charging , same question, different way. HELP

[ttles714]

2001.. ox66..250...There are two positive leads coming off the motor. One is for the starting battery and one for the auxiliary house battery. Both leads are supposed to charge their respective battery. Question 1 > are the batteries isolated from each other ? Q #2 If they are isolated, what engine component keeps them isolated. OR should I have an isolator installed ?? There answer here will help me to figure out what is going on.

Thanks to anyone who can help me out here

[throrope]

I'm no expert and never saw your outboard, but I suspect the large lead is for powering the starting motor from the battery and the small lead is from the outboard's alternator for power to the boat. I've never fussed with ours, but now you got me curious and if it wasn't dark outside, I'd go and check.

Every "house" vs starting battery configuration I've seen happens outside the outboard. The simplest configuration and what we use is a manual two battery Perko selector switch.

[ttles714]

switches

I have one selector switch for each motor ( 1-2-both-off) and one selector for the house batteries ( on-off) ...I guess what I am asking, If anyone knows, Do the motors have "built in " isolators that keep the house and starting batteries from discharging into each other ? And if so , What
component on the motor would do that. I need to get into the bilge and really take a close look at the wiring ... I thought if someone had a little knowledge of what I am asking it would get me one step ahead. I was hoping one of the techs here would help put me on the right course. It's an older boat that is still fairly new to me.. I am sure batteries have been replaced and wiring moved around through the years. Thanks for your input , much appreciated

[boscoe99]

The two leads (main battery cable and isolator lead) are isolated from one another.

Isolation is normally done in the rectifier/regulator through the use of diodes.

[rodbolt17]

what boscoe said.
V6 yamaha's since about 1990 have a built in battery isolator circuit.
this will allow house battery charging isolated from engine battery charging.
most riggers simply don't know its there.
most EFI 4 strk 150 and above have it as well.

[throrope]

Rodbolt & boscoe - Thanks, learn something new every time I'm here.

[ttles714]

thanks

thanks all... I will check the service manual to check the charging circuit .... If one of you guys has any advice or best procedure.. it would be very welcome and appreciated

[ttles714]

guessing ??? on the regulator

Checking voltage I find that the port engine is putting out almost 14 volts to the starting battery and no volts to the house batteries. The starboard is charging at 12.8 to 13.6 to both starting and house batteries.depending on the battery charge state. So I am thinking the port regulator is bad. The OEM Yamaha service manual is not so hot in describing the service information to the non professional. Can I use a standard multimeter ? AND (if I am reading the manual correctly) lighting coil voltage should be 14VDC and the regulator should be 12VDC both at 1500-3500 RPM ???? is that right. I assume the test harness they refer to is a jumper that connects between the connector plugs allowing the circuit to remain connected and a place to connect the meter.... Can Anyone help me out here . ?? thanks..... ADDED, I have a Stevens CD77 Peak reading volt meter, can this be used on the yamaha ?

[rodbolt17]

on some applications the CD77 is preferred, not all applications.
are you sure your port engine is actually hooked up to the house battery?
most the time only one engine is attached to the house battery.
house battery charging with the engine is strictly up to the guy that rigged it, not Yamaha.