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Top Battery

Discussion in 'Technical Discussion' started by Capt Ralph, Aug 9, 2018.

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  1. Capt Ralph

    Capt Ralph Senior Member

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    We have a 32Vdc boat. 4 x 8v batteries in series, make up each of 2 banks.
    Each bank runs half of the ship and cranks it own engine.

    Thru the many years we have been onboard I keep checking/adding distilled water and hydrometer testing the banks every 6 o_O months. Plus our 24Vdc inverter bank, gen-sets and electronics 12Vdc batteries.

    Seems the 32Vdc banks last 4 years. Somehow their in a rotation, every two years one bank gets replaced.
    The top Battery (25 to 32Volts) always needs more water and gets weak first in the bank.
    This past week, the port top battery was reading weak one year ahead of the norm.

    As an experiment, I had this one weak top battery replaced. We will see what happens to the rest of the bank as they start their fourth year.

    I think the top 12v batteries in the 24V bank may use just a bit more water also.

    Is anybody else out there noticing top battery issues in their in-series battery banks?
    Adding extra water vs the rest of the bank?

    Any thoughts?
  2. Capt J

    Capt J Senior Member

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    The battery that the positive comes off of generally seems to always use the most water from what I've seen. I think the heat created when a load is put on it and charging it tends to do it.
  3. cleanslate

    cleanslate Member

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    I will have to admit that this topic is a bit to deep for my pea brain. All I can say is they just do, and just keep on keeping on! Lol. I would go with Capt J's response. I do not have the pleasure of housing that many batteries.
  4. Capt Ralph

    Capt Ralph Senior Member

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    The top battery was replaced and all is well. All cells test even. All batteries carbon pile load test perfect and even.
    I'm not a fan of replacing only one out of 4 in a series bank but it seems to have worked this time.
    We will see what happens next year as their cycle comes up.

    The inverter batteries are doing well also but it's coming near to EOL for them also. Love to throw some L16s AGMs in there.
    I'm getting close to retiring (again) so less winning the FL Lotto, that may not happen.
  5. ranger42c

    ranger42c Senior member

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    Our two main battery banks are similarly configured... but we're 12V...

    What do you mean by "top" battery? Haven't heard that term before... Relative to positive and ground cable attachment points?

    -Chris
  6. Capt Ralph

    Capt Ralph Senior Member

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    We have a 32Vdc boat. 4 x 8v batteries in series, make up each of 2 banks.

    The bottom battery, it's negative post is tied to the engine block and the negative battery buss.
    In series or daisy chained to the next battery, from positive to negative terminals.
    The forth battery completes the bank and makes the 32V (4 x 8v). I call this battery, whose positive lead goes to the positive buss, The Top Battery.

    Top and bottom battery could describe the 2 x 6V bats in a 12v bank.
    Top and bottom battery could describe the 2 x 12V bats in a 24v bank also.

    I'm afraid my terminology has showed it's age and confused some folk again.
    Sorry about that.
    Almost like DNA showing where people come from, most of my vocabulary and slang is from my up-bringing around the south/east end of the Okefenokee Swamp & Jacksonville S Georgia.
    Learned much from my mentors and ole farts before me in this same tight & slow area.
    Gone are them and the good ole days.
  7. ranger42c

    ranger42c Senior member

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    Got it, thanks.

    Just from reading, I thought all batteries in the series were supposed to age identically when wired that way.

    Thought it's supposed to be more likely to see your symptoms if both positive and ground come off the same battery (i.e., at one end of the series)... hence not recommended to connect this way...

    Hmmm...

    -Chris
    Last edited: Sep 7, 2018
  8. Capt Ralph

    Capt Ralph Senior Member

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    That's what I was taught.
    I guess these ole low tech batteries didn't get the memo.
  9. Capt J

    Capt J Senior Member

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    They are. Just usually the one the positive is connected to is the first to go. The others are very shortly behind it.
  10. Capt Ralph

    Capt Ralph Senior Member

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    I sent my question (#1 above) to the support tech at our battery supplier Saturday.
    His response this morning;

    " It seems like battery 1 takes a heavier beating than the rest of the batteries. Imperfection in cabling, fusing, breakers and all other “resistors” seems to play a bit of an effect on the life n battery 1.
    I do not have a great answer for this, it is just something we have seen as well. "
  11. Beau

    Beau Senior Member

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    Capt

    As we discussed in another thread I have two banks of two 8D batteries. I have been successful for the past 19 years in changing only one battery at a time. I have logged several 4 year cycles and can almost pinpoint the next battery to fail. I date the battery on day of install. Each seems to last about 4 years. I check my water levels every month and test the batteries at the beginning and end of each season.
  12. Capt J

    Capt J Senior Member

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    Yes, but had they all been changed at one point in time. Then all of them would be due to be changed at the 4 year mark when 1 shows signs of distress.
  13. Capt Ralph

    Capt Ralph Senior Member

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    If I remember, Beau floats an Ocean Yacht.
    All is 12V till the 24V mains are started. A double solenoid splits the batters and makes 24V for starting, then when running, all is back to a dual 12v bank.
    2 x dual 12v banks then run the ship.

    Skippy J and I can see the problem, while in parallel 12v, one of the two is getting old. Could even be bringing the mate battery down early.

    However, if Beau is happy, then I'm happy.
    Lets go fishing.
    Even a bad day fishing is better than any day at work. :D:D:D
  14. Beau

    Beau Senior Member

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    Its a post 50, but...I replace one battery a year on a 4 year rotation and have had no problems
  15. Capt Ralph

    Capt Ralph Senior Member

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    Brain Fart.
    It's a Post. Not with the Ocean rig.
    I was poorly remembering another comment, sorry to insult you and your ship.

    Bottom line; if Beau is happy, then I'm happy.
  16. Capt J

    Capt J Senior Member

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    You should just break the bank apart every 6 months and shuffle them around and the bank will last longer. :D:D:D:D:D

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