Now I'm new to this, but I wire houses and am descent with DC as well, so I purchased a 800 watt inverter that operates between 10 and 15 volts. I am in a band touring the country in a van and my game plan was to wire my inverter permanently off the battery lead and have permanent AC outlets. I figured this would more or less make a generator- - a motor powering an alternator powering an inverter giving you AC outlets. I'm not sure how most people typically install inverters but I figure:1 battery, 1 engine, 1 inverter. I know some people use two batteries, which I want to stay away from. In my mind, if I always use the inverter when the engine is running, everything will be dandy, other then a slight decrease in gas mileage. SO I did it and here's the problem. It dosn't work. When the engine is off, i test 13.5V, my inverter works excellent, but I don't want it draining my battery. When the engine is on, I tested 15.5V, over loading the 15V limit on the inverter and rendering it useless. What do I do? Is there any type of small in-line transformer I could get to drop the Voltage between 10 and 15V? Or is there somewhere else I could hook the inverter up that will get less then 15.5V? How do people usually do this? Like I said, I don't want to run off a battery that is not constantly being charged. I don't want to risk completly killing the battery and I don't want to be partially draining my battery then recharging it, as this is not good for the battery. thank you guys for any advice or tips. I only need to drop the voltage a half of a volt!!!!

 

does the inverter have a voltage regulator or an adjustment screw or **** on it to adjust the output on it. Some do, some don't.

 

You don't need a transformer, you would need a Voltage Regulator. You are coming straight from the battery. If you haven't, I would also put in an inline fuse.

 

The unit does not have a voltage regulator on it. And as far as an inline fuse, the inverter itself has two fuses in it. I don't think I need an inline one considering the unit is already protected and I am using 6ga to wire it. Where can I get a voltage regulator? and how would I pick one that could drop 15.5V to 12V? Thanks again guys

 

If your alternator is putting out 15.5 volts, there's a problem. More than likely internal(alternator)or external voltage regulator, depending on year/model. It should be putting out at the most 14.5. I've hooked up a couple voltage inverters and never had a problem.

 

It now tests 14.5 .V. I've tried everything. Can't get the voltage down to 12?

 

thats a small inverter so you best bet would be to run it from the cigerrette lighter or a power point depending on what you have. most power points will only put out 12 volts and power points or cigerrette lighters will work with the ignition off

 

I am a little late posting this, but ... I would use one or two high amperage diodes wired in series. Most diodes have a voltage drop of 0.5 to 0.6 volts, so with 15.5 volts coming in, you should see about 14.4 volts. You may need to heat sink the diodes. You can get a 40 amp diode from all electronic corporation for $3.50. The disadvantage of this is the diode and the heat sink cannot touch the body of the van or a short circuit will result. Keep in mind a 40 amp diode is only good for 480 watts at 12 volts. The diode can handle some surge current. Those 12 volt chargers / starter units use these types of diodes.

Add more diodes for a higher voltage drop. A high wattage resistor just would not work well.

 

You need a fuse as close to the battery as possible, that's standard practice. If that wire without a fuse rubs through to the chasis and shorts anywhere... you'll end up burning your vehicle to the ground...regardless of a fuse on the load, its the voltage on that wire TO the load thats dangerous

You wont find a simple voltage regulator to operate the way you need it, with that power handling. go for the diodes...
i got a ton of high current diodesthat you can have free if you pay shipping, email me....

and you can simply wire a 2nd battery in parallel for more current (longer life with the car off) if you please.

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