Lifeline AGM 8d's, where is the date code? Load testing 8d's

[cattledog]

Hey guys,
I have two starter banks, each with two Lifeline AGM 8d batteries for a total of 4 of these beasts on board. The batteries sit in fiberglass boxes so I can only see the top of each 8d.

Curious - does anyone know where the date codes are stamped on Lifeline 8d's? I think these batteries were all installed at least prior to 2010 and I would like to know how old they are. I can't see the sides or the bottoms of the batteries without lifting them out.

I hit each 8d (separately) with two 10 second 300 Amp loads with my tester this morning. Holy crap the tester was BURNING hot after I was done with the 4th battery. Anyhow, these batteries are older for sure but seemed to load test just fine. None of them dropped below 11 volts while under load and they all returned to a resting voltage of 12.8-12.9 after testing. I used the 500 amp load tester from Harbor Freight for my testing and it seemed work well - much nicer than the smaller 100 amp tester they sell.

Does my testing sound reasonable in terms of a health check? Each bank spins the 8v71ti it serves with authority but I know my banks are maybe a bit oversized so I thought the individual batteries should still be checked.

Chris

[Boatsb]

I'd get a battery analyzer and see if they check out on it but 5 years is not old for lifelines. I'm not sure where the date code was put. It's usually put on by the installer but there is a possibility that there is a manufacturing date somewhere too.

[cattledog]

Pretty sure the batteries were installed before 2010, how far prior to then I am not sure. I have one of the digital battery analyzers from Harbor Freight as well - I can give that a try as well. I have an easier time trusting the carbon pile analyzer because you can see it actually working the battery as it gets red hot lol, something genuine about that vs the "computerized tester thing."

[Boatsb]

I have a $300 analyzer not from harbor freight to test batteries. I'm not sure I'd trust chinaman on the cheap analyzer.

[bigbill]

is there a sticker with a letter followed by a number on the side of the batteries? they use this on automotive batteries. a-3 would be jan. of2013...d-15 would be april of 2015 the letter is the month and the number is the year

[cattledog]

Thanks guys.

I will have a friend come over and help me pull one of these monsters out so I can look for a date code label. I guess asking where the label is was silly, one will need to come out no matter what! Annoying that they don't put a date code label on the top of these things.

Chris