Bulkhead bypass vs ammeter bypass

crackedback said

Run a protected direct charge wire from alternator to starter relay and leave the OEM wiring in place. Make darn sure the bulkhead connector is in great shape. Mad is OK, I perfer to not cut up harnesses. The cutting can be avoided.

Those packard terminals I'll use a 56 as an example, you don't really want to run more than about 20, maybe 25 amps on a spike across those connectors. A 60+ amp load from an alternator is not kind to bulkhead packard connectors.

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^^^ This right here! @crackedback is right - leave all the underdash wiring in place. Just run a battery charge wire to the B+ terminal on the starter relay. Protect the wire with a "4 number larger" fusible link (ie. 6ga wire with a 10ga fusible link). Presto and done!

The battery charge current will go straight to the relay and not the tortuous path through the bulkhead connector. The ammeter will now no longer show much, if anything, as there should be very little current flowing through it.