Storm Story

[Brian McGowan]

I am putting this here since I can't think of a better place to put it. Enjoy.

Homemade generator test
Last night during a storm the power went out. I fired up the 24LED light fixtures I have around the house for emergency use that run off my batteries. I have brand new batteries in the garage that I got yesterday and have not hooked up yet so I am stuck with the bad ones that are still in the system. I called the power company when I got home and they said it would be back on around 8:40PM. It was about 7:30PM and power had been out for about an hour already. I decided to try out my home made generator. (lawn mower engine hooked to a car alternator) I dragged it away from the house and put some gas in it, hooked it to the batteries with the Anderson 175A connector and started it up. I got a big resistor and hooked it up to the field coil of the alternator and got current flowing to the batteries. Then I ran an extension cord from the big pure sign wave inverter at the batteries in the garage into the house to the refrigerator. Turn on the inverter and throw the switch on the outlet strip and the fridge fired right up. While that was running I plugged the “house” circuit into the outlet strip. This goes to a pair of 4 outlet boxes mounted in the basement so I can run extension cords around the house to various places. One of these cords runs into my computer room to an outlet box that has a relay and 2 power cords in it. One cord plugs into the wall and the other into my extension cord from the inverter. When power is applied to the extension cord the relay activates and switches the box from house power to inverter power. From there it was a short extension cord to the fan in the window so I could cool the house down. About this time I called the power company again and our time had been pushed back to 2:00AM. I was glad I fired up the generator. Next we made sandwiches for dinner and I ran a cord from the outlet box in the basement to the entertainment center and fired that up so we could be amused while we ate. After that I called the power company again and they said power would be restored at 6:00AM. Still glad I fired up that generator. We did some chores around the house until about 10:30PM when the generator ran out of gas for the second time. I shut off the inverter and we went on batteries for the rest of the night. I was still able to do chores due to the lighting. About 12:30AM the power came back on. Still glad I fired up the generator. 6 hours without power. About 2.5 hours with the generator running. The alternator never got warm to the touch and the air coming out was only lukewarm. As crude as it was it did actually prove that it works and I can keep myself alive if I need to. There are many improvements to be made and I am working on them as fast as conditions allow. This was a good and successful test and it performed exactly as I expected it to.

[Dan Lenox]

Brian,

Way to go!

You mention that the alternator was a lawn mower engine connected to a car alternator.

How big a battery bank were you using?
How much power do you think that it was putting out?

Dan Lenox

[Brian McGowan]

My generator is a 4.5HP lawnmower engine hooked to a Chrysler alternator. I chose this alternator because it does not have a regulator built in so I could drive the field coil any way I wanted. I put a big fat resistor in line with the field coil to limit it’s power. I will make a rough guess and say I was putting out 35-40A. I think I could safely get 60A (1HP ish) out of it. A proper charge controller would also help. I have plans for one I could build or there are commercially available units with proper charge profiles for deep cycle FLA batteries. At some point the intent is to get a small diesel engine. I had only 5 gallons of gas for the lawn mower but in the shed I had 30 gallons of B100 for my Mercedes. I would rather have been using that. I can’t afford a Lister knock off and it is just too massive for me to handle but I have been thinking about a water cooled 4-5 HP diesel engine from Carroll Stream. These are in the neighborhood of $400.00.

The battery bank that was hooked up consists of 3 Everstart type27 115AH Marine/deep cycle from walmart. These are really beat and probably operating at less than 1/3 of their rated capacity. I really abused the crap out of these during my learning process. As an example, on Saturday I went out to the garage around 11:30AM and the solar charge controller was already limiting at 14.1V. I fired up the inverter and started my compressor to charge my air tank from 90-120PSI. During that 8 minute period the voltage went down to 11.9V. Within 20 minutes it was already limiting at 14.1V again. The new batteries are 4 Everstart Maxx29 125AH Trolling/Deep cycle/marine/starting. I figure this should give me a good safe buffer so I can stop the generator and refuel and restart without interrupting service. Sometimes the batteries were charging and sometimes discharging depending on the load at the time which is kind of what I was after. I am still not ready to get real batteries yet and I am totally convinced that lead/acid batteries by their nature are unsuitable for alternate energy applications.

I was running the AC box fan which draws 2A @ 120VAC and either the entertainment center which draws 1.9A @ 120VAC or the fridge and I can’t remember how much that draws but I will measure again. The fridge is an efficient one which draws 1.1kWh/day as opposed to the old one that it replaced which drew 3.5kWh/day. I have an automobile radiator fan which draws 5A @ 12VDC and moves as much air as the box fan which I set up last year to vent the house but it has been so cool I haven’t set it up yet this year. It probably costs me 20+ amps @ 12VDC to drive the box fan with the inverter so the auto radiator fan is far more efficient.

That’s all the time I have right now.
Brian