I’ve tried permanent marker but it wears off in a few weeks, i want to keep pairs together for balancing purposes (NiMH and lithium in future)
You could keep them together in those battery carrier/protector/ case things - These.
Simple but effective, rubber bands round them.
Paper labels on each of the pair.
i have engraved numbers on the tail cap fo some of my non protected cells. with one of those electric engravers.
I like to label my eneloops on the white top of the cell with a fine permanent marker. The positive button keeps it from getting worn off very quickly.
Other options include more shrinkwrap and attached labels, but i tend to just write a a few times on each cell with marker and refresh it as needed. Redundancy helps since it won’t all get worn off at the same time 
+1
you don’t find this accelerates the peeling off of the label?
I engraved only the bare metal contact part.
I use the Brother PT80 label printer to create labels
Most permanent marker are long lasting only on fabric. There are specialized markers for plastic.
Here are a few examples: ( I am not advocating these links or sellers, I am merely showing you whats out there )
All-Weather Plastic Tag Marker link
or gold or silver.
Pilot Super Color Gold and Silver Marker Pens link
I am sure you can purchase something similar locally. Many office supply or art stores have them.
Re-wrap the cells with clear heat-shrink with a new label under the heat-shrink.
I use different coloured Sharpies to draw a circle/half circle around the white top. You only need a few colours to mark up several sets.
I have taken to writing where I bought it and the date, numbering 1, 2, 3 etc or 1,2 if paired up then covering that with 2” wide clear packing tape. The packing tape is strong, won’t peel off easily and is thin enough to not hamper the cells going into the battery tube.
I tried clear shrink wrap and in many cases that additional layer made the cell to big to fit in the light. I am also going to start putting a very clear solid + in Red at the top in 4 places around the diameter before taping to aid in placing the cell in the charger. For some reason panasonic has labeled their cells in such a way that they appear to be backwards, doesn’t seem intuitive. And Samsung 20R’s are not quick to identify positive pole at a glance. I need help with a positive identifier to ensure I don’t mess up. Get in a hurry sometimes, although I’ve been good about not hurrying so far where the cells are concerned, only inverted one in the charger once. But what can it hurt to have a nice solid red + identifying the positive end?
CD/DVD markers would be the same I would guess???
I use a label maker too. It provides legible text, plenty of characters which is important with all the cells I have, and comes off cleanly. The only problem is it comes off too easily, especially the top clear layer. I have to remember to press down the label again occasionally.
Additional battery info goes into a spreadsheet. I'll need that spreadsheet soon to match sets of cells.
I do the same as these guys, you can put a lot of info on a small label if you use a small font or just match cells by numbers, letters, or a combo.
I do basically the same except I use regular scotch tape. Haven’t had any issues with the tape coming off.
Very simple. Permanent marker + clear tape on top.
Cheap, widely available, quick, and simply works. My labelling last for years, and not even showing much signs of fading.
I use my wife’s nail polish. She has more colors than I have batteries and I have a lot of batteries.
Yeah, but what do you use to mark the batteries.
Dangit now the cat is out of the bag. :bigsmile: