Alternator Output - What is Normal?

YYZRCYYZRC Georgian BayMember Posts: 3,883 ✭✭✭✭✭
When I'm at idle, my VV shows 14.x volts both port and starboard.

When on plane, my VV was showing around 12.x volts starboard and 13.x volts port.

I swapped the alternators and now show 13.x volts on starboard and 12.x volts on port.

Weak alternator?  What's normal?
2008 350 EC on Georgian Bay

Comments

  • aero3113aero3113 Long Island, NYMember Posts: 8,178 ✭✭✭✭✭
    I would say the 13.x is the normal one.
    2008 330EC
  • GrahamuGrahamu Lefroy, Lake Simcoe, ON, CDAMember Posts: 705 ✭✭✭
    At cruise I'm at 13.4 volts, Genset not running so charger off.
  • YYZRCYYZRC Georgian BayMember Posts: 3,883 ✭✭✭✭✭
    Thanks @Grahamu - sounds like one of mine is normal and one is maybe a bit weak.
    2008 350 EC on Georgian Bay
  • Dream_InnDream_Inn Annapolis, MDMember, Moderator Posts: 7,184 mod
    I agree, one is a bit weak.  I've always seen 13.X when alternator is running.

    Dream 'Inn III -- 2008 400 Express

  • YYZRCYYZRC Georgian BayMember Posts: 3,883 ✭✭✭✭✭
    Ordered two DB electrical replacements. Was the same price as what I paid 3 years ago for my 330! Shocking!
    2008 350 EC on Georgian Bay
  • GrahamuGrahamu Lefroy, Lake Simcoe, ON, CDAMember Posts: 705 ✭✭✭
    I think I would have removed the bad one and had it re-built, cost used to be around $120.
  • YYZRCYYZRC Georgian BayMember Posts: 3,883 ✭✭✭✭✭
    edited September 8
    Brand new is $135 and zero downtime. Not OEM but I have used DB before and they worked great. 
    2008 350 EC on Georgian Bay
  • GrahamuGrahamu Lefroy, Lake Simcoe, ON, CDAMember Posts: 705 ✭✭✭
    YYZRC said:
    Ordered two DB electrical replacements. Was the same price as what I paid 3 years ago for my 330! Shocking!
    Sounded like you paid an arm and a leg, good price if they are ignition protected 
  • YYZRCYYZRC Georgian BayMember Posts: 3,883 ✭✭✭✭✭
    edited September 8
    I was surprised they weren’t +30% like everything else seems to be!

    https://a.co/d/fYwfccI
    2008 350 EC on Georgian Bay
  • earl1z19earl1z19 Catawba IslandMember Posts: 281 ✭✭✭
    Did you happen to take a reading from the alternator directly at the post on the back? It should read 14.2 or so. The connections for the vv sometimes show an inaccurate reading. You may have actually not had an issue at all
  • YYZRCYYZRC Georgian BayMember Posts: 3,883 ✭✭✭✭✭
    I’m not keen on climbing into the bilge while the boat is up on plane. I will install the new ones and if they don’t perform better, I will return them. Amazon is awesome. 
    2008 350 EC on Georgian Bay
  • mattiemattie Sarnia, OntarioMember Posts: 1,057 ✭✭✭✭
    FWIW: Both of mine run 13.4V on plane. Smartcraft guages.


    246BR, 276BR, H310BR current
  • earl1z19earl1z19 Catawba IslandMember Posts: 281 ✭✭✭
    YYZRC said:
    I’m not keen on climbing into the bilge while the boat is up on plane. I will install the new ones and if they don’t perform better, I will return them. Amazon is awesome. 
    I hear ya, I have one that runs at 14.1 and one that runs at 13.5 while on plane. The lower reading alternator puts out 14.2 at idle at the pole on the back of the alternator itself. I will be interested in seeing if your situation changes with replacements and if so I may consider changing mine. Let us know how it works out
  • 212rowboat212rowboat Member Posts: 2,584 ✭✭✭✭✭
    edited September 15
    the computer is where you are getting the reading via vessel view... and some dash's too... 

    the alternator produces what the alternator produces and if it's regulated AT the alternator it can be hard to determine... if it's at the computer and beyond, you can check the alternator at the post.  

    that reading is more about electrical usage and battery condition than alternator output, anyway.  a healthy battery is 12.6vdc at rest.. it takes 13.5vdc or so to actually charge a battery and 14.5vdc to really charge a battery full blast- over 15 isn't uncommon but it usually demonstrates a regulator about to give up the ghost...

    while underway your charge shouldn't fluctuate, but it could be different from bank to bank as the alternator may be wired to charge separate systems which may be at different states of charge due to usage. 

    flooded lead acid can't take the charge lithium or mats can.  likewise, a system set to charge a flooded lead acid may not be charging another type of battery- especially lithium- as thoroughly as it should be... lithium likes higher voltage and volume (amps) than flooded can handle without swelling... gotta keep your systems matched. 

    so long as your readings don't fall below 12.6vdc underway don't make any stress for yourself... stress if it's above 14.5vdc for prolonged periods (showing the alternators are producing but your batteries are weak) or below 12.5vdc (demonstrating your alternator isn't taking over for the batteries while underway)... 

    before computers and LED's complicated these things, the easiest way to tell if a battery or an alternator was weak was to use a 12vdc halogen bulb at the battery itself- when the engine revved if the bulb brightened- the alternator was good but the battery weak... if it dimmed while the engine was underway the batteries were being drained by the engine and teh alternator/generator couldn't keep up.  i guess this could still be done, but your computer may think about that extra draw and form some idea about setting a code none of us would be able to decipher.  
  • YYZRCYYZRC Georgian BayMember Posts: 3,883 ✭✭✭✭✭
    edited September 15
    Received and installed (on the port side) one of the two new alternators. Shows 14.8 at idle now, hopefully get her out this weekend to see what it reads at cruise. 


    2008 350 EC on Georgian Bay
  • tricountytrailtricountytrail Member Posts: 75
    YYZRC said:
    Received and installed (on the port side) one of the two new alternators. Shows 14.8 at idle now, hopefully get her out this weekend to see what it reads at cruise. 




    Did you install the vessel view link or gateway ? I have the gateway but can only display on my simrad instrument tab and I don't get the fault data. Wondering if there is a workaround to get the vessel view screens like you have without the vessel view link?

  • YYZRCYYZRC Georgian BayMember Posts: 3,883 ✭✭✭✭✭
    I have the VV link dual motor version. 
    2008 350 EC on Georgian Bay
  • tricountytrailtricountytrail Member Posts: 75
    YYZRC said:
    I have the VV link dual motor version. 
    I tried to return my gateway to partsvu and upgrade to vesselview link but it was outside there 30 day window. I want faunt data but do have access to a rinda diacom. Can your vessel view display exhaust manifold coolant temps for both sides? I do not beleve they are in the nmea 2000 data stream.
  • YYZRCYYZRC Georgian BayMember Posts: 3,883 ✭✭✭✭✭
    edited September 20
    I am not aware of a sensor in the exhaust manifold on my boat. The only coolant temp sensor I’m aware of is in the thermostat housing. 


    2008 350 EC on Georgian Bay
  • tricountytrailtricountytrail Member Posts: 75
    Thank you couldn't find it even with laptop but there is a sensor on both manifolds that will alarm over 212 degrees.
  • earl1z19earl1z19 Catawba IslandMember Posts: 281 ✭✭✭
    YYZRC said:
    Received and installed (on the port side) one of the two new alternators. Shows 14.8 at idle now, hopefully get her out this weekend to see what it reads at cruise. 


    Were you able to get some time out on the boat to see if the alternator corrected the problem?
  • YYZRCYYZRC Georgian BayMember Posts: 3,883 ✭✭✭✭✭
    Not yet. Received the second DB alternator yesterday - maybe get out next weekend as this weekend is looking uncooperative weather wise. 
    2008 350 EC on Georgian Bay
  • YYZRCYYZRC Georgian BayMember Posts: 3,883 ✭✭✭✭✭
    Better now with two new alternators. 


    2008 350 EC on Georgian Bay
  • earl1z19earl1z19 Catawba IslandMember Posts: 281 ✭✭✭
    Glad to hear it worked out for you. I have now added them to my list of things for next year! I figure its worth a shot as seeing the display show 13.5 or so drives me nuts.
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