C’mon, admit it… you’ve got a pile of discarded AA’s somewhere in your drawers as well:

With all the JeeNodes and room nodes I’ve been trying out around here – and the modest results with the rooms.pde sketch w.r.t. battery life so far, I’ve gone through all these much faster than I would have liked to:

Went through over 60 here at Jee Labs, in the past year or so. So much for the environment!

Enough is enough. I’m switching to the Apple charger with the Eneloop NiMh’s. And with the new AA Power board, it looks like a single AA cell per node might be enough.

But wait! Are all those AA cells really empty? Time to find out!

Since the AA Power board is so efficient, I though it’d be interesting to see how many of those “dead” AA cells are truly empty. Note that the AA Power board can pull juice out of a battery and generate 3.3V even when it’s supplying less than half its original voltage:

So let the battle begin: which cells really can no longer drive a JeeNode as wireless test node?

The result surprised me quite a bit. These 10 were completely dead:

But the rest – which is ALL the batteries shown in the first picture – still worked!

This doesn’t mean that any of these batteries will last very long. But still – they drive the JeeNode and its on-board RFM12B transmitter well enough to send out a fresh packet once a second. Which means that even with an output voltage less than 1.1V, they are still able to a briefly deliver a 80 mA peak current once a second (i.e. 3x the current required @ 3.3V) !

Hmm, now what … charge an Eneloop with all that residual energy, perhaps? :)