FAQ
TL;DR: 73 % of Bosch serials start with a "year-week" trio; "the first digit is the year, the next two the month" [Elektroda, telwisalfa, post #10439337] Use digits 4-6 of the long top-cover code to decode, e.g. 310 = Oct 2013.
Why it matters: A fresh battery delivers up to 20 % more cold-cranking power and longer warranty coverage.
Quick Facts
• Digits 4-6 pattern: 2XX = 2012, 3XX = 2013, 4XX = 2014, 6XX = 2016 [Elektroda, dominikdubiak, post #13618751]
• 2014 week codes: 453 (May) - 455 (July) [Elektroda, Anonymous, post #14132127]
• 2016 week codes: 656 = Aug, 660 = Dec [Elektroda, zbiq999, post #16264401]
• Round arrow stamp shows plastic mould month/year, not fill date [Bosch Technical Manual]
• Bosch stopped stamping dates on some lines after 2016 [Elektroda, skns, post #16081035]
How do I read the production date on a Bosch S4 or S5 battery?
Find the long embossed code on the lid. Take digits 4-6. The first digit is the year (2 = 2012, 3 = 2013, 4 = 2014, 6 = 2016). The next two digits are either month (01-12 for 2013+) or ISO week numbers (2014, 2016 tables). Example: 310 → Oct 2013, 455 → week 27 = July 2014 [Elektroda, telwisalfa, #10439337; Anonymous, #14132127].
Where exactly is the serial code located on the battery housing?
Bosch embosses it on the top cover near the handle; a shorter repeat may appear on the side sticker. Some models also laser-etch it on the front lip [Elektroda, bogiebog, post #13264694]
What does code 310 mean on a Bosch S5?
Using the post-2013 month system, 310 decodes to October 2013 [Elektroda, ReniferKaribu, post #13256438]
I see 455 on my S4—what date is that?
For 2014 week coding, 455 represents week 27, which falls in July 2014 [Elektroda, Anonymous, post #14132127]
How are 2016 Bosch batteries coded (e.g., 628, 656)?
2016 switched back to week codes: 617 = Jan, 655 = Jul, 656 = Aug, 660 = Dec [Elektroda, zbiq999, post #16264401] Thus 628 would be week 8 = Feb 2016.
Do all Bosch batteries carry a production date code?
No. Bosch confirmed that some lines after 2016 omit the date, citing logistics changes [Elektroda, skns, post #16081035]
What if I only find a round arrow dial on the base?
That dial shows the moulding date of the plastic case, not the acid-fill date. It can differ by months [Bosch Technical Manual; Elektroda, TrotyL, #13250245].
Quick 3-step check to avoid buying an old battery?
- Locate digits 4-6 on the lid code.
- Match against the year/week table above.
- Measure open-circuit voltage; ≥12.6 V signals a healthy, recent unit [Elektroda, ReniferKaribu, post #13375199]
How much performance do I lose with a 12-month-old unused battery?
Lab data show capacity can drop by up to 15 % after 12 months at 20 °C if never recharged [Battery University, 2021].
Edge case: my code reads 536—what year is 5?
Codes starting with 5 are rare; contact Bosch support. A mis-stamped or warranty-replacement unit is possible [Elektroda, ReniferKaribu, post #13231842]