Have to replaced battery in the tx61u-it solar powered wireless temperature sensor

Expensive if bought from the item manufacturer as a spare part

Google search "replacement battery for coma solar powered led motion sensor light model no. 052-7808-4 might produce results.

Most battery packs are fairly standard but first you need to remove it in order to identify it - voltage, type, capacity in order to search further or to wade through the huge list on sites such as ebay.

Taking the vehicle to ford an having the modual programmed . You can't just replace these modules . Give them the old one ,check for DTC'S - diagnostic trouble code's . Nothing you can or should do.
NOTE: Some PCM DTCs may inhibit A/C operation. If any PCM DTCs are retreived, diagnose those first. Refer to the Powertrain Control/Emissions Diagnosis (PC/ED) manual. DTC Description Action to Take B1003 Mode Door Short/Failure Go To Pinpoint Test F . B1200 Stuck Button Button held too long may set DTC. ATTEMPT to clean buttons. If code returns, INSTALL a new electronic automatic temperature control (EATC) module. REFER to Section 412-01 . B1251 In-Vehicle Temperature Sensor Open Circuit Go To Pinpoint Test A . B1253 In-Vehicle Temperature Sensor Circuit Short to Ground Go To Pinpoint Test A . B1255 Ambient Temperature Sensor Open Circuit Go To Pinpoint Test B . B1257 Ambient Temperature Sensor Circuit Short to Ground Go To Pinpoint Test B . B1342 EATC Module Faulted INSTALL a new EATC module. REFER to Section 412-01 . B1676 Battery Voltage Out of Range Go To Pinpoint Test Q . B2266 LH Blend Door Failure or Short For vehicles not equipped with electric heater, Go To Pinpoint Test K .
For vehicles equipped with electric heater, Go To Pinpoint Test L . B2267 RH Blend Door Failure or Short For vehicles not equipped with electric heater, Go To Pinpoint Test K .
For vehicles equipped with electric heater, Go To Pinpoint Test L . B2268 Steering Wheel Control Switch Circuit Open Go To Pinpoint Test D . B2269 Steering Wheel Control Switch Circuit Short to Ground Go To Pinpoint Test D . B2426 RH A/C Solar Radiation Sensor Open Circuit Go To Pinpoint Test C . B2427 RH A/C Solar Radiation Sensor Circuit Short to Ground Go To Pinpoint Test C . B2795 LH A/C Solar Radiation Sensor Circuit Short to Ground Go To Pinpoint Test C . B2796 LH A/C Solar Radiation Sensor Open Circuit Go To Pinpoint Test C . U2050 No Application Present INSTALL a new EATC module. REFER to Section 412-01 . All Other DTCs - REFER to the Master DTC Chart in Section 419-10 .

Here is the manual for your product - battery information is in there

http://www.lacrossetechnology.com/tx61/manual.pdf

Mine stopped working about 2 weeks ago (May 2018) after about 8 years of service. I had tried the recommended procedure to depress the reset button on the sensor, but it still would not reset / reboot the temperature sensor. I suspect the non removable batteries to be the issue failure so I am about to crack the case open to try to troubleshoot the issue for confirmation.

Had same problem on my unit and temporarily removing the battery and charging it for 24 hours with a modified 7.5 volt 200 ma. power adaptor seems to resolve the issue. Lamp is now working, hope this fix will last. Seems the solar panel does not charge the battery fully. Tried locating a replacement battery to no avail. The battery is 8V3.5AH, no other model information. Battery is 3.75" H x 3.5" W x 1.75" D

You shoud use new batteries because you dont know how old the ones that are present are. You should also use lithium battteries in the weather station sensors because they last longer and have better low temp response. The batteries should have marks on them that correspond with the marks inside the sensors.

The light will only stay on as long as the battery lasts. My guess is that will not last all night. What you can do is buy a light sensor switch (or even a light sensor socket adaptor is available to save you from having to wire it in) to keep a light on during the night. You can use a CFL or even an LED lamp to save electricity, but it is unlikely that a solar-charged cell will power even one of thes all night long.

Batteries must come out of both the temperature sensor (transmitter) and base (clock and temperature display). Leave out for about 4 minutes. Replace the batteries in the temperature sensor FIRST and set it about 5 - 10 feet away from the base. Replace the batteries in the base and leave them both set without touching any buttons for at least 15 minutes (usually only takes 5 minutes or so). The temperature should start to display. You can set the clock manually to the correct time and have it get the updates via radio in the evening or night. Should work after all this just fine. (have done it alot of times this way over the years)

Good luck.