In this article, we focus on alkaline batteries, including their advantages, disadvantages, and chemistry.
The following illustrations are for Duracell's MV1500 Quantum AA battery. Figures 1-3 show examples of alkaline discharge curves in the form of voltage at various loads and temperatures. Figure 4 shows the battery at two load rates and illustrates the effect on internal resistance.
Voltage versus service hours for several constant currents. Observe the interpolated black curve that I added.
Voltage versus service hours for several constant-power loads.
Voltage versus service hours for several temperatures with a 100mA load.
Voltage and internal resistance versus depth of discharge
for the Duracell MV1500.
Rechargeable alkaline batteries
Rechargeable alkaline batteries are sometimes called RAM batteries. The early technology was developed by Battery Technologies Inc. and licensed to Grandcell, Rayovac, Pure Energy, and EnviroCell. Additional patents have been developed to expand on the technology. The most common sizes are AAA, 9V, AA, C, and D. These batteries are manufactured fully charged and have much better charge-holding characteristics than regular rechargeable batteries like NiMH and NiCd.
These alkaline types are specifically designed to be rechargeable, with reasonably high recharging efficiency, for up to about 20 cycles. They have been designed for low-drain, periodic use, where the depth of discharge is slow and no more than 25% on average. Deep discharging reduces the cycle life substantially.
With regard to capacity, rechargeable alkaline batteries are about two-thirds as strong as their non-rechargeable counterparts. Also, terminal voltage after recharge is somewhat lower, typically recovering only to 1.4 V or so with the best brands. Also, you should recharge these batteries only using the specific charger recommended by the manufacturer.
I haven't personally tried to recharge ordinary alkaline batteries, but I believe it is technically possible. I have heard reports that, so long as the battery hasn't been discharged too deeply, it is possible to recover up to 90% of capacity with a special type of pulse charging using the Battery Xtender.
Last but certainly not least, when it comes to the disposal of alkaline batteries, this is generally easy, but you should refer to individual manufacturers for specific instructions. In my next column, we'll look at some more tips and tricks, and we will consider another battery technology. In the meantime, I welcome any questions or comments.