Currently, because the pucks are being tested with AAA non-rechargeable batteries, and the “hockey pucks” use energy very quickly, AAA rechargeable batteries seemed like an alternative to the non-rechargeables we have been using.
The batteries we have been purchasing from the machine shop are about $15.00 for 48. Online through Amazon, it looks like AAA batteries mostly sell in 4-pack units. Eneloop and Energizer batteries both run at about 12.00 for a package of four, which looks like 138.24 for the same 48 batteries, making them 9.216 times more expensive.
The only thing to consider is the cost of time for rechargeable batteries versus regular batteries. For the rechargeable batteries, considering we would need about 60 just to instrument a unit of 30 pucks, we would need to solder a few battery cases together so that we can charge a great number of batteries at the same time using the recharger that we already have in the lab.
Last time I purchased Eneloop batteries, I got them at http://www.lowmarkup.com, and the price was about $50 for 30 of them (but they were AAs). I think the ratio could be lower than what you calculate, but still they are expensive and time-consuming to charge and manage the charging, plus you need good chargers. When we get to badges with rechargeable batteries, it will be somewhat simpler because with the new design we can use USB to charge. There are some very inexpensive wall-warts with USB output, and it would be easy to set up something to charge lots of badges.
Comment by tedherman — November 22, 2009 @ 8:32 pm