2 batteries and alternator charging question

[U Rest U Rust]

I have replaced both batteries. I have a switch to choose the battery of choice. when i installed the new batteries, i cleaned up the wiring (I thought) and now it seems (not sure) that bat 1 does not get charged while running only battery 2 charges from the alternator. I did correct the battery charger wiring last week so when on shore power both are being charged. I guess my question is:

Are there 2 wires comming from the alternator to charge bats??

1989 mercruiser 5.0

Thanks
Jim

 

[U Rest U Rust]

Re: 2 batteries and alternator charging question

OK then. does anyone have a wiring siagram for the alternator?? Will that tell me the wiring for charging 2 batteries???

 

[Silvertip]

Re: 2 batteries and alternator charging question

You do not need to change anything from the alternator. The charging line from the alternator must connect to the COM terminal on the switch OR at the starter solenoid where the battery cable connects. To charge both batteries under way, you must have the switch set to BOTH. If its set to "1" only battery 1 will charge. If set to "2" only battery 2 will charge.

 

[U Rest U Rust]

Re: 2 batteries and alternator charging question

got it. thanks

 

[backyard mechanic]

Re: 2 batteries and alternator charging question

Has anyone thought about the charging capabilities according to the electrical draw/equipment in use? If the Merc alternator/rectifier is 9 amp (no fins on rectifier) there may be a continuous full load against the batteries. The alternator may be at max output at or near WOT with the smaller rectifier depending on what draw you put on the batteries.

The point is; if battery drain is greater than the charging capabilities use caution when turning on nav lights, w/s wipers, depthfinders, radar and other heavy draw equipment. It may be part of your "charge" problem...

There are larger 16/18, 16/24 and 40 amp alternator/regulator/rectifiers. The larger regulator/rectifiers have fins. The alternators/regulators/rectifiers are not all the same. Good news is, these greater amperage alternators are available with a greater wallet opening.