replaced alt and all batts still low guages

[jc27]

I Put 4 New Batterys And 2 New Alternators In My 96 370da . When Charger Is On Guages Are At 13 Turn Of Charger And They Stay At 13, Start Motors They Both Drop To 11-12 ,rev Motors Up They Drop Lower Around 10 . I Put Meter On Batterys It Reads 13.5 Before Alternator Replacement It Was 12.2 What Can I Check Before I Bring To Searay Please Help

 

[fc3]

Been there. Done that. Not doing it again.

Did you do all of the tests I posted to your previous thread?

 

[Four Suns]

Been there. Done that. Not doing it again.

Did you do all of the tests I posted to your previous thread?

It's always good to ask the same questions in a different post to see if the answers from the same people are consistent. It's a test Frank.

 

[fc3]

Guess I failed.
Oh well.

 

[jc27]

I Did Test You Told Me To Do And Alternators Were Bad Replaced Both And Guages Still Go Down When Rev Motors. Sorry New To Site I Guess I Should Have Put In My Other Post. Trying To Avoid Going To Searay For 115.00 An Hour ,i Did Not No If With Everything I Replaced That Would Narrow Down What Was Wrong. Plus I Run A Bar Not A Motor Shop So Doing My Best To Fix Myself.

 

[fc3]

Generally speaking, if the voltage drops when the engines turn faster, that usually indicates one or more rectifiers are shorted. Normally, I test that by putting an oscilloscope on the output stud and look for the AC ripple. Sometimes you can tell by listening to the stereo. Listen to something that's quiet and turn the volume up. A blank cassette works. Then start the engines and rev them. You're listening for a whine or whistle that follows the engine speed. You need to know if that whistling noise is greater or the same as what's normal for your boat.

It's unusual for both alternators to go bad at the same time. Do you have a battery isolator?

Best regards,
Frank

 

[mrsrobinson]

Our port alt gauge always reads 10-11, starboard is fine. In fact, the port gauge will read 2-3 at times, especially at idel. We replaced the gauge, same result.

I personally do not worry too much about this as we always have 14 amps at the panel gauge and plenty of power to start the port engine. Volt meter tests is always good too.

 

[jc27]

Thanks For Help I Do Have A Isolator FRIEND Is Going To Look At It This Week Always Something

 

[jc27]

Ok When Boat Is Off Guages Read Around 13 When Start Boat They Drop Below 12 When I Get Rpms Up Guages Rise Up To Normal But When I Slow They Start To Drop Is This Normal Or Should I Check Something. When I Put Meter On Battery When First Start They Read 13.0 After Keeping Rpms Up Meter Goes To 13.9 And Guages Normal At Around 13 Any Ideas.

 

[AndersonAcres]

When Start Boat They Drop Below 12 When I Get Rpms Up Guages Rise Up To Normal But When I Slow They Start To Drop Is This Normal Or Should I Check Something. QUOTE]


I have seen boats operate in this manner without problem for long periods of time.

Maybe the best solution is, when doing the test Frank suggests, is to have a tape in the player that plays "Don't worry, be Happy!" rather than silence.

 

[jc27]

ok ,hope the song works because i am always worried