Backup Generator - Car or Lawn Mower?

[valterra]

Wiring up my system with a new kick-butt inverter that hopefully will run my downstairs freezer.  The idea is that in a prolonged grid outage, we won't potentially lose the hundreds of dollars worth of meat.  

During intermittent (couple hours) outages, I do the usual - leave it alone, don't open the door, etc.  But I worry the whole time about when the power will come back on.

I have other things to spend money on right now - a good tower for my new genny, more solar, etc. - and power outages are a rarity, so I can't justify the expense of a standalone generator.

Someone kindly suggested that I just use my car if it ever comes to that.  That's a great idea, and it got me thinking.  I have a car (Scion xA), a Jeep, and a ride-on mower ("Lawn Tractor").  The lawn tractor is your typical Sears 42" jobber.  I can get all the specs if that is a factor.

I've been wondering if the lawn tractor would produce enough charging power, and also be more efficient than the automobiles.  My thought is that even an idling car has to spend energy on power steering, everything inline with the serpentine belt, etc.  I'm not much of a car guy, so I'm just guessing here.  But my thought is that the lawn tractor is a "simpler" device overall, and therefore possibly more efficient?

PS - before I get flamed - I KNOW gasoline is expensive.  This would be for emergencies only.  

[ghurd]

Do you know what gasoline costs?

Mowers have tiny little alternators.

Some have a 'large' magneto, some use the starter motor.  Probably other types too.

No mower expert here.  Even if the neighbors think I am.

Couple local guy's have about 12~16 HP lawn tractors.

The charging systems do not keep up. They use a battery charger between uses.

I would be kind of surprised if they make 2A more than the motor needs to run.

Who needs a lawn mower with a stereo, CB, air horn, and turn signals?

It seems like they do.  LOL

G-

[spinningmagnets]

Disclaimer: I have never had an RE system, but I hope to have one some day...

I highly recommend having a back-up generator from the start to save your RE battery from being deeply discharged. Its my understanding that if you are now connected to the grid, you can use that to top off your RE battery pack when there is no wind/sun.

If you have no grid, a back-up generator is a vital piece of equipment (IMHO).

That being said...first I would get a large chest style freezer (opens like a laptop computer), and attach additional insulation. Put a couple of jugs of water in there, and during an outage the block ice will extend its usefuleness.

Bar-be-que some freezer meat the first day of an outage to make room in the freezer for some of the more sensitive or expensive items from the fridge that are slowly warming. You can even go "old-school" and put one of your ice blocks on the top shelf of the fridge to help it last longer.

Concerning the lawn mowing tractor; lawn mowers are thrown away on a regular basis. They typically have a clogged air filter which leads to a rich carbon-fouled plug. This results in hard starting and difficult pushing from the dull blade thats never been sharpened. After 3 years or so, no one pays $50 to have someone fix it when they can get a new one for $150, so, fixable mules can be found in the trash for free.

There's a dozen examples on the web where someone has taken a free lawnmower, fixed it them selves, and attached a pulley set that spins an alternator to provide 12 volts.

Your riding mower has a bigger engine than most push mowers. It would not be difficult to temporarily remove the blade and attach a pulley set (in an emergency) to run a fairly large generator head.

The famous Amatek (and other Permanent-Magnet-Motors / PMM's) are fun wind projects, but are not huge power producers. Perhaps a similar PMM/3-phase servo motor would be very useful for this purpose.

If you think this would work for your situation, of course you would need to fabricate mounting brackets with a control panel and then test the output, so the set-up would be standing by when such an emergency hits.

Just a couple ideas to kick around. Best of luck, and have fun.

[frackers]

My power cut insurance was a really cheap Chinese 2-stroke 750watt generator. Two years ago it was NZ$99 so I guess thats less than US$75 and has been very useful to power a drill, small angle grinder away from grid power sockets as well as the freezer in an emergency. Light enough to pick up with one hand it still starts on the first pull.

The regulation is rubbish (running a 100watt inspection light and 'blipping' a drill made the bulb blow due to overvolts) but its OK for steady state operation and for the peace of mind it was a very good investment.

[wpowokal]

A frezer will last 3 days left entirley alone, if you have a ride on mower make a detachable bracket for an auto alternator, slip the mower drive belt off, alternator one on and start chargiing.

allan down under

[Chagrin]

Just throwing out the number, lawnmower engines ~6-24HP have a 15 amp alternator. Anything not 15 amp is quite a rarity.

Spark for the plugs is in no way connected to the mower's battery/alternator, so saying that the alternator provides just enough power that it "needs to run" would be incorrect. Well, assuming that the rider doesn't require a radio in order to run the mower . The spark is controlled by the ignition coil and magnets on the flywheel; that's how it controls the timing. When you shut off a lawnmower engine you're actually grounding the coil to prevent it from sparking.  

[FuddyDuddy]

Simply look at Otherpower.com and then search for "Maytag Battery Charger" to get some more ideas.

FuddyDuddy

[luv2weld]

Here is a site for emergency preparedness---

http://theepicenter.com/tow1230.html

Here is their page with brackets for those small lawnmower engines.

http://theepicenter.com/tow02077.html

You could either buy one of their brackets, or look at it and make

one yourself.

Ralph

[Norm]

I have a riding mower with 12 hp briggs & Stratton and the

 battery is always charged up

enough to start the engine (which kicks over

and starts the first try....in warm weather)

if I leave the throttle at idle and let the engine warm up

I notice that even at full throttle, the ammeter only indicates about 2 amps,

but that could be because the battery is fully charged?

 I've never tried charging another battery, but

I imagine it is capable of charging at least

5 amps??

[Jeff]

Just for a quick reference. I'm definitely NOT one of the "guru's" here!

I always USED TO state you needed about 6 1/2 horsepower per 45 amps in alternator. I say used to:

 I know from experience when I ran my 45 amp alternator with an OLD Kohler 6 3/4 hp generator engine. The 110v AC part of it was shot, but the engine would just run the alternator if I raised the throttle slightly above idle.

 After some cool tips from this site, I tried eliminating the external regulator, and replacing it with the inside light dimming knob from an old T-Bird. This regulated the input to the field on the alternator, and greatly reduced how much HP I needed to start it charging. I have a 4 3/4hp 2-stroke self-propelled lawnboy mower. I removed the belt to the drive axle, mounted that same 45amp alternator on it, and also an idler pulley I could use to engage/disengege the alt. It has no problem starting & running the alternator.

So...depending on how you regulate the alternator, 4 1/2 to 6 1/2hp per 45amps alternator. Since your mower is 12hp, you might want to find a 60-75amp alternator.

Just my 2 cents

[valterra]

Plenty of ideas for me to "'speriment" with here.  Thanks guys.  For now, I wanted to avoid building something new - I don't need another project! - and going with something out of the box, like the car or lawnmower.

If I get the gumption to hook it up, I will put a 50/50 Ammeter inline and see just how much the mower shoots into my batteries (a pair of 6v 200AH Sam's Club golf cart batts).

Then I'll do the same with the car.  

But my original post was questioning if a lawn tractor was a more EFFICIENT generator.   e.g. does it burn less gas sitting there in idle?  I imagine I was right about that because nobody corrected that part.

Great ideas guys!  Thanks!

[Norm]

A car idiling might be more efficient at charging

batteries versus a lawnmower engine running at

3/4 speed to produce the same amounat of current

.....especially if the car has fuel injectors and

computer that figures the proper fuel ratio for

economy at idle.

[valterra]

THAT makes sense, too.  :-)  But I guess there's no way for me to know then.  Unless I could actually calculate gallons of gasoline used versus power generated, there wouldn't be any way to compare?

[Norm]

Gas guages are pretty accurate on mine each mark

is a gallon....an ammeter thru the cigarette

lighter to the battery being charged should give

you a pretty good indication.....course your

voltage regulator may or may not botch everything

up....no guarantees this will work...just speculaating

[jonas302]

I agree with Ghurd that the lawnmowers I have worked on have dismal output basicly noithg at idle and the stator would burn up mighty fast some big mowers might have better output but your car is usually capable of between 50-120 amps so use your car  or add on alt to something else I think would be best

I just checked my scangauge my 00 f-150 4.2 v-6  drinks   .55 gal per hour at 975rpm

I like the idea of using a piece of dependable equipment that gets used often compared to trying to start a dedicated generator in the hour of need also my truck always has at least 10 gals of fresh gas in it so last time I needed it for a rare 24 hour outage I may have spent $10 and saved probly 200 in the frige

[bob g]

if it were me i would just belt an alternator up to the lawn tractor

gear it right so that it will turn the alternator at about 3k rpm at just above idle

and use the reostat to provide crude regulation.

i doubt that engine will burn a half gallon per hour charging maybe 30-40amps

but do get a 100amp or larger unit if possible,, 30-40amps continuous on a large alternator will run forever without problems. and if you need more amps just throttle up the motor and crank up the reostat which is very acceptable for quick charging if you keep an eye on the batteries and don't overheat or overcharge them, which probably is not likely in an emergency situation and the batteries are pretty much drained anyway.

i don't think there is a car on the planet what will idle while producing charging current and use less fuel.

also i you botch the connections when it is dark and rainy or your tired you end up toasting the add on alternator on the tractor, something you can replace easily ourself, toast your car alternator or do other damage and you have an expensive repair and your on foot maybe,,, or maybe even a tow bill.

my vote is an add on to the garden tractor

bob g

[jonas302]

I was just thinking about that it might be hard to get a car or lawnmower close enough to the house in the winter so would have to plan for that to I guess I would be have to hook  on to a loader in a winter emergency as my wires are to short to reach the driveway