SF Ultra 2 and Kroma battery question

Hi all, although I have had these lights for a while this is my first time on the forum so if the post is in the wrong place please tell me. I am going through a lot of SF batterys. I have some RCR 123A 650mah Batterys I got for my old Z2 before I realised I could not use them in that tourch.

My question is can I use them in the Ultra 2 and Kroma, they fit and work but are there any risks/downsides involved in useing them. Dont want to damage the torches.

Thanks for any advise
Andy

Leef makes a 18s body for the U2 and Kroma they work for both lights available at lighthound.com

Hi, excuse my lack of knowledge here but what is an 18s body ? does this mean that the batterys I have will cause damage to the torches and I need another solution / buy more parts etc ?

An 18s body takes 1 18650 cell. AW is a well-known 18650 manufacturer, and you can buy his cell at lighthound. (lighthound.com) As for your cells, I believe both of them use a buck circuit, so depending on the voltage of your cells, you may be alright. What is the voltage of your RCR123's? 3.0 or 3.7 volts?

Hi and thanks for your help. My cells are RCR 123A 650mah 3v Lithium-ion batterys. I have put them in and tryed them and the tourch works fine but dont want to do any damage to either torch through prolonged use. The Kroma has the low power coloured LEDs to and I was not sure about these.

Hi Atoady and :welcome:


The problem with these Surefire lights normally lays in the fact that most RCR123 batteries just do not fit inside the body because their diameter is slightly higher than normal batteries (primaries).

In case as you say the batteries you have can be inserted into the body you can use them. What I do to stay on the safe side is to leave them to rest for about one hour after charging so their voltage is not too high. Maybe useless but better safe than sorry....

Just found the email from months ago, I asked a simmilar question but the Kroma had not long been out any I could find no threads on it. The answer I got was as follows. I dont understand any of this as you guys seem to so am wondering if anything has changed as its been out for a bit now and there may have been more tests done ?

My RCR 123A batterys slide in just fine, it was the below email that had me worrying as to if I could use them but I could not find the email before.

"The U2 is a BOOST circuit, it boosts the voltage up, so you have to keep the input voltage under the Vf of the led,
The L5 is a BUCK circuit, it lowers the input voltage to match the led.
So, NO, I would not recommend using 2 Li-Ions in the U2.
A single Li-Ion works well though, if you want to use one of the 2x123 length Li-Ion cells.
But I would not recommend 2x123 Li-Ions

"The U2 is a BOOST circuit, it boosts the voltage up, so you have to keep the input voltage under the Vf of the led,
The L5 is a BUCK circuit, it lowers the input voltage to match the led.

Hmm as far as i know are the 2 circuits almost the same and are they both buck/ boost.
I use a 18650 with both of them without any problems.

A few threads on this subject:

https://www.candlepowerforums.com/threads/89686

https://www.candlepowerforums.com/threads/180688

https://www.candlepowerforums.com/threads/142477

https://www.candlepowerforums.com/threads/133944


:wave: