Car battery woes

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Ampdog

R.I.P. 23 June 2022
Joined
Aug 27, 2006
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Location
Pretoria, South Africa
Hear ye - Hear ye - Help ye, kindly!

Why is it that I seem to lose car batteries mostly because of high resistance developing in the cell  interconnects?

Typically, the electrolyte would be in order (fully charged, checked with hydrometer)) by external regulated constant current source if needs be, but the starter solenoid gives the typical rapid in-out symptom. Voltage drop at terminals will be down to <10V when running starter motor. When charging with a constant current, (5 - 7A), the terminal voltage will go higher than usual. Normal would be 14,6 - 14,8V at that current, in the above state it might rise to 15V+. Thus my conclusion that an internal connection has picked up resistance.

I am talking of some 5 - 6 batteries over a decade+ (not all my own car!). The battery life would be typically +/- 2 years. The charging systems are checked, voltage-wise and with clamp-on amp-meter, etc.
I (we) mainly used Sabat batteries; I have heard that many other brands also have their 'cores' made there, only with different labels on the outside.

As far as I know cell plates could develop surface resistance, the effect of which will typically show up under heavy current. But I always thought that electrolyte charged to its correct s.g. indicated that there are no 'sulphating' of plates.

I perhaps need to go back to basics here, but while looking for the necessary information, members' experiences would be informative.

Thanks!

[PS: Perhaps interesting; when the first of 'solid electrolyte' batteries came out some 28 years ago from GM, I immediately bought one for my then Chev Kommando station wagon. At the time I appeared to be the only person having had satisfaction with them. The CSIR fleet got about a dozen, all discarded after barely a year; mine lasted for 4,5 years - the longest a battery ever lasted for me. This technology is now back, but a little expensive for me.]
 
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