Which AA batteries should you buy?
With expertise in designing and developing electronics devices for use in a range of applications, BitBox enjoys exploring new products. One such project investigated the use of AA batteries as many products rely on power. We were curious to know, which AA batteries were best.
Managing Director Quentin Lister set Tom, one of our summer students, the task of making a battery tester. Its purpose would be to measure the capacity of disposable AA batteries. Tom created an active load for an AA cell which could be programmed using a small microcontroller to drain current in a controlled fashion. Following the BitBox way of working, Tom made a prototype, then designed a PCB and finally built 5 identical battery test units. Tom wrote the embedded code so that each battery tester could autonomously take calibrated measurements as the AA batteries were drained. A separate piece of software ran on a computer to capture the measurements so we could analyse the data at the end of the test. Tom wrote a number of web pages to summarise the results and explain how the tests were performed. The content of these pages have proved very interesting. And not just to us; we receive over 100,000 hits a year!
In May 2013 broadcaster Channel 4 came to BitBox to film a repeat of the tests. This was for a feature on alkaline batteries for the consumer program Super Scrimpers. The television program was broadcast in early May 2013. The results of both tests were surprising.
- Don’t bother buying zinc batteries (usually the cheapest). They don’t last and are not cost effective.
- All alkali batteries have similar performances. Batteries that have lots of marketing behind them don’t perform that much better. So, just buy the cheapest alkali cells that you can!
- Lithium batteries do perform very well – if you actually need their performance.