The battery with 18650 size, 3.6 V voltage and 4000 mAh capacity is basically compatible with the old Nitecore P12 torch, as this torch supports 18650 batteries. The NL1840 is a protected Li-Ion battery with button top, which is suitable for the P12.

However, it should be noted that the newer Nitecore NEW P12 is primarily designed for 21700 batteries, but also supports 18650 batteries. The NL1840 is therefore a suitable choice for the old P12, but there are also other 18650 batteries with different capacities and discharge currents, which may be better depending on the application. The NL1840 has a maximum continuous discharge of 5 A, which is sufficient for many applications.

If you want higher performance or a longer runtime, a battery with a higher discharge current or capacity might make sense, provided it is mechanically and electrically compatible. However, the NL1840 is a high quality, protected battery from Nitecore with 4000 mAh capacity and 500 charge cycles, making it a good choice for the old P12.

To summarise: Yes, you can use the NL1840 for your old Nitecore P12. Whether there are "better" ones depends on your requirements, but the NL1840 is a solid and compatible option.

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