Absolutely loved SunKing's Charge=Float=Absorb

[Roberto2]

But, I have a Bank of 4x AGM's and can absolutely not determine SoC of the Bank.

For nearly a week now, I have measured the Rest-Voltage to be above 13.2 Volt of the Bank.

I am very scared to overcharge, and was hoping someone could tell me that if I keep the Voltage to 14.8 for Charge , 14.5 for Float and 14.5 for Equalize,>> If I will end up Overcharging?

Kind regards here from South Africa
Rob

[Mike90250]

You have to follow your battery Mfg's charging regime. Different brands have different voltages and dwell times. Sorry i can't be of more help. Maybe someone else will chime in,

[Roberto2]

You have to follow your battery Mfg's charging regime. Different brands have different voltages and dwell times. Sorry i can't be of more help. Maybe someone else will chime in,

Thank you kindly for your reply Mike.

AGM's have a Float of between 13.2 and 13.8 .....a Charge(Absorption) of between 14.25 and 14.9

From what I have read AGM's are not to be Equalized and therefore I set the equalize setting of my controller to the same voltage as the Float setting.

So, the voltages are not of a concern to me, but what is my concern, is whether keeping the settings on the controller for days on end and not using the battery bank, whether this will lead to overcharge.

Here are my settings again>>14.8 for Charge(Absorption) , 14.5 for Float and 14.5 for Equalize

Thanks
Rob

[GeorgeF]

I've asked before about charging in offgrid situation. Short & to the point answered by "Internet dog".

IMO, if you are not using your batteries for days, perhaps you better can float @ lowest float voltage as per specs of your battery after FSOC.

[Mike90250]

AGM sometimes have 2 duty ratings : Cycle and Float

Cycle would be daily usage, and the higher voltages are used to insure a good charge for the next day

Float is like the light in an EXIT sign, and those applications use the lower voltage to not overcharge the battery while it sits full

Only you can decide which "blend" of voltage to use, how many days it sits without usage. I'd say anything over 4 days with no usage, I'd use the lower Float settings

[Roberto2]

I've asked before about charging in offgrid situation. Short & to the point answered by "Internet dog".

IMO, if you are not using your batteries for days, perhaps you better can float @ lowest float voltage as per specs of your battery after FSOC.

Thanks for the immage info George. So, basically if I am using the Bank , then I should ...>>> 14.8 for Charge(Absorption) , 14.5 for Float and 14.5 for Equalize

Thus , If I am not using the bank, I should 14.8 for Charge(Absorption) , 13.8 for Float and 13.8 for Equalize

[Roberto2]

AGM sometimes have 2 duty ratings : Cycle and Float

Cycle would be daily usage, and the higher voltages are used to insure a good charge for the next day

Float is like the light in an EXIT sign, and those applications use the lower voltage to not overcharge the battery while it sits full

Only you can decide which "blend" of voltage to use, how many days it sits without usage. I'd say anything over 4 days with no usage, I'd use the lower Float settings

Mike, Yes thanks for the exit sign explanation, it makes sense.

What I can not understand is, why understanding is so difficult

Hey, bye the way, (changing the subject a little), best of luck to you guys with the Great reset. Ours if fully underway, here in South Africa.

Shalom to ya all.

[GeorgeF]

AGM sometimes have 2 duty ratings : Cycle and Float[B]

.....

Only you can decide which "blend" of voltage to use, how many days it sits without usage. I'd say anything over 4 days with no usage, I'd use the lower Float settings

Mike,
Lets take this Rolls example:
someone chooses for "bulk absorbtion" @ 14.88v in a tropical country and a huge Rolls bank for for example mini-grid with a lot of mppt , daily cycling, its better NOT to float with lower float-voltage. No difference to follow the Rolls setpoint between a huge bank vs a tiny bank for SHS at home and you only "true float" if you dont use the battery bank for days, right?

[Roberto2]

Mike, I use the AGM table for charging. Here in South Africa my ambient temp is roughly 20celcious

AGM Charging.jpg

After a day's charging the bar-graph on my controller shows +- 30% State of charge. This is after more or less a full week of no/non use of the bank, and this is my concern.

Although the fully rested test in the morning is 13.2 to 13.3 volt.

[GeorgeF]

13.2v - 13.3v open circuit voltage is I think "full state of charge (FSOC). After reaching the charge-setpoint of 14.88+ and when resting ofcourse the voltage will go down.

[Mike90250]

I don't bother with ambient temp, because the controller is programmed to adjust the voltage according to the Battery Temp Sensor. That's a must have !

And the controller seldom has enough brains to actually know the true state of charge of the battery. You do better with the factory voltage chart and a thermometer.