Hi Peter.
Your -50/+50 ammeter monitors (ie. works-off) the voltage drop across your main fusible link. (Hence my question before about what readings you were getting on it when that fusible link was running hot because those readings should have been HIGH .... if everything was was intact in your ammeter circuit that is.)
In other words, your -50/+50 ammeter is really a milli-voltmeter that's had the face calibrated in units of current.
And if you charge via a different wire (than the one holding your main fusible link), your ammeter will then only be reading "discharge current" (so it won't be influenced by your planned high-output alternator anyway).
And even if you did choose to put your high-output alternator current through your main fusible link (and modify/enlarge both this fusible link and the wires it protects to handle it), provided the fusible link is sized correctly (ie. large enough to handle the new high-output) your ammeter will still be able to handle it (but the "50" numbers on the face will of course look low in comparison to your alternator output).
Whenever your fusible link is sized too small (or getting hot for other reasons such as "broken strands) your twin 5A ammeter fuses should protect your ammeter from burning out regardless of what current your fusible link is carrying. (That is the purpose of those two little fuses in your engine bay near your battery.)
You must realise that the -50/+50 design is not like the old -30/+30 design (where all the current passes through it's internals). Only very small currents pass through the -50/+50 ammeter.
And my experience is that the OEM -50/+50 ammeter never does more than "twitch in response to indicator/hazard blinking" in cruisers that are in completely original/stock condition anyway.. (So it's best to rely on a voltmeter to monitor your alternator performance and just leave the ammeter "for show" to keep the dash looking OEM.)
Anyway ... So what all this blurb is leading to .... is that whatever way you look at it ... there's no problem at all in leaving your ammeter connected.
