I have been buying cheap primary lithium coin cells for many years, and recently I had enough. I have tried many different brands; they are all okay... as a motherboard backup battery. Over the years I added a few more smart sensors in my house. They run on CR2032. The battery life isn't great, but I can deal with swapping the cells every 6 months. But it's the CR2025 in my car keyless remote that broke the last straw. I remember clearly the original Panasonic battery lasted more than four years before I had to change it. You can never forget your first time.
The remote would work fine the first few weeks. Then after three months or so, it would be very unreliable. So I either have a go at penetrating the keyhole or squeeze the buttons on the remote, hoping that the battery would summon enough charge to send some radio pulse. If it doesn't work, then I would press the buttons rapidly as if it would build up enough voltage to fire the IC. So after a few weeks of suffering from weak radio transmission, I unwillingly swap the battery. The used battery has enough charge to light up a green 5mm LED, so my son would inherit it to go with his LED collection.
Finally, one day when walking past the battery display at Kmart, I decided to purchase the $6 CR2025 2pk Duracell. At that moment, I feel disgusted for supporting overpriced branded luxury goods. Plus, what do I do with the other cell? It would sit unused, it would self-discharge, and it won't be fresh when I need it next time. Why don't they sell it for $3 1pk when most devices only need 1 cell? I would even pay the $3.50 greedy price. Does pricing an expensive $6 2-pack coin cell trick consumers into believing it's the best? Am I a victim? Why is it so much more expensive than the Kmart Anko brand $5 4-pk cells? Will it be 2x the performance? Questions like this flew over my mind while watching the old lady curse at the self-checkout machine.
Anyway, I got to the car park, and with zero self-restraint, I tried to unseal the luxurious Duracell; unfortunately, I failed miserably due to the child-safe design. I guess that's where part of the $6 goes. Preventing coin cell electrolysis from happening in little kids intestines... So I had to penetrate the door keyhole again, and the steering column lock would also share the same key and action. They seem happy, clearly evidenced by the explosion going on in my little 4-cylinder air-fuel-powered engine.
When I got home, I tested the Duracell, and I'm glad it works. It sends the rolling codes effortlessly, and I would walk away further and try to beat the distance at risk of draining the cell. More than 2 years have passed the same luxury cell has been in my remote, giving me a good radio service daily. I feel stupid I should have paid the luxury tax in the first place.
Recently, I began to wonder, are there no high-performance cheap cells? How do you tell them apart? I googled, but I didn't get a conclusion. Most people are happy buying cheap Amazon cells. Oh, remember the other twin CR2025 luxury cell? I took it out and poked it with the trusty DMM. 3.3xx volts open load. I have seen this with the cheap cells, so it's not distinctive of a luxury cell. Next, with my octopus-like fingers, I manage to hook up a 5mm white LED and chopsticks hold with the DMM probes. The result is much more obvious. The voltage drop of the luxury Duracell cell is way less than those of cheap brands.
I remember I have an RC3564 internal resistance tester. The Duracell CR2025 measured 19 ohms, a slightly used Maxell CR2032 20 ohms, and a new Energiser CR2016 22 ohms. Then, all of the fake and cheap brands vary from 40 to 120 ohms. They were purchased recently; I spent about $45 on many various brands, including branded fakes. I do not know if a low IR is an indication of a good cell, it's just based on my findings.
So I finally have some conclusion. I have not done a full discharge curve test, so I don't know how well these cheap cells do in the long run. I also haven't test them with various loads. However, we know from the loaded white LED test that the voltage drop was enough to determine the cell performance under load. Secondly, there are lots of manufacturers it's just my poor luck I haven't been able to source good cells. The fake cell out there is an enormous industry. Don't believe in cheap 'genuine battery' claims. Of course it's a battery; what else can it be? Only buy from trusted sellers, pay the luxury tax, and get fresh, genuine stock.
Finally, cheap cells have their place. They are perfectly fine in super low-drain duty, such as a motherboard backup battery, a digital watch or a simple LCD clock. For high-drain devices, liberate yourself with some luxury cells.
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