I use a 9v battery for input. I have one meter in series with the positive side of the battery on the circuit's "plus" power line. The second volt meter also measuring amps, sits in series on the output of the boost converter, to the load (led strip) again on the positive side, not that I think that matters.
I'm not sure what you mean by DMM.
I know the amps are high as the wires on the 9v battery become warn/hot when the full load is on. So the 1.8Amps (at one point I had more LEDs on the strip and the load was 2.2Amps). When I run the strip by itself on 9v, it has a 0.33Amps - so this is what I'm trying to understand.
That's for the ideas ... once I get DMM I may be able to try to adjust for that. However, since the wires are getting hot I'm pretty sure the measurement isn't that far off.
DMM is digital multi meter
you can't measure current with a volt meter, so I guess you are using the current functions of 2 different DMMs
the current, unless you are using a clamp meter, is measured by checking the voltage across a resistor of stable and known value
so, in your case, you have a (small value) resistor (inside the multimeter) in series with the input of the voltage booster circuit that so might even get as low voltage as 8.5V or less
the lower the input voltage the higher will be the current needed to boost the output voltage
you can directly connect the load to the voltage boost circuit and use the other DMM (
don't forget to move the banana jack to the Voltage position) to read the actual voltage at the input of the circuit
in any case I think the greatest part of the error comes from the spikes in the input current