We know, we know. Generally speaking, you should try and switch your household devices over to rechargeable cells rather than using disposable alkaline batteries. But while they might seem increasingly quaint in the lithium-ion era, features such as a long shelf life make it worth keeping a pack of disposables around. So which ones should you buy? That’s what [Moragor] wanted to find out with his personal battery analyzer.
Designed as a shield for the Arduino Mega 2560, the analyzer combines a small programmable electronic load with a INA219 current sensor, OLED display, and SD card reader. The user selects the cutoff voltage and discharge rate before the test begins, and once it’s running, data is collected every second and saved to the SD card for later analysis. Once the battery voltage reaches the predetermined value, the test is over and you’re ready to put a new cell through its paces.
After testing 27 different brands of batteries, [Moragor] tabulated all the data and produced some helpful charts to illustrate the results. With few exceptions, the performance level for most of the batteries was remarkably similar. If anything, the test seemed to show that higher tier batteries from companies like Duracell and Energizer actually performed slightly worse than the mid-range offerings. Perhaps the biggest surprise is that, when the per-cell cost was factored in, the local cheapo batteries provided a better value than anything else in the test.
While the selection of battery brands may be different from where you live, the data [Moragor] collected is still a fascinating even if you don’t recognize some of the names on the chart. Of particular note is the confirmation that lithium batteries handily outperformed any of the Alkaline cells tested when it came to high-drain applications. We’d still rather they came in rechargeable form, but at least it’s a step in the right direction.
The lead-acid rechargeable battery is a not-quite-modern marvel. Super reliable and easy to use, charging it is just a matter of applying a fixed voltage to it and waiting a while; eventually the battery is charged and stays topped off, and that’s it. Their ease is countered by their size, weight, energy density, and toxic materials.
The lithium battery is the new hotness, but their high energy density means a pretty small package that can get very angry and dangerous when mishandled. Academics have been searching for safer batteries, better charge management systems, and longer lasting battery formulations that can be recharged thousands of times, and a recent publication is generating a lot of excitement about it.
Consider the requirements for a battery cell in an electric car:
- High energy density (Lots of power stored in a small size)
- Quick charge ability
- High discharge ability
- MANY recharge cycles
- Low self-discharge
Lithium ion batteries are the best option we have right now, but there are a variety of Li-ion chemistries, and depending on the expected use and balancing and charging, different chemistries can be optimized for different performance characteristics. There’s no perfect battery yet, and conflicting requirements mean that the battery market will likely always have some options.
Continue reading “Better Battery Management Through Chemistry”
[K.C. Lee]’s entry for the Hackaday Prize won’t cure cancer, wipe a disease from the planet, stop an alien invasion, or save the world. His battery charger and analyzer is, however, a useful little device for determining the charge and discharge characteristics of batteries, and can also be used as dual channel electronic load, current source, or power supply.
Inside [K.C.]’s device are all the tools required for charging and discharging lithium-ion, lead acid, and NiMH batteries. He’s doing this with a few slightly unusual circuits, including a SEPIC DC to DC converter, and an ‘analog’ PWM controller. these two techniques together mean [K.C.] can get away with smaller caps and inductors in his design, which also means less ripple on the output. As far as battery chargers and dischargers go, this one is very well designed.
Control of battery discharging and charging happens through a SILabs 8051-based microcontroller with USB. The UI is a simple Nokia LCD and an app running in Windows. If you want to save the world, this isn’t the project for you. If you need to test a few rechargeable batteries, this is a great device to have on the workbench.