home made 12 volt generator

captain ron · January 23, 2007, 07:51:41 PM

As not to hijack gr8njt's thread I'll start a new one. From what I gather you can run your inverter continuously off of an alternator! This turns on some light bulbs in my head(very dim) Why would anybody spend the big money for gensets when you can do this?
Here's a few questions about this set up.
1. can you run your inverter that much safely?
2. Can you produce 220 volts?
3. How big of alternator would you need?
4. how big of motor to drive alternator?
5. How inexpensively can you build something like this?
6. could you set it up to turn on automatically when battery voltage gets down to 50%
7. do I sound stupid?

Nick Badame Refrig/ACC · January 23, 2007, 08:01:25 PM

Capt. Ron,

Hay, I see a bulb lit in your camp....

What did you have in mind for a source of engine?

Bill Glenn [homegrowndiesel] has a setup like you are thinking. 12v generator.. He has a great system but, the engine is a little loud.

Nick-

DrivingMissLazy · January 23, 2007, 08:04:56 PM

Ron, why not use the inverter output to run an AC motor to drive the alternator to charge the battery to run the inverter to run the AC motor to run the alternator to run the inverter to run the AC motor to run the alternator.
Richard

Quote from: captain ron on January 23, 2007, 07:51:41 PM
As not to hijack gr8njt's thread I'll start a new one. From what I gather you can run your inverter continuously off of an alternator! This turns on some light bulbs in my head(very dim) Why would anybody spend the big money for gensets when you can do this?
Here's a few questions about this set up.
1. can you run your inverter that much safely?
2. Can you produce 220 volts?
3. How big of alternator would you need?
4. how big of motor to drive alternator?
5. How inexpensively can you build something like this?
6. could you set it up to turn on automatically when battery voltage gets down to 50%
7. do I sound stupid?

captain ron · January 23, 2007, 08:12:28 PM

Quote from: DrivingMissLazy on January 23, 2007, 08:04:56 PM
Ron, why not use the inverter output to run an AC motor to drive the alternator to charge the battery to run the inverter to run the AC motor to run the alternator to run the inverter to run the AC motor to run the alternator.
Richard

Trust me I already thought of that

perpetual power

DrivingMissLazy · January 23, 2007, 08:15:31 PM

Well, I tried

Richard

Quote from: captain ron on January 23, 2007, 08:12:28 PM
Quote from: DrivingMissLazy on January 23, 2007, 08:04:56 PM
Ron, why not use the inverter output to run an AC motor to drive the alternator to charge the battery to run the inverter to run the AC motor to run the alternator to run the inverter to run the AC motor to run the alternator.
Richard

Trust me I already thought of that perpetual power

gr8njt · January 23, 2007, 09:45:52 PM

Capt Ron,
You do not sound stupid. It's a good idea that can be taken forward and improved upon.
I've read about these home made gensets a while back in 1999 fearing the arrival of Y2K
I do not know if this link will help you brighten up that lightbulb but this site have detailed instructions on how to built one with readily available supplies. If you scroll to the bottom of that page, they have cheap prices for parts needed to put a project together.
Good luck!

Dallas · January 24, 2007, 03:48:54 AM

Ron,
How about this for a 240V inverter?

http://www.affordable-solar.com/sma.sunny.boy.6000u.inverter.htm

or one of these:

http://www.sunpowercorp.com/inverters/

or this:

http://www.donrowe.com/inverters/aims_3000_240V.html

There are lots of different inverters out there.

Len Silva · January 24, 2007, 06:08:32 AM

Cap'n,

That's just how some of the variable speed generators such as the Onan Quietdiesel work. An alternator rectified to DC, powering an inverter.

Len

Lee Bradley · January 24, 2007, 08:36:37 AM

Just looking at the inverts Dallas listed:

The first two use DC voltages in excess of 100 volts and the last one is 12 VDC but you would need 500 ADC for the 6000 watt output.

Dallas · January 24, 2007, 10:00:42 AM

Quote from: Lee Bradley on January 24, 2007, 08:36:37 AM
Just looking at the inverts Dallas listed:

The first two use DC voltages in excess of 100 volts and the last one is 12 VDC but you would need 500 ADC for the 6000 watt output.

I only posted those as ideas to go by. I left the actual finding of the inverter that would work for each individuals application up to the student.

However, looking at the one, (and several others that require high VDC), if you think about it, 240V DC isn't that hard to come up with. that would be 20 12V batteries, plus the amp draw is only 25A.

With the last one, needing to draw 500a DC is that much out of line with what you draw on a large 120V inverter.

All it takes is thinking outside the box instead of blindly following in the footsteps of everyone else. After all, isn't that why we've chosen bus conversion as a hobby?

Dallas

Don4107 · January 24, 2007, 10:34:14 AM

Way back when my father-in-law built a alternator to maintain his house batteries when on Ham Radio field adventures. It was a single wire alternator hooked to a 3hp Briggs and Stratton engine. A small base, two pulleys and a belt. It is still around somewhere.

Might take some research or experimenting to see how big an engine vs how many amp alternator vs gearing. I suppose that without too much thought a manual controlled regulator could be designed to limit engine load.

Lee Bradley · January 24, 2007, 10:36:13 AM

Not arguing just listing requirements, those high DC voltages are not usual for buses but anything can be done. As for the 500 amp load that is just a fact of life when you run a big inverter off 12 volts.

DrivingMissLazy · January 24, 2007, 10:41:41 AM

I built hundreds of inverter systems for the UPS industry. The DC bus voltage was either 300 volts or 600 volts DC. For sure you did not want to stick a screwdriver across those terminals. LOL
Richard

Jeremy · January 24, 2007, 10:52:15 AM

Ever since I have been driving I have had a morbid and irrational fear of being stranded with flat batteries - so I'm liking this idea of having another way of charging batteries should my generator fail (and potentially a much faster way of charging too). I also like the whole 'inventiveness' thing, and definitely disagree with those who say 'You must do it this way because everyone else does'.

What would be a really neat solution perhaps would be to arrange the additional small engine so that it could somehow be made to turn the existing bus alternator, rather than having to supply a new alternator and all the associated cables and switching etc required. It wouldn't really be feasible to change belts over each time, but I expect a clever person could work out some kind of electrical clutch mechanism to allow the alternator to be turned by either engine. Perhaps the electric clutch thingy off a belt-driven air conditioning pump could be adapted?

Jeremy

DavidInWilmNC · January 24, 2007, 11:14:56 AM

It might be more reliable and a lot quieter to use one of the smaller Yamaha or Honda generators. You could then power a charger for the batteries. It might be more economical than having to run a big genset just to charge the batteries. Of course, you'd have to have gasoline on the bus, but some of us do anyway.

David