Bad Battery Out of the Box -- Tests Good???

btrayfors · #1 (**permalink**) 01-18-2012

I ran across something very puzzling today...something I've never seen before.

Yesterday, I purchased a new little AGM battery from West Marine. It's to replace the AGM battery in my dingy which just gave up the ghost after 3 years of service (bilge pump, fathometer, lights). A small solar panel keeps it charged.

The new battery is a SeaVolt Deep Cycle AGM32.... 32AH @ the 20-hr rate and 240 MCA.

Brought it home, put it on the bench, intended to test it and fully charge it before putting it in the dingy.

It tested as follows:

12.44 volts resting and 411 MCA (with a Midtronics MDX-650 tester).

That made sense because new AGMs always test way more than their rating with this tester.

I assumed this was a good battery which just needed charging. And, in fact, the Midtronics tester message was: "Good battery. Needs a full charge."

So I stuck it on a 30A smart charger. Almost immediately the charger beeped, said it was FULL, and gave me an error message that the battery would not take a proper charging current. Indeed, it only took about 2 amps maximum for a couple of seconds. This battery should easily take 30 amps or more.

After fooling with the smart charger settings awhile, and verifying that the charger was operating correctly by testing it on another battery bank, I hooked up a second charger. Same thing: the new AGM wouldn't take a charge. I measured only about 1.2A charging current with 14.6 volts input.

An hour later I measured the resting voltage at 12.4VDC.

So...here's a brand new AGM which tests very good but won't take a charge.

Anyone ever seen this before?

Rick? Brian? Maine? (maybe this is why you and I don't like AGM's :-)

PS>>> it goes back to WM tomorrow :-)

Bill

Maine Sail · #2 (**permalink**) 01-18-2012

Quote:

Originally Posted by btrayfors

I ran across something very puzzling today...something I've never seen before.

Yesterday, I purchased a new little AGM battery from West Marine. It's to replace the AGM battery in my dingy which just gave up the ghost after 3 years of service (bilge pump, fathometer, lights). A small solar panel keeps it charged.

Ah AGMitus.... Know it well..

Quote:

Originally Posted by btrayfors

The new battery is a SeaVolt Deep Cycle AGM32.... 32AH @ the 20-hr rate and 240 MCA.

Brought it home, put it on the bench, intended to test it and fully charge it before putting it in the dingy.

It tested as follows:

12.44 volts resting and 411 MCA (with a Midtronics MDX-650 tester).

That made sense because new AGMs always test way more than their rating with this tester.

I assumed this was a good battery which just needed charging. And, in fact, the Midtronics tester message was: "Good battery. Needs a full charge."

So I stuck it on a 30A smart charger. Almost immediately the charger beeped, said it was FULL, and gave me an error message that the battery would not take a proper charging current. Indeed, it only took about 2 amps maximum for a couple of seconds. This battery should easily take 30 amps or more.

After fooling with the smart charger settings awhile, and verifying that the charger was operating correctly by testing it on another battery bank, I hooked up a second charger. Same thing: the new AGM wouldn't take a charge. I measured only about 1.2A charging current with 14.6 volts input.

An hour later I measured the resting voltage at 12.4VDC.

So...here's a brand new AGM which tests very good but won't take a charge.

Anyone ever seen this before?

Rick? Brian? Maine? (maybe this is why you and I don't like AGM's :-)

PS>>> it goes back to WM tomorrow :-)

Bill

Bill,

I saw this once with a GEL battery. We hit it with a carbon pile a few times, at 50% of CCA, and it started taking current. Did you try and hit it will a good load? We still returned that battery so have no clue what the outcome was.

AGM's can do funny things.... BTW the SeaVolt batteries are generally Deka/East Penn and the same batteries are now sold at Sam's Club under the Duracell brand for about HALF the price of West Marine.. Don't think they have the small AGM but they do have the group 31's AGM, 6V, 24, 27 & 31's in wet as well as a 12V golf cart battery which is quite cool.

erps · #3 (**permalink**) 01-18-2012

Well, since we're talking about strange things with batteries, I had something good happen to my bank that I can't explain.

House bank made up of 2 volt cells, six in series around 600 ah. Age, around 15 years old. Since we've had the boat, I've never seen more than 12.45 resting volts out of the bank, even after equalizations, it keeps dropping down to around 12.45. I've measure each cell separately to see if there is voltage drop somewhere and found that the individual cells add up to the same 12.45 volts or so. I'm still able to pull a couple hundred amps out of them no problem, so I figured I wouldn't worry about anymore until they get worse.

So the other day I go down and check the voltage after they have been sitting a week, and found that they measured 12.70 volts. I turned on a couple of lights and they dropped down to 12.65 volts with a small load.

So has anyone ever seen batteries resurrect themselves?

jrd22 · #4 (**permalink**) 01-18-2012

Ray- probably just karma catching up with you for being so patient and polite over in Off Topic:-))

mitiempo · #5 (**permalink**) 01-18-2012

Bill

I am not a fan of AGM's or West Marine.

btrayfors · #6 (**permalink**) 01-18-2012

Maine...

Thanks for the info on the faulty gel. No, I haven't tried any heroics yet with this little AGM, and won't. I'll just exchange it, and take my tester along.

Brian...

I understand your comment about WM but don't forget: WM has a price matching policy, i.e., they'll match any price. They also carry the DuraCell-labeled AGM's and will match Sam's Club or anyone else's prices. That's not bad.

Even better, they have a no questions asked exchange policy, and lots of retail outlets around the country. Convenience is worth something, IMHO :-)

Thanks, guys.

Bill

mitiempo · #7 (**permalink**) 01-18-2012

True, but in Victoria WM is the store everybody ignores. There is a local store that has been around for decades that has long term staff that are experienced as well as excellent pricing - Trotac Marine.

WM would only match another Canadian price here anyway. The Canadian end of WM is not on par with the US operation as far as I can tell.

mdbee · #8 (**permalink**) 01-21-2012

Common issue. The charger is being fooled by a very low battery. Hook another charged battery to the new battery. Positive to positive, negative to negative. Now hook up your charger.

more info:http://www.optimabatteries.com/produ...agmbattery.php

PS: don't blame AGM's - just need to learn the differences in them.

mitiempo · #9 (**permalink**) 01-21-2012

12.4 isn't a very low battery - actually about 70% SOC.

donradclife · #10 (**permalink**) 01-22-2012

Quote:

Originally Posted by mdbee

Common issue. The charger is being fooled by a very low battery. Hook another charged battery to the new battery. Positive to positive, negative to negative. Now hook up your charger.

more info:Optima Product Support : Tech Tips

PS: don't blame AGM's - just need to learn the differences in them.

Gotta blame the battery here--Bill knows what he is doing and measured 14.6 volts at the battery, which means the charger is putting out.