AGM question

Naio,

This question will not hyjack your discussion thread because no one knows what it is or cares ... but how is your little EX650 working out for you?

(Ours still starts right up and charges our two AGM RV batteries just fine. We used it again dry camping at Quartzsite this past January!)

Two answers:

The voltage under load depends on several things
1: The state of charge
2: The size of load
3: The condition of the battery (As batteries age the voltage under load drops)
4: The type of battery Note this is an 4A, 4B, in that "Starting" or Deep cycle, AGM or Flooded, all makes a difference)
5: the SiZE of the battery


And then there is this question: When was the last time your VOltmeter was calibrated? (how accurate is it I have a couple around here that are not much better than a light bulb (Does the needle move/light light).

Naio,

Thoroughly confused now?

Just charge the battery as you always do. Use it as you always do. Don't worry about it.

Life is meant to be enjoyed not agonize over a battery. :)

Voltage alone is about as "useful" as judging a woman's morality by the color of her eyelash liner.

Now in contrast to the critique...

An Amp Hour Meter will tell you "Where You're Really At". Guesswork is expensive. I can only wish my guesswork was good enough to eliminate the expense of an am hour meter. Maybe when Alzheimer's sets in, I can start "saving money".

RoyB wrote:
This is a handy voltage chart for batteries...

This chart is often posted here, but it should not be used by OP. This is flooded, while AGM (typically) have higher voltages. He should refer to his particular AGM battery specs.

It depends which AGM you have. For example mine are surplus acid so 50% is as deep as I wish to go. Starved acid run out of "working fluid" before discharging too far--but I'd still avoid "crashing" them.

Ignore the battery chart that was posted as that is for flooded lead acid technology.

An AGM may only be about 60% charged with a 12.6 resting Voltage. A 100% charged AGM is above 12.8 for sure and many, if not most, AGMs rest at 13 or above Volts.

HTH;
John

Sounds like a light load, and get used to not knowing much about the state of your battery. As niner said, unless you disconnect your batt and let it sit overnight and THEN test it, it isn't going to give you an absolute reading.

Instead, keep using your battery as you please, mindful of the ah rating and 20-hour rate of discharge it was designed for. Over time, when the battery fails to power as much stuff for as long as it used to, your battery is getting old. When the failure to hold a charge becomes a problem, it's time to replace the battery. This will typically be four years.

The OP has learned on this forum that the deeper the battery is discharged the sooner it will grow old. Also that the faster that the battery is discharged the sooner it will run out of charge (Peukert effect). I recommend the OP use and enjoy the battery!

GordonThree wrote:
12.41 sounds like a light load. Carry on, enjoy the ride :)

I would say exactly the opposite.

That much of a drop would indicate to me that there is a LARGE load for the size of the battery OR the battery is no longer up to it's designed capacity.

Not that a large load will hurt anything, mind you, but the voltage might drop to an unacceptable level fairly quickly.

Naio read up on the Puekert effect.