Anyone know the answer to this? (Dexcom wants $650 for a new transmitter - seems a bit much for me!)
Bob,…in theory, yes, you might be able to open the device and recharge the battery or replace the battery, if it is not re-chargeable…however, you will never be able to reclose the device so it sits back on the sensor correctly…because the internal board and battery are all over molded in one piece…nice job of injection molding…so you will never be able to do it…the two pins you see on the bottom is the way the device measures the change in resistance/voltage, these are not for charging the device…you only can buy a new transmitter
Bob, here’s (probably) a more important problem for your idea:
The transmitter battery is probably NOT rechargeable. Rechargeable Lithium-Ion batteries have less than half of the energy density (Watt-Hours per gram) which is achieved in some of the non-rechargeable (AKA “Primary”) Chemistries. The transmitter battery might be a model which was already approved by FDA for use in another medical device, e.g., pacemaker. And the particular kind of battery used in pacemakers, Lithium-Iodide, is fairly safe when damaged. (ummm, that’s why it is used in pacemakers 
Here’s a table: http://en.wikipedia.org/wiki/Lithium_battery
But you DO NOT! want to go digging into a Dexcom Transmitter to replace the battery! If Dexcom uses one of the ultra-high energy density Lithium-Thionyl-Chloride batteries, the ones which were developed for use in spacecraft. Crack one of them, and you could be poisoned – these are not batteries which you can buy “at a store”, and people who haven’t been trained in working with them need to stay away.
Really. I mean it. And BTW, thanks for listening to my tirade.
Don’t go there!
thanks for the info!