> For the complete documentation index, see [llms.txt](https://tankmate.gitbook.io/tankmate/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://tankmate.gitbook.io/tankmate/tankmate-user-guide/tankmate-wifi-sensors/tankmate-v2-wifi-sensors/v2-battery-replacement.md).

# v2 Battery Replacement

{% hint style="info" %}
Prior to October 2021, TankMate v2 sensors were supplied with a single C size, 3.6V lithium battery. These can be hard to source, and there are a variety of similar batteries that do not work in a TankMate sensor. **We recommend removing the C-size battery completely, and installing a 3 x AA battery adapter.**
{% endhint %}

**Recommended AA Batteries:  Energizer Ultimate Lithium L91 (AA size, 1.5v)** / or **Alkaline** type

{% hint style="warning" %}
Please check how your existing battery is connected to the board! Later models use a white plug, while 

v2.01 and v2.30 PCBs with **screw terminals -** use this type:

* JayCar - [3 X AA Side by Side Flat Battery Holder](https://www.jaycar.co.nz/3-x-aa-side-by-side-flat-battery-holder/p/PH9274)

v2.60 PCBs require a **JST PH 2.0** **plug-in connector** **-** use this type:

* DigiKey - [1738-FIT0619-ND](https://www.digikey.co.nz/en/products/detail/dfrobot/FIT0619/10230092?s=N4IgTCBcDaIIwHYDMAOAtAMQJIBUAMAbHAJxoByAIiALoC%2BQA)
  {% endhint %}

![](/files/t9dvJfPHmAXfM33YX9cm)

{% hint style="warning" %}
Note: the following battery types **will not be suitable** to power a TankMate unit

* **Heavy duty** type cells 
* A single **1.5V C-size** cell 
* **ER26500** C-size lithium
  {% endhint %}

![](/files/NmtCqGcq3BnCIIN9SJxF)

**Tools required:** Phillips / Pozi screwdriver #2; Flat screwdriver #1

1. Open the sender unit - remove the 4 x screws on the lid 
2. Turn the unit OFF, using the slide switch 
3. Remove the existing C-size lithium battery 
4. \*If your unit has a plug in connector (v2.60) - pull out the existing battery plug (with pliers) and insert the plug for the new 3 x AA battery pack. Skip steps 5-8. 
5. Undo the two screw terminals (marked 1 and 2 below) and remove the existing battery leads 
6. If present - remove the C-size battery holder - held down with double sided tape 
7. Insert the leads for the new 3 x AA battery pack. The wiring should match the image below:     1. RED || 2. BLACK 
8. Tighten the screw terminals 
9. Insert the 3 x AA cells 
10. Power the unit ON (check status LED). If the LED does not blink, check the battery connections 
11. Close the lid, ensuring the seal is in place. Replace and tighten the 4 x screws