Xtar 18700 2600mAh (Black)
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Official specifications:
- XTAR 18700 2600mAh Protected Li-ion Battery
- Voltage: 3.7V
- Battery Capacity: 2600mAh
- Cell: Sanyo lithium cell inside
- Size(mm): 70 (length) x 18 (body diameter)
- Net Weight: 48g
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The battery is called 18700, because it is nearly 70 mm long, but protected 18650 can be just as long, only unprotected batteries are 65 mm long.
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This battery has a high voltage at low loads.
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The two batteries has slightly different internal resistance and trip current (This might be related).
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Conclusion
The high voltage can be an advantage in smaller (i.e. 3-4 watt) lights where the battery replaces two CR123 cells.
It is a very good battery.
Notes and links
How is the test done and how to read the charts
How is a protected LiIon battery constructed
More about button top and flat top batteries