jreddington
Member III
I've had to replace the alternator on my '84 E-28.
The original had just one battery output and I assume that the regulator sensed and controlled 12 V (nominal) right at this point.
My replacement is a Mando. In addition to the output, iginition, and ground connection, there is a "battery sense" terminal.
This sounds like an opportunity for improvement since you would measure and control off the actual battery voltage, compensating for the voltage drop from the alternator to the battery (or actually the common on the selector switch). This seems to allow a faster charge since the regulated output voltage at the battery would be a little higher during bulk charging, but taper off to the same trickle amps as before since with low amps through the cable, the voltage difference between the alternator and battery would be less at this point of charge.
From what I see, this would involve connecting a wire running straight from the sense output to the common terminal on the battery selector switch. This would allow sensing of whatever battery is selected (or close to that since there would be some drop between the common and battery positive post).
The question is, should this line be fused?
Pro is general good practice and ABYC standard that all circuits be fused.
Con is fusing would probably have to be an in-line fuse. I find that in line fuses are generally a reliability problem, usually a contact / corrosion issue on the terminals (even with a liberal dosing of dielectric grease). More importantly, if I do get an open on this line due to a fuse blowing or bad contact, would this tell the alternator regulator that the battery voltage is 0 and the field current would max out and the alternator put out tons of amps, frying itself and/or the connected batteries.
The alternate is to jumper the sense connection to the alternator output post which should make it work just as the old one did.
The original wiring diagram does not address this since there is only the output terminal. Has anyone ever upgraded to this type of alternator? What is your experience with it? Does anyone have another Ericson or replacement engine where the wiring diagram shows proper wiring for this sense termninal?
The original had just one battery output and I assume that the regulator sensed and controlled 12 V (nominal) right at this point.
My replacement is a Mando. In addition to the output, iginition, and ground connection, there is a "battery sense" terminal.
This sounds like an opportunity for improvement since you would measure and control off the actual battery voltage, compensating for the voltage drop from the alternator to the battery (or actually the common on the selector switch). This seems to allow a faster charge since the regulated output voltage at the battery would be a little higher during bulk charging, but taper off to the same trickle amps as before since with low amps through the cable, the voltage difference between the alternator and battery would be less at this point of charge.
From what I see, this would involve connecting a wire running straight from the sense output to the common terminal on the battery selector switch. This would allow sensing of whatever battery is selected (or close to that since there would be some drop between the common and battery positive post).
The question is, should this line be fused?
Pro is general good practice and ABYC standard that all circuits be fused.
Con is fusing would probably have to be an in-line fuse. I find that in line fuses are generally a reliability problem, usually a contact / corrosion issue on the terminals (even with a liberal dosing of dielectric grease). More importantly, if I do get an open on this line due to a fuse blowing or bad contact, would this tell the alternator regulator that the battery voltage is 0 and the field current would max out and the alternator put out tons of amps, frying itself and/or the connected batteries.
The alternate is to jumper the sense connection to the alternator output post which should make it work just as the old one did.
The original wiring diagram does not address this since there is only the output terminal. Has anyone ever upgraded to this type of alternator? What is your experience with it? Does anyone have another Ericson or replacement engine where the wiring diagram shows proper wiring for this sense termninal?