From: Andrew Sandford (tdr-l) To: tdr-l@listserv.acns.nwu.edu Date: Wednesday, July 31, 1996 2:43 pm Subject: Re: On 31 Jul 96 at 14:53, Amir Polak wrote: > Hello everyone, > > I am working with the Tektronix 1502b with Campbell interface. > The system is working automatically in the field reading every 2 > hours. Inside the TDR on the main board there is a lithiumbattery > (3.5 v , 750 mAH) that should last for 10 years. In the past 4years > I had to change 3 batteries. > > Does anyone working with this kind of system had the sameproblems. > The battery in the 1502 often runs out early for customers who run the system at higher temperatures. The quoted 10 year life is at room temperature. As with most electronics, especially CMOSmemory, the leakage currents (which is the primary drain from thisbattery) go up almost exponentially with temperature, e.g. at +50 C you might find the battery life is on 1-2 years, presuming the battery was absolutely fresh when you bought it. (The battery used israther rare and expensive, so may have been sitting on a supplier's shelf for a few years.) As a special solution, for a customer of ours who was having this problem. We added a AA battery carrier inside the 1502, wired to the connection, on the circuit board, where the original battery was. This allowed the user to use an AA sized, 3 V Lithium battery, which not only had much more capacity (2.1 Ah), but was cheaper and easy to change when it discharged. This is very easy to do, but if you attempt to do this be careful that the battery carrier is of good enough quality to prevent the battery dropping out when the unit is being moved, and take be careful not to short the battery as Lithium batteries can get very hot is accidentally shorted. Good luck. -- Andrew Sandford Phone: +44 (0) 1509601141 Campbell Scientific Ltd. Fax: +44 (0) 1509601091 14-20 Field Street, Shepshed, email:andrew@campbellsci.co.uk Leicestershire, United Kingdom, LE12 9AL