Battery problems

[Hondaman]

I have a couple of sealed (AGM) batteries in UPS units. When the batteries fail the self tests (one is an APC UPS and one Conext), replace the batteries. Very simple.

I also have one in another application. It demands lots of power for starting, then the alternator replenishes it within a few minutes of riding (Yamaha V-Star Classic 650).

Will I get any notice when this thing fails? A week or so ago, a fellow with an AGM got stranded at the VFW hall after a charity poker run (I think it was a new, 2008-09 Indian, not an old 1998-99 model).

If mine fails,would taking it out and warming it up in my hands do anything? Should I get a replacement lined up now (original = 7 years old)?

Electrically, what's happening? When the AGM battery reaches EOL, do the chemicals decay the same or different than an old-school lead-acid battery? Any thoughts?

[Krankshaft]

Filled lead acid and SLA are pretty much the same except SLAs use a soaked (sulfuric acid) glass mat between the plates instead of the case being filled with sulfuric acid and the plates hung in there. Because of this SLAs are also known as starved lead acid batteries.

These glass mats act like a sponge holding the acid on them which is why these batteries are known as non-spill able. They are then sandwiched between the plates.

Over time lead acid batteries develop sulfation on the plates. Lead sulfation is a natural component of the discharge process. When the battery is recharged most of it is converted back. Over many charge and discharge cycles this sulfation layer grows larger on the plates and blocks the acids contact with the lead reducing the batteries capacity. This process is accelerated dramatically if you let the battery fully discharge and leave it that way.

That's why all SLAs in storage should be recharged regularly or trickle charged constantly.

However even if you leave the battery fully charged the sulfation process still occurs. Also independent of these factors a lead acid batteries lifespan is also reduced by ambient temperature hotter temps = shorter life.

While an SLA may still function beyond the average lifespan it's capacity (the amperage it can put out) will have dropped significantly.

[Krankshaft]

The best way to test your battery to see if it needs to be replaced is to use a load tester.

It's simply a resistive element in a box connected to a volt gauge. When the load (the resistor) is connected to the battery it draws a certain amount of current determined by the resistor. During this process the battery voltage will drop if that voltage drop which you read on the gauge is in line with the batteries capacity rating at that current then the battery is ok.

In other words if the battery can provide a certain amount of current (usually the max current from the starter) and the voltage drop is within parameters it's ok.

[Junk Parts]

The parts store I deal with has a computerized load tester. Its great in that it doesn't kill the battery during the test. It measures such things as internal resistance, current and voltage...ect. There should be a lable on the top of the battery listing CCA and voltage. These specs are punched into the tester befor the test. In just 30 seconds the tester will tell you if the battery is over the hill. I think the rule is when a batery CCA declines by 20% or is it 30% its time for a new battery. Good luck! I'm on year five with my big redtop in the car. It was stored for a year dead flat and since has been run flat four or five times by us because of various charging system and leaving the lights on failures. Its still working but it just may pass away this coming winter.

[Krankshaft]

Those electronic testers use whats called a conductance test and don't actually put a load on the battery. As sulfation builds up since it's a good insulator conductance between the plates goes down. The tester checks this against the CCA you enter into it and issues a pass / fail.

I'm still skeptical about their reliability especially in borderline situations.