Volvo penta 5.0 OSI current drain

[imported_ironmike]

Greeting all,
I purchased a 2006 Monterey 302 last year. Spent last Spring/Summer replacing the composite drives. The boat was setting for a while so I had to remove the batteries and charge them up, I replaced one of them. I noticed that I had a slight spark when connecting the port battery even with the main battery switch turned to the "off" position. I hooked up a multimeter and discovered that there is a 0.20 mA drain of the port motor. Maybe this isn't major but the starboard motor measures 0 mA. I just had the positive and negative cables connected to the battery. I disconnected the dash harness and still had the current drain. I was wandering what could cause this or if anyone has had this issue? At this point, I understand the alternator and starter are connected. Looks like there are three wires in the engine harness that are tapped up connected to the starter along with the positive cable. I didn't disconnect them yet since I ran out of time. Any suggestions to troubleshoot this issue. Could it be that the starter or alternator has an internal short?

 

[jerryjerry05]

Might be the radio or an automatic pump switch.
Unhook the negative cable, hook a test light to the N post and then to the end of the N cable, the light should come on.
Then start pulling fuses and when the light goes off that's your problem???

 

[QBhoy]

Hi. If this engine has any domestic ancillary wired to the battery, it will be the issue. Perhaps not common if you live in a warm climate, but here in Scotland most boats like yours have blown air heating installed. These must be wired direct to the battery and usually always take a little power on standby. If you have dedicated leisure batteries in addition, you may have a split charge relay system controlling the charging to each bank of batteries. These diode systems can occasionaly partly and intermittently pass or drain between banks, should they be faulty. Just a thought from me. All the best.

 

[imported_ironmike]

Thanks for your replies. It's not a radio or bilge pump since I have disconnected the dash wiring harness and all the wires from the battery terminals except the negative and the positive cables going to the engine. There are also no ancillary devices. The battery was just purchased. Looks like there are 3 additional wires connected to the starter post where the positive cable is. I do have manual with the schematic. The schematic shows a connection to the alternator and a 40 amp fuse. I was asking if anyone every experienced a short in the starter on alternator. I will get to it this weekend. I will remove all the wires connected to the starter coming from the harness, reconnect the battery cable and connect them 1 by 1.

 

[Grub54891]

I'd disconnect the alt first. If the diodes are bad it will backfeed/draw power from the batt. It may charge fine when running but check it out anyway.

 

[Lou C]

Agreed if the diodes in the alt are bad then it will pull current from the battery. Try disconnecting the alt and watch the meter.