Volvo 5.0 OSI Charging Problem

[tarjas]

I have a 2006 Volvo 5.0 OSI that has a charging problem. Batteries (new) measures 12.6ish. On engine start the voltage climbs to around 13v then slowly decreases. Over time the battery runs lower and lower. Essentially no or little charge gets to the battery. I replaced the alternator suspecting the regulator was bad. Did not fix the problem. I took my old alternator to a shop where they bench tested it up to the rated 75 amps, held voltage fine. Any ideas on where I should start trouble shooting? My first thought is a bad ground somewhere. Thinking I should connect a wire directly from the battery negative to the alternator negative to test. Do any engine systems have a bearing on alternator charge? Its my (limited) understanding that the regulator controls how much the alternator outputs. Thank you in advance for any help. Cheers.

 

[Don S]

Re: Volvo 5.0 OSI Charging Problem

Do you have an automatic charge relay or isolator in your system?
You need to look at all your connections, including the connections on the engine, the battery switch and any place else. Wing nuts are NOT acceptble. regular nuts tightened with a wrench are.
Don't forget, battery cables are both positive and negative and have 2 ends each. Loose crimp on connections on the cable are also no good.

 

[tarjas]

Re: Volvo 5.0 OSI Charging Problem

Thanks for the response, my plan is to go through each connection I can find/get to and tighten/clean. Should be a fun project,,

 

[Don S]

Re: Volvo 5.0 OSI Charging Problem

Should be a fun project,,

Ok, but since I do this for a living, being a "Fun Project" just isn't part of the deal anymore for me.
But have at it. You will then understand where all the wireing goes.
PS: If you have an engine serial number, I can probably point you to the correct engine manuals and wiring diagrams.

 

[tarjas]

Re: Volvo 5.0 OSI Charging Problem

My engine is a 2006 5.0 OSI-F in a Larson Cabrio 240, will have to get the serial next time I'm near my boat. No charging relays, just 2 batteries and a standard battery switch. Thank you again for the help.

Do you have an automatic charge relay or isolator in your system?
You need to look at all your connections, including the connections on the engine, the battery switch and any place else. Wing nuts are NOT acceptble. regular nuts tightened with a wrench are.
Don't forget, battery cables are both positive and negative and have 2 ends each. Loose crimp on connections on the cable are also no good.

 

[tarjas]

Re: Volvo 5.0 OSI Charging Problem

Well, I am one happy dude.. figured out the problem. Followed the wiring diagrams from the shop manuals, there is a grounding bolt on the port rear side of the motor that is ultimately connected to the battery ground. The bolt holding the wire loops was loose and the loops were corroded. Cleaned them with a wire brush and tightened, now charging at 13.8 volts. Went out today and it was nice not having to worry about running out of juice. If anyone has a grounding/charging problem, suggest you check the port side bolt first. Cheers