AGM Battery Charging THE PRIME DIRECTIVE

Smitty77 wrote:


Curious which Magnum you have that will show you the AH's going into the battery?

MS2812, at least as far as the Magnum Tech explained to me, does not give you the 'Charging Amps' going into the battery. It is the combination of AH's being consumed, and AH's going into the battery bank, that is displayed. (If your Shunt is seeing say 10 Amps of draw from the bank, and the Magnum Inverter/Charging is putting out 6 AMPS, the Magnum Remote display would reflect 16 Amps. It might also display on Line One of the display, that the battery is Absorb mode, where as the Line 2 should display the Voltage (Say 14.4V for this example.) that the Absorb is programmed to. Along with also on the Line 2, the Amps of '16A'.

I must have asked at least three different ways, was their anywhere with the ARC-50 Remote Display and the BMK-Meter option that I could see the actual Charge Amps, as in Taper Down to Amps, specially going into the Batter Bank. The end result was always, nope!!!

Hard to reach the appropriate fully charged Tapered Down Amp, when you have not display of this value:)!

Maybe I am not understanding correctly, the BMK Amps reading is the actual charge amps and is what the Magnum will use to determine done amps, from the manual:

Info: If DC loads are connected directly to the batteries and a Magnum battery monitor
is not installed, the Absorb Done Amps setting should not be used. To charge the
batteries—plus run the DC loads—the charger must increase the current delivered to
the battery bank. This may result in overcharging the batteries since the return amps
reading will be skewed by the DC loads.

Info: It is highly suggested that you install a battery monitor if the Absorb Done Amps
setting is used. If a battery monitor is not installed, the Absorb Done Amps setting
relies on the METER: 01B DC Amps value to determine when to transfer out of the
Absorption charge mode. This is the most accurate DC amperage measurement.

The BMK reading DC Amp BMK under BMK Meters is the value it will use and should be accurate regardless of DC loads so long as the shunt is installed correcty. If the charger is putting out 16A but the BMK says 10A then 12V loads are taking 6A. The main display will say 16A as that what the charger is putting out, but it should end absorb based on BMK reading.

Also absorb end based on SOC should do this for you so I am curious as to what it didn't do right, again from the manual:

The battery’s state of charge—which is the best indicator of the condition of the batteries—is
indicated on the METER: 05B Battery SOC display. This display shows that the batteries are fully
charged (i.e., SOC = 100%) once the following three conditions have been met:
1. The charging voltage has stabilized over a period of time (see Figure 8-1).
2. The charging current has decreased to a low % of the AHr capacity—normally less than 2%.
3. The AH that were removed from the battery are within 1% of fully being returned.

Its not very adjustable but on paper it seems to be doing the right thing, but setting absorb done to amps with a bmk installed should let you do Lifelines exact recommendation of:

A voltage setting of 14.3 volts ± 0.1 volts (7.15 ± 0.05 volt for a 6 volt battery) should be used when the battery temperature is 77°F (25°C). The battery is considered to be fully charged when the current drops below 0.5% of the battery’s rated capacity (0.5A for a 100Ah battery).