Trying to get familiar and learn something with electric system! Just replaced 1 year old redtop optima battery that went to 8 volts when put under load at autozone with their tester!With old battery car would click,click,click but when charged for 5 or 10 minutes with 10 amp charger it would start right up! Car would start several times then same click dead battery condition!ALL connections clean and tight and also have moroso shutoff switch in back.Bypassed ignition switch with remote starter switch on selonoid to starter and same click so i assume ignition swich is good! They checked voltage at trunk mounted battery with car running and had 13.53 volts! At non running it showed 12.52 volts! So today i brought down old optima and they gave me a free replacement since it was 1 year old! Installed and car fires up fine and hopefully fixed problem.Picked up digital voltmeter there also for 20 bucks as i would like to have for trouble shooting! Car starts up with sometimes a 25 amp reading on the interior mounted amp meter gauge but will come down to 5 to 10 amp reading in less than a minute! Electric fuel pump using relay mounted in trunk to battery and when not hooked up amp meter reads about 5 amps less! Running 100 amp 1 wire alternater powermater and do not have the old external regulater hooked up any more!Showing 12.52 volts at horn relay and alt. with car off.One thing that did not look right is with moroso shut off swtch off,i still showed .2 volts at horn relay and alt.!Starter is 2 month old unit from advanced auto! Just looking for anything that does not look right while trying to learn a little on the elecrical system!Sorry to ramble on so long and any info or advice is greatly appreciated as always! thanks much, AL (11.64 at 115.5 best 1.54 60 foot street strip 327 5 spd.)

With trunk mounted batteries you have to be very judicious about keeping the electrical connections tight and clean. Most starters start to loose their umph at 8 volts. Also, the starter can draw nearly 100 Amps during a crank. If the battery provides a steady 12volts during crank (unlikely), you've got 4 volts of "head-room" to work with on the battery voltage. At 100 amps, it would take only 4V/100A = 0.04 Ohms of resistance to make the starter stop working and that ain't much. In reality that 12volt battery probably drops to 10 volts during a cranking in which case 0.02 Ohms of resistance is all that it takes to stop cranking.

It's hard to say what's going on in your case. I'd get rid of the ammeter - especially if it is an in-line type. Volt meters give you a better visual on electrical system health IMHO and don't present a resistive load to the electrical system.