What is this battery

[Diyisfun]

I have an led pir light.
Two rechargeable batteries voltage measures 3.05 & 4.52 so I'm guess 1 battery is not charging.
The dimensions are 18mm dia & 78mm long approx.
When I search to find the battery type, on Wikipedia, I reckon is battery '18650', when I search to buy this battery it says its 3.7v.
Any help appreciated.
Thanks

 

[Nozzle]

Take a look at the wide range of cells available at a pro place like CPC Farnell, Rapid Electronics or RS Components.

Nozzle

 

[foxhole]

It’s a standard rechargeable, have the same battery in my video door bell and high performance torch . Also found one in phone boost charger .

 

[JohnD]

3.7v sounds like a lithium battery

Maybe your "4.52v" one is overcharged and will come down under load?

If you have two in series it would be 7.4v

 

[Diyisfun]

3.7v sounds like a lithium battery

Maybe your "4.52v" one is overcharged and will come down under load?

If you have two in series it would be 7.4v

They are in parallel

 

[JohnD]

like this

https://en.wikipedia.org/wiki/List_of_battery_sizes#Cylindrical_lithium-ion_rechargeable_battery

 

[Diyisfun]

like this

https://en.wikipedia.org/wiki/List_of_battery_sizes#Cylindrical_lithium-ion_rechargeable_battery

That's where I found it bit the voltage is different.

 

[ntb]

That's where I found it bit the voltage is different.

The voltage varies with charge. A fully charged LI ion battery will read about 4.2V and when fully discharged*, around 3V.
*discharged to a safe level - go too low and damage occurs which can lead to the smoke coming out if charged again.