Thank you all for your help. First of all the reason I wanted to

correct the problem was because I have both a DC Ammeter and an AC

ammeter on the electrical panel, as well as an AmpHour battery monitor,

and its just nice for them all to correspond if at all possible. But

if there's a chance that it will hurt things to add a capacitor I

definitely won't do it.

The problem is that the inverter probably outputs a waveform with some

fast rising and falling edges, rather than a smooth sine wave. Even

if it did produce a perfect sine wave, there is a fast edge every time

you turn it on, or connect the capacitor. The current through a

capacitor is proportional to the rate of change of voltage across it.

Fast edges imply large currents.

I have seen power factor capacitors added by having small inductances

in series, to limit the peak current, but it is tricky to keep the LC

resonance from being excited by any harmonic in the system (which

would also produce large current at that harmonic frequency).

The only thing I really care about is the DC

Ammeter and the DC battery monitor. My question is are these DC

readings still accurate as far as true amount of amps being drawn from

the battery banks even when the inverter is putting out way more power

AC?

The DC meter should represent an accurate measure of load on the

battery. AC power factor current represents energy borrowed and

returned each half cycle, so it heats the inverter up a bit, as it

sloshes back and forth through it, adding to its losses, but it

doesn't change the average DC load much. It just adds ripple to it.

But a DC meter should average that ripple and give an accurate average

answer.

Right now to run the compressor I get about 45 amps DC and 9 amps

AC... so should the 45 amps DC be accurate? Thanks again for your help.

It is an accurate measure of battery drain. It might drop a few

percent if you could eliminate the power factor current, because the

inverter would be wasting a little less power because the borrowed and

returned energy would be sloshing back and forth between motor and

capacitor, instead of between motor and battery, through the inverter.