Battery Comparisons in QRP Applications

These two graphs illustrate the cost & weight required to achieve a given discharge curve. In the case of rechargeable batteries, cost is derived from the initial cost of the batteries and charger divided by the expected number of charge/discharge cycles typical of the battery type. For non-rechargeable batteries, cost was averaged from several online & local sources.

Smaller Batteries

compare - smaller

Larger Batteries

compare - larger

Conclusions

These tests are comparative – a QRP rig will discharge the batteries differently than my steady 300 mA rate used for the batteries tested here. However, some of the differences between battery types are so large as to render this irrelevent when comparing one type to another. For years, I used nothing but AA alkaline batteries in the field (and at home to manually plot discharge curves). Then I switched to LiPo batteries and made the same manual plots, using either my ATS3, KX1 or Norcal 40A. Comparisons between these battery types closely represent the curves shown here, which were done automatically (allowing me to sleep through them in some cases!).

Each QRPer has his own expectations from a battery during QRP TTF, FoBB, Field Day or whatever else drives some of us to operate amongst the critters afield – how much operating time is required, the weight you’re willing to carry & the price you’re willing to pay.

Remember when looking at these graphs to not only pay attention to the Amp-Hours (X-axis) of a given battery but the rate at which voltages decreases. Alkalines steadily decrease in voltage throughout their discharge while LiPos stay virtually steady till the bitter end. This available voltage over the life of a battery’s charge directly translates into RF available out of your QRP rig.