AGM's only reading 12.4 v

[hellosailor]

Eh, guys?
Unless Rick has LIFELINE BRAND AGMs, he cannot and must not follow their procedure for equalizing the batteries. Lifeline apparently builds their product differently and every other AGM naufacturer I have spoken with has emphatically said DO NOT EQUALIZE THEIR BRAND because you will outgas the battery, perhaps warp it, and certainly damage it.

As for 3-stage charging, bear in mind there are now MORE SOPHISTICATED charging routines, such as the continuously varying ones used by MPPT controllers, which lead voltage by a small amount and then push the rest as amperage. (Subject to thermal sensing and other limiting.) Some fairly respected vendors--like Johnson Controls (JCI) have siad outright that 3-stage charging is now obsolete and the microprocessor controlled chargers will do a better job, faster. #-stage is now the equivalent of "good Dacron sails". You can do worse--but you can also do better.

[Sandero]

The wierdness around battery charging theories is getting old. One would think that these engineers could figure this out in theory and then bench test it.

I got my AGMs about 4 or 5 years ago and I would have thought that the company that manufactured them had designed them based on some sort of "science" or engineering data. And these folks should have a good idea of how they perform behave in real world situations like "loads" and charging.

Admittedly "real world" can produce some unusual conditions, but one would think that for "normal" use "they" would recommend and know the optimal way to charge their batteries.

So some EE's come along with a new gizmo/protocol and it makes everything old world charming.

yea right.

Will an EE who knows something about this please stand up.

[wallandj]

A couple of other thoughts:

Using open circuit voltage to determine state of charge is very error prone. Its better than nothing but that's about it. Using it determine the condition of the battery is probably not much better. The battery must be truly open circuit for at least 24 hours and not under any load when the measurement is taken.

You didn't mention the temperature under which the measurement was made (the 12.6V, that is). I have no data but I would suspect that all this is temperature dependent i.e. 12.6V at 0 degrees C might be pretty close to fully charged. We are talking electrochemistry here...

You might also check your charger's output voltages to see if they conform to those the fellow above quoted.

Good luck.

Dave
Tartan-372

[Sandero]

My batts are always in business since they are powering the S2a and the bilge pump and the radio memory circuits and the Link20. Frankly I don't have much cofidence in the accuracy of the Link20, but I don't know what would be better.