New poster questions on Fenix lights/batteries


Newly Enlightened
May 25, 2023
Hi new poster here; hopefully this is the right category. Pardon my utter lack of knowledge of batteries and how they operate in general. I had a question about the Fenix PD35R handheld flashlight and the Fenix HM50R V2 headlamp. My goal is to be able to use the same rechargeables for both lights. The PD35R comes with a 18650 3.6V 12.24Wh battery (ARB-L18-3400), and can use 2 CR123As in a pinch. The HM50R V2 comes with a 16340 3.6V 2.52Wh battery (ARB-16-700P) as well as an ARB-16-700UP micro-USB battery, and can use 1 CR123A or 1 RCR123A in a pinch.

However, even though the PD35R handheld can use 2 CR123As, it will not light up with 2 RCR123As or with either of the 16340s that the HM50R V2 uses.

My questions are: why doesn't the RCR123A or 16340 work in the PD35R, and is there a CR123A-sized battery that will work in both of the lights? Is there a quality handheld/headlamp combo out there that uses the same CR123A-sized battery type?

Philip A.

Newly Enlightened
Nov 17, 2018
The PD35R and HM50R are both USB rechargeable... Why do you want to swap batteries??? You don't even need to open the battery compartment for years.

Edited to add: Also, using 2 CR123 batteries entails risks of fire, explosion, chemical burns on skin, and permanent damage to lungs... This can happen with poor quality batteries, but also with high quality batteries when one of them has a significantly higher charge than the other one. I'd not run a flashlight on two CR123 for that simple reason...
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