Battery`s

[denboy]

Just renewed my baty`s that have been on the boat now for 7 years so they were getting tired ,after checking all 4 with a hydrometer i found that in all the batys the first cell nearest the positive post were all kaput the other cells were fine any thoughts as to why?

Oh and cheers Vince new ones working a treat.

[Gibbo]

Just renewed my baty`s that have been on the boat now for 7 years so they were getting tired ,after checking all 4 with a hydrometer i found that in all the batys the first cell nearest the positive post were all kaput the other cells were fine any thoughts as to why?

Oh and cheers Vince new ones working a treat.

 

Loose battery connections causing the end cell to run at a higher temperature than the rest.

 

Gibbo

[Justme]

Would it not be the same reason why we get told to wire the banks in so that the load is spread over each battery evenly?

 

IE the end one get more charge & supplies more load.

 

If you think of each battery as 6 x 2v individual cells then it seems to make sense.

 

If not then I am wasting my time moving round my 2v cells to even out the wear.

Edited August 8, 2009 by Justme

[Gibbo]

Would it not be the same reason why we get told to wire the banks in so that the load is spread over each battery evenly?

 

IE the end one get more charge & supplies more load.

 

If you think of each battery as 6 x 2v individual cells then it seems to make sense.

 

If not then I am wasting my time moving round my 2v cells to even out the wear.

 

No.

 

The cells are in series so any current in one of them must be the same as in any others. So whatever causes it cannot be electrical. It simply cannot.

 

End cells dying before the others is a well known fact of life but only with batteries (ie 6 cells already built in together) not individual cells. The only two things that are different between the end cells and the inner cells is the end ones have the battery terminals on them and will conduct heat to/from the surroundings faster. Whatever causes it must be related to one of those two things.

 

Gibbo

[denboy]

No.

 

The cells are in series so any current in one of them must be the same as in any others. So whatever causes it cannot be electrical. It simply cannot.

 

End cells dying before the others is a well known fact of life but only with batteries (ie 6 cells already built in together) not individual cells. The only two things that are different between the end cells and the inner cells is the end ones have the battery terminals on them and will conduct heat to/from the surroundings faster. Whatever causes it must be related to one of those two things.

 

Gibbo

so i take it from that my baty`s have deceased with old age then

[pirate paul]

so i take it from that my baty`s have deceased with old age then

If the prob is the cells are getting hot (may be they are closer to the engine, or the neg side cools quicker.... heat sink principal ) perhaps the electro lite is evaporating at the hot end.

[pirate paul]

If the prob is the cells are getting hot (may be they are closer to the engine, or the neg side cools quicker.... heat sink principal ) perhaps the electro lite is evaporating at the hot end.

Could be vibration.

[Sir Nibble]

No.

 

The cells are in series so any current in one of them must be the same as in any others. So whatever causes it cannot be electrical. It simply cannot.

 

End cells dying before the others is a well known fact of life but only with batteries (ie 6 cells already built in together) not individual cells. The only two things that are different between the end cells and the inner cells is the end ones have the battery terminals on them and will conduct heat to/from the surroundings faster. Whatever causes it must be related to one of those two things.

 

Gibbo

Is this something you have identified by research Gibbo or are you speculating?

 

This is me speculating.

If the dud cells have been identified with a hydrometer then that suggests a low sg which implies an incomplete chemical conversion within the cell, which in turn, given the current is as has been said the same as through all other cells, implies that the plates have shed a lot of their active material. quite likely heat but since the end cells are the ones NOT adjoined on both sides by another heat generating cell I would theorise that differential expansion as a result of the temperature gradient may be to blame.

Alternatively, perhaps vibration from the cables is transmitted through the terminal and causes the shedding.

It's an interesting phenomenon and worth getting to the bottom of.

[pirate paul]

Is this something you have identified by research Gibbo or are you speculating?

 

This is me speculating.

If the dud cells have been identified with a hydrometer then that suggests a low sg which implies an incomplete chemical conversion within the cell, which in turn, given the current is as has been said the same as through all other cells, implies that the plates have shed a lot of their active material. quite likely heat but since the end cells are the ones NOT adjoined on both sides by another heat generating cell I would theorise that differential expansion as a result of the temperature gradient may be to blame.

Alternatively, perhaps vibration from the cables is transmitted through the terminal and causes the shedding.

It's an interesting phenomenon and worth getting to the bottom of.

mORNIN Ithrik one end is hot, the the other... vibration doubt full but poss.

[mayalld]

mORNIN Ithrik one end is hot, the the other... vibration doubt full but poss.

 

It would seem that some fiend has been moving the letters about on your keyboard

[Gibbo]

Is this something you have identified by research Gibbo or are you speculating?

 

I'm really just trying to stress the point that is cannot be electrical. It simply cannot be.

 

Whatever else it is, must be physical. Temperature? Vibration? I dunno. I just know it can't be electrical.

 

Gibbo

[pirate paul]

mORNIN Ithrik one end is hot, the the other... vibration doubt full but poss.

Afternoon ....I think one end is hot, the other is cold. The internal resistance of each cell is dependent on temperature, resistance is higher at the positive end the positive end there for charges slower than the neg end.

 

Vibration is a possible cause but I doubt it.