I was at a gem and mineral show today and ran across a rechargeable battery technology I had never heard of before. The NiZn 1.6V batteries are fairly new, though they've been around longer than I would have suspected.
At 1.6V these AA and AA batteries are a lot closer to the voltage of the equivalent 1.5V alkaline. The vendor whose table I saw them at uses them for his UV light (used for examining fluorecing minerals). These lights won't run with 1.2V NiCad or NiMh, but they work just fine with the 1.6V NiZn batteries.
If you run your robots from 4xAA alkaline batteries, like I do for many of mine, you may have been frustrated by the need to step up to five batteries if you wanted to use rechargeables. Now these NiZn batteries provide an alternative that I thought was worth looking into.
I didn't buy them, but I started some research when I got home. I found a great review by an engineer on Amazon.com of all places. Look for the top review by NLee the Engineer.
Basically, here's the story on these batteries from NLee the Engineer. I haven't verified any of this myself.
- Higher voltage for a rechargeable is their primary selling point above NiMh.
- Their capacity is about 1500 mAh (artfully advertized as 2500 mWATTh).
- Fully charged, they are actually about 1.8V, so if your application might be sensitive to overvoltage, you may be in trouble. For example, Running an LED light with two of these batteries at 3.6V instead of 3.2V for very fresh alkalines will lead to a very bright light... but may reduce the lifetime of your LEDs.
- Number of discharge cycles is only 200, compared to 800-1000 for NiMh. After 12-16 full discharge cycles, the average charge capacity dropped 5% from the original value.
- Longevity after 20-30 deep discharge cycles (down to 0.9V) has killed some of his batteries after a year.
Nevertheless, for some robotics applications, these may be very nice to try. They have comparible capacity to a NiMh. If your robot has a 5V LDO voltage regulator that needs at least 0.5V above the regulated voltage, four of these freshly charged batteries would start you at 7.2V. That's a lot of headroom before they drop to 5.5V and need a recharge. If you are not draining them down to near zero, you might not have some of the problems NLee ran into. (He's using them for camera flashes, I think.)
My robot GRAB-E may get a set of these to try out. It's only $13 for a charge and four AA batteries. Worth a try.
Anyone seen or used these before?