Lights on Display Screen but not heating water - How To Test Your Batteries

Created by Smarttek Support, Modified on Wed, 14 Dec 2022 at 10:14 AM by Smarttek Support

How To Test Your Batteries 

Flat or damaged batteries will effect how your Smarttek Hot Water System will operate. The gas safety solenoid valve needs 3 volts to stay open, If your hot water system is shutting down randomly it may be time to replace your batteries.

If the battery bar symbol on your display screen is full (4 blocks) when the water is running this will mean your batteries are above 3V and should operate correctly.

If your battery bar is 3 blocks or less, it's time to change your batteries.
(3 blocks or less confirms the electrical circuit is complete, however the batteries are not supplying above 3V for your unit to operate)

The best way to test your batteries, is still by following the quick steps below and we highly recommend this if you are experiencing any inconsistencies with your units performance!

Tools Needed

1 x Phillips head screwdriver (size 2)
1 x multimeter, if you don’t own one try and borrow one. 


Step 1 - Open your battery box lid. Locate and remove the two screws, lower the battery box down so you can access the two spade terminals at the back of the battery box. 

Step 2 - Close the lid on the battery box and use your multimeter and test the volts at the back of your battery box, Do this by touching both metal spade connectors at the back of the battery box. It should read over 3 volts.
(Note: Your multimeter will need to be set to DC Volts for this test)

Step 3 - Do the same test again with the gas bottle off, run water through your hot water system so the lights on the display screen come on. 

Check the voltage as the hot water system is trying to turn on. This should remain above 3 volts.

This reading will need to be holding OVER 3v for your Smarttek Hot Water Unit to operate correctly. 

If it drops, you have flat or damaged D-cell batteries and you will need to replace your D-cell Batteries.


What is the best batteries to buy for your Smarttek Hot Water System?

Any Alkaline (LR20) Battery will perform well. You will find Active Energy batteries from Aldi Stores and Duracell Batteries will give you the longest battery life.

How long should batteries last?

A good set of Alkaline (LR20) D-cell batteries should get you around 40 Hours of shower time, We recommend replacing your batteries at least every 12 months. 

Why do batteries with high resistance not work? 

Batteries corrode from the inside which causes resistance and batteries with high resistance don’t produce the same volts when put under load. 

Points to Remember

  • All Smarttek Hot Water Units require 2 x D-Cell batteries with a combined battery power under load of over 3v, with 3.1v or higher being optimal.
  • If the combined battery power of the 2 x D-Cell batteries drops to, or below, 3v you have dead or damaged batteries and it is time to change them.


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