How old is too old for a new battery?

[crayiii]

I'm in Martinique and would like to buy 4 new 6v AGM batteries but the only ones I can find have been in the store for about 6 months. Is that too old?

[Pete7]

The better batteries like Rolls and Trojan will have a date of manufacture (DOM) or date code on them which is really what you want to know. After all how long did they take to get to the island from China or the US?

I sent a pair of Rolls back in the Spring because the layer of dust suggested no maintenance and the date stamped in the case said there were 20 months old. Just not acceptable for the price they were charging. Replaced with Trojans at 6 months old, clean and fully charged from another supplier.

Pete

[crayiii]

These are Mastervolt 6v 400ah. I'll go back to look for the manufacturer date but how old is too old?

[john61ct]

I'd rather have a top quality maker six months older than the common stuff.

Even longer is fine if they've been topped up periodically.

Only way to really tell is a capacity test, within 10% of rated Ah is a normal starting point for most, even quality lead brands.

Sometimes you just have accept what's available.

Do some proper commissioning cycle's, go easy during the breaking in period, you might end up with longer life than fresh off the factory floor without those steps.

And ongoing care practices have 10x the impact, makes all of these other issues seem minor.

[verb88]

load test them... or ask the vendor to, if you have not purchased yet

[Scubaseas]

What john61ct said.



AGMs have a very low self discharge rate. 6 months old should be OK but the best way to tell is with a capacitance style tester. Even at 1 year old AGM should be fine s long as the battery tests out OK.

[john61ct]

The context for my remarks, is compared to what else is available for sale in that location.

In a more competitive market, I'd go to a fair bit of trouble to find fresher inventory, or a dealer who has been diligent keeping inventory topped up to 100% Full at least monthly.

I think it is a crime not to do so, definitely reduces the batteries' lifespan.

Just that in a remote/primitive location, likely forced to choose the lesser evil.

[GordMay]

An AGM battery, when left unattended, should only discharge at a rate of 1% to 3% per month (when stored at 20°C); and even after 6 months sitting idle, can be recharged and put back to a full charge.
A normal wet cell battery discharges at a rate of up to 4% per week.
Lower temp = lower discharge. Higher temp = higher discharge (The self-discharge doubles for every increase in temperature by 10°C.).

[john61ct]

Yes but with any lead chemistry, sitting for an extended time, at **any** SoC lower than true 100% Full, will cause reduced longevity.

Even 98%, if it's for a couple of months, will have a measurable impact.

The longer the time, the lower the SoC, the more significant the "damage".

So, yes, normal practice is poor in normal distribution channels, especially low-volume locations where the retail outlet is overseas and far from the factory.

Not trying to overstate the problem either though, in such places beggars can't be choosers, and as I stated, better an older top-quality battery than a fresh example of an ordinary mediocre one.

[KTP]

AGM you want to sit at 100% and Lithium you want to sit at 30%

[boatpoker]

Batteries sit in frozen boats, uncharged here in Ontario for 6 months every year. Don't recall noticing a difference in longevity over our southern cousins.

[KTP]

Frozen is actually really really good for a AGM, as long as it was fully charged before being subjected to the cold.

The lifetime of a AGM (and most Lithium) is directly related to the temperature it is stored and operated in.

You don't get as much energy out of the battery when it is cold, but it doesn't degrade nearly as fast.

[KTP]

From the Lifeline technical manual:

"Batteries should be stored in the coolest environment available, preferably not exceeding 68 degrees F. The higher the temperature the faster the battery will self discharge and require boost charging. See Appendix C for data on storage time vs temperature."

Six months at something like 20 degrees F is probably about the same self-discharge as two months at 80 degrees F.

[GordMay]

Originally Posted by KTP

From the Lifeline technical manual*:

"Batteries should be stored in the coolest environment available, preferably not exceeding 68 degrees F. The higher the temperature the faster the battery will self discharge and require boost charging. See Appendix C for data on storage time vs temperature."
Six months at something like 20 degrees F is probably about the same self-discharge as two months at 80 degrees F.

Indeed.
http://lifelinebatteries.com/wp-cont...cal-Manual.pdf

Originally Posted by GordMay

An AGM battery ...
Lower temp = lower discharge. Higher temp = higher discharge (The self-discharge doubles for every increase in temperature by 10°C.).