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Re: (ET) Battery bad lot? Open ?



The voltage reading would depend on how high the impedance of the meter is.High enough impedance, with no load a sick cell can look fine.With a mechanical issue, the specific gravity can look top notch, but the battery will not produce the current required under load if the internal resistance is high enough.

I've seen batteries do some strange things. Like being able to pull current out of one, but having an extremely high resistance to charging.Or to have a high output impedance, but still react normally to charging.The scariest one are the ones that the electrolyte starts bubbling in one or two cells during a load test. :(

RJ

JohnR wrote:
If Open inter cell connector, would not a voltmeter show ZERO volts ?
NO current could flow, if there was an open connection between adjacent cells.

If one cell was shorted, but the others semi OK, you would see the sum - approx 2 volts per cell, of the good cells - or approx 4 volts, as was reported initially.

A load tester is always interesting also - just to see if the other two cells drop quickly ... but, with one dead cell, who cares ... as other post said ... time to recycle the battery !

John

----- Original Message ----- From: "RJ Kanary" <rjkanary nauticom net>
To: "tbamc" <tbamc gbta net>
Cc: <elec-trak cosmos phy tufts edu>
Sent: Wednesday, April 22, 2009 3:55 PM
Subject: Re: (ET) Bad luck? bad lot? bad owner?


Sounds like a mechanical issue.Fractured plate hanger(s), or an open inter cell connector.In that case, the cell would be "open" instead of shorted. A shorted cell would result in the violent overcharging of it's neighbors.At this point the result is the same......another battery for the recycler's pile. :(

RJ


RJ

tbamc wrote:
<With it going from 6.25 to 4.1 makes me think bad cell. >

My first thought also, but cell s.g. same in all three. Not the case if just one cell shorted?

Thon


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