Charging issue .

wellbuilt

 Hi all , I have a 48 volt system with 16 golf cart 215 ah battery’s in series parallel configuration . 

  It seam like I have one battery with a weak performing cell . 

  1.265 or so , the rest of the bank sits at around 1.275 or a little better . 

  The one battery cell is the last cell in the bank and the battery reads colder then the rest ? 

 My Temp comp is located in the center of the bank . 

  Last year the cell lagged behind all winter no matter what I did , I raised the voltage on my inverter charger to compensate for the cold battery’s . 

 If the battery’s are cycled every day they stay up around 45o if they sit for a week they could be 30o 
 The  weaker battery stays about 4/5o cooler then the bank ? 

  Of course the low cell is the one that is hardest to check 😖 
   I did not write down the sg when they where new . 

      This time of year when it warms up and I get some good sun so the battery’s can float the cell  starts to match the rest of the bank and look ok till Christmas ? 

 Do yo think moving the cold battery in to a better warmer spot could help my cause ? Thanks for your response John

Dave Angelini

Hey John !
Me thinks you are severely overthinking this. Just watch that cell. Make it your pilot cell.
  .030 differences or more are what you need to deal with.
All batteries should be easy to check so if moving will correct that....

wellbuilt

K thanks Dave , just checking . 

 The one battery is just in the rear string in the corner . 

BB.

I find it hard to believe that a series string of batteries have "positional/locational" issues (other than if one end of the string is cool, and the other end is cooking in sun/heat). However, we have had a few posters over the years that say they have seen issues with batteries based on physical string location (i.e., battery near the + or - end of the string have low or high SG relative to the rest)--And at least one that "rotates" his batteries in a string(s) once a year as part of his maintenance.

-Bill

wellbuilt

Thanks for the reply bill , as Dave said I don’t want to over think this , but it just seam to me that if the bank is temp compensated and the sender is in the center of the bank and the last battery in my box on the outside wall is under charged ? Maybe it needs more charging because it is colder ? 

BB.

A "dead cell" battery--Nothing much you can do.

But if you have a "chronically low SG" battery and a high SG battery, might be worth swapping them and see what happen.

There have been some folks that would take the bank out for a "ride" (take home for season, or some work/charging at home/with utility power)--And the vibration of the trip seemed to help some cells too (knock off sulfation, etc.?).

-Bill

wellbuilt

If the numbers don’t improve I’ll try swapping them around before winter , thanks bill 

Dave Angelini

I have seen very few banks that did not have a few cells that were off from the highest. A cell that is .010 low is in the noise. My point was you seemed to indicate that it was harder to check. That is an installation issue and not a battery issue to me. What ever is causing it to be hard to check should be corrected. When they do let go some day, use L16's and lose the second string of GC's.

wellbuilt

Thanks for the reply Dave 
 the battery is all the way in the back , I can get to it but it’s a little harder to reach . 

 I figured checking all the other cells was enough . 

  My battery box was made for l16 so I will switch for my next set . 

  I’m have good luck with the golf cart battery’s , I have a set in my trailer that still reads good after 5 seasons now 
    Sg is still reading 1.265 or more I can pump water with them for a hour or so . Not bad for cheapies 

Dave Angelini

Once a year you have to look at them all.  A couple pilot cells should be looked at bi monthly to determine health or warn in time to move from preventative EQ into corrective EQ. Peace of mind kind of thing. The beauty of flooded is they do give you warnings if your eyes are open. They very rarely fail (if installed right) catastrophically like lithium can. 

 Many folks just skip most of this and get the bad news without any warning. That can really suck in a remote place. It still is a free country right? I triple bill sometimes when needed.  Some folks never listen unless they are billed for it.  We are all different.  My favorite are the ones who say, I can just go to candles for a few months!

wellbuilt

Thanks Dave , I’m going to use the bank for a few more weeks then do my spring check . 

 They seam to be all charging really well , it was a long winter on generator . 

Dave Angelini

Really jealous about the long winter. Our wildflowers are way ahead of normal and our rainfall is way behind normal. Friday and, oh look it is almost happy hour! 

wellbuilt

 no shortage of snow ice and rain here I had 4” the other day and now  the place will be a mud puddle till 
 June , the temps drop into the 40s at night .