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Old 11-16-2012, 13:50   #14
LongGun1's Avatar
Join Date: Apr 2005
Location: N E Louisiana & N Arkansas
Posts: 12,786
Originally Posted by Contact View Post
I figured I'd throw this out there and see what everyone thought about it, I'd like some feedback on it, and if it's a decent plan, it might even be something for other people to consider.

A few years ago my work switched vendors, and we ran a clearance sale on our power inverters. I got an amazing deal, and was able to acquire 2 800 watt inverters, and a few 400 watt inverters for less that 50 bucks for all of them if I remember right.

The 400 watt inverters can either be connected directly to the battery, or plugged into a cigarette power source, while the 800's must to be connected directly to the battery.

So, onto my actual question, my vehicle has a 125 amp alternator, and since everyone seems to agree that inverter generators are the way to go if you can afford them, is there any reason the vehicle couldn't/shouldn't be used for backup/emergency power for a temporary loss of power? Obviously the car would use exponentially more fuel than a dedicated generator, but if you only need it for a couple days and you have a good running, reliable vehicle, it could prove useful.

Moreover, is there a limit to how many inverters I can plug up? I don't know how much a 125 amp alternator would safely run if the car is just sitting there idling with most of it's own accessories turned off. I know with the 400 watt inverters, the limit would be on the actual circuit that it's plugged into, but for the 800's, they would be connected directly to the battery, so as long as the car is running, and the battery stays charged, they should be fine.

This is definitely not my long term survival strategy, as a car would use its gas up in a matter of a couple of days depending on how much we needed to run it, but since we just made the investment of a new home a few months ago, we haven't had the extra disposable income (or the need, luckily we've had no power outages) for a dedicated generator with transfer switch, but I think as long as I kept it modest with the stuff we needed to run, I think it could work.

So I guess the point of this thread is to lay out my current primary plan for a friendly analysis, and if nothing else, this primary plan could eventually be my Plan B once I get a dedicated generator for the house. I am fortunate that the home we purchased had to be completely remodeled after a fire a few years ago, so all of my appliances are newer energy efficient appliances. I also wonder if there would be any way (or need) to hook my 800 watt's together to give them a 1600 watt capacity to run some of the larger appliances or a space heater if necessary. Obviously the major concerns would be to run the fridge, and washer/dryer.

Let me have it!!

1st....lots of good advice!

I would consider a different path than the one you are currently on..

A little background on myself...

My educational background is electronics engineering, military experience primarily was in electronic communications, my current career is in industrial electrical/electronics/process automation/robotics, I have a side business dedicated to backup power, also I attend renewable energy industry expos, seminars, subscribe to industry publications, etc

Pictured below is the completely automated 8 KW (20 KW Surge) 120/240 sine wave inverter/charger setup I installed & configured in the NE La home...(my other backup setup of 20 KW {44 KW surge} Exeltech MX Inverters is in N Arkansas)

..will automatically transfer power from a failed grid to battery powered inverter backup in a fraction of a second..

.. & it has been providing seamless backup power for my family since the late 1990's...

Survival/Preparedness Forum

AC power sources for the Power Panel are an 8 KW (24 KW surge) fuel efficient, low-rpm Diesel genset..

& the Grid..

For the DC side...this 16 ea. "Golf Cart" battery configured 48 VDC DC Battery Bank (17 KWH usable at 80% DOD) shown here being replaced in early 2006 (still on this 2nd set)

Survival/Preparedness Forum

Now for the advice...

..rather than trying to pound a square peg into a round hole with the gear you currently have..

(possible carbon monoxide issues with running a vehicle for extended periods with accelerated wear, possible damage to your vehicle electrical system {inverters like you describe are designed to convert DC on a short term basis from batteries to 120 VAC used for low power electronics & such, not high power devices like heaters/dryers/etc...not to invert 12 VDC from alternators...and the best batteries for this use are deep cycle...not starting batteries} ,wasting precious gasoline, large power losses/inefficiencies in a inexpensive 12 volt inverter setup, possible damage to your new appliances with modified? sine wave inverters, attempting to sync & stack inverters likely not designed for that purpose, possible invalidation of insurance coverage with a jury rigged non-UL rated setup, possible long runs of expensive heavy gauge copper wiring needed for minimal voltage drop with a 12 volt system, lots of effort expended for little gain, possible dangerous environment for family members or non-knowledgeable others attempting to energize components in an emergency, etc )

..why not sell the gear you have ..

..& work towards a setup (like the one pictured above) that will work well for your purposes?

If you have a tractor...especially a diesel one..

..there are PTO generators that will work well for providing backup power.

Also, there are welding rigs that also work very well as a whole house generator.

Either of the above can be integrated with an battery backed inverter/charger to have an automated backup power system.
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"Accuracy first, Speed second.....Speed first, Accuracy never"

Last edited by LongGun1; 11-16-2012 at 14:34..
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