I'm not particularly savy on auto electrical, but thought to pass this on. Some time back experienced problems keeping the battery up in my 57 car. Went to the electrical shop where battery came from. Long story short, the Tech said they determined a loss of voltage in the original wiring harness on the cross member. So they replaced that wiring. There was some improvement, but still not what it should be. When I again had a similar problem, I checked it with a volt meter. Still not getting much over 12V at the battery. However, remembering back the Teck also said he had seen these kind of problems before, because of inadequate size wires going thru aftermarket Amp Guages. The total wiring for my guage was about 14 ft. of what appeared to be 14 guage. I replaced it with # 10 wire from a friend. Even though I had trickle charged the battery a few days previous, as soon as I fired up the engine, at slightly over idle, the guage jumped to 20 amps for a minute or so. I don't recall it ever going up that high previously. Voltage checks at the regulator & battery showed well over 13 Volts briefly. I hope this info helps someone else.

Paul