In need of some carbon-zinc batteries for a finicky thermostat, I did a Google search and couldn't find enough information on discharge capacity to make an informed decision. Thus, in the best CPF tradition, I opted to test them myself and post the results here.
In this comparison, I test the four cells available to me at local retailers, plus the PKCell cells on offer at Amazon.
I tested the cells under a 100 mA load, the lowest discharge setting on my Opus BT-C2400 analyzer, to get the best estimation of how the cells would perform under low-drain applications such as my thermostat.
I've also evaluated the cells at 300 mA, the approximate current draw of my Mini MagLites with incandescent krypton lamps.
Analysis was performed in a room with an ambient temperature of 67°F/19°C.
THE TEST CELLS
All cells purhcased in mid-March, 2022.
e-Circuit Super Heavy Duty: USD$0.22/cell; paid $1.25 for 6 at Dollar Tree. Made in China. Expiry date of 05-2024 stamped into negative terminal suggests a shelf life of three years.
Eveready Super Heavy Duty: USD$0.77/cell; my local hardware store was sold out; paid $3.06 for 4 with Amazon Prime; on offer for $0.45/cell at Battery Junction. Made in Indonesia. Production date of 10-20 and expiry date of 10-23 printed on negative terminal indicates a shelf life of three years.
PKCell Extra Heavy Duty: USD$0.69/cell; paid $5.49 for 8 with Amazon Prime; on offer for as low as $0.20/cell in 100 cell lots at Amazon. Made in China. Expiry date of 12-2024 stamped into negative terminal suggests a shelf life of three years.
Panasonic Super Heavy Duty: USD$0.31/cell; paid $1.25 for 4 at Dollar Tree; can be found for less in huge lots on Amazon. Made in Costa Rica. Expiry date of 11-2025 printed on negative terminal suggests a shelf life of four years.
Rayovac: USD$0.95/cell; paid $3.79 for 4 at Family Farm & Home; on offer for $0.32/cell at Battery Junction. Made in Vietnam. Stamped with date code STJGV1. Expiry date of 01-2024 suggests a shelf life of two years--or these are old stock with a three-year shelf life.
TEST RESULTS
DISCHARGE TO 0.9V UNDER 100 mA LOAD:
Rayovac: 777 mAh +/- 3.7%
Panasonic: 759 mAh +/- 1.25%
PKCell: 718 mAh +/- 1.5%
Eveready: 678 mAh +/- 0.2%
e-Circuit: 669 mAh +/- 0.2%
DISCHARGE TO 0.9V UNDER 300 mA LOAD:
Rayovac: 590 mAh +/- 5.9%
PKCell: 564 mAh +/- 4%
Panasonic: 513 mAh +/- 5.3%
Eveready: 509 mAh +/- 1.5%
e-Circuit: 467 mAh +/- 6.4%
OBSERVED VOLTAGE, FRESH FROM PACKAGE:
e-Circuit: 1.66-1.67V
Eveready: 1.62-1.65V
Panasonic: 1.65V
PKCell: 1.65-1.66V
Rayovac: 1.62V
CONCLUSIONS
The Rayovac finished at the head of the class under both 100 mA and 300 mA test loads. These are the cells that I'll be deploying with my thermostat going forward. Clocks and other devices which only function well on carbon-zinc cells would be another logical application for these.
The Panasonic would be my choice for remote controls along with flashlights and radio receivers that receive infrequent use, owing to their superior shelf life. I've deployed dozens of these over the years and have never had one leak.
The PKCell turned in a strong second-place showing under a 300 mA load. For those who can make efficient use of bulk lots, these could represent a superior overall value for use with flashlights and other sparingly-used devices drawing around 300 mA. Additionally, the PKCell uses a slimmer cannister than the other cells. If you have a device for which most AA cells are a tight fit, this could be a consideration. Conversely, these slim cells rattled around annoyingly when deployed in my mini MagLite; some Scotch tape applied around the cannisters effectively remedied this.
I see little incentive to choose the Eveready cells when the Panasonic and PKCell batteries offer superior as-tested performance at a lower cost.
The e-Circuit cells frankly surprised me in that they were actually competitive in these tests, especially under a 100 mA load. For low-drain usage, there could be value to be found with these cells.
I will be testing the AAA versions of these cells soon. Stay tuned.
In this comparison, I test the four cells available to me at local retailers, plus the PKCell cells on offer at Amazon.
I tested the cells under a 100 mA load, the lowest discharge setting on my Opus BT-C2400 analyzer, to get the best estimation of how the cells would perform under low-drain applications such as my thermostat.
I've also evaluated the cells at 300 mA, the approximate current draw of my Mini MagLites with incandescent krypton lamps.
Analysis was performed in a room with an ambient temperature of 67°F/19°C.
THE TEST CELLS
All cells purhcased in mid-March, 2022.
e-Circuit Super Heavy Duty: USD$0.22/cell; paid $1.25 for 6 at Dollar Tree. Made in China. Expiry date of 05-2024 stamped into negative terminal suggests a shelf life of three years.
Eveready Super Heavy Duty: USD$0.77/cell; my local hardware store was sold out; paid $3.06 for 4 with Amazon Prime; on offer for $0.45/cell at Battery Junction. Made in Indonesia. Production date of 10-20 and expiry date of 10-23 printed on negative terminal indicates a shelf life of three years.
PKCell Extra Heavy Duty: USD$0.69/cell; paid $5.49 for 8 with Amazon Prime; on offer for as low as $0.20/cell in 100 cell lots at Amazon. Made in China. Expiry date of 12-2024 stamped into negative terminal suggests a shelf life of three years.
Panasonic Super Heavy Duty: USD$0.31/cell; paid $1.25 for 4 at Dollar Tree; can be found for less in huge lots on Amazon. Made in Costa Rica. Expiry date of 11-2025 printed on negative terminal suggests a shelf life of four years.
Rayovac: USD$0.95/cell; paid $3.79 for 4 at Family Farm & Home; on offer for $0.32/cell at Battery Junction. Made in Vietnam. Stamped with date code STJGV1. Expiry date of 01-2024 suggests a shelf life of two years--or these are old stock with a three-year shelf life.
TEST RESULTS
DISCHARGE TO 0.9V UNDER 100 mA LOAD:
Rayovac: 777 mAh +/- 3.7%
Panasonic: 759 mAh +/- 1.25%
PKCell: 718 mAh +/- 1.5%
Eveready: 678 mAh +/- 0.2%
e-Circuit: 669 mAh +/- 0.2%
DISCHARGE TO 0.9V UNDER 300 mA LOAD:
Rayovac: 590 mAh +/- 5.9%
PKCell: 564 mAh +/- 4%
Panasonic: 513 mAh +/- 5.3%
Eveready: 509 mAh +/- 1.5%
e-Circuit: 467 mAh +/- 6.4%
OBSERVED VOLTAGE, FRESH FROM PACKAGE:
e-Circuit: 1.66-1.67V
Eveready: 1.62-1.65V
Panasonic: 1.65V
PKCell: 1.65-1.66V
Rayovac: 1.62V
CONCLUSIONS
The Rayovac finished at the head of the class under both 100 mA and 300 mA test loads. These are the cells that I'll be deploying with my thermostat going forward. Clocks and other devices which only function well on carbon-zinc cells would be another logical application for these.
The Panasonic would be my choice for remote controls along with flashlights and radio receivers that receive infrequent use, owing to their superior shelf life. I've deployed dozens of these over the years and have never had one leak.
The PKCell turned in a strong second-place showing under a 300 mA load. For those who can make efficient use of bulk lots, these could represent a superior overall value for use with flashlights and other sparingly-used devices drawing around 300 mA. Additionally, the PKCell uses a slimmer cannister than the other cells. If you have a device for which most AA cells are a tight fit, this could be a consideration. Conversely, these slim cells rattled around annoyingly when deployed in my mini MagLite; some Scotch tape applied around the cannisters effectively remedied this.
I see little incentive to choose the Eveready cells when the Panasonic and PKCell batteries offer superior as-tested performance at a lower cost.
The e-Circuit cells frankly surprised me in that they were actually competitive in these tests, especially under a 100 mA load. For low-drain usage, there could be value to be found with these cells.
I will be testing the AAA versions of these cells soon. Stay tuned.