Yes, it's easy to add an external battery at a 2465B NVRAM


Why add it? :
Before this operation I couldn't read the NVRAM on my programer and after I could do it .. I was happy!

I used this Dremel head
Before begin .. insert the NVRAM in a socket to protect his fragile pins !!

I started in front of the first "A" of text "DALLAS" ... this is where is located the pin 7 of IC
(Luckily the DS1218 is a old DIL8 case with his large pins which will makes research easier)


Carefully I came down and widen the hole very near of case until i seen the copper appear
(It's the good moment to measure the internal battery voltage between this copper and pin 14 of the NVRAM)
Then i widened it enough to be able to solder a wire

Maybe a piece of advice : do not widen it too much on the side of the "D" and "L" of dallas so as not to short-circuit, with the dremmel head, the pins 7 with 6 or 8 of DS1218 because I don't know if that could kill it? .. see inside picture below

I cut the branches of my socket to be able to easily pass the wire
Then I soldered two wires:
- positive on pin 7 of DS1218
- negative on pin 14 of NVRAM

My final solution :
I decided to keep the original NVRAM equipped of an external battery
For the battery I chose this one on Amazon