Determining SOC

[zingarofunkart]

My small system is up and running but ive had difficulties determining SOC of my battery. A volt meter is out as the surface charge exist. Ive just got my smart charger but I don't know if I should use it on my smaller 6 v 12 ah batts wired to 12 v. The 6 amp charger works great on the 28 ah agm but again I have difficulties determining the STATE OF CHARGE.

My system is 2 Duracell 27dc wetcells, 2 28 ah agm and 12 6v 12 ah wet cells wired for 12 v (these are portable and wired to 3 v led bulbs)
Discounting stuff over 3 yr old I have around $300 in the system so I would like to keep the cost less than 10%.
any ideas thx z

[dnix71]

SOC doesn't tell you much practical. Most AGM's have a range of float voltages that the maker considers acceptable. If you can charge to that voltage then your battery is "full."

If you get a Turnigy meter and a Kill-A-Watt meter you can measure what you are putting in and what you get out. When measuring what you get out stop the charger at "full" voltage and wait until the pack drops to 12.6v and see what the Turnigy says, then look again at 12.5v and then stop when you get to 12.4v Once you've done that you will know the real capacity of the pack.

12.4v is as low as you should go with an AGM on a regular basis. Some AGM's are name-plate rated going all the way to 10v or 11v, but that's for a one time sacrifice.