Possible 2003 Volvo 5.7GXI Alternator issue

[KJSmitty]

My first question on iboats:

Purchased my current Cobalt used with 60hrs on the clock. One item I noticed from day one was the volt gauge never exceeded 13 volts (manual states 14+ etc.). Did not have any issues with actual charging given our use the first two years yet this year I have had several instances of low/dead batteries. Had the dealer check it out and they "claim" the alternator produced 13.5 volts for them. As mentioned, I have never seen the gauge over 13 (at any RPM) and my checks at battery and alternator while operating resulted in a max of 12.8 - key off the battery was 12.5.

What I see on the gauge during operation is typically right around battery voltage ~12. If while cruising I tap/operate the trim it will jump up just under 13 yet quickly drop back down to 12.

Any thoughts besides the fact the alternator could be close to death?

Also, my Volvo tech stated the engine had to be 1500 rpm or more for the alternator to be "excited" (not that that makes a difference with mine). I found that odd to say the least given how much idling and low rpm operation, stop/starts etc boats encounter.

Mine is a dual battery setup with isolator switch. Above is consistent regardless of selection/switch position. (75 amp alternator).

Thoughts?


Thanks all.
Smitty

 

[searay3]

Re: Possible 2003 Volvo 5.7GXI Alternator issue

Load test the batteries just to be sure. Clean tight cables at both ends. Engine, battery, alt. If all checks I would bet the voltage regulator. Could be the isolator has poor connections inside, but I would think that to be rare.

 

[Don S]

Re: Possible 2003 Volvo 5.7GXI Alternator issue

With a VOM (test volt meter), check the output voltage of the alternator at the alternator orange terminal. If it actually reads 14+ volts, test the voltage at the helm volt gauge. It's highly possilbe your gauge is faulty.

 

[KJSmitty]

Re: Possible 2003 Volvo 5.7GXI Alternator issue

With a VOM (test volt meter), check the output voltage of the alternator at the alternator orange terminal. If it actually reads 14+ volts, test the voltage at the helm volt gauge. It's highly possilbe your gauge is faulty.

Tech did mentioned that once (faulty gauge). So I did just that, with exception to testing at the gauge. Voltage was the same at the alternator as at both batteries - engine idling (I believe I reved to 1500 as well). Max: 12.8v.

Thanks Don S.

Thanks SeaRay3
- I did that as well - even ended up replacing battery number 2. Voltage reg is within the alternator and I was told they do not rebuild/repair them. Next will probably be an alt swap but I wanted to solicit your opinions etc.

Warranty or not it's a pain to drag down to the shop and have them crawl all over it. Given my knowledge and capabilities I hope to talk them into just letting me perform the swap.

If it wasn't so windy I would be on the water vs the keyboard!

Thanks men.

 

[Don S]

Re: Possible 2003 Volvo 5.7GXI Alternator issue

Take the alternator off and have it tested and checked out.