| Characteristic | A123 | LiIon/LiPo | Nicads/NiMHs |
|---|---|---|---|
| Voltages | |||
| Peak charge voltage | 3.6v officially but can go up to 4.2 with little damage (but not regularly) | 4.1 or 4.2v but significant damage likely from about 0.1v above that | No limit but usually charges to over 1.5v |
| Nominal voltage | 3.3v | 3.6 or 3.7v | 1.2v |
| Voltage under significant load | 2.95v @30A (actual test) | ~3.3v | ~1.0v |
| Minimum discharge voltage | 2v officially but almost empty at 2.5. Can go to 1.0 | 3v in theory but many have to go down to 2.75 to get capacity and some require above 3v | No limit |
| Voltage sensitivity | Not sensitive to straying outside recommended voltages (2-3.6) | Extremely sensitive to straying outside voltages (usually damages pack) | No significant voltage boundaries |
| Discharge curve | Very flat | Noticable reduction in power over discharge | Fairly flat |
| Balancing | Minor issue; required but less frequently and with less precision | Major issue; complex with large packs | Not normally required |
| Other characteristics | |||
| Capacity | 2300 and 1100mAh only | Wide range of sizes | Wide range of sizes |
| Weight | 70g for 2300 | Similar for same capacity and C rating but newer cells can be lighter | Much heavier |
| 'C' rating | 30C | 20C common, 30C becoming more available | Not usually a constraint |
| Charge rate | 5mins claimed; 10A (15mins) on 'their' charger; float charge allowed | 1C (1.5-2hrs); float charge not recommended | Nicads 25mins, NiMHs 1C (1hour); float charge OK but Nicads can develop 'memory' |
| Memory | No | No | Nicads Yes (bad) NiMHs No |
| Shelf losses | Low | Low | High (bad) |
| Cycles | 1000 claimed | Often only 10-50 but can be several hundred | Not normally an issue with active cells but they often die if not used |
| Internal resistance | Low | Most are much higher (bad) but improving steadily | Low |
| Packaging | Hard aluminium cylinder | Soft plastic bag | Hard steel cylinder |
| Availability | Initially as DeWalt DC9360 and DE9360 36v power tool battery pack; a few 'modelling' dealers emerging | Widespread | Widespread |
| Cost | Expensive list price; better on ebay | More expensive than A123's but dropping progressively | Difficult to compare |
| Temperature on charge | Excellent (very little rise even with fast 15min charge immediately after flying) | Can be dangerous (extremely high risk of combustion if settings are wrong) | Nicads OK (but warm after 25min charge)/ NiHMs poor (some get hot at 1C) |
| Temperature in use | Excellent (luke-warm at 15C) | Dangerous especially when not cooled or worked near their C ratings | Nicads excellent / NiMHs good |
| Size | Bulky | Compact | Poor (need 3 times as many for same voltage) |
| Environmental issues | Said to be OK | Less OK | Nicads are bad, NiMHs OK |
| Long-term Storage | Not known | Deteriorate if not stored at mid-voltage (~3.8v) in cold conditions | Nicads tend to die if not used regularly; NiMHs tend to fade away too |
| Other issues | Don't turn the 'button' on the cell. Not recommended but ends are solderable | Terminals are flimsy One terminal may require aluminium solder (if tab breaks off) | Not recommended but ends are solderable |
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