Power Inverter Question

Have considered getting a large power inverted for mobile power in an emergency. My question is what effect do they have on a vehicles battery/charging system. If an inverter can supply 2500-3000 watts, that seems like it would be an incredible drain on the vehicles battery/charging system. I imagine most alternators can't put out that kind of current. ( I could be wrong ). Would you burn out the alternator after the battery was drawn down? Would the inverter just not function? Am I wrong about the alternators ability to supply that kind of current?
Thanks
Barry

On Fri, 2 Dec 2005 16:40:30 -0500, "Barry" wrote:

Have considered getting a large power inverted for mobile power in an emergency. My question is what effect do they have on a vehicles battery/charging system. If an inverter can supply 2500-3000 watts, that seems like it would be an incredible drain on the vehicles battery/charging system. I imagine most alternators can't put out that kind of current. ( I could be wrong ). Would you burn out the alternator after the battery was drawn down? Would the inverter just not function? Am I wrong about the alternators ability to supply that kind of current?
Thanks

Nope. Not wrong at all. Even the alt on my f350 diesel is only like a 120a model which would be about 1440W maximum output. Also, a big inverter needs big cables. I've thought of putting a 500 or 1000 unit under the hood to run an electric impact wrench, just haven't found the space yet. Brief bursts probably wouldn't kill an alternator, full time 3kW probably would.

"Barry" wrote:

Have considered getting a large power inverted for mobile power in an emergency. My question is what effect do they have on a vehicles battery/charging system. If an inverter can supply 2500-3000 watts, that seems like it would be an incredible drain on the vehicles battery/charging system.

It is, and inverters of that size aren't designed for use with car batteries, but for use with deep-cycle batteries.

I imagine most alternators can't put out that kind of current. ( I could be wrong ).

An average car alternator is good for about 75 watts (less than 7 amps at 12 to 14 volts).

Would you burn out the alternator after the battery was drawn down?

It can happen.

Would the inverter just not function?

Many cut out when the battery can only supply around 10 volts. (voltage drops as the charge is drawn out of the battery)

Am I wrong about the alternators ability to supply that kind of current?

It is all a matter of time. Add a couple of trolling motor batteries to the car battery and connect everything with good welding cable to provide for the increased current, and your alternator can charge the batteries for long time to provide enough energy to run a high-wattage appliance for a short period of time. You cannot run a high wattage appliance continuously, because you have to take less out of the system than you put in.

Thanks
Barry

"Harry Chickpea" wrote in message

"Barry" wrote:
Have considered getting a large power inverted for mobile power in an emergency. My question is what effect do they have on a vehicles battery/charging system. If an inverter can supply 2500-3000 watts, that seems like it would be an incredible drain on the vehicles battery/charging system.
It is, and inverters of that size aren't designed for use with car batteries, but for use with deep-cycle batteries.
I imagine most alternators can't put out that kind of current. ( I could be wrong ).
An average car alternator is good for about 75 watts (less than 7 amps at 12 to 14 volts).

I think you mean 750 watts. A 100 amp alternator can supply about 1300-1400 watts.
Combined with the battery it would be possible to provide more power but only for a limited time as it would run down the battery. I would suggest to the OP to limit the inverter to around 700-800 watts unless additional deep cycle batteries are installed and seperate from the vehicle battery.

Would you burn out the alternator after the battery was drawn down?
It can happen.
Would the inverter just not function?
Many cut out when the battery can only supply around 10 volts. (voltage drops as the charge is drawn out of the battery)
Am I wrong about the alternators ability to supply that kind of current?
It is all a matter of time. Add a couple of trolling motor batteries to the car battery and connect everything with good welding cable to provide for the increased current, and your alternator can charge the batteries for long time to provide enough energy to run a high-wattage appliance for a short period of time. You cannot run a high wattage appliance continuously, because you have to take less out of the system than you put in.
Thanks
Barry

In article , hchickpeaREMOVEME@hotmail.com (Harry Chickpea) wrote:

It is, and inverters of that size aren't designed for use with car batteries, but for use with deep-cycle batteries.

It isn't the battery that is the limiting factor here, it is the alternator. Car Battery or Deep Cycle will not have any effect on the inverter as long as the alternator can keep up with the inverter draw. Even if the alternator can't keep up, the difference between Car Battery and Deep Cycle will not be significant except for some slight effect on cell integrity under large discharge conditions.
Bruce in alaska -- add a <2> before @