Westy Battery size/replacement Demystified

Last January bought and had installed 2 new coach batteries before I went to Key West. Cost was $220 each plus tax and $30 to install from Battery Warehouse. The fellow just attached straps to the terminals and yanked them out with a little grunting, that's it; no jacks, no help. AGM type 105 amp hrs, group 31. Originals were Gel and only 85 amp hrs. AGM not as sensitive to overcharging. I've attached a pic of our original West Coach battery and of the new battery as well as it's data plate.

The sizing is actually very simple. And actually the only one that I came across in the Yahoo Westy group that nailed the size was Ernie w his Sears die-hard AGM. It's simply group 31 and a PERFECT fit. Most everyone else that I read about in this group has purchased a group 27 which is taller and a little shorter in 2 dimensions and wider in the other. So no mods needed to the hold down bar with a type 31. I swear the guy had the batteries out and in in about 5 minutes flat. I wanted my $30 install fee back. I've had these these generic Battery Warehous batteries in all my cars and have for years so am pretty confident I'll get good service from them.

So far so good. It's been almost 8 months since installing them.

Here's the original Westy Coach Battery


Here's a partial pic of the new Battery Warehouse Battery


Here's the data plate from the new Battery Warehouse Battery


Here are the installed Battery Warehouse Batteries. Notice the convenient handles making removal pretty.


I asked the fellow at the Battery Warehouse about standard Group Sizes. He said they're all identical. (some folks have told me there are variations) The following seem to support that but I wouldn't swear to it. All I know is that Ernie's group 31 from Sears was a perfect fit and my group 31 from Battery Warehouse was a perfect fit (used up all the space w/o being too tall (needed no modification of the rigid steel hold down strap as seems to required as reported by some on in the Yahoo group for his type 27. The Battery Warehouse guy took one quick look at my Excide Gel's and said that's a type 31. I do know that w/in a specific group size, there are different fitments meaning location, orientation and type of terminals could vary. Since the footnotes say that the overall dimensions include the terminals, maybe the various terminal types could be the cause for variation from the tables????

The following is from http://www.batteryfaq.org/. If you click on BCI Group Number below you get the overall sizes for Battery Groups. Note the 2 footnotes:

Battery Selectors or Fitment Guides allow you to determine the correct replacement starting battery for your vehicle based on the vehicle manufacturer's recommended specifications, such as Cold Cranking Amps, (CCAs), Amp Hour capacity or the BCI Group Number or ETN size. A good manufacturers cross reference list for Sealed Lead-Acid (SLA) deep cycle batteries can be found on the Battery Solutions Web site.

Another chart here: http://www.gglotus.org/ggtech/battery-bci/battery-bci-size.htm#note2

I just want to correct some miss information. It is a common myth that AGM batteries are less susceptible to over charging. It is the complete opposite. AGM batteries are more easily damaged due to over charge than are flooded batteries. An AGM battery is also referred to as a starved electrolyte battery. The electrolyte is captured in a glass mat. It is not free flowing liquid like a flooded battery is. If you shake an AGM battery you do not hear any sloshing of the electrolyte. Since the electrolyte in an AGM is captured, it is harder for the battery to dissipate heat. Most rapid chargers limit the charge voltage to 14.5 V on an AGM battery and allow 15.5 V on a flooded. This is so the battery does not gas.

Where AGM's excel is in their better resistance to damage do to cycling. Most AGM batteries will withstand cycling better than flooded batteries. Also, AGM batteries generally have higher reserve capacity.