Thread: I need batteries

Okay, I looked it up. Group size is the size of the case, like stormcloud said. You can have different capacities in the same group. Number of plates, thickness of plates, type such as wet cell, agm, lithium all affect capacity. The 27 group agm's I bought were longer in width and length, but shorter in height than the Cabela's group 31 agm's.

I was wondering what the group size meant.

So it seems that group size is the size of the case only, but a larger case can be made to have more amp hour capacity than a smaller one by having more and larger plates. A cheap group 31 battery can also have less amp hour capacity than a high quality group 27. It all boils down to the number and size of the plates. Below is copied from on-line.

Battery Council International(BCI)


Does Size Really Matter?
I often hear people say they are going to increase the size of their batteries by replacing

their Group 24 batteries with Group 27s. Unfortunately they are under a misconception that

group size and battery capacity are related.


Group Number:

Standards for automotive and marine batteries are set by the Battery Council International

(BCI)
. They have defined Group Number for various batteries. The group number has no relationship to the capacity of the battery. It is only a grouping based on the physical outside dimensions of the battery, and whether the lugs are on the top or sides of the case.


The BCI definition of Group Number is:
"BCI GROUP NUMBER
-
The BCI Group Number defines a battery by describing the following characteristics:

A.) Its maximum dimensions (L x W x H)
B.) Voltage (6 volt or 12 volt)
C.) Post configuration
D.) The type of terminal used (top, side, flag, etc.)



It should be noted that the BCI (Battery Council International)Group Number does not designate a battery's capacity, it merely


defines the above listed physical characteristics.

Okay let me give my 2 cents! Have heard all the stuff about how brand doesn't matter and all that! However I bought my Optima TM batteries either 5 or 6 years ago and still going strong! There is a difference! When theirs says maientaniance free they mean it as there are no caps to check water! Actualy I am using the same battery for all 3.Now you can't run to SAMs or Walmart or even Auto Zone and get any Optima batteries. Not ever Blue Top is the same either! D31M is the one I have and the one you want if Optima is what you want! I could have gone through 6 batteries and all the headache that would have come with that. To me just not having to change the out is only part of it, also saved me from getting out on the water to find a bad battery!Oh and not to mention mine were somewhat abused as my boat was stranded in its slings for over 1 1/2 years and a couple time went dead because I didn't go charge them, still they hung in there!My 2 cents and if you read enough on the Optima site you may end up with not too!

Originally Posted by PawPaw "gene"

So it seems that group size is the size of the case only, but a larger case can be made to have more amp hour capacity than a smaller one by having more and larger plates. A cheap group 31 battery can also have less amp hour capacity than a high quality group 27. It all boils down to the number and size of the plates. Below is copied from on-line.

Battery Council International(BCI)


Does Size Really Matter?
I often hear people say they are going to increase the size of their batteries by replacing

their Group 24 batteries with Group 27s. Unfortunately they are under a misconception that

group size and battery capacity are related.


Group Number:

Standards for automotive and marine batteries are set by the Battery Council International

(BCI)
. They have defined Group Number for various batteries. The group number has no relationship to the capacity of the battery. It is only a grouping based on the physical outside dimensions of the battery, and whether the lugs are on the top or sides of the case.


The BCI definition of Group Number is:
"BCI GROUP NUMBER
-
The BCI Group Number defines a battery by describing the following characteristics:

A.) Its maximum dimensions (L x W x H)
B.) Voltage (6 volt or 12 volt)
C.) Post configuration
D.) The type of terminal used (top, side, flag, etc.)



It should be noted that the BCI (Battery Council International)Group Number does not designate a battery's capacity, it merely


defines the above listed physical characteristics.

PPG......I see you found the same mistake I did on another site (Firestone, I believe)......and that is the reference to the maximum dimensions....quote...."(A.) Its maximum dimensions (L x W x H)"......correct me if I am wrong but I believe that should be..."plus"....not "times".......as in (L + W + H).....and that should give you an answer close to 24, 27, 31, etc......

am I seeing this right?......pass the

Add the inches, but you could do it in millimeters than convert to inches.

You're seeing it right, these new techies don't know anything about punctuation, capitalization, abbreviation, spelling, or many other common English language usage norms. I hope I didn't confuse anyone. To sum it up, get the largest group that will fit in your space and then get the largest amp hour capacity lin that group and you should be good to go.
"gene"