Let's talk about batteries

[Ronbo]

Thought I'd share some info about batteries and what I know about them...

As you are well aware typical car batteries are basically available in two flavors, standard lead-acid and gel cells...

Lead acid batteries use lead plates and sulfuric acid / water electrolyte. The "cell" generates 2 volts so 12v car batteries have 6 cells in series. When charging hydrogen gas is released through vents in the upper caps, therefore batteries inside passenger compartments (and trunks) should always have vent tubes that run to the outside air. You'll see these (if someone didn't take them off) on corvettes, VW's and other production cars.

With this in mind to add voltage = more cells, to add current = larger plate area + more electrolyte.

Over time the batteries degrade from sulfer deposits that form on the plates and in effect "insulate" them from the electrolyte as well as the acid itself not recovering from the loss of sulfer. This process is actually reversable by applying "pulsed" DC current to the battery, several companies offer conditioners like this one: The Battery Life Saver electronic device Deep cycle batteries are also vulnerable to this condition although they are constructed to reduce the effect. (well, somewhat)

OK, so along comes the gel cell. Lighter, more current by size, sealed (no venting hydrogen), tougher, yet still lead acid. Why?

Since the electrolyte is a gel the plates can now be much thinner as the gel absorbes vibrations that would normaly be transmitted through the liquid electrolyte. Thinner plates means more plates per a given space, more plate area = more current. Also since the electrolyte is thicker it doesn't readily give up hydrogen gas during charge/discharge cycles and the sulfer transfer is minimized as well. Since the hydrogen is staying put we can seal it shut.

Of course I'm skimming over a lot of other "minor" improvements like plate alloys and chemical "tweaks" to the electrolyte. The higher CCA's we see today in standard car batteries is mainly due to improved plate designs. Although IMHO cases have gotten considerablely worse. Almost every battery I see today starts swelling within a year.

I really like the gel cells but they're still very expensive, the above conditioner is a great investment to extentd the life of your batteries. I bought one some time back and ran it on some old batteries that were on there way to the recycle pile. My "toaster" battery tester showed a CCA above what the battery was rated at. These were from my old boat, gave them to a friend. (I'm now boatless) Ran it on my van and the 2yr old battery jumped right back. (the sides are still swelled so it's getting replaced anyway) BTW they're not kidding about the time, I ran it for about a week every evening on the van and for two weeks on the boat batteries.

Like to hear from anyone who has anything to add... The Kirkham will be my first experiance in running a gel cell in a car. I maintained some rather large -48v backup systems at the paging co. I worked for in the past.