LogTag in New Zealand makes excellent data recorders including the TRIX-8, a temperature logger that has a 3 year battery life. It is one of a few of their models that is said to need replacement when the battery gets low. Many other models have replaceable batteries. If you use the TRIX-8 then you will be happy to know that you can get the battery replaced by a new rechargeable battery in an easy to open case and a 6 year minimum life guarantee for just $45. On top of that, you can use one TRIX-8 as a trade-in – if you send 2 units in and can use just one unit returned, the price is $30. To get the $30 price, use the link below to send $45 and then when I get 2 units I will refund $15.