I now have three versions of the Olight that are rechargeable via magnetic chargers and contain modified batteries, but the modified battery is only required to run the M2R Pro Warrior.
Due to the dual switches the M2R Pro warrior uses the negative and positive on the head side for operation. It uses the modified battery inserted with the positive side toward the head and will not operate with other 21700 protected batteries. It uses the same battery as the Seeker 2 pro, but inserted and utilized differently. In fact the M2R pro Warrior can operate with the side switch even if the endcap switch is not on the light at all if the battery is held firmly with your thumb.
The seeker 2 pro uses the same battery, but utilizes it differently. The battery inserts upside down and only uses the negative contact on the positive side for charging. Due to that, an unmodified 21700 protected button top battery can be used as well to operate the light, but will not charge in the light. Many chargers that will charge unprotected 21700 batteries will not allow the protected 21700 batteries to fit, so make sure that is not an issue. I have 1 source for the batteries, and 2 chargers that work. Orbtronic has protected 5000 mah 21700 batteries. The Hohm Tech School is a 4 bay usb charger that can accept the longer batteries and Olight makes a dual magnetic charger that can charge it as well. Either can be had for around 10 bucks. The Orbtronic battery is around 12 vs 27 for the Olight modified battery.
The S2R batton II uses a similar modified 18650 battery, and like the seeker 2 pro the battery has the normal negative closest to the head. It can likewise use other protected button top batteries to operate the light, but they can’t be charged in the light. The endcap is not removable, so the battery is changed by removing the head. Special tip, I learned the hard way…remove the clip that is on the head before changing the battery. The clip is positive charged while clipped on the head and will short if it touches the negative on the battery. I learned this the hard way, but fortunately there was some spark, but no damage.
So in summary, the S2R batton II and the Seeker 2 pro can both use protected button top batteries not modified by Olight to operate. The M2R pro Warrior, however can only use the Olight modified battery due to the dual switches. It is the only one of the 3 that uses the negative on the positive side for operating the light. The main battery negative on that light is only used for the bottom switch and charging. Only the modified batteries can be charged in the lights on any of them.