1250W Power Inverter current draw

 

I have a 1250W (2500W peak) power inverter for use in my Tent Trailer,
and was trying it last weekend.

I tried with a coffee maker (which I know are pretty hungry things).

I have a 30A fuse going between the power line and the battery, which
was getting tripped all the time.

Do you think its valid to draw 30A or more from the battery when trying
to supply 1000W to a device?

 



     Do the math for yourself.  In this case the proper formula is: Current =
Power/Voltage  or 1250 divided by 12.  For a momentary surge, it culd be as much
as 2500/12.  Do you now have the slightest doubt why your 30 amp fuse blew?

     If you want to live off of 12 volts, go to a truck stop (or a web site that
sells to truckers) and get yourself some 12 volt appliances (the drain might
still be heavy, but more efficient than with an inverter.

Vaughn

 

What size cables you think would give less than 10% voltage loss from
battery to inverter at 200 amps? Lets assume the cables are about 3
feet.  0 gauge? 00? 000?

 


BobG wrote:

 It's not a matter of "think", even. It's just a matter of looking it
up on a voltage/amperage drop chart, and the net is full of them, even
automated ones.

To be honest, even with the distance that short, it surprised the hell
out of me.

DJ

 



As  Vaughn has pointed out "do the maths".

However, the very fact that you tried to run a 1000 watts from a
"battery" ( presumably an automotive battery?), tends to show that you
really need to do some reading, especially if you didn't understand
that 30 amps would not be enough.

1. If it is a 12 volt battery then the minimum current required would
be 1000/12,  or about 90 amps (actually it will be more).

2. Few ordinary automobile batteries would either provide this for
very long, or respond favourably to this type of treatment. ie not
only would it "go flat" very quickly, but the life of the battery
would be considerably shortened.
(Running the engine while drawing the current would be a help - but
depending on the vehicle - the alternator is unlikely to produce more
then 50% of the current  -  still you might get away with it!)

3. The falling battery voltage may cause the "low voltage" cutout to
trip out the inverter before you get your coffee made (disaster!)

4. Sometimes I wonder why 1200 watt inverters are made to run as RV
accessories (on 12v systems), when they seldom explain clearly enough
on the outside of the package the current that will be required if run
at full power.

Having said that, I run a similar (1500 w) 12v inverter at my holiday
home, even running a 1500 watt chainsaw, but I have something over
800amp-hr of battery to power it.

I hope you find ways to do what you want.

Eric Sears.