Battery charging profile specifies only one setpoint

[NicaSol]

Landed in Solar Panel Talk while searching for battery setpoint charging profiles.

I live in Nicaragua and had to replace my batteries recently. Given the political situation in Nicaragua and resulting economic embargoes, the only batteries available were Ritar lead carbon AGMs (DC12-200C). According to the vendor, and Ritar's spec sheet, they are "well" suited to cycle use.

What led to my inquiry is a change in the charging profiles over two spec sheets for the same battery. The spec sheet provided by the vendor (from 2017, V17A-0; link= http://www.ritarpower.com/upimg/20171023205635821.pdf ) lists both a "cycle use voltage" (adsorption?) and a "float charging voltage" setpoint.

Float Charging Voltage 13.6V-13.8V @25C Temp Comp -3mV/C/cell
Cycle Use Voltage 14.6V-14.8V @25C Temp Comp -4mV/C/cell

Although a setpoint range is specified in Ritar's spec sheet, my vendor recommended 14.4 for bulk/absorption and 13.7 for float.

When a friend asked about the batteries I retrieved the spec sheet and noticed it had changed. The 2019 version (V19B-0; link= http://www.ritarpower.com/upimg/20191230111910838.pdf ) had only one setpoint, "cycle use voltage";

Cycle Use Voltage 13.8V-14.0V @25C Temp Comp -4mV/C/cell

and the following text added to the description:

"It is specially designed for daily heavy cyclic discharge use with feature low boost charge voltage, it should not be used under float charge, it must be charged and discharged daily for cyclic use. Especially suitable for the application of PSOC."

The vendor doesn't understand the change and Ritar hasn't returned my inquires for nearly two weeks. If forum members can shed some insight about the change and why just one setpoint (and so different) I would greatly appreciate hearing from you. Given where I live a forum such as this the only expertise I have access to. Thanks in advance.

[Mike90250]

The voltage will be dependent on both:

how deeply you cycle the battery
how long you are able to recharge.

You have to develop a seasonal protocol for insuring the batteries get fully charged at least 3x a week, This prevents sulfation. If the days are short and cloudy, you need to charge at higher voltage to push more watts into the batteries before you loose sunlight, or you become forced to burn generator fuel.

Since you have sealed batteries, counting amps Out vs In, and correlating that with battery voltage, you can develop a pretty good charge chart for your individual system.
Sealed batteries are VERY sensitive to any overcharge. They will vent excess gas, that once vented, means you have lost electrolyte that can never be replaced.

When new, the batteries will be 95% recharge efficient, and when aged and about to die, this falls to about 80%. Treated well, they should last 3-5 years. Abused, they can last 1-2 years.
So if you can find a totalizing battery meter to count amps in vs out, you will be on your way to being able to intelligently monitor your system

[NicaSol]

Thanks Mike about the use of a totalizing battery meter. The batteries are cycled max to about 65-70% SoC. We have a good 5 hours of sun (maybe 5.5-6.0 depending on cloud cover) pretty well all year. I've quite happily and successfully used two sets of FLA batteries (Trojan t-105s and L-16s) over the last 14-15ish years. AGMs are new to me, and my only option.

About the setpoints though, any thoughts on the change from specifying two; a cycle use (14.6V-14.8V) and float (13.6V-13.8V) to just a cycle use of a considerably lower range (13.8V-14.0V) for the same battery? Also, I'm not familiar with the term cycle use; is that the same as bulk/absorb? Could this be a precaution against over charging as you mentioned? 14.0 seems low compared to what I've read for other AGM brands.

[Mike90250]

This is the sort of thing that experience teaches you . How much to charge after such and such a discharge If you have enough sun & solar in the forecast, you can use the microwave

but don't be this guy

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