Power out - inverters

[Doc1]

One By One's "power out" thread prompted me to post this. Does everyone have at least one inverter? You know...the electronic boxes that convert (commonly) 12 volt direct current - such as your vehicle produces - into 115 volts alternating current? Inverter prices have dropped unbelievably through the years and there's little excuse not to have one (or more) in your preps. This is especially true for those in hurricane country.
I got my first one, in a trade, way back in the mid-'70s. Back then, they were seen as almost mystical - and very expensive - temperamental pieces of kit! For all that, they didn't have much capability. Now, as with most consumer electronics, they're cheap and reliable and their capacity has grown by orders of magnitude.
You have two ways to go with inverters: Modified sine wave and pure sine wave.
The true sine wave inverters produce AC current exactly like your household mains current, a series of smooth up and down waves. The modified types produce an approximation of this in a series of "up and down steps." The sine wave types are the most expensive (by far) and least efficient. The modified versions are far cheaper and more efficient. There are countless internet sources of info and I strongly suggest that all preppers become knowledgeable about this technonolgy.
Here's a very brief synopsis of inverter capability based on my own experiences.
Smallish inverters of 400 - 500 watts will allow you to run a couple of small fans and some lights. Not much, but it will greatly increase your comfort level on a hot, muggy southern day. Medium inverters of, say, 1000-1500 watts will let you run a great many more appliances. My 1500 watt (3000 watt surge) Xantrex will operate our small deep freezer with no problems and powers a 5000 BTU window AC unit. Our 3000 watt (6000 surge) Wagan inverter is at the level where you can accomplish some serious work. It will run a circular saw, electric chainsaw and even - though barely - our shallow well pump.
In the post-Katrina environment I lived off of inverter power for many, many weeks. It was not as convenient as mains power, but was incomparably better than having no power, which was the case for the vast majority of folks down here.
When you investigate inverters, remember that they don't produce power. They merely convert it - at a cost of some efficiency - from one type to another. While almost any car's alternator and battery combination can operate small inverters, if you want to move up to large capacity types, you may have to upgrade your alternator and battery setup.
If you don't have at least one inverter yet, seriously consider adding this item to your preps.

Best regards
Doc

 

[oldladydoolin]

I have wanted to add one or two to my preps but don't know which one to buy. Any suggestions?

 

[RCSAR]

Where is a good (cheap) place to get a 500 to 900 watt pure sine wave inverter?

I have a modified sine wave and the blower I used with it ran slow and hot. Some motors and other things don't like modified sine wave at ALL.

RCSAR

 

[Wolfman]

Can you give us a run down on battery use and performance. What kind of battery bank and charging system do you use?

 

[fairbanksb]

Do they store power or do you have to have them connected to your vehicle while they are in use? If they store power, how long will they operate on a full charge?

 

[Double_A]

Can you give us a run down on battery use and performance. What kind of battery bank and charging system do you use?

Yes please do as the inverter is only half of the system.

 

[jed turtle]

i have a powerstar 1300 watt inverter that has worked well for several years (modified sine wave) and a larger true sine inverter that was salvaged from an old office setup to supply power to a bank of computers when power unexpectedly shut off. that runs the office here when the power goes out.
i am thinking about buying a few of these soon:

http://shop.sportsmansguide.com/search/search.asp?r=MainHeader+KW+Box&a=browse&k=inverter

Just plug this compact wonder into your vehicle lighter outlet to power or charge cell phone, camcorder, laptop, tools, portable stereo, video game, you name it. Has both AC and 12V DC outlets, powering up to 6 amps. Its plug-in adjusts 45° for convenience. Terrific quality, with high surge capacity and electronic circuit protections. Low-battery shutdown prevents excessive battery drain. Compact 5 5/8 x 2 7/8 x 1 3/4", 7 ozs.

 

[captskip9]

Where is a good (cheap) place to get a 500 to 900 watt pure sine wave inverter?

I have a modified sine wave and the blower I used with it ran slow and hot. Some motors and other things don't like modified sine wave at ALL.

RCSAR

For the best prices go to E-BAY got mine there just check the sellers feedback on happy customers and you won't go wrong.I have 2 small ones (500watt,700watt)and one large one 1500watt they do use a lot of battery power but when you need 110 volt power and don't have a generator that's the way to go.I have used mine for weed wacking from my lawn tractor battery when i am down in the back 40. cant beat them also when you need a drill or saw out in the boondocks to.i have used my big one with the sine wave for my computer and monitor with good results best time is 4-5 hours use before charging the battery back up but the bigger the power drain (electric motors )the shorter the run time .Don't expect to use an electric heater with one it won't like it for long.

 

[LoupGarou]

Good thread Doc1.

Also need to remember that since they convert power from one type to another that they need to get their power from somewhere, and that it will be a little more wattage in than wattage out. For example a 300 watt inverter outputs 300 watts at 115-120VAC or about 2.6 amps, it uses 13.6VDC input (12V nominal) at 23 amps from your battery to do it. A 3000 watt unit outputs 26 amps but consumes either 222.4 amps at 13.6VDC (the reason that there are very few 3000 watt inverters that are designed for "12V"), 111.2 amps at 27.2VDC (24V nominal), or 55.6 amps at 54.4VDC. Your car's alternator is probably in the range of 70-120 amps, and about 30 amps are needed to run the systems that are in the car, the rest is used to charge the battery and run "accessories". So that gives us 30-80 amps to play with, keeping 10 amps aside to charge the battery (if you don't leave at least 10 amps to charge the battery, you may not be able to start the car next time...). So, with 30-80 amps, we could run anywhere from a 300 watt inverter to as much as a 800-1000 watt inverter. Most of the good MSW inverters are from 90-98% efficient so it is close to a watt input=watt output formula.

But here is the catch (you knew there had to be one, didn't you...), most alternators only put out the full amount of power (amps) when the engine is above idle, and usually when it is above 1600 rpms. If you hook up your inverter, and draw full power, check your battery voltage to see if it is heading down below 12.5, if it is, your alternator is not keeping up with the charging (try increasing engine rpms to 2000 rpms (highway/driving range)). If this corrects the voltage issue, then your alternator is not going to charge unless your engine as at that rpm or higher.

Edited to add:
Also make sure that you do not let the battery go below 11 volts when using this. A quick use (a few minutes) with the engine off may work with a smaller <300watt inverter, but anything longer is asking for trouble. The battery in your car is designed for lots of current for very short periods of time (starting the car) followed by >15 minutes charging, it is not a deep cycle battery and drops below 11 volts harm them. Plus if it was to drop too low, you might not be able to start the vehicle to charge it back up. Your best bet is to get two deep cycle batteries (or AGM batteries) in parallel, make a cart and put the inverter on the cart as well (a few companies sell them ready made, but they all use only one battery). This way, you can run it wherever you need to and either use your car, or a home charger to recharge it. Plus, if you run the inverter till it hits low voltage cut-out, since it is on deep cycle btteries and not on your car, it won't kill the batteries, and you can start your car and charge it back up.

Loup Garou

 

[Cardinal]

Thanks Loup, I was going to ask about a deep cycle Marine battery.

 

[Doc1]

Everyone's questions

It's hard to be terribly specific, because everyones situation and hardware will be different. try to share some of my general experiences and information, but I strongly recommend that you do a lot of 'net research to understand the technology well. That's exactly what I did when putting all of my emergency power systems together.
First, remember that inverters don't create or store energy. They are only conversion devices. You need a power source to start with. We use only diesels to accomplish this, but I understand that most of you will use gasoline powered cars or trucks. These will work just fine. The advantages of diesel will be saved for one of my other threads ;-)
When you go from 12 volts to 115/120, you're dealing with a power factor of around ten. This means that - roughly - 100 amps of 12 volt power can be expected to yeild only 9 or 10 amps of 115. Give yourself a little safety factor because of inverter inefficiencies and line loss, etc. Common household wall outlets provide 15 or 20 amperes of 115 volt a.c. power by comparison.
You can't draw more power than your alternator is capable of putting out, right? Seems simple enough, but I have seen guys run big inverters off of small alternator/battery combinations and then wonder why it didn't work out well for them! Actually, you can run big inverters off of small batteries and alternators, but you can't draw a lot of power from them for very long. As the battery is depleted, the alternator won't be able to keep up.
Another thing to keep in mind is that an automotive alternator is not designed to produce maximum current at idle speeds. It's designed to achieve a balance under normal driving conditions. Sitting in your driveway at idle, your hypothetical 100 amp alternator might only put out 30 amps or so. It may even produce none! Some alternators only kick in at higher RPMs.
As an example, I designed my little diesel pickup to act as an emergency generator. It has a tiny stock 50 amp alternator. I fabricated a special bracket to hold a 180 amp alternator (with dual belts) with a small diameter pulley (to increase alternator revs) and run this concurrently with the stock unit. It works fine at idle for most common loads, but when I need to power a big current drain like our well pump, I need higher revs. I literally get under the hood and jam a stick into the throttle linkage to bring the revs up to a high idle. Real high tech, eh? LOL!
IMPORTANT: Unless you have the ability to monitor your battery's state of charge, do not turn your engine off until you have turned the inverter off and given the battery a chance to recharge. It's possible to draw your battery down unknowingly while operating the inverter - even with the engine running - so that you can't restart the vehicle!
Aftermarket high-output alternators are available for most vehicles. Ebay is full of them. Additionally, many alternator shops can install rewound and rebuilt alternators designed to produce higher current at low RPM. A very inexpensive modification is to simply install a smaller diameter pulley on the alternator. This gives you higher alternator revs at idle.
I do not yet have a big battery bank, though that is in the works for a future project. I do have a small homemade battery bank in our bus, feeding one of our inverters. This is nothing more than several junkyard batteries I reconditioned, that are in circuit, with a battery isolator. We only use this to run a few lights, maybe a TV and radio or computer. For bigger loads, I start the engine to power up the alternator. For now, all of our setups are basically designed to be used with running diesel engines. We have a lot of non-electric alternatives such as kerosene lanterns and stoves, as well as propane appliances.
As to motors getting hot or running sluggishly with inverters, this can be a problem. Induction motors do not like modified sine wave power. Some run fine on it...others less so. Universal motors, such as found on electric saws and drills have no problems with modified sine wave power.
Here are our real world experiences running appliances on modified sine wave inverters:
a.) Lights. No problem.
b.) Computers. No problem
c.) Microwave. No problem
d.) Electric fan(s). No problem
e.) Power tools. No problem
f.) Small chest freezer. No problem
g.) 5000 BTU AC unit. Runs OK, but has a slight buzz. An electrical engineer friend attributes this to "hysterisis" and says it won't be a problem as long as the buzzing is minor.
h.) Well pump. This runs - only off our largest 3000/6000 watt unit - but does not seem terribly happy about it! It gets hot and runs somewhat sluggishly. I only did this on an as-necessary basis to bring up water pressure and did not leave it in circuit to operate automatically.
These guidelines are ONLY guidelines and might not be the same for you. Your AC might be a different brand, have different windings or capacitors, etc. Perhaps your specific well pump would run better than mine.
Other things need to be considered practically. You should consider something like a $10 China Mart fan to be essentially disposable. In the unlikely event that inverter power did evenually fry one, so what? Same with our little AC. It was only $80. It still works fine after many weeks of inverter use and it was a blessing to have in the September and early October heat following Katrina. Even if it had been damaged after that period, I would consider it to be a more than even trade off!
As to pure sine wave inverters, they are too rich for my blood. Even the small ones are many hundreds of dollars. Ones large enough to run big motors go into the thousands.
Finally, as a (very) general rule - though you need to verify this for yourself - I think most modern vehicles could easily run a 400-500 watt inverter with no problems or modifications whatsoever. Just clamp it to the battery and leave your engine running. As you get into larger inverters, you should examine your electrical system and consider mods as necessary. Any vehicle's engine has more than enough power for even the largest inverters and alternators.
Hope this helps.

Best regards
Doc

 

[Green Co.]

Inverters are a good prep item. Before Rita hit last year, I mounted two deep cycle 12v boat batteries and a cheap ($19.95 @ truck stop) 500 watt inverter to a small hand-cart/dolly. Just with this setup, I operated a laptop, 12" b/w tv, and a 20" box fan and various lighting.

The box fan ran pretty much continuously, LT & TV about 4 hrs each day. I would recharge it each morning from our generator. Just this small amount of power can make life in the south bearable.

 

[LoupGarou]

Just picked up another small inverter last weekend just for use with the laptops. RadioShack is selling the small Xantrex inverters (80 watt/100 watt surge and 170watt models) for $29 and $49. If you happen to have a RS store near you that is closing (several around the nation are), they will knock off an additional 70% off. I just picked up the "100 watt" one for under $9!

Yes, 100 watts ain't much, but it will power my laptop and other small items, and I can run it directly off my solar panels.

Loup Garou

 

[Dennis Olson]

Want inverters? Go to ANY large truck stop. All sizes, priced (usually) pretty reasonably. That or eBay...

 

[LoupGarou]

Want inverters? Go to ANY large truck stop. All sizes, priced (usually) pretty reasonably. That or eBay...

But try to stay with the name brands. I have seen many of the cheaper "china made knockoffs" have horrible stats, like THD in the dangerous levels, just the basic frequency control, and wild voltage swings. I try to stick with either Xantrex, Statpower, or Vector Engineering. Paying an extra $30-$100 for the inverter might save your $2,000 laptop or other items.

I picked up the Xantrex just because it is slightly bigger than a deck of cards, weighs almost nothing, and will fit in my pack with the flexible solar panels. I have bigger ones including two of the 5.5KW true sine wave ones.

Right now, Home Power magazine is doing a survey of everybody that has had equipment damaged by MSW inverters, making note of what brand, what model, what devices were damaged and other data. So be careful with any MSW inverter, if your device starts running much hotter than normal, or if it is not acting right, stop using the MSW inverter (or try another brand).

Loup Garou

 

[Dennis Olson]

I would never run precision electronics on an inverter. IMO that's asking for headaches...

 

[idelphic]

i am thinking about buying a few of these soon:

http://shop.sportsmansguide.com/search/search.asp?r=MainHeader+KW+Box&a=browse&k=inverter

Jeb - Only draw back to these is that you have to becareful with them.. really any inverter. While they are powered,.. or for the cig liter model above,.. when they are plugged in, they are running. so you will kill a battery without trying.

I know... Had to jump start my truck because I left mine plugged in. Was a good lesson. I used it to charge my cell phone.

I try to keep all my tech elec to 12v. Inverters lose a bit on the conversion.

 

[idelphic]

I have used mine for weed wacking from my lawn tractor battery when i am down in the back 40. cant beat them also when you need a drill or saw out in the boondocks to.

LOL.. not a bad idea Capt... If you mower has a larger battery then mine, should run for a bit.

Been thinking of how I can hack mod my mower... Was already considering adding a altenator to it some how... Po'mans Genny

 

[idelphic]

Thanks Loup, I was going to ask about a deep cycle Marine battery.

Go AGM... Regular batts will gasify and 'leak' and make a over all mess...

 

[idelphic]

I would never run precision electronics on an inverter. IMO that's asking for headaches...

I agree Dennis... I have a NEC MobilePro PDA (read one of Loup's Posts... lol).. I can run for a while,.. but have found that the main battery just does not last as it once did.

I have a few 12v7Ah AGM batteries,.. I can run it off that tied to a trio of solar panels.. The solar panels will charge the PDA,.. but the added AGM Battery gives me long run time. The panels excess charge the battery. Giving me double life so to speak.

Even today when it's cloudy, I can charge the PDA on the trio with no problems, without the battery. I just add the battery for power balancing..

Also.. I have a Vector mobile power station. It's a box with a 1000w inverter on top, and a AGM battery box. Also has a air compressor. I use it mainly right now to inflate the tires on the mower. But have a 12v Solar maintainer on it.

Regretablly,.. I will be moving it to the basement soon.. so I will have to devise another solar route.

Solar is a good resource.. shame I can't do more with it right now...

 

[tsherry]

So what happens...

If you use a modified sine wave inverter, that feeds a UPS? Does the UPS clean up the power for high-quality electronics?

(Obviously, I'm not an electrical engineer).

 

[Dennis Olson]

It will, BUT - if the UPS "alarms" all the time, it'll drive you nutz.

 

[LoupGarou]

If you use a modified sine wave inverter, that feeds a UPS? Does the UPS clean up the power for high-quality electronics?

(Obviously, I'm not an electrical engineer).

Depends on the UPS, some are MSW themselves and some are TSW (True Sine Wave). Plus some are constant conversion and some are passthrough. The constant conversion TSW are the best, but most expensive, they will fix any power problems since they always process the power fully, basically charging a battery and then using that battery and charger to power a TSW inverter. These things weigh a lot, so they are not "easily portable". I have both Trip-Lite ones as well as APC units. Most of the units out there are passthrough though, where it passes linevoltage through the UPS until the power drops and then the inverter kicks in. Some of these are TSW and some are MSW, but if you are feeding it with MSW, you still output MSW until the first inverter drops, then you run on the UPS's inverter. That being said, try what you have, if it runs warmer/hotter than normal, or if it starts acting funny, stop using the MSW inverter. If you really have to use a MSW inverter and are really worried about damage, look into a device called a Power Conditioner, I used to use a lot of them here in CVA while I was working for DEC (the power here can get "glitchy"). They take AC in, and through a series of transformers and filters, reshape the wave and dampen the voltage spikes and sags to the point where the power is at least "cleaner" if not "clean". You can find these things still around and possibly on eBay. Warning, try to find a nearby source, since these things are HEAVY! Shipping one would be a nightmare since most of the good ones weigh more than 200 pounds (read: Not easily portable). You might also want to check around with some of the businesses that used mainframes since when they converted over to PCs, many left the Power Conditioners where they were, simply because nobody wanted them and they were heavy. Power Conditioners are one of the few things outside of a motor-generator set that will reform sine waves back to shape.

Loup Garou

 

[WalknTrot]

Yup...a larger one about 800 watts and a smaller 75 watt to use to power a CFL lamp or charge a cell phone. No sense wasting the battery power if you don't need it. Also keep one of those jump-pak charging units plugged in all the time ready to go. They are very handy for portable power.

 

[shane]

For my laptop, when on 12vdc battery bank (pair of 4D AGM's, total 420 amps), I got a dc to dc converter that changes power for it directly from 12 vdc to the correct dc voltage needed by it, thus bypassing the need for any inverter there. Also, using 12vdc fans, radios, and LED's for most lighting.

Have also used an inverter to run a very small microwave. Yes, it draws a lot, but not for long, so battery drain is minimal before re-charging via solar panels or oversized alternator on engine. I use the smaller Vector 'pocket' inverters for the smaller jobs, like recharging cell phones, handheld radios, and "AA" rechargeable batteries.

- Shane

 

[BornFree]

It is better to have a smaller inverter as well as a larger one. If you only running a single lamp for instance then it is better to use a 100-300 watt inverter than a 1000watt one. The reason being that the "Self consumption" current of the smaller inverter is less, and you will get a longer run time for the lamp. Maybe even a few more hours. It does make a difference.

 

[BornFree]

Thanks Loup, I was going to ask about a deep cycle Marine battery.

Walmart has a great deal on large marine batteries. I believe you can get a really big one for around $70.00

 

[Doc1]

Survival alternators

Closely related to the concept of inverter power is the choice of alternators. We preppers should look at this with two criterion in mind. One is reliability and the other is parts availability. Power production is actually further down my list.
Reliability is important in all cases and has bearing on ultimate costs. Parts availability is a consideration in a post-SHTF scenario where you can't order online or go to the local auto parts store.
Here are my choices, in no particular order.
a.) Delco 10si. There are probably more of these alternators in junkyards and older running vehicles than any other single model. Your grandkids will be able to scrounge parts for these. They are very reliable and easy to rebuild, but don't put out that much current...typically 40 to 60 amps. There are some individual models that put out higher current and all of them are easy to upgrade. Parts are cheap and you could teach your 10 year-old daughter to rebuild one in 30 minutes. If memory serves, these came out in '73 and were in use through much of the '80s. Though I'm not currently using a 10, I have a few lying around the shop and keep a couple of rebuild kits for them. They can be pressed into service in place of many other alternators.
b.) Delco 12si. Very similar to the 10, just a little newer.
c.) Delco 17si. This is a larger, old tech alternator which, though not as common as the 10 or 12, is still easy to find in junkyards and auto parts stores. They are commonly rated at 80 to 100 amps. I have a 100 amp model on the Bug out Bus.
d.) Delco 22si. This is a newer, hi output alternator. Most are rated around 150 amps, though it's common to see rebuilds at 200 amps or higher. This is the one I use in my Isuzu to do generator duty.
e.) Delco CS130 & CS144. These are newer gen Delcos that are optimized for higher current output at lower RPMs. They aren't considered as reliable as the older SI series, but are better current producers. Parts are more expensive, but they are common and easily found in junkyards. The 144 is a higher output alternator than the 130. Depending on version, you can expect 80 to 140 amps from these machines. Their voltage regulators are much more sensitive than those in the older SI series. I wonder how susceptible they would be to EMP effects? I just added a CS144 to our listeroid gennie to provide 12 volt current and to act as a backup to the main gennie head. If it ever goes out, I can easily replace it with a 10, 12 or 17. One other thing, the mounts are the same for the 10, 12, 17 and CS144. I'm sure many others fit too. The wiring is different for the CS and SI series, but those mounts are identical which can be important for someone doing a homemade rig.
You may have noticed that all of my suggestions are for Delcos. I'm not partial to them for any other reason than their availability (and the availability of parts). If you have a supply of Ford or Chrysler alternators and understand their technology, that could be the way to go. They're common enough. In truth, the old style Chryslers were probably more reliable and stronger than the Delcos, but they're not as common and didn't have built-in regulators.
Whichever you choose, just make sure it's something extremely common that you can find parts for in a problematic future.
Other than powering batteries and inverters, you can do an amazing range of things with alternators, including modifying them to use as welders and high voltage generators.
I have thought on this at length and while some people believe that post-SHTF (assuming things get that bad) they'll just live a non-electric, 19th century existance, I believe that the ability to produce even modest amounts of electricity will be a huge survival asset.

Best regards
Doc

 

[BornFree]

Some vehicles only have like a 30 amp alternator. So leaving 10 for the car with all major items such as headlights, wipers...ect turned off. Then that only leaves you 20amps to play with and that equates to only about 240watts. If you start running your headlights or other items then this drops even more. That is assuming that you are trying to keep your battery from discharging by not exceeding the current that the alternator can put out. If you have 60 or 80 amp alternator then you have more room to play. About 120 watts for every 10 amps.

 

[LoupGarou]

It is better to have a smaller inverter as well as a larger one. If you only running a single lamp for instance then it is better to use a 100-300 watt inverter than a 1000watt one. The reason being that the "Self consumption" current of the smaller inverter is less, and you will get a longer run time for the lamp. Maybe even a few more hours. It does make a difference.

Good point, since an inverter runs the most efficient at almost full power. Also use a meter and check the standby current draw from the battery when no load is on the inverter. A lot of times the smaller inverters can take more on standby than the larger ones do. You don't want to waste battery power if the inverter is not being used, so watch the standby current draw and unplug it from the battery (or switch the inverter off) if you can.

Also, check Sams for the deep cycle batteries, I picked up 4 a few months ago and they were $47 each. I'm not sure if they were the same size as the Walmart ones, but it wouldn't hurt to check. They will also take in an old car battery for the "core" on the deep cycles, saving you a few bucks.

Loup Garou

 

[BornFree]

You can't beat the old Delco's. I remember back in the 70's the Chrysler alternator failed on a regular basis. When GM came out with the built in regulator then you could eaisily expect to do 100K plus miles on one. I have owned a lot of GM's and that has been my experience. However the smaller GM alternators that were around in the 90's were junk. The windings burned out eaisily and the bearings were known to fail a lot. In fact that was what started the saturns on fire...If anyone remembers that recall. The bearings in the alternator would fail sending the amature into the stator. This would essentialy short the main B+ wire on the alternator to ground. Since the wire path was long on the saturn and was not fused then this would start a fire. Just some history for those that are interested.

 

[sparkky]

on a larger scale, you computer office worker types can keep your ears open for someone "outgrowing" their current UPS (uninterupted power supply). most places replace their batteries long before they are trash because they can't afford the risk of bad batteries when they need them.
in the last six months I've had one customer GIVE me a 3000va UPS, with batteries and a 10,000va with batteries.
used UPSs don't always seem to have a big resale value in the business world.

 

[Rex Jackson]

It all comes down to how much you want to spend vs how many appliances you need to run. I prefer keeping my system mobile.

I have 4 Interstate UL-16s
4 solarex panels (150w ea)
2000w Inverter

that runs....

6-45w light bulbs
Police scanner
A P-III 600 with a TV Card w/ a 14" monitor
a P-III 1300 w/ a 17" monitor
A laptop
a router
a cable modem
a rechargable battery charging station
coffee pot
solder gun
electric tools (electric chain saw, etc.)

If I need to run the heater, microwave, and any other high consumption 115v appliance I shut down the PCs and plug my car into the battery bank (with jumper cable style connectors). I govern the throttle to 1200 rpm and let it run. I also have more deep cycle batteries on reserve with several mis-matched panels for if the SHTF.

I have installed/wired some very nice systems with diesel and natural gas generators as backup to the solar. I prefer using a vehicle as a generator (just me). To run a normal size home you should have 32 batteries, twin 4000w inverters - strapped out of phase to get your 220v. (I prefer this over a 10k 220v inverter), and 32 - 150w to 200w panels. I would replace 16 panels with 16 wind mills in windy/less sunny locations (like NY). With such a system you wont wear on components, it will always be there for you in time of need, you wont have a utility bill and you should have plenty of power left over to sell back you your utility company.

12v PC power supplies
http://www.opussolutions.com/index.php?p=product&id=25

My favorite Inverter - 24v (you need wire your batteries to equal 24v)
http://www.xantrex.com/web/id/44/p/1/pt/8/product.asp

a reliable supplier
http://www.solardepot.com

 

[BornFree]

Next time I am at Sam's club then I will have to check on those.

 

[registered_lurker]

OK, I want to chime in... This may be helpful for some of the people who have posted in this thread

First, inverters will produce one or the other type AC outputs, either a sine wave:

or a modified sine wave

Notice the sine wave is a smooth up and down ripple, while the modified sine wave is made up of stair-steps. Some problems arise from these stair-steps, specifically that while these steps approximate the voltage of a sine wave, at the peaks [top and bottom] the modified sine wave keeps the voltage at a high point for a longer period of tme than the sine wave. This means a higher wattage at the time the modified sine wave is at upper and lower peaks, and that wattage is usually dissipated in the form or heat.

So if you are running an AC motor on a modifed sine wave inverter this heat show up in the windings of the motor, and after a time will heat up the varnish on the copper windings, and after a time will cause that varnish to cook or carbonize, or to flake off, and then you are one unfortuate event away from a short between the windings which will invariably burn the motor's winding up. Usually this will not cause a fire, but it is a possiblility.

Usually you will be ok with a modifed sine wave if your electrical device transforms the AC to a usable DC, like most PC's, clocks, TV's, radios, etc. I would wonder if incandescent lamps have a shorter life with a modified sine wave. I would not run AC motors with a modified sine wave if I had another choice, especially in the long run.

Power conditioners are a wonderful thing. I have one between the generator and the house, an old industrial demo unit I got in Dallas / Mesquite from a guy named Wes Pettinger at ONEAC [one AC, shameless plug]. It's a multi-thousand dollar unit used in semiconductor testing areas... I got the demo for a hundred bucks. The two scatches on the cover do not hinder its performance at all. If you can get an industrial demo unit it's the best way to go.


OK, I use a small 300 watt inverter I bought at Wally World, I'm sure it's a modified sine wave, and use it as an emergency charger for my laptop battery.

I have a small 700 watt modified sine wave inverter, and have used it to run a small plasma monitor, a DVD player [the VHS player motor drags with this size] a fan, a 60 watt lamp, laptop, Inkjet printer and external mass storage device, and a digital clock [the clock gains time with this inverter]. One fan stopped working one time, I'm not sure if the inverter burned it or if it just wore out.

I have a 2500 watt modified sine wave inverter, and use it to run all of the above, plus a dorm size refrigerator and a coffee pot. In 14 months I burned up the refrigerator motor twice, now working to burn up the third. Since the coffee pot is used for a shorter time each day, and the heater coil is designed to dissipate the heat, it seems to be doing ok.

I hope this is of some help to someone. Good luck!

 

[captskip9]

I forgot about using a GM internial regulated alternator,i put one on my old chevy it is a 1964 and thouse old generators/alternators with point type regulators with only 30 amps were bad for causing dim lights at idle .Now i have a 70 amp alternator and it runs my converter just like my chevy truck and it was easy to bolt on and with one wire it's a breeze to hook up.

 

[Big Bob]

Sam's club in my area has 500 watt inverters for just under $30.00.

I have had one of these for several years. They are made by Vector who also makes Black and Decker inverters sold at Wal-Mart.

Check Pep-Boys auto for Vector inverters, They have an ad in the Sunday paper here. 2000 watt for around $200 after rebates.

I bought an old Radio Shack 300 Watt inverter at a ham fest recently.
It was bought in the late 70s. It seems to work fine, It is much larger that a newer one of the same size. Looks like a power supply with lots of vent holes in the case and no cooling fan.

donrowe.com has inverters and class T fuses online also a good F.A.Q. page.

I heard a story about a guy who had a 1200 watt unit in his work van with no fuse. Something shorted out and burned it to a crisp. I am sure his boss was very impressed.

A fuse and holder are much cheaper than a new vechicle.

 

[Guy_Incognito]

I'll reinforce the recommendation for Delco alternators and I'll add one thing:

If you've got the space for one, go for a 25 or 26SI alternator. They are pretty much indestructable. Big bearings, brushless design (no brushes to wear out - yay!), the regulator and rectifier can be removed and replaced with a 1/4" and 5/16" socket in about 10 minutes.
All the electronics are sealed in the rear end cavity and are pretty much waterproof. Good for wet/salty environments as the bits that have a positive potential are all sealed off in the rear cavity - as opposed to standard alternators where it's all just rusting away out there in the breeze.

I use them at work underground on loaders and trucks in the hottest, wettest, crappiest conditions imaginable and they last many thousands of hours at full output without missing a beat.

 

[Nuthatch]

Big Lots currently has 100 watt inverters for cigarette plugs for under $15.

 

[Jerry]

A bit on batteries -

In the sizes most are looking at (automotive) there are pretty much three choices, with variations on a theme. The first is the starting battery one has in their car. It is designed to deliver huge amounts of power for very short duration, and has an amazing tendency to self destruct when asked to do other than it was designed for. This usually shows up as going dead quickly, and not holding a charge. I was told once by a battery wholesaler that a starting battery has 5 times it can go dead (lights left on, etc.) and then it's shot. Don't know if it's true, but it does give one perspective. Figure 10 to 15% discharge is okay.

The second most common is the dual purpose, starting/deep cycle battery, often referred to as a marine/RV deep cycle battery. They very often last for 2 to 3 years starting and keeping the house lights on in the RV. One really doesn't want to deep cycle them, although they are better able to withstand it than a starting battery. Figure 25 to 35% discharge is okay.

The last category is a true deep cycle battery, often referred to as a traction battery. One will find them powering electric golf carts, platform lifts, forklifts, electric vehicles (couldn't resist throwing that in) floor cleaners, telephone co. backup, etc. These batteries are designed to be consistently discharged to 80% although one will get much longer service if they are not discharged below 50% of capacity. This is the type of battery installed in alternative energy systems.

The deep cycle comes in several configurations each having their own merits. For our purposes the major distinction is sealed or flooded. The first is as it is described and can be operated on it's side (or bounced around in a car) without leaking. It is known as a starved electrolyte battery and this will affect it's performance and longevity; interestingly these batteries are very sensitive to charging voltages and should have a voltage specific charge pattern. Too high a voltage and the electrolyte will gas to hydrogen and oxygen and at a certain pressure in the battery, will burp out the gas and leave less electrolyte. This can be a problem with a battery that only has so much electrolyte in it, and will lead to premature failure. On cold days an automotive alternator will charge at too high a voltage and will decrease the lifespan. The two major choices for a sealed battery are AGM (absorbed glass mat) or gel type. The gel can give a bit longer amperage at a lower current than the AGM, and the AGM can offer larger (huge) amounts of power in shorter duration than the gel can.

The last category is the lowly flooded lead acid battery. It has been around since the 1800's. If you are not going to be mobile than this is the battery for you. What I would call the entry level is the golf cart battery; which comes in a 6 volt configuration (some can be 12 volt with half the capacity) and differing capacities. The most common is a T-105 which loosely stands for Traction-105 minutes at 75 amps. This is about a 225 amphour battery. This battery case can also be a T-125 or a T-145 (260 AH), at higher cost and weight, and would equate to a group 24 sized battery. It is interesting to note these batteries are rated at higher working amperages than starting and marine/RV batteries which often cite minutes of reserve (at 25 amps before dropping to 10.5 volts which is fully discharged in a 12 volt battery) and cranking amps. The expected lifespan is 2-4 years.

The next level is an L-16 which is a larger, heavier battery than the golf cart and has flag type terminals one bolts the cables to rather than the round automotive post of the golf cart battery. The L-16, for it's size and weight only holds 350 to 375 amphours, but the tradeoff is shown in an expected lifespan of 4-8 years. Following the L-16 are batteries of individual 2 volt cells placed into a case with formed buss bars between the cells and usually 2 large cables leaving the battery with an Anderson style connector on them. These are pretty much forklift batteries and will give longer than 10 year life if kept charged and shallow cycled. The last that I know of are very large 2 volt cells in plastic cases loaded into racks and use buss bars instead of cables. As an example, the battery I was looking at this past week was rated at 3900 amphours and each cell weighed 650 lbs. !

Sorry for the dissertation. To get back to the point, I think the flooded golf cart battery is the best deal for the dollar. They don't really mind being overcharged as long as they are fed with distilled water. They can put out 400 to 600 amps for a minute or so at a time and not complain. In electric car circles, the hourly expected capacity from this battery is about 60 percent of it's 20 hour rate. That's a lot of juice.

Remembering that this is a 6 volt battery, one will need two in series to make a 12 volt battery. I would suggest connecting cables of 2 gauge or larger. When one puts together the battery bank, one will make a series/parallel battery. Two batteries make a 12 volt battery (series), and then 4 sets of these two part 12 volt batteries are hooked up postive to positive and negative to negative all the way to the end of the line using 1/0 cables or larger. One can then hook up the inverter feed cables to opposite ends of the battery so that the negative cable is at the right side and the positive cable is at the farthest left side. This configuration will ensure that the battery will charge and discharge equally. Be sure to put a Class T type fuse between the battery and the inverter, and also between the battery and any direct loads. If you buy these eight batteries and cables from your nearby wholesaler, he will probably give you a break. My wholesaler made me a dealer for the day when I bought 20 batteries from him.

What do you get for your 7 or 800 dollars ? Eight T-145's will give you about 12 and a half kWh if you take them flat. One can pretty easily put a high capacity alternator onto a 5 HP gasoline side shaft engine and have a pretty good 12 volt charger that will use far less fuel than a V-6 or V-8 idling in the driveway. Everything is relative and even the basic setup with 2 batteries give a good increase of standard of living. Solar panels can be added, perhaps a small wind powered generator, and one can pick up 12 volt appliances at sales and shops. I found a clip on, oscillating 6 inch fan that plugs into a cigar lighter socket ! Boy is that terrific to have. Alternative energy stores sell compact flourescent bulbs that run on 12 volts DC and screw into a standard medium base socket. Translation ? You can put these bulbs into your floor and table lamps and run them direct from the 12 volt battery. No inverter, and higher efficiency.

I hope the above has taken some of the mystery out of storage batteries. Those with knowledge who can help clarify will hopefully step in to fill in missing pieces, or offer alternate strategies. Good luck in your pursuits. J.