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Old 05-29-2016, 04:57 PM
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Default Battery tech: AGM vs AGM+

I bought a NOCO Genius G7200 battery charger, which has 2 AGM modes in addition to the mode for regular car batteries.

12V Norm: 14.5V
12V COLD/AGM: 14.8V
12V AGM+: 15.6V

Battery manual says "AGM+ charge mode is designed for 12-volt advanced AGM batteries only. These are a new battery technology typically found in start-stop micro-hybrid vehicles. These batteries accept a higher than normal charging voltage around 15.5 volts. 12V AGM+ charge mode is NOT suitable for traditional AGM batteries. Consult the battery manufacturer before using this mode."

My 4-year old DEKA Intimidator 9A34R says this on the top: "Advanced AGM Technology"

So I'm trying to figure out which charging mode I should use. I'm suspicious that the "Advanced AGM" on the top of my old Deka battery is marketing language, not the newer type of AGM battery. But I can't find anything like an owner's manual for Deka batteries that would specify a charging voltage.
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Old 05-29-2016, 07:57 PM
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Search the Deka website for charging instructions. There should be something there indicating proper charge voltages.

My guess would be the 14.8v setting. My charger just has three positions labeled by the battery type.
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Old 05-30-2016, 08:10 AM
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The Deka 9A34R:
IMPORTANT CHARGING INSTRUCTIONS: WARRANTY VOID IF OPENED OR IMPROPERLY CHARGED. Do not install in a sealed container. Constant under- or overcharging will damage any battery and shorten its life! Use a good constant potential, voltage-regulated charger. Charge to at least 14.4 volts but no more than 14.6 volts at 68F (20C). The open circuit voltage of a fully charged 12-volt AGM battery is 12.8V at 68F (20C). As the battery charges, the building internal pressure (voltage) causes resistance to the charge. Therefore, the on-charge voltage must be higher (at least 14.2V) to overcome this internal pressure (voltage) during charging.
According to this user manual:

12V NORM mode is 14.5V at 7.2A
12V COLD/AGM is 14.8V at 7.2A
12V AGM+ is 15.5V at 7.2A.

Of those 3 the one that I would select would be 12V NORM. I don't know what the algorithm is or what the stated values mean, but it's possible that the 12V COLD/AGM would be right but only if the charger is smart and doesn't overcharge to 14.8V, which may be damaging to the Deka.

Charging profiles will indicate correct voltage and current through the cycle, so a smart algorithm would monitor both and switch between constant voltage and constant current through a 3 or sometimes a 4 step profile. The per cell values are also specified at a temperature, usually 25C, and may have to be adjusted if it's warmer or colder. In the winter you may be fine using 12V COLD/AGM with the Deka but in summer perhaps not.

FWIW, the Optima Red Top can tolerate 15.6V for a rapid recharge cycle with the stipulation that the battery temperature never exceed 125F. So the 12V AGM+ mode may be appropriate for that. Normal float and cycle charging for the Red Top is a max of 15.0V, so for that I'd select 12V COLD/AGM. Even though a battery such as this says it can tolerate 15.6V I'd still not use the mode for it, it's generally not a good idea to abuse batteries like that. A rapid mode is something you may see used with infrastructure UPSes, fire trucks and cop cars where they're not as concerned that they have to rotate batteries on shorter schedules.

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