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  1. #1
    Member thommo59's Avatar
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    Is my voltage too high?

    200 pro Xs 2b783466, crank battery decided to die to, it’s a 975cca agm. Was showing 12.8v last night, an hour or so fishing and not enough to crank the engine over, was showing 11.1v. Jump started the engine with a portable jump pack and ran fine the rest of the day, however, the moment the engine starts, and at idle or 5k, the smart craft is showing 14.6v. Shut it down, 13v, start the engine 14.6v.
    Do I have an issue?
    2018 TRX 18. 2020 Mercury 200 Pro XS V8

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    #2
    Your alternator is charging,hence the 14.6v output,but your battery needs load tested to see if there's a bad cell. My 200 Pro XS 4S voltage shows 14.7v on VVM.

  3. Member thommo59's Avatar
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    #3
    Quote Originally Posted by Robby Moser View Post
    Your alternator is charging,hence the 14.6v output,but your battery needs load tested to see if there's a bad cell. My 200 Pro XS 4S voltage shows 14.7v on VVM.
    Thankyou, knowing yours shows 14.7 on VVM makes me feel better, I get 14.6 on VVM so same. I think I’ve had a cell go bad, I guess any age battery can fail. This was strange how quick is died, so something crazy going on. Everything like terminal, leads, connections etc are perfect. I’m ridiculously anal with maintenance so this really annoys me
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    #4
    a bad battery will overwork an alternator until both fail finally-- lots of the electronics do not read it correctly either
    Last edited by mactlman; 12-22-2022 at 07:11 AM.
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  5. Member lpugh's Avatar
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    #5
    14.6 charging voltage is what it should be for a good fully charged battery. If the battery has a high resistance it can show max regulated charging voltage all the time when running. You sir have a very bad battery, the voltage readings you have prove this. Replace the battery, charge it to full charge. Then start the motor, voltage will start off at around 13.5 and slowly come up to 14.4 to 14.6. The bad battery will go to 14.4 to 14.6 almost instantly
    Thank You Leon Pugh

  6. Member thommo59's Avatar
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    #6
    Quote Originally Posted by lpugh View Post
    14.6 charging voltage is what it should be for a good fully charged battery. If the battery has a high resistance it can show max regulated charging voltage all the time when running. You sir have a very bad battery, the voltage readings you have prove this. Replace the battery, charge it to full charge. Then start the motor, voltage will start off at around 13.5 and slowly come up to 14.4 to 14.6. The bad battery will go to 14.4 to 14.6 almost instantly
    Thank you Leon, yes instant that I start the engine, it goes 14.6 and stays there. Looks like it’s time for a new battery again.
    2018 TRX 18. 2020 Mercury 200 Pro XS V8

  7. Member thommo59's Avatar
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    #7
    Well, I just put another battery in and exactly the same thing, the moment it starts, jumps straight to 14.6-14.7v on both smart craft and VVM, what now? Could this be an alternator issue? If the regulator in the alternator was faulty would it read like this?
    Last edited by thommo59; 11-07-2022 at 05:02 PM.
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  8. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #8
    14.7 VDC is within acceptable voltage range.

    On your AGM... were you connected to the threaded posts, or with a clamp-style terminal?

    Often find the battery itself is ok, but the threaded posts have been compromised.


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  9. Member thommo59's Avatar
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    #9
    Quote Originally Posted by EuropeanAM View Post
    14.7 VDC is within acceptable voltage range.

    On your AGM... were you connected to the threaded posts, or with a clamp-style terminal?

    Often find the battery itself is ok, but the threaded posts have been compromised.
    100% on the terminals Don, I have dropped the battery off to the shop, they didn’t have a load test but tested with there equipment as ok. It’s being left for a couple days with no connections to see if voltage drops. Sunday night it was 12.8, Monday night 12.7, this morning 12.6v, all with nothing connected. I’m so meticulous with connections, batteries, terminals etc, and this was a like a kick in the family jewels to me, I hate failures when my maintenance is so regimented
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  10. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #10
    Hate that too! We saw a rash of the earlier batteries where they wouldn't perform in the boat, yet they load tested with flying colors at the store.

    What we found was the threaded posts have a seal inside the battery (it's essentially a bolt with a seal on it). Over time, vibration would distort the seal allowing acid to creed up the threads of that "stud" and result in high resistance between the end plate and stud (but the clamp style posts still had great capacity). This is why I recommend the clamp-style posts.

    That being said- we both know if a man made it, there will always be a failure rate.


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    #11
    totally normal charging voltage

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    #12
    Quote Originally Posted by EuropeanAM View Post
    Hate that too! We saw a rash of the earlier batteries where they wouldn't perform in the boat, yet they load tested with flying colors at the store.

    What we found was the threaded posts have a seal inside the battery (it's essentially a bolt with a seal on it). Over time, vibration would distort the seal allowing acid to creed up the threads of that "stud" and result in high resistance between the end plate and stud (but the clamp style posts still had great capacity). This is why I recommend the clamp-style posts.

    That being said- we both know if a man made it, there will always be a failure rate.
    What brand of battery were you seeing this issue with?

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    #13
    Quote Originally Posted by Capt James View Post
    What brand of battery were you seeing this issue with?
    Wasn't brand specific- have seen it on numerous batteries. First noticed on the old Sears Diehard Platinum 31M (a Northstar 31M) that Sears discontinued.


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  14. Member thommo59's Avatar
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    #14
    Well the battery tested fine after sitting at the battery place for 3 days, printed out the little ticket saying battery good, and gave it to me so I’ll run it again on the weekend and see what happens. Still has me beat why it dropped to just over 11v in a bit over an hour. Both the VVM and smartcraft reported that voltage when it wouldn’t crank. Right now it’s holding 13v according to my multi meter, VVM and smartcraft.
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    #15
    Quote Originally Posted by thommo59 View Post
    Well the battery tested fine after sitting at the battery place for 3 days, printed out the little ticket saying battery good, and gave it to me so I’ll run it again on the weekend and see what happens. Still has me beat why it dropped to just over 11v in a bit over an hour. Both the VVM and smartcraft reported that voltage when it wouldn’t crank. Right now it’s holding 13v according to my multi meter, VVM and smartcraft.
    Hope it works for you now. To support what Don said about load testing batteries, my 2016 F150 recently started to crank a bit slower than usual. I have a load tester and checked the voltage and load tested the battery. My load tester (not sure how accurate it is) showed the battery in the green (good). I changed the battery anyway due to its age and slower cranking. The new battery cranks the motor faster just like the original used to, all is back to normal. So the load test on that flooded lead acid battery was not a reliable test and all the connections looked good and clean with no corrosion.

  16. Member thommo59's Avatar
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    #16
    Ok so the gremlin appeared again today of course at the furthest end of the river and no phone service. Charged last night, 12.8v at key on this morning, no issues for 5 hours and no pumps on, just graphs. Stopped and started maybe 6 times changing spots and all ok. Time to leave and bang, not enough to crank over, just the solenoid noise. Tried a few times, no good but suddenly my auto bilge pump kicks in, hasn’t been running prior, like the low voltage spike started it, so I disconnected. VVM and Smartcraft show 11.7v not enough. Put my small jumper pack on, still no go after several tries. Leave the jump pack connected for 10 mins and. just enough to get it going. 14.5v on the guages whilst running all the way back. Take it to the battery shop again, shows 12.9v and no issues. This time they agree to replace it as goodwill.
    The smartcraft and VVM are only going to get data form the same location, I C wish I had a multi meter on board to test at the terminals.
    Something crazy going on here, every terminal etc is clean and tight. The only weak link I can see between battery and engine is the battery on off switch. It looks fine inside and out, but the fact it will start with the help of the additional jump pack sort of negates that.
    Any ideas?
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  17. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #17
    Jump pack doesn't necessarily rule out the switch. Simplest method to do so is to BYPASS the switch, moving the engine cables directly to the cranking battery terminals, and see if you have further problems.

    Problems continue: Likely a plate problem in the battery.

    Problems cease: Likely the switch.


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    #18
    I would also double check your bilge pump, make sure it’s functioning properly and doesn’t have a short in wiring or a short in the motor/float switch. Could be possible it’s pulling current without running. Not sure how a voltage drop or spike could cause it to turn on as the float needs to be activated to complete the circuit. Some bilge pumps are both automatic and connected to a manual switch at the console. Wiring could be bad and/or pump could have been clogged.
    Last edited by leonreno; 12-22-2022 at 02:13 PM.
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  19. Member thommo59's Avatar
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    #19
    Quote Originally Posted by leonreno View Post
    I would also double check your bilge pump, make sure it’s functioning properly and doesn’t have a short in wiring or a short in the motor/float switch. Could be possible it’s pulling current without running. Not sure how a voltage drop or spike could cause it to turn on as the float needs to be activated to complete the circuit. Some bilge pumps are both automatic and connected to a manual switch at the console. Wiring could be bad and/or pump could have been clogged.
    Yep something funky there, pump is clear and clean but as soon as I tried starting the engine on low voltage, the pump kicked in, bilge was clean and empty so I disconnected to plug to the pump to stop it. Fine when it’s plugged back in.
    And thanks Don, new battery now in so at least that’s eliminated.
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    #20
    (I'm an auto tech) I've got a Midtronics digital tester, as well as a Mac load tester that I can put a variable load on a battery. Occasionally 1 of these testers will show a battery to be good but it will fail with the other. 1 time out of every thousand or so a battery will pass with both type of testers but still won't perform properly.

    I had one a couple weeks ago that passed with both testers but still had problems in the truck. The truck didn't have a parasitic draw, any kind of wiring problem, or a starter problem. I suspect it was something with the connection between the posts and the plates. I left it sitting on my bench for a few days and tested it multiple times. I finally failed once, but passed again later.