| Re: Flat battery today ...alternator? [message #370494 is a reply to message #370485] |
Tue, 13 September 2022 10:11  |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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boybach wrote on Mon, 12 September 2022 12:46John, my experience is that the old batteries gradually lost their oomf but yes indeed these new ones fail suddenly...
What's up with that? lol
Larry
Larry,
I'm not John,
But I happen to know. This is all about batteries that are FLA (Flooded Lead Acid) types.
If you look into a new battery (pry open the caps of a service proof type) you will see that the plates are packed very close together. If you happen to have an older one around that you can look in, you will see more separation between the plates. That is the difference.
There are fibre glass mat separators to keep the plates apart. When an FLA battery is working, things are moving and one of the things that move that should not is the antimony in the lead grids that support the lead foam that makes up both plates. The more the battery is charge cycled the more of it moves. It actually gets dissolved into the acid (electrolyte) and get moving around until it plates back out again. Unfortunately for us battery users, when it plates back out it can form a dendrite (kind of like a metal pine needle) that can grow though the mat and connect the plates.... GAME OVER
Older batteries had more space between the plates, so the dendrites had to grow a lot farther and with the separator being less dense, they often broke off before shorting the plates. So, that had to die by having the sulfur in the acid form an insoluble version of lead sulphate (PbS04) on the lead foam of the plates. This will not easily go back into solution and is not conductive so the battery looses capacity with age and cycles. Lead sulfite (PbS) is normally formed and dissolved in the charge/discharge cycles.
FLA batteries can also die by drying out. This accelerates the formation of lead sulphate. The charge cycle always has to cause out-gassing that is the water component leaving the electrolyte.
Now, on to the inevitable questions:
Why do the manufactures do this?
* New batteries are smaller so they can fit more on the truck. OEs like smaller batteries because they take up less space in the vehicle.
What do higher cost batteries do different?
* They reduce the amount of antimony in the support grid so it can't plate out and short a cell. This also makes weaker grids that are a manufacturing problem.
Can I add water to the battery and maybe extend its life?
*Maybe, if you pry open the caps of a service proof battery, and you can see the separators over the top of the liquid, you might add DISTILLED (not de-ionized) water, but be careful as there is often no split ring level gauge built in there.
I bet I left someone with a question of two. Come back and if I know, I will say so and also not.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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