Well this surprised me! The Rayovac (I should say, This Rayovac, with the blue label) followed the discharge path of Duracell pretty closely. Much closer than the Energizer. We will see how it holds up under a constant current of 400mA.
I was going to wait until tomorrow to add the results of the 400mA constant current discharge, but It was done when I woke up so I decided to post it as well before heading off to work.
This test would almost make you wonder if Rayovac is just Duracell in different clothing. It's not, the mechanics of the case are different enough between them. Still, those discharge curves are Close!
I was working on something where I needed the higher voltage of an alkaline battery (about ready to go into way too long of an explanation) blah, blah... just trust me, I needed an alkaline battery. Anyways I have not bought alkaline batteries for a couple of years now (I am pretty hard-core about rechargeables) nonetheless I found myself standing at the store looking at two identically priced packs of batteries and wondering "which one should I get?" I spent way to long standing there, thinking, wondering, to the point that I am pretty sure the store workers started getting suspicious of me. I finally decided to just buy both. I would settle this question once and for all!! Not really, things are always changing, but you get the point.
The two batteries are relatively equivalent. Both AA, both manufactured the same year (this year), neither set of batteries claims something the other does not. For the first test I decided I would just discharge them with one of my basic chargers loaded up with an SD card to store all the data. To be totally fair, I would even use the exact same slot on the charger (realistically this part is a little over the top, the two slots are pretty closely matched) and I would put the whole charger in a box to help with any possible effects from temperature change do to air movement or anything. I set the charger to "Drain" and clicked the button.
The battery is discharged through an onboard 3.9 ohm resistor. After discharging one cell from each pack I uploaded the data to my computer and found this:
The Duracell lasted more than an hour longer than the Energizer (the bottom axis is in hours). This was exciting! While I was at the store I also noticed these new (new to me, remember I don't buy alkalines that often) Duracell batteries that claimed to have the "World's Most Advanced Alkaline Hi-Density Core." Oh wow! That sounds pretty good.
But apparently regular Duracell's already have almost the worlds most advanced core because I didn't noticed a very dramatic difference between these and regular Duracell's. Definitely not worth the cost premium for a few extra minutes of run-time.
I decided that perhaps I was being a little too harsh on these new Duracell Quantums and maybe I should give them another chance under slightly different circumstances. I redid the whole test, but this time using a constant current load at 400mA. For this I needed to pull out my LCD charger.
The LCD charger is capable of doing constant current discharges when the non-LCD charger can't (unless the drain current is set low like 200mA, then the smaller charger can do constant current discharge). I popped in a cell and again to be absolutely fair (and a little excessive) I made sure to do all test in the same slot of the charger.
And yes, I made sure to put it in a box again.
This is what I found:
The Duracell Quantum seems to preform a little better under heaver loads and the difference becomes more apparent towards the end of the run. I still don't think they are worth the extra cost, but at least they are actually a little better under the right circumstances.
I don't have data from as many different batteries under constant current conditions, but even still you can see how all of these stack up against each other as well as NiMh and Lithium when drained into a resistor.
The thing I love about rechargeable batteries is how they maintain a flatter discharge for longer. This often gives them a more usable run-time in more power hungry applications. As far as standard size batteries go, the Energizer Lithium is still the most power for a given packages size, but you definitely pay for it!
I went back to the store and couldn't help but realize I was missing Rayovac brand batteries in my test, so I bought some.
Lasts as Long as Duracell, we shall see about that! : ) To Be Continued...
It actually started out as a legitimate, day job, work related question... and then it turned into several hours of distraction. I had seen several projects like this elsewhere on the internet and so when the need arised, I remembered what I had seen and then improvised with what I had.
The basic idea here is making an image one pixel at a time. This could really just as easily be done with a photodiode (or other light sensor) to create a black and white image as well. However in this case instead of focusing on the "light" part of the electromagnetic spectrum, we move down to the realm of heat rays (or lack there of, depending on what you are imaging). Now I am fully aware that the cost of thermal cameras is becoming more accessible and that there are also sensors which instead of a single thermopile, they contain a small array... but I didn't have either. I had a single thermal sensor, some old stepper motors, some wood and other random electronic parts. Plus it was late at night and not to many places where open.
I really did throw this together. No really! Being late at night I didn't even bother cutting the wood in fear of waking up my kids, so I just grabbed scrap pieces and used them as is. I found the balancing point of the top piece with the motor on it, the extra length and weight of the wood ended up serving as a counter balance to the hardware. I used epoxy putty, super glue, two kinds of tape (electrical and kapton) and even baling wire... oh yeah! While I waited for glue to dry (or cure) I wrote the firmware and a processing sketch to create the final images.
So how does it work? It is like a one pixel thermal camera. It scans up and down, left and right and makes the image one pixel at a time. Similar to slowly scanning an entire scene with an infrared thermometer.
The very first image I made was a side shot of my laptop (right hand side in the image below) with a homemade benchtop linear power supply driving a power resistor behind it.
After that worked I quickly grabbed an incandescent light bulb (all the way to the left) along with anything else that would put off heat and made another image. I also tried decreasing the step size of the motors in an attempt to increase resolution. However as you can see in the image below, although the resolution is greater, the sharpness is really limited by the field of view of the sensor. The good thing about this test though was that from then on I didn't waste anymore time with higher resolutions because I already knew I was at the limit of this sensor.
Now that I felt more confident in my setup, I decided it was time to try and add some color and take a thermal selfie.
I started this image a couple of times and quickly realized it was really hard to sit still long enough to allow a complete scan without moving, sneezing or cramping up. I ended up dropping the resolution and the number of readings I was averaging before I could handle it. I have my arms folded with my hands under my armpits. You can see my thumbs sticking up in yellow.
I did another shot of my desk and the incandescent light before moving outside to take a scan of my backyard. In the bottom picture (the one of my yard) you can see how my concrete patio was still warm even long after the sun had gone down. The device was siting on my fake wood back porch so that is the pinkish stretched out rectangle you see at the very bottom of the image. For the backyard one I had it scan pretty long, so it is like a panorama, that is why things are so distorted.
Changes I think I would make (but probably never will due to time) would be to add a photodiode with a lens (like I mentioned earlier) in parallel with the sensor so that I could get a black and white image along with the thermal image from exactly the same perspective and point of view. The two images could even be overlaid with some transparency set between them. Otherwise you try and do stuff like this (below) and it's just not the same.