Ron, here's my suggestion. Buy a Van's ammeter (part number IE VAM40) and shunt (IE VAMSHUNT40). Current prices are $62 for the pair although I'd wager you can find a used set for less that someone has removed in favor of a new EIS installation.
There are multiple places in which to install the shunt but I suggest installing it in the alternator B-lead, right next to the protection device (i.e. ANL current limiter) on the firewall if you have one there. Reason: it's easy and it's relatively safe (against shorting and sparking).
The pundits will tell you a shunt in that location measures only alternator output. True enough, but when the battery is fully charged (which should happen a few minutes after engine start), alternator output /is/ the sum of all load currents. You can turn on your landing lights, pitot heat, heated seats, etc. and see a current increase corresponding to each device's usage. Of course, you can also see the total current being supplied by the alternator.
It's nice to see my B&C 40A alternator supplying only 9A for the EFIS, radio, intercom, etc. under normal ops <g>.
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Joe