Thoughts on Accu Cells

Recently, new technologies in Accu Cells have emerged, such as the widely known A123 LiPo cells. In particular, for outdoor qrp activities it is suggested to use these cells due to their superior capacity/weight ratio. However, these cells are more difficult to handle: charger, load balancing during loading cycle, low voltage damages, form factor and voltage of the single cells prevent usage in other common devices. Furthermore, the Ready-to-Use NiMh cells, i.e. Eneloop, have overcome the issues with excessive self-discharge.

In order to find out whether it is reasonable for me to upgrade my outdoor equipment to LiPo I made a rough order of magnitude estimation for some characteristic properties of different accu cells.

(a) Weight Efficiency := Weight / Capacity
(b) Cost Efficiency := Price / Capacity
(c) Lifetime Capacity := Lifetime * Capacity
(d) Optime = Estimated operation time of my ATS 4 based on the properties given in the user manual

The results are summarized in the table below and some more details on the calculations can be found in the PDF.

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Efficiency of Compared Batteries
Battery Voltage (V) Capacity (Ah) Cost Efficiency (€/Ah) Weight Efficiency (g/Ah) Lifetime Capacity (kAh) Optime (h)
A123 9,9 2,3 25 111 16,1 6,3
Eneloop 9,6 (8C) 2,8 9 84 3 7,7
Eneloop 12 (10C) 2,8 11 105 3 7,7
Lead Gel 12 2,2 5 491 1,1 6,0

Conclusion

From the table above I conclude, that the technical properties of the new A123 LiPo batteries are impressive, when it comes to lifetime capacity. This is probably the reason, why these cells are contained in mobile phones and laptops. The operation time and the weight efficiency are outperformed by “conventional” Ready-To-Use NiMh cells for half the price.

For my outdoor qrp activities it does not really matter, whether I can be on the air for 6 or 7 hours. As a matter of fact, weight and overall handling is of great importance for me. Eneloop NiMh cells are currently the best choice. In addition, with conventional AA cells I can also power other common devices.

Additional Data

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