Delco Alternator single wilre

grewvin1

Petty Officer 2nd Class
Joined
Apr 2, 2012
Messages
189
1987, Mercruiser 5.7L engins have Mando 55amp alt. want to install Delco 72amp alt. single wire. Is this easily done by getting rid of the red and purple excite wires? All I need to do is attach the orange to battery wire?
 

sam am I

Commander
Joined
Jun 26, 2013
Messages
2,169
Yes.....both connectors where the red wire(remote sense) and the purple wire(excitation) went to are wired internal to the one wire alt such that you can just tape off/remove the existing red and purple wires and it'll run with just the charge wire(orange typically I think)

BUT, two things.......

1) One wire alts obviously can't make up for voltage drops due wire resistance in the charging path, they are fixed/limited internally to local values, therefor and primarily/specially at higher charge demand rates, the battery will not be provided "as proper of voltage potentials" and therefor charge current will lower and therefor charge rate times can lower, C/5.2 verses C/5 just as a simple and slight example.......Work around is to run as large of wire as possible to lower the charge path resistance(R) to limit the voltage drop V(ir), which voltage drop V(ir) is also of course a function of what current(I) the alt is supplying....... V(ir)=IR.

2) Self exciters typically and initially at each start up require you to spin up around 1500-2000 RPM's before they light up and start charging. Therefor, that work around is that you'll have to be aware at times to slightly "over rev" to get it to excite to begin charging then you may back off on the RPM's and it should remain charging at say 1000 RPM's for example. You can watch/use your dash volt meter to verify it came up. i.e., you'll typically see the volt meter needle suddenly jump from 12'ish volts to 14'ish as you're increasing in RPM's.

This had been my experience running a few of them over the yrs anyway, hope it helps ya........GL
 
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