron battery at the beginning of the 20th century for electric cars. Before big oil caused them to give up on the idea.
Eccles at 17:54
Thanks.
Does that mean that if I have say a 120Ah battery, and I deplete it to 50%, then recharging to 75% would be fairly quick. For the same 30Ah consumed, if I only have a 60Ah battery, and try to charge it from 50% to 100%, it will take much longer. According to the Xantrex manual, it’s design to take another battery connected in parallel. In effect, I would have 2 x 60Ah, trying to charge it from 50% to 75% approximately. Perhaps only using the DC output of the genset?
The Truecharge 40+
Made by Xantrex
Charges up to three battery banks simultaneously.
Recommended battery size 400 Ah and up:
So you could buy three 220 amp hour batteries for 660 amp hours of storage. You can rotate the batteries for use but charge all three at the same time while the gen is running.
You could use RPh’s generator at 15:52 and burn one gallon of gas over four hours. If you rotate the batteries per night then each battery will have been charged 12 hours (4 hours each day x 3)by the time you get to it.
40 gallons of gas would last you 40 Days. Also the generator would only be at half load with the True Charge 40. So the fuel would last longer and give you more charging time or you could use the left over power for other items during the four hours that it is running.
And if you had Hillbilly Bill’s set up, you would have a 4th battery in the rotation.
I heard that HBB’s next battery is so big that he’s going to lift his house on top of it for a better view.
Bronco Bill at 19:25
You are always in a good mood. Speaking of Red Wine Flu Killer :), did you sse the wine will recommends on his site listed above?
From Will at 22:41
Merlot~Cabernet Franc Blend with Elderberry
Anon-YYz - Unfortunately, the rate of charge depends on the absolute state of charge in the battery. So if you discharge it to 50%, then you won’t get a very fast charge, and if you discharge it to only 75% full charge, then refilling it is still as slow as if it were coming up through that point during a full recharge. No free lunch
Spok - You need to be careful putting battery banks in parallel. the batteries must all be the same, with the same wear on them and at the same state of charge. Otherwise, there are currents that flow uncontrolled from battery to battery. not at all what you want, and in some instances downright unpleasant.
spok at 18:55
Eccles at 20:23
Thanks for recommendations.
I am leaning towards solar to charge battery packs (Xantrex 60Ah and 20Ah) for running DC appliances such as laptop and genset to run AC appliances such as fridge while I still have fuel. I may just have to conserve. If it rains all week, and I still have fuel, then I will charge the battery pack from genset. The price of the Xantrex 40+ charge (about $400) is such that I may be better off buying a third source of power that requires no fuel i.e. smallest wind turbine 400W output.
Does anyone have experience with small wind turbine? What are the main considerations?
Eccles at 20:23
None of the batteries are connected to each other. The Truecharge 40+ Charges up to three battery banks simultaneously. The three banks can be at different charge levels.
Bronco Bill at 19:25
Actually, I’m going for quantity rather than quality. I plan to soon own every deep-cycle battery in stock at my local Wally World. I must say though, they are darned hard to sneak in the house!
Let me interrupt these theoretical discussions with a report from the field:
The battery I used for my tests was fully charged (actuall 13.1 volt reading) at the start of the test. I connected my oldest laptop with a DC adapter and started a DVD playing in full screen. The laptop battery was nearly drained to simulate SIP conditions. Occassionally during the test I also puttered around on the laptop accessing web pages. When the DVD was finished playing, the battery was reading 12.6V which pleased me immensely. I plugged in one of my Swiss Army lanterns, again using the DC adapter, and left it to charge overnight. This morning the lantern was charged and the deep-cycle battery voltage was flipping back and forth betwen 12.5V and 12.4V. Obviously I was very happy with this. I have the batery connected back to the solar panel and I will measure the capacity at the end of the day.
Lesson learned: Use DC adapters whenever available!
Now, I just need to accumulate enough batteries to have a sufficent bank for the panels on the roof and other batteries that can be used with the free-standing panels in different combinations.
Spok wrote: “Speaking of Red Wine Flu Killer :), did you sse the wine will recommends on his site listed above?”
The Elderberry wine actually comes in a sweet and dry now. The Vintner hasn’t updated the site yet.
Most laptops operate on a voltage higher than 12VDC. The older ones often use 15 or 16 VDC with 18 and 19 being common for the newer and large display ones. The actual input range accepted will be something wider, such as 16 - 20 for an 18VDC specified laptop, but good luck on actually finding that.
In any case you can make a much more efficient source for powering a laptop directly from a 12VDC battery by bootstraping an isolated output DC/DC converter on the battery in a common mode manner. This is far more efficient than using an inverter to go from DC to AC and then the laptop’s AC adaptor to go from AC to DC.
A low cost inverter and AC adaptor are typically in the 75–80% efficient range. Assuming 80% for both, the double conversion means you are only 64% efficient overall. That means if the laptop requires 50W you are pulling 78W, losing 28W in the two conversions. A DC/DC converter is typically 85% efficient. In a bootstrap configuration it is only converting the voltage required above the battery voltage. In the 50W example, an 18VDC input laptop is drawing 2.8A. The DC/DC is required to provide 5.5VDC above the average battery voltage (18–12.5) which at 2.8A is 15.4W. At 85% efficiency it will pull 18.1W meaning it is losing only 2.7W. This is a power savings of almost 25W over using an inverter and AC adaptor.
To do this you need to get a DC/DC converter that is rated for more power than required, 25% more would be a good derating athough you could go down to 10%. In the example this is 19.3W (15.4 X 1.25). Select a DC/DC in the closest wattage range, without going too much under the derating. 20 and 25 watt DC/DCs are common DC/DC wattages. You then need a DC/DC that has the proper input voltage range, i.e. 12VDC over a range that the battery will be experiencing - especially if you will be charging it when the DC/DC is connected. For a 12VDC battery that ranges from a low of about 10.5VDC for a compeletely dischanged battery (something you don’t want to be doing for lead acid batteries) to about 13.5VDC during charging. Fortunately DC/DCs commonly come with a 2:1 input range for a nominal 12VDC input which is a 9–18VDC input range. You then need a conversion output voltage that is the difference between what the lap top needs and the average battery voltage. In the example this would be 5.5VDC (18–12.5). A 5.0 output is a standard for DC/DCs. The large wattage ones can often be trimmed ±10% too so the DC/DC could be adjusted to have 5.5VDC output.
So this means you get a 9–18VDC input to 5.0VDC at 20W, minimum, output, ISOLATED, DC/DC. To conect it up you connect the DC/DC’s plus and minus input up to the battery, observing the polarity. You then connect the DC/DC’s minus output to the battery (or DC/DC input) plus. The DC/DC is now connected bootstrap and the DC/DC’s plus output, relative to the battery minus, will now have the battery voltage plus the DC/DC conversion voltage. On a fully charged battery this will be 13.0 + 5.0 = 18.0VDC. As the battery discharges the bootstrapped voltage will fall too. While there are some tricks you can play with the trim voltage to offset this, it is not generally requied because the laptop usually has adequate headroom on the down side. You could, however, easily trim the DC/DC output voltage up a half volt.
Some considerations: 1. It is very hard to get any real data on a laptop’s input range. However, you can conservatively assume that it is easily ±10% of what is on the label. If your input voltage is too much higher you may blow out the laptop’s internal power supply. If the input is too much lower the laptop will usually just shut off. 2. The DC/DC and laptop are very sensitive to polarity reversals so make sure the polarities are correct before connecting either. 3. Once you figure out the polarity on the lap top input connector(usually center positive) the ubiquitous DC barrel connector cable will be permanently attached to the DC/DC so there is now little risk of reversal. The problem usually comes in attaching the DC/DC to the battery if this is not made permanent. An inline fuse followed by a reverse baised rectifier diode (i.e 1N4000) is a good idea here. 4. To work in a bootstrap configuration the DC/DC must be isolated. Most are but some are not. If it is isolated, the isolation volatge will be specifed in the data sheet (typically 500VDC for the larer wattge DC/DCs) 5. If you need an odd voltage (e.g. 21VDC) you can use two DC/DCs. You need to calculate the current flowing at the DC/DC’s bootstarp voltage and rate accordingly. 6. Put a cigarette lighter plug on it and it will now work in the car too. CAUTION: do not leave it connected when you turn off the engine. A “load dump” can easily generate a 60V spike that will blow out the DC/DC.
These same principals will apply to any DC powered device that uses an AC adaptor. This is the most efficient way of powering them and will save you precious watts from your alternate power source. It is really not that compliccted after you do the first one.
I’ve run my lap tops off a spare car battery when camping in the mountains this way for years.
pfwag at 12:02
My laptop uses 19V and I already bought a 12 Volt DC laptop adapter. How much more power do I save if I use your method. Is it correct to say that I need to buy a 12V to 7V converter, a special fuse, some 12V plugs, and wire 12V + 7V in series? Can I use the same set up to charge the laptop battery directly from a 15W solar panel so I don’t lose power by charger a 12 volt battery and then draining it into the laptop battery? You mentioned car battery which I understand is not the same as deep cycle. Would you please explain.
A sunny day got my battey almost back to where it was before the test. The voltage reading was 12.8–12.9V when the charge controller indicated it was no longer feeding power to the battery. Since I am using a cracked panel in a considerably less than optimal location I was happy with that.
My next project is to start constructing a rolling charging station using a lawn/garden cart, a two battery bank and two solar panels.
HBB- On your recommendation I ordered those panels from Northern. I spent a few hours yesterday unpacking and checking them; they were very well packed and I was pleasantly surprised to see the connectivity hardware that comes with them. Nifty! each panel is wired with a hookup connector and comes with plug ins for wiring, 12 vehicle plugin, test LED and + - battery clips. Dimensions for those interested are 13 3/4 x 38 1/2, with 4 screw holes 2 ea T&B. I got 20 of the 24 I ordered; expect the rest on Monday.
BTW while I was looking at the best price for Outback inverters, I ran across a sale that Wholesale Solar is having on Kyocera 130W panels-
http://www.wholesalesolar.com/
$590 for 130 watts is about as good a deal as I have seen in a while. I have no affiliation with this outfit, have not dealt with them and make no recommendations, but I am going to look into this further. Caveat Emptor!
RPh wrote: “Has anyone actually tried a diy solar air or indirect water heater (Im in a northern clime subject to extended freezing)? Asthetics are modestly important, as the wife wont want the house to look like crap.”
I’d built a solar window heater many years ago (my current home is passive solar). There are a number of solar space heater diy projects at http://www.builditsolar.com/Projects/SpaceHeating/Space_Heating.htm
In terms of aesthetics, you can paint the outside of a solar window heater to match your house’s exterior color scheme. Not knowing your wife’s aesthetics threshold, at least you can make the case that this is a family safety measure, similar to fire escape ladders, smoke detectors, etc.
kerosene heathers…one like this description anyone tried to use foodoil in them? A mixture of high quality kerosene, or maybe a ethnanol mix? The camping stoves of the old type or the new modern multifuels can virtualy run on anything, but Im not sure with this heathers.. I would like to use biofuels for enviroment reasons, and hopfully also for economic reason. Maybe I can grov my own oilseed harvest :)
urdar-Norge at 10:33
I have a similar heater, not exactly, but similar. It works very well. One thing to note is that when turning it off, you should carry it outside first, or the smell of the Kerosene vapor may drive you up the wall. I’m sure it (the vapor in the air) isn’t good for the health either.
Stick with Kerosene, not Ethanol or any other mix.
LMWatBullRun at 08:27
My original delivery was not safely packed, the retail box was loose inside a flimsy cardboard box. The replacement panels for the 3 damaged ones were packed much better. The upside is that I now have 3 extra panels that work, even if they are cracked. The extra connectors are a definite plus, I was happy to have them and I have made good use of them. I think you will be pleased with their performance.
ANON-YYZ:
If you already have a 12VDC adaptor it is a 12V to 19V DC/DC converter. Since it was designed for use in a car, it has an input range of something like 10 - 15VDC and is protected from the 60V load dump spike. Assuming resonable efficiency, it would not be that mush less efficient than the procedure I described above. Probably not enough power savings to make it woth the effort unless you were going for maximum efficiency.
The only way you would tell waht its efficiency is would be to measure it: power out divided by the power in. Usually they are targeted for powering your laptop off your car battery so efficiency is not important but cost is. I have seen some low cost DC/DCs that were down in the 60–65% efficiency range which is equivalent to using an inverter and AC/DC adapter. In that case the bootstrap method above will be much more efficient.
As for the parts, you are partly corect. Nobody makes an off-the-shelf 12V to 7V DC/DC that I am aware of (and it is my business to know). You could use two 12V to 3.3 DC/DCs, which are very common. A fuse is a fuse - nothing special there.
Most likely you don’t need to go all the way up to 19VDC. My large screen Gateway M680 runs just fine with an 18V input. Maybe I’ll run a test and see how low it will go. It’s leased.
The problem using a 15W solar panel to charge a laptop directly is that a solar panel’s output will probably not be within the range of what the laptop requires. You have to carefully test what the solar panel’s output is under no, light and full load operation and then see if that is compatible with the laptop. Murphy’s Law say’s no.
If the panel will charge a more forgiving lead acid battery directly you are only losing 5 - 10% of the panel’s output power to charge the battery (i.e. you put more power into the battery than you can get out)
A lead acid car battery and deep cycle battery are the same chemistry. The major difference is that the deep cycle battery has much thicker plates. BTW: one of the best deep discharge batteries you can get is an Optima Marine. Sometimes they are sold under different names. You can always tell as they have what looks like 6 round cylinders molded together to make the 12V battery. Just make sure it says “marine” as they also make car batteries too. Next is probably the Hawker deep dishcarge battery - they are very commonly used for electric wheel chairs. Or they make an even better one for the military.
You can always tell good deep discharge batteries because the manufacturer will rate how many deep discharge cycles (make sure they say 100% discherge) the battery will provide at some temperaure, often 70 or 77F. Next important thing is how they define a “cycle” I haven’t looked in a good while but I believe that is to the point of a loss of 10% of capacity. You are on the knee of the curve there so continual deep discharging makes progresively greater loss of capacity. No rating: caveat emptor. IDEALLY, you don’t want to discharge even a deep discharge battery all the way to completely discharged. Not doing so will make the battery last MUCH longer. FYI: you will destroy a car battery with just a few 100% discharge cycles.
spok at 19:55 --- I try. Shoulda seen me in my early days here, though….I’ll check out Will’s site.
HillBilly Bill at 07:44 --- Have you gotten ‘round to “investing” in any Deep Cycle Gel marine batteries yet? Hadn’t seen you mention anything about those…my buddy has a big ol’ live-aboard houseboat, and he swears by them. ‘course, he recharges them with shore power…
Bronco Bill at 18:46
Nope, I’m going with Wally World SLABs. Readily available and relatively cheap.
Any recommendations for a source of high output 12V alternators? (850 RPM delivering 150 A)
Anonymous- I am just “zipping through” here at lunch, so my one quick thought might be to acquire a wind turbine and refit it to belt drive. Then you ought to be able to drive it at the right RPM for those many amps. (Assuming it is a large enough turbine to begin with).
The only other thought would be to see what kind of retrofits are available for police and emergency vehicles. SOme of them have very large electrical systems.
And moving right along to Part 10
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