This post contains a breakdown of maintenance free, gel and lead acid motorbike battery part numbers.
The motorcycle battery part numbers are commonly used examples of motorcycle battery part numbers with a brief explanation of what the letters and numbers mean.

Vintage Bicycle Serial Number Database
Bicycle Serial Number Search

Maintenance free batteries

Schwinn Bike Dating After 1965, Schwinn serial number sequences, while appearing to be confusing on first sight, follow several general rules. If the first letter is a 'A' through 'M' it refers to production month ('A' = January, 'B' = February, etc.). The letters 'I' and 'O' are not used, to avoid mistaking them for numbers. You’ll probably use the French system for road wheels and call your wheel a 700c. Under the ERTO system, your wheel is actually 622 mm. 622 is also the same as a mountain bike 29” rim. Mountain bikes generally use inches instead when talking about a wheel and tire size. The bike I'm looking to find the year on didn't have the same color schemes on bikepedia or anywhere on the internet for that matter. I'll post a pic on a new thread and maybe so of you guys would know. Also does Cannondale only make one color pattern per bike model?

Battery reference (YTX12-BS)	What the reference means
Y	Manufacturers mark, different manufacturers use different letters
T	Manufacturers mark, different manufacturers use different letters
X	High performance battery
12	Indication of performance level of battery (lower numbers equal lower power output)
–
B	Type of terminal or supplied with acid bottle
S	Sealed battery or supplied with acid bottle

Battery reference (YTX14L-BS)	What the reference means
Y	Manufacturers mark, different manufacturers use different letters
T	Manufacturers mark, different manufacturers use different letters
X	High performance battery
14	Indication of performance level of battery (lower numbers equal lower power output)
L	Polarity location (which way round the terminals go)
–
B	Type of terminal or supplied with acid bottle
S	Sealed battery or supplied with acid bottle

Gel filled batteries

Battery reference (YTZ12-S)	What the reference means
Y	Manufacturers mark, different manufacturers use different letters
T	Manufacturers mark, different manufacturers use different letters
Z	High performance battery
12	Indication of performance level of battery (lower numbers equal lower power output)
–
S	Polarity location (which way round the terminals go) and configuration

Battery reference (YT7B-4)	What the reference means
Y	Manufacturers mark, different manufacturers use different letters
T	Manufacturers mark, different manufacturers use different letters
7	Indication of performance level of battery (lower numbers equal lower power output)
B
–
4	Polarity location (which way round the terminals go) and configuration

Battery reference (YT7B-BS)	What the reference means
Y	Manufacturers mark, different manufacturers use different letters
T	Manufacturers mark, different manufacturers use different letters
7	Indication of performance level of battery (lower numbers equal lower power output)
B
–
B	Type of terminal or supplied with acid bottle
S	Sealed battery or supplied with acid bottle

12 Volt lead acid batteries

Battery reference (YB16AL-A2)	What the reference means
YB	Manufacturers mark, different manufacturers use different letters
16	Indication of performance level of battery (lower numbers equal lower power output)
A	Indicates a different size of the same capacity battery
L	Polarity location
–
A	Location of the opening for the venting exhaust
2	Type of terminal

Battery reference (Y50-N18L-A2)	What the reference means
Y	Manufacturers mark, different manufacturers use different letters
50	Cranking or starting power (higher number means more power)
–
N	Vented type battery
18	Indication of performance level of battery (lower numbers equal lower power output)
L	Polarity location
–
A	Location of the opening for the venting exhaust
2	Type of terminal

Battery reference (12N12A-4A-1)	What the reference means
12	Battery voltage
N	Vented type battery
12	Battery capacity at a 10 hour rate
A	Indicates a different size of the same capacity battery
–
4	Polarity location
A	Location of the opening for the venting exhaust
–
1	Type of terminal

6 Volt lead acid batteries

Battery reference (6N2-2A-1)	What the reference means
6	Battery voltage
N	Vented type battery
2	Battery capacity at a 10 hour rate
–
2	Polarity location
A	Location of the opening for the venting exhaust
–
8	Type of terminal

Disclaimers:
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What Does A Bicycle Serial Number Mean