The question is why use AA's or C's, or other batteries to make up 6 Volt batteries? The answer is production run costs and simple economics.

I will tackle the latter answer first. The reason why AA's cost so much in comparison is because the market will pay it. Why should companies charge less, if we pay this amount?

I know it's simplified, but it is the bottom line.

Now to the more technical issue, production costs. The cost equation for a battery can be broken down into raw material costs, assembly costs, packaging costs, transportation costs (to get product to market), marketing costs, and finally any product mark-up along the way. As can be seen, the raw material and assembly costs are just a small part in the overall process.

The assembly line (at least the one I am familiar with, again back in Wisconsin) had three parts. The first part mixed the chemicals that make up the inner parts and fed into the battery case (i.e., assembly of the battery inards). The chemicals, depending on whether alkaline or normal are all the same, the only cost difference would be in the housing and other parts of the base battery, plus the volume that could be produced per hour. Now here is one of the cost savers when it comes to the 6 Volt. Larger Batch runs are more efficient than smaller batch runs (i.e., setup time for line factors in). If a line can produce a product for both AA's and 6 Volts, let's say, it would be more cost effective. There is no difference at this point, other than the small incremental cost of additional raw materials per battery for the 6 Volt. The raw material cost would most likely, however, be negligible compared to production run costs.

The second part of the assembly line is the wrapping. This is where as another person pointed out the Ray-O-Vac, Kmart, or Wal-mart, etc. label gets put on the battery. My guess is here there would be a little additional cost for this portion of the line, but as long as you can sequence your day/shift runs properly so as not have assembly machine down-time, you could have a proper queue on this segment of the line.

The final line segment in the plant is the bubble-pack line. This is where the batteries get packed into their end-market packaging (e.g., 4-Paks, 8 packs, etc.) and the packaging get put into boxes for shipping. This is where the AA's and AAA's have higher costs since there is more handling of the individual units as compared to 6 Volts where are packed directly into boxes (most likely -- I only worked on a study during college regarding the bubble-pack line of AA's and AAA's). So, here you would add an additional cost factor into the assembly process due to the additional machine and handling time the smaller batteries require.

I hope this helps in understanding the plant costs. I have no idea what the marketing and transportation costs may be.

Cheers,
TC