Batteries for digital locks

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Summary: Alkaline type batteries (eg. Energizer Max or Duracell) should be used and changed every 8-10 months as a rule of thumb. 

1. How often to change batteries?
   
   Gateman and most Samsung locks require 12 months cycle change (assumption: 10 entries a day and alkaline batteries are used). To avoid battery liquid leaks, we suggest a more diligent 8-10 months replacement cycle (and never leave batteries in the lock beyond 1 year). Remember to check the battery compartment for battery liquid leaks every 6 months. ​Digital locks are designed to give you low battery warnings but you should not wait until then; they are warnings!
   
   [Additional notes: ​The battery cell expands near the end of it's power due to chemical changes. The risk of battery liquid leaks rises towards the end. Err on the safe side and replace batteries earlier than later]
   
   
2. What batteries type to use?
   
   Use alkaline type batteries. These batteries have the word "alkaline" printed somewhere on the battery body. If the prints are too small for you to read, go with the following two: Energizer Max or Duracell. 
   
   What not to use: You should not use carbon-zinc batteries because these run out of power 3-4 times faster than alkaline batteries. Battery power also dips dramatically near the tail end and low battery indicators may be missed. Eveready "Super Heavy Duty" is an example of carbon-zinc type battery. The wordings may lead you to believe it is super heavy duty but the low price tells you the truth.
   
   [Additional notes: You do not need expensive lithium batteries because digital locks are not high currents discharge devices like your flashlight, cameras etc. You should not use rechargeable batteries because the manufacturer says so]
   
   
3. How many batteries? 4 or 8 pieces?
   
   Most locks have requirements for just 4 batteries. So, that's about it.
   
   Some locks allow up to 8 batteries: the additional 4 pieces could be useful if your lock is optionally equipped with remote control or bluetooth option. If they are not fitted with those options, then the rule of thumb is:4 batteries are enough.
   
   [Additional notes: Some locks come overloaded with functions and it may state 8 batteries when replacing batteries. Good luck with that. Stay with simple locks if you have not decided on your next lock.]
   
   
4. What brand of batteries?
   
   We are not intimately familiar with every battery brand and their supply chain. We can however put on our thinking hats and rationalise along the following lines to minimise chances of poor quality battery:
   
   - buy from high traffic​ outlets (supermarkets, petrol kiosks) on the assumption that the batteries have not been on the shelf for a long time (alternatively read the dates on the batteries)
   
   - avoid heavily discounted batteries or batteries priced very low 
   
   We think Energizer Max or Duracell at NTUC supermarket are decent brands to use.
   
   
5. What if the batteries run out of juice?
   
   Fear not as this has been a design consideration since the first iteration of digital locks from many years ago. When the battery is low, the lock will play a melody when it operates. There is usually a visual indicator battery low as well. In the event you miss all these indicators (say when you are away on vacation), and the batteries are completely depleted, just get a 9V battery from the supermarket and plug it in from the outside to give it enough power for you to unlock using one of the access methods (pin etc.).
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See pictures below for AA size and 9V Energizer Max alkaline batteries.
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