MAD ammeter bypass question

One reason is that the ammeter will no longer function so you will know longer know whether and how much the battery is charging or discharging.
A voltmeter can indicate whether the alternator is producing power at the regulated voltage (depending a bit on where its measuring). So we can assume the battery is charging properly when we see 14ish Volts on meter. That makes it resaonable substitute. But just as the ammeter can't directly indicate system voltage, the voltmeter can't tell us if the battery is actually charging or or overcharging. There are advantage s to each.

MAD's method is poorly thought out. It sends power to do everything all the way to the battery, then through a bunch of connectors and extra fusible links. So that's a long path with lots of connections. And if there is a battery short, now there are two links in parallel ??? so that means twice as long to burn through. On older vehicles the purpose of the alternator is to run the car, any accessories, and recharge the battery after starting.

Mattax said

From Chrysler's 1960 Master Tech booklet.
View attachment 1715892982

The wiring scheme changes slightly over the years but the overall strategy always used the ammeter in the same manner. It only shows battery discharge and charging. The 1976 a-bodies got a remote shunted ammeter. Instead of using a wide metal plate in the ammeter, most of the current flowed in parallel through a wire of known length in the engine bay.


This is a typical standard wiring scheme. Of course details vary with years and options.
View attachment 1715892983
Power to run the car is supplied by either the battery or the alternator.
If the alternator can not provide sufficient energy at approximately 14 Volts, its output voltage will drop.
The battery begins to assist when the its voltage and the alternator's are equal.
It takes over when its voltage is higher.

Click to expand...

Chrysler had some better ways to address large power draws, some of these heavy duty wiring schemes were only offered to fleet buyers, but others came as a standard option for everyone. The one we've seen the most on FABO came on cars equiped with electric defrost grids on the rear glass, starting may around '72.

In 1975 Chrysler split the alternator feed on the engine compartment side for all A-bodies. So that reduced the load on the alternator output wire going through the firewall connector.
In '63 and '65 they used a ring terminal connector instead of a push on 1/4" spade. But even those can be melted given enough current.

that's prob more than you wanted but hope it provides some insight