I got the charger number by glancing at the manual, which I have as a PDF in my "manuals" folder.

For the purchase dates for the 1st generation batteries I simply remembered that I bought them at Circuit City and that it was at least a few months before Circuit City went out of business, so a quick Googling gavee me that it was in 2008 or earlier.

For the 4th generation batteries I bought them at Amazon so simply have to type "eneloop" in the purchase history search and it shows me.

The charger includes a "Refresh & Analyze Mode" that rechargers the battery, rests for one hour, discharges the battery (and notes the capacity), rests for one hour, and the recharges the battery.

They recommend doing this every 10 cycles. I don't strictly follow that schedule, but I do occasionally do a refresh/analyze to see if a battery has degraded and needs to be retired. And so I have a spreadsheet to record the last refresh/analyze and the result.

Here's what columns are in that spreadsheet:

Number: I've written a number on each battery with a Sharpie so I can tell them apart.

Bin: when a battery is not in use or in the charger, it is in a small numbered storage bin. This is the number of that bin.

R/A: the date of the last refresh/analyze.

Years ago: a computed column that is simply the difference between now and the R/A date, in years

Capacity: the capacity found during the last R/A.

Prior Capacity: the capacity found during the previous R/A, so I can see if it has gone down much.

Total cycles: how many times I've charged the battery.

Cycles before last R/A: how many times the batter was charged before the most recent R/A.

Location: what the battery is in, if it is not in the charger or its assigned bin. Example values are "bathroom scale" and "TV remote".

Date deployed: if the battery is in a device this is the date it went in. Blank if it is not in use.

Days in use: the difference between the current date and the date deployed column, in days.

Charged: for batteries in their bins this is the date they were last charge.

Ago: Difference in days between now and the date in the "Charged" column.

That sounds like it might take a lot of work, but it doesn't. Let's say the batteries are getting weak in the TV remote, which uses two AA batteries. I take a quick look at the spreadsheet, looking at the "Charged", "Ago", and "Capacity" columns to pick a couple of batteries that aren't too far apart in capacity, and were last charged not too far apart. I enter "TV remote" and today's date in their "Location" and "Date deployed" columns, and clear their "Charged" columns, and go put them in the remote. (If the remote's batteries are still good enough that I don't actually need to change them immediately I might first put the replacements in the charger to top them up).

For the batteries that come out of the remote I clear their "Location" and "Date deployed" columns, add one to the "Total cycles" column, and stick them in the charger.

When I noticed they are fully charged, I put the date in the "Charged" column, and put them in their bins.

I've got some other things on the battery spreadsheet not directly concerning rechargeable batteries.

For some devices I track battery life. That too is pretty simple. Each such device has a table that consists of two columns:

Date: the date of a battery change

"Used For" or "Years Used": how long those batteries lasted. For the last row in the table, that is how long the batteries have been in use so far. For any prior rows it is how long it was until the next battery change. "Used For" if in days, "Years Used" if in years.

For these tables they have a label above with the name of the device, and a subheader saying what kind of battery they take. For example here is the table for my car:

2006 Honda CR-V
group size 51R
---------------
Date
2013-12-08 4.0
2017-12-23 5.6

There are also tables for my iPhone and iPad where I record battery life/health information as reported by CoconutBattery. Every few months I'll plug those into my Mac and check them.

For example I can see from the iPhone X's table that it had 100% capacity when I bought it on 2018-07-03. By 2021-04-30 it was down to 96.3% and had 189 cycles. By 2022-12-19 it was down to 92.2% and had 299 cycles. I then had the battery replaced, and after that on 2022-12-21 it was at 102.0% (!) and 0 cycles.

Finally, for things that use batteries that are not AA or AAA or car batteries or UPS batteries I have a section that simply lists which device uses which battery type. For example I can see from this that I have these things that use CR2032: HP-15C Limited Edition, Casio FX-702P, guitar case humidity meter, an old tuner that I don't use anymore, and the remotes for my garage door openers.

This comes in handy when buying new things. Suppose I'm deciding between two things and see that one uses a CR2032 and one uses a CR2020. A glance at my spreadsheet tells me that the only thing I currently have that takes CR2020 is an old Casio watch. Since I haven't used that watch in decades, but do have things I currently use that use CR2032 (humidity meter, garage door openers, and occasionally the HP-15C) that will be a point in favor of getting the device that uses the CR2032.