Diesel gennie alternative(s)

If any of you have been following the Listeroid gennie thread (which I've contributed heavily to), you know that I lust after one of those rigs. Unfortunately, we've had a couple of financial bumps recently and I don't have the cash to go that route yet.
I need to get my generator setup(s) ready for this hurricane season, (which is just around the corner) so I'm looking at some alternatives. I invite board input.
Last year when Ivan hit the coast, we skated as far as damage, but the neighborhood did lose power. I hooked my 500/800 watt inverter to one of our small diesel trucks idling in the driveway and that was enough for lights and a couple of fans.
I'm thinking about taking this concept to the next level because the electronics are becoming so cheap.
We have two Isuzu light diesel trucks and a big diesel-powered school bus. The Isuzus have (IIRC) 50 amp alternators. The bus has a massive 160 amp single wire Delcotron alternator, powered by an 8.2 Detroit.
My thinking here is to buy a 2000/3000 watt inverter for the bus, maybe an extra 1200/1800 watt alternator for the Isuzus and keep our old 500/800 as a backup. I have lots of heavy welding cable to make connections and 2000/3000 inverters (modified sine wave) have fallen to around $150 - $200. The 1000-1200/1800 (surge) inverters are down to around $100 or so. This is incredibly cheap compared to pre-rollover costs! Even the price of the big 150 - 200 amp alternators has fallen from a few years ago.
If I'm doing my math correctly, it looks like the bigger inverters, powered by the bus, could run an AC or fridge and the mid range ones could run a lot of appliances off of the Isuzus.
This isn't meant for long term viability and I fully understand that idling an 8.2 diesel is not terribly fuel efficient just to run a fridge or AC, but I'm looking at nearer-term hurricane preps (though a little Isuzu idling barely sips fuel).
I'm even thinking of buying a 200 amp alternator and installing it on one of the Isuzus as an auxillliary for stand-alone genny use. That actually would be pretty efficient and very easy on the four cylinder engine. All of these options should cost me less than $500, be reliable and last a long time.
Your input is invited! thanks.

Best regards
Doc

Doc,
you should consider this setup, of course this is a 3.5 hp setup, so you'd not get your AC running with other items.
http://www.timebomb2000.com/vb/showthread.php?p=1359284

Costco has a xntrex 1200W for ~$90 -- I don't remember the surge.
PM me if you wnat mroe info or a unit.

I've been thinking along the same lines as you Doc1. I have a small Ford diesel tractor and have been considering mounting an auxilliary generator on it for some time now. But I'm thinking about one of those heavy duty ST heads George and Joel sell up in Oregon. That project will probably require a different engine pulley grouping but maybe I can get around that somehow.

I've also been thinking about using one of those small Changfa diesel engines and setting up a portable aux power system that would produce up to 2.5 KW using a high amp car alternator, regulator (if necessary) and one of those modified sine wave inverters. It would be set up about like my diesel water pump I'm working on. All mounted to a heavy wooden base plate. But I'll build a frame under the generator outfit and make into kind of a wheelbarrow type setup to make it easy to move around. I'm still in the thinking stages though and working on my cash flow situation so I can get to work on something, anything to use as a backup for the short or long term. I'll keep an eye on this thread because I'm definately interested in what you come up with on your little diesel truck backup projects.

Here's what you want:

http://www.timebomb2000.com/vb/showthread.php?t=138201

I would suggest a moderately small battery bank between your gen and the inverter. This would allow not running the source continuously which is prolly a bit of overkill from what you say you need to run. With a batt bank you store that extra. Even only 2 6V golf cart batts can raise your source use efficiency remarkably. The fridge cycles and the AC sorta does too, so you optimally want to cycle your source.

Tips: in a SHTF turn your fridge to lowest setting so that it makes most efficient use of ON/OFF power. Add outer insulation too. Freeze water jugs during the ON cycles too. UNPLUG it when power source is intermitant. This is important to protect it's motor from surge spikes. Same precaution with ACs.

[Modified Sinewave (adv hype)=modified squarewave ]

Another note. The inexpensive inverters WILL destroy your fridge/AC motors if they do not have their modified waveform output very close to sinewave. The Xantrex/Trace/Tripp/etc inverters do, the $100 ones don't.

FWIW FYI: My Trace DR1512 (2.5K surge) will just barely start an older (6A cont/15A start) window AC...runs OK afterward. of course that equals a 60A cont draw off the DC source! 150A+ for the brief start draw!! So do your math homework.

BTW the Trace will also charge battbank at up to 70A. Don't recall the Tripp DC input. rate.

I was thinking along similar lines until I can get a generator. Namely, some golf cart deep cycle batteries, an inverter, and my F-250 diesel as a charger.

I am not a mechanic, nor an electrical guru - my probably stupid question for anyone is: How well will an engine charge a battery bank if you simply idle the engine? Somewhere - way in the back of my brain - I seem to recall that alternators don't have enough oomph to recharge batteries if the engine is only idling. (Possibly because of all the other vehicle electronics.)

David

My truck gen rpm needs to be pushed up slightly..don't recall exactly offhand but it wasn't much..something like 2krpm (1.2k normal?) I think. But my eng is only a 4cyl gas. The big prob comes when you wanna push 30-60A thru wire for any distance. Your normal jumper cables will fry under a continuous load.

For instance a 20ft copper wire(s) run @ 13.5VDC w/60A load requires #1 size wire to keep the line loss (read resistance heat) under 3%. 3% loss drops the 13.5V to 13.1V and is the recommended maximum loss allowed for DC charging systems..otherwise your so-called 12V batts never really charge fully (but you warm the environment). 1% loss is mucho better! Size #0 would be about right for that distance @ 60A. #00 better. (note: that's open-air wire run..not in conduit or behind walls) But..if your gen source is 14.5VDC then that 20ft run needs to use #0000 for a 1% drop (sometime labeled 4/0), or #00 for 3% drop.

Kimber said:

I was thinking along similar lines until I can get a generator. Namely, some golf cart deep cycle batteries, an inverter, and my F-250 diesel as a charger.

I am not a mechanic, nor an electrical guru - my probably stupid question for anyone is: How well will an engine charge a battery bank if you simply idle the engine? Somewhere - way in the back of my brain - I seem to recall that alternators don't have enough oomph to recharge batteries if the engine is only idling. (Possibly because of all the other vehicle electronics.)

David

Click to expand...

Max & David,
Looks like we're all on the same page here! I'm not an electrical genius either, but hey, we all learn from each other right? I like Max's idea of mounting an ST gennie head instead of an alternator, but there are a couple of problems for me. Even the small ST heads weigh in at around 100 lbs or more. I can't see any practical way to mount these on my little Isuzu engines (in vehicle) for reasons of both space and weight. I do have a spare Isuzu engine in the shop that I could build a skid for and mate to an ST, but then that takes us away from the concept of a vehicle generator. Also, the STs have to be run within a constant RPM range, so they couldn't be used while actually travelling.
David, as far as charge rates at idle, I can tell you that it depends strictly on the alternator. Some of the big (150 - 200 amp) alternators put out around half their rating at idle and handle heat better than typical smaller alternators. I'm looking at a "fast idle" stationary operation in my Isuzus and their little 2.2L engines. The 8.2L Detroit diesel in the bus could probably move smallish mountains without noticing the extra load.
I'm not going to mess with my wife, Margie's Isuzu. She has an '86 TD Trooper II in mint condition and besides being a super prep vehicle, it a rare collectible. On the other hand, my '83 P'up is rusty and highly disreputable-looking :-) so I don't care about keeping it stock. I need to retain the stock small alternator, because it's also the vehicle's vacuum pump.
I think if I remove the stock AC compressor I can use that bracket to install a big 150-200 amp, single wire Delco. I could place a couple of golf cart batts in the bed and tie a 2000 watt inverter to that. Bingo! Instant diesel hurricane genny. I'd leave the alternator belt disconnected 'til I needed to use it.
The bus already has a big alternator, so I think I only need to add house batteries, an isolator and inverter. Bingo! 2nd diesel hurricane genny (and I should do this anyway as part of the RV conversion).
Will these inexpensive modified sine wave inverters burn out ACs and fridges as has been suggested? I dunno... Still, new 5000 BTU ACs are on sale locally for $77 and used dorm size fridges are in the classifieds cheap on a regular basis. I'm willing to experiment a little with cheap stuff and if the instructions don't specifically say NOT to use a new AC with an inverter and it fails, well, back it goes under warranty!
The price of the electronics has fallen dramatically. Scanning eBay prices, I see 2000 watt (3000 surge) Coleman and other modified wave inverters for around $150 (maybe $170 - $180 with shipping) and those in the 1200 - 1500 watt range are a little over $100.
Another thing to consider is that these mods will give me a basis for future improvements. Down the road, I might fall into a good deal on a big pure sine wave inverter. I wouldn't need to change anything, except to swap out inverters.
Some of the other stuff can be done very cheaply. Junkyards will have the hi amp alternators at half (or less) of new/rebuilt costs and you could get away with used batteries to start with. I like the Delcotron single wire alternators 'cuz the wiring is so easy and the part most likely to fail, the internal regulator, is easy to change and costs less than $15.
None of this replaces my dreams of a big Listeroid chugging away on an ST gennie head, but I'm looking at the near-term possible instead of the longer term desireable.
This weekend I'll order a big inverter and keep you posted.

Best regards
Doc



One of the advantages

What I'm wondering is if you can power an inverter directly from an internally regulated automotive alternator? Or do you need a battery as a buffer between the two? Does anybody know? I just found a 1500/3000 watt modified sine wave inverter for $93.50 and I'm thinking seriously about buying it. It's a Xantrex Xpower portable model. All I really want my small power unit to do is keep my fridges (2) and freezers (3) going for a few weeks until I can get all the food dehydrated or eaten or sold or traded etc... I have aladdin lanterns for light so I won't be running a generator after dark much anyhow except for every four hours or so to keep the fridges and freezers cold and frozen.

Not well

MaxTheKnife said:

What I'm wondering is if you can power an inverter directly from an internally regulated automotive alternator? Or do you need a battery as a buffer between the two? Does anybody know? I just found a 1500/3000 watt modified sine wave inverter for $93.50 and I'm thinking seriously about buying it. It's a Xantrex Xpower portable model. All I really want my small power unit to do is keep my fridges (2) and freezers (3) going for a few weeks until I can get all the food dehydrated or eaten or sold or traded etc... I have aladdin lanterns for light so I won't be running a generator after dark much anyhow except for every four hours or so to keep the fridges and freezers cold and frozen.

Click to expand...

Max,
I asked one of my friends at a local alternator shop about this. He says definitely go with a battery (or battery bank). It's much easier on the regulator and serves as a buffer, as well as providing a reservoir of surge power.

Best regards
Doc

Thanks Doc. I already have two 6 volt golf cart batteries banked for 12 volts and it will be an easy thing to do. I just wondered if it was necessary to cycle those deep cycle batteries unnecessarily is all. I guess so and oh well. It's only money right?

And what about modified sine wave inverters killing fridge and freezer motors? I've done a bit of research this morning and afternoon and all I've found out is that they make the fans run a little faster which doesn't harm the fan motor or the inverter. I think that was for induction motors. Are most fridge and freezer motors induction motors? Heck I don't know.

Can somebody help me here on this Xantrex modified sine wave inverter and it's effects on a refrigerator or freezer please? I'm teetering on a buying decision and need some help. Pretty please with sugar on top?

sorry max, you're speaking chinese to me...

Damn. I'm going to go ahead and get it and suffer the consequences. We don't have much time left.

I agree

MaxTheKnife said:

Damn. I'm going to go ahead and get it and suffer the consequences. We don't have much time left.

Click to expand...

Yep, I think I'm going to just go ahead and get that first big inverter (and I doubt that we'll suffer any consequences). These things are cheap enough now that they're almost a "must have" prep item. Anyway, I've been plenty happy with what my 500/800 watt Statpower inverter would do, I just need more juice!
Oh, here's a hint for making up heavy cable. I find that used welding leads are commonly available inexpensively. Most scrap yards have some that they bought for copper value. It might need some taping in a few rough spots. To make terminals for this is easy, too. Just use appropriate diameter pure copper water pipe. Cut off a piece about two inches or a little longer. Put the bare end of the cable in halfway and peen it down tightly with a hammer. Then hammer the other end flat and drill the size hole you need. Easy.

Best regards
Doc

A "modified sine wave" inverter puts out a "chopped off" waveform. This is only an issue with precision electronics. Your appliances should be fine.

I just bought it. I'll live with it

I think I'm going to go the recycled lawnmower route for now. I have an old mower that I picked up in trade that's never been fired up since I had it. The deck is pretty heavy duty so it should hold a battery and mount an alternator pretty well. I think I'll find a used 100 amp GM alternator at the junk yard. Then I'll mount the inverter between the handlebars and wire everything up. I eventually like to replace the gas engine with a 6.5 HP Changfa diesel and double everything for increased output. So many projects, so little time.

Anyone considering using a MODIFIED SINE WAVE power source for electronics best reconsider, I've lost too many internal power supplies in computers and radios to this problem. If this is your only source of power consider an "battery back-up" in line with your electronics, these smoothe out the sine wave problem and keep your equipment up if your genny goes down unexpectedly.

delectric said:

Anyone considering using a MODIFIED SINE WAVE power source for electronics best reconsider, I've lost too many internal power supplies in computers and radios to this problem. If this is your only source of power consider an "battery back-up" in line with your electronics, these smoothe out the sine wave problem and keep your equipment up if your genny goes down unexpectedly.

Click to expand...

Okay, I know this involves transferring power from dc to ac to dc to ac... but what about plugging a UPS into the inverter and plugging the electronics into the UPS... that should take care of that problem, shouldn't it?

I'm going to chime in again.

And, again, this is beyond my knowledge base at this point. My first step will be likely be running stuff of my Excursion diesel - and I have a sportsman's guide Vector 700 watt/1400 peak inverter as a test device. Realistically, and as much as I love the Listeroids and ChangFa's, my first step will likely be a warrantied 5.5-6 KW portable diesel (sorry Max - I've flipped so many times on this don't worry, I may again.) The outlay for some these seems to be under $3K. Not bad, when you're pressed for time and don't have enough of a mechanical engineering background to play with the imports. I'm going to need to use it for rented power equipment in the middle of nowhere. Later, after it becomes somewhere, then I'll think of a more permanent solution. (I would love to have the background Max and Brutus have - but the time element is a big factor. I'm lucky if I have half a day per week for stuff like that. Yes, I'd probably have a lot more time if I wasn't wedded to the Internet. )

[Total Drift alert - Today, for example, I had a nice drive up to the Philly suburbs and met Ed, his wife, and son. Ed's the one moving back to Kansas with the previously extra pre-2K dehydrated food. Wonderful people! If even 20% of the TB community is like them, time spent chatting here is worth all the cracks I get I home and at work.]

For our one critical electrical device, my wife's Dell laptop, I've solved this by paying through the nose (perhaps needlessly) for a Dell DC converter (roughly $120 - or 5-10 times what Radio Shack charges - pun intended.) We already know her laptop runs off the cigarette lighter with this DC converter - so why plug it into something else at this point? And, I figure that if I can keep a 12 volt system charged, somehow, an inverter is irrelevant to the laptop.

Anyway, I'm posting because of what I found to date about modified sine wave inverters. None of the information below is product specific ("some", etc.) but it's enough for me to splurge for a pure sine wave when I get that far. Especially, the variable power tool comment below. I put in bold type my particular concerns with the modified form.

Note: As a practical matter - I think if I eventually get a portable diesel generator, I can run tools directly off of it and not worry about this. Power tools straight off a generator should help with any load issues. However, someone please correct me if you've heard of electronical equipment having problems with portable 5-6 KW diesel generators.

David

=====================================================

Choosing An Inverter: Modified Sine Wave vs True Sine Wave

True sine wave inverters provide electricity that is basically the same or better quality as utility-supplied electricity. True sine wave inverters therefore supply electricity that is compatible with virtually any appliance or electrical device. However, true sine wave inverters cost more than modified sine wave inverters. Thus modified sine wave inverters are commonly used. The following is a list of the electrical devices that can have difficulty running on electricity produced by modified sine wave inverters:


Even the very popular Trace SW Inverters, which are a refined modified sine wave inverter in which the sine wave is made up of very tiny steps, have problems running some appliances. Appliances which can have a problem with the electricity produced by Trace SW Inverters are:

Some new furnaces because of the microprocessor in the furnace control. Note: In the event that a furnace does not operate properly, on either a modified sign wave inverter or a full sign wave inverter, the electricity to the furnace controller can be modified further by installing a power conditioner (also called a constant voltage transformer) on the line to the furnace controller only.
X-10 home automation systems.

Other Advantages Of Trace SW Inverters

Trace SW Inverters include a gen start, which is compatible with most makes of generators, as a standard feature. Without the gen start an additional control would be needed to auto start. They also work with smaller generators than modified sine wave inverters.

When true sine wave is required, the Exeltech MX Series or XP Series inverters are the highest quality and have a mean time before failure of 21 years.

http://www.solarwindworks.com/Design/Design2/design2.htm

=======================================================

I did some research on the web on the advantages of true sine-wave over modified sine-wave inverters. Here are some things I found:

True sine-wave is clean power like utility-supplied electricity.

Inductive loads like microwaves and motors run faster, quieter, and cooler on true sine-wave.

True sine-wave reduces audible electrical noise in fans, fluorescent lights, audio amplifiers, TV, and game consoles.

True sine-wave can help prevent crashes in computers, weird print-out, and glitches and noise in monitors.

True sine-wave will reliably power devices that will normally not work with modified-sine wave inverters such as, laser printers, photocopiers, certain laptop computers, some fluorescent lights with electronic ballasts, power tools having "solid state" power or variable speed control, some battery chargers for cordless tools, digital clocks, bread makers with multi-stage timers.

Ron's concern does seem well-founded. I will get with Krogen and replace the modified sine-wave inverter with a true sine wave inverter. It looks like the Prosine may be twice the price of the Freedom, but it seems to be worth the difference.

Kelton

http://kk44pineknot.typepad.com/the_adventures_of_mv_pine/2005/01/inverters_modif.html

MaxTheKnife said:

Can somebody help me here on this Xantrex modified sine wave inverter and it's effects on a refrigerator or freezer please? I'm teetering on a buying decision and need some help. Pretty please with sugar on top?

Click to expand...

Inverter: Trace (Xantrex) DR1512 Modified waveform.

I've run below listed appliances for up to 8hrs continuous 6 times over the last 3yrs, (heh..not all appliances at once of course) Uncounted logged times for an hour or so (weekly/daily at times of momentary blips/brownouts), w/o any problems or "component destruction". In case you can't tell I live in grid-hell. LOL

Chest Freezer, 6A draw/13A startup.
Fridge, 4A draw/8A start (50hz !!)
Microwave Oven 1200W (cooked OK, turntable motor sounded different)
Desktop computer (several models and their peripherals..printer, USB/Network hubs/etc), LCD monitor, CRT monitor, VCR, Bearcat scanner, Stereo/Radio/Tape player, AC fans, 6000btu window AC.

The above are all on a separate circuit breaker box so when grid drops the inverter/battbank takes over..instantly..just like a little puter UPS. In fact the Trace has been my only puter UPS for that whole timeframe. Of course I added surge-protectors for that line also because the Trace doesn't have those embedded.

My backup (and recharger) for the battbank is a Yamaha YG-2800i, which also uses a modified waveform inverter. That has run my whole trailer with all of the above and more, for 1 realtime grid drop of 10hrs and 2 test runs of 8hrs each. No problems with any appliances nor their motors. With only 2800W (3000 surge) I do have to paly musical chairs with the large draw appliances...but the electronics stuff never even hiccups. Motors have shown no damage. I do know a bit about this stuff BTW.

Only anomaly was the Microwave turntable motor that had an wavering sound to it. Didn't seem to hurt it tho.

ChainedLightning said:

Okay, I know this involves transferring power from dc to ac to dc to ac... but what about plugging a UPS into the inverter and plugging the electronics into the UPS... that should take care of that problem, shouldn't it?

Click to expand...

AFAIK a UPS is little more than a battery charger, battery and an inverter. I havent tried it yet but I imagine you should be able to just hook up its battery terminals to your DC source.
I bought an old UPS to try this a few years ago. Its still sitting here doing nothing

Thanks Synap. I did a good bit of research about modified sine wave inverters and couldn't find anything definitive about running full sized refrigerators or freezers. I'll be playing musical power supply with my appliances too but then again, after doing some work with my little Kill-A-Watt meter it looks like I can plug them all in at once (but probably not). I have a large 16 cubic foot chest freezer that only pulls 110 watts steady state. I don't know what the turn on watts are because I haven't been lucky enough to catch it at the right time. But on a 24 hour test, the Kill-A-Watt meter says it's consuming about 3 KW hours per 24 hours. That's not bad at 6.5:cent: per KW hour. Anyway, it's a lot of fun dinking around with this figuring and such. I've learned a bunch about my different appliances and their power consumption using that Kill-A-Watt meter. I feel better about buying that Xantrex 1500/3000 watt modified sine wave inverter now. Thanks Synap.

Conversation with electrical engineer

I had a conversation about the modified wave inverters with an electrical engineer (a board member who has been kind enough to advise me).
He says that I should have no problems with my electrical applications using the modified wave inverter, as long as my current is adequate and the inverter is rated sufficiently for the load(s). Electronic loads could be a problem, but he suggests the easiest solution is to power a UPS from the inverter to run sensitive loads.
Another suggestion - which pat myself on the head, I came up with and he agreed ;-) - is that deep cycle batteries are probably not the best solution for my intended use. He believes that automotive starting batteries are better, because I don't anticipate using these to power loads unless my engine is running and the alternator is charging. The starting batts are better at handling transient high surges. Obviously, these aren't the best choice if you intend to operate equipment for any length of time on batteries alone.
So bottom line: To operate an AC, freezer or fridge and other motor loads, my proposed system, consisting of heavy alternator (150-200 amps), heavy truck battery and 2000/3000 watt modified wave inverter will work fine. If I want to power computer or other sensitive load, use a UPS.

Best regards
Doc

Thanks for the info Doc. That's mostly all good news. I've found some good deals on hi amp alternators and ditched my lawnmower recycling idea. I have a 5 HP gas engine with a horizontal shaft that will work much better. And it's already mounted on a small trailer set up for pumping water from our pond to an old 2,000 gallon fuel tank we used to use for watering our garden. Yes, I'd rather have a diesel engine but I've kind of relaxed about that now. I just need power generation equipment long enough to keep our freezers and refrigerators going until I get all the food processed from them. After that, I won't need electricity any more but I'll still have some solar and diesel powered stuff to fiddle with. I'm just worried about the short term power and that's what I'm working on now.

My new inverter

Max,
I just scored a New-In-Box Wagan, #20072, 3000/6000(surge) watt inverter on eBay for $193.00. It hasn't arrived yet, but I'll post a performance review after it does. I've seen a lot of those Xantrex 1500/3000 inverters on eBay in the $100 range. That's the one you just bought, isn't it? Have you had a chance to check it out yet? I'm interested in those and would like to get one for a 2nd vehicle if yours checks out OK. Let us know.

Best regards
Doc

I am building a charger from a 5 h.p. tiller engine. I am using a 61 amp delco alternator. I tried a 78 amp unit. It seemed to work the engine to hard for long term use. I learned that you don't want to use a pully more than 3 inch diameter. I had a 5 inch Dia. and it was working my engine way to hard. The big 100 amp alternators are great but don't be suprised if one of these is to much for a 5 h.p. engine. My 78 amp would stall the engine with a really low battery using the 5 inch pully when you turned the switch on. After I complete the one i am working on I am going to look for a used/broken riding mower to get a 12- 15 H.P. engine to make a high output charger using a big alternator.
Good luck

First of all, you guys might want to do a search because we have had many discussions on TB2K about SW vs. Mod SW over the years.

I've been messing with inverters for close to 25 years. The first one was a Tripp square wave - ok for lights and a tube radio. Next was a Trace 812 modified SW. It was Ok BUT it couldn't start some motors such as the refrigerator I had when I first bought it. Therefore, I'd want to have some assurance from the manufacturer that it would start any motor before I spent the bucks for any modified SW inverter.

I currently have dual Trace 5548's. These are full sine wave and run anything - of course they cost a ton of money - four grand apiece.

Todd

bump

Can someone help me here? It is my understanding that the evaporator part of the freezer(like those tubes on the back of the fridge) gets warm and SHOULD BE PERMITTED TO COOL WITH AIR MOVEMENT for best performance of the freezer.

But on new freezers the evaporator is HIDDEN, BURIED in the outside wall (which gets hot). SO HOW WOULD FURTHER INSULATING THE FREEZER WITH BLANKETS HELP?? Wouldn't that prevent this heat from escaping and thus force it to warm the inside of the freezer?

aint', I'm pretty sure the extra blankets trick is just meant for helping keep it better insulated when it's not running. Like you, I would think wrapping it up while running wouldn't be a good idea, re: overheating, etc.

I will have a few relevant comments (again) on modified sine wave inverters and equipment running off them. (And I am an electrical engineer. My specialty is power and power conversion.)
But first I have to run a test:
Will my modified Sine wave inverter [3.6kVA Trace] run a UPS (one Triplite and one APC) without kicking the UPS in? I doubt it very much because the sensing circuits in the UPSs will not tolerate the waveforms from the inverter and will switch immediately to inverter mode and exhaust their internal batteries in short order.
Which they will also do with most generators. I will confirm that with a test.

A few quick notes:

1. Be very carefull running multiple small inverters off of the same DC source. A lot of the smaller (800-2000 Watt units) have their AC ground NOT tied to their DC ground and you can fry things if they do end up "connected", or at least give you a tickle if you happen to touch two differently powered devices.

2. You might also want to look into more loads that can be run direclty off of the batteries (DC 12V) Check out http://www.albeotech.com/products.htm for some ideas. You should also pick up a copy of "Home Power" a solar magazine. I run a lot of solar panels both for my home and for my Amateur Radio gear. People who deal with solar run loads look for the most efficient products out there because of the high price of the panels.

3. Try to find good batteries. Deep cycle will work, but try to find a deal on large AGM batteries. I keep a watch on the ones used in telecomunications racks. I can usually find them for about $0.80-$1.10 per AH (Amp/Hour) for the Yuasa brands and even less for other brands. Check http://www.hyperpowerusa.com/page3.html You need at least 180 AH for each 1000 Watts that you want to pull out per hour if you want to run "quiet mode" with no generator. You will need at least 120Amps of alternator and 3.5 HP of engine for each 1000 Watts of power that you plan to use, and add 25-40% more (Amps and HP) if you plan to charge those batteries while still drawing that load.

4. Keep a watch on depth of discharge. 50% of charge left on a 13.8V (12V nominal battery) is not 6.9V! It is actually closer to 11.2V OCV (open circuit voltage), or 10.4V under load. 0% charge is 10.2V OCV or 9.0V under heavy load. Any time a lead acid battery drops below 10V it is doing damage to it, deep cycle batteries and AGM batteries minimize this problem, but it still happens to a lesser degree. The key to long battery life is keeping them charged properly.

5. Keep any DC cables (especially to and from batteries) oversized and well protected with fuses. I have been getting "damaged" 28V starter cables from 727/737 series airplanes from a friend of mine. They are about 30-40 feet long and have two 2/0 (1600 Amp (large)) copper conductors and a set of smaller wires to turn on the planes APU. These things make great solar battery box cables. Check with your local airport and see if they are tossing some anytime soon. After they get their outer covering torn (which only seems to happen on the control cable) they must stop using it and get a new one. They come with a set of BIG two pin connectors and a smaller three pin connector, bolt cutters work fine removing them. The better your DC cables are, the less loss and more power transfer you will have to the rest of your system.

Just a few tidbits...

Loup Garou

Maybe I should reply to different subjects in different posts:

A lot of info is already in the previous posts.

To alternators:

These are three phase AC generators whose output is ripply DC from a three phase bridge rectifier (internal to the alternator.)
Alternators depend on a battery for proper voltage sensing and regulation,
so you can't run one without a battery! Consider an alternator, a voltage regulator and a battery as ONE unit!

Remember that your lights dim with an old battery when your car idles.
Idle speed is totally insufficient for alternators to provide headlight power (which might be 15 Amps or so.)

To inverters: as pointed out before, the startup capability of an inverter depends not only on it's rating but also on the source (battery) feeding its input.
Going from 12V to 120 Volt means the input current demand is TEN times that of the output current demand and that includes start surge peaks!

In cases where inverters "trip out" at load start up, the reason is often the inability of the battery to supply the needed current and not the inability of the inverter to handle it.

Lesson;
One must match inverter capabilty with a large enough battery and heavy enough cables to get everything out of the inverter that it is rated for!

Sub-Lesson 1:
Inverters have an internal input cut-out voltage circuit to protect it from thermal destruction AND to protect the battery from over-discharge. 10.5 Volts or lower.
The voltage drop on the cable between battery and inverter is significant insofar as it decreases the voltage that the cut-out circuit sees. So if there is .5 Volt drop on that cable, the inverter will cut out at 11V battery voltage because it sees only 10.5V. (This can get outright mean during start surges.)
So you design the interconnect cables not for current carrying capability (Ampacity) but for voltage drop!

Sub Lesson 2:
Likewise, you keep high current connections at a minimum! A connection between battery terminal and cable may be ONE MILLIOHM. If your start current demand on the AC side is 30A, it is 300A on the DC side. With two connections, you lose .6 Volts right there! Beware of adding milliohms!

Voltgage regulator and battery ought to be close together.
When the voltage regulator is part of the alternator, then the alternator and the battery ought to close togther. Inverter and battery MUST be close together (unless you like paralleling welding cables).

Things that are kind of easy with solar (regulator AT battery) are getting more complicated wth alternators, especially when these are still in automobiles...

Ratings: I am not sure if alternators are rated for continuous duty.
Does anybody know?

WFK..don't have the link anymore (too tired to dig for it) but as I recall the GM alternators can be run continuously under 80% load (rpm dependent output)..BUT..it's heat that will kill 'em. Heat also lowers output. Ordinarily a moving vehicle provides adequate airflow cooling. That just the radiator fan will do so at rest I don't think so. Perhaps just having the hood up would compensate. Boat folks have that problem and go to specialty alternators designed to handle the heat and continuous max load. Ample Power is one product. Prestolite is another..highly regarded for emergency vehicles.

Oh yeah..almost forgot to add, and it's important if you're gonna use 'em for emergency backup. (BTDT) With GM Delco's it's a good idea to pack a few replacement diode modules and know how to replace 'em. They're not terribly expensive..cuz they make/sell a lot of 'em (hint hint). Not a hard job to replace, but a Chilton's or Motor book makes 1st time easier. If you start hearing a wire whine the diodes are 'leaking' or 'open', and on their way out. (FYI: Whine is caused by a large AC component being pushed on the DC wiring.) GM seems to cut large corners on those diodes' quality.

Hey, this is all great information! Thanks for the time and effort WFK, LoupGarou and Synap!! Much appreciated. I'm getting started on my homemade generator project using a heavy duty truck battery, a 5 HP gas engine, a 105 Amp GM one wire alternator and a Xantrex 1500/3000 watt inverter today. Well, first I'm going to try an 80 amp alternator to see how that goes. If that engine will carry the load and the battery stays charged while running my appliances then I'll be good to go. I can get the 80 amp one for free and that's a good incentive.

And speaking of alternators... Here's one I found on ebay. The description says it's a mini-alternator. Is this a good deal or too good to be true?

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33573&item=7972809663&rd=1

Square, modified sine, sine wave

print and keep.
This is from an old Trace manual. There is nothing Trace specific here; it's all basic
stuff and it applies to a 120-Volt sine wave.