Woo Hoo..New AGM Batteries

Hi Mex,

With respect, my surplus acid AGM telecom units recommend a maximum charging rate of c/5 (i.e. 20%). They are unusual in that the specific gravity is 1.3. They represent a small sub set of the AGM market which are more usually a starved acid design.

I was lucky enough to run into someone on facebook whose job it is to maintain many cell phone tower battery banks. He warned me to not exceed the suggested charging current. It seems to me, the issue may be that surplus acid AGM's may behave in a similar manner to flooded jars when being charged. They may gas--which for a flooded cell is no bad thing but for a surplus acid AGM would not be the best thing to do. I am guessing that exceeding c/5 may cause the jars not just to gas, but also to vent. Of course, that is a big "no no" with a jar where distilled water can not be added.

When the bank is hungry, I do limit the charging current by adjusting the input amperage to the Magnum inverter/charger.

I've had them in service for a year now and am delighted with them.

MEXICOWANDERER wrote:
Someone commented on a 4 ampere constant charge rate for a 10-ampere AGM battery. Snide comments. Ignorant comments. I know of NO absorbed glass mat battery that cannot safely accept a 40% of total amp hour charge amperage that does not exceed 14.4 @ 25c temperature compensated volts. God almighty, the Lifeline group 31 safely accepts NINETY AMPS charge rate. All font on a forum looks the same - beware.

yes..I;ll check out the DROK boosters

i have a small one in my dash for voltage control on the instruments/gauges

and another one as a 'chassis' battery maintainer, powered from the house solar wiring

Ya might want to check out the 600 watt DROK booster on Amazon. The voltage does not hump and slump with load like with the Meanwell type power supplies. Use it with your Vector. Watch the input fuse rating limit however.

Whip out the right diet for the AGM and management gets a lot easier. No guesswork.

right now
charging at 8.6amps, 1% is 6.75amps
volts reading is 14.13v
i need to connect the Vector 40amp to boost the voltage to 14.4
i'm considering a 'DC booster' project or maybe a megawatt project
to do this more reliably than the the vector charger

About 90-92% for many but not all.

One of the more "misunderstood" and rote misguided theories of amateurs is that somehow bulk charging 14.4 volts needs to be defeated to "float" immediately.

HORSE

PUCKY

An AGM battery can tolerate 14.4 volts (temperature corrected) FOR HOURS and not be damaged.

When an AGM fills to capacity they do not act like a flooded battery

AGM amperage drops to almost zero.

Battery lifespan suffers to a minor degree with continuous MINOR LEAGUE overcharging.

But please address the FACT (not hyperbole, hearsay or fiction) that tens of thousands of AGM batteries routinely "suffer" automotive charging system voltages and underhood temperatures of 150 degrees plus. Please look. Please find. Please post an AGM battery manufacturer's SUGGESTION that their absorbed glass mat battery must not be used for automotive under hood use. Automotive and diesel truck alternators do not have a float setting.

The point is...

Allow the AGM to achieve FOURTEEN POINT FOUR VOLTS

Allow the amperage to droop to ONE PERCENT of rated amp hour capacity

This is as close of a "Fully Charged" formula as you will ever get.

Please avoid comments that border on the absurd like incredible voltage levels combined with unbelievable temperatures. If you relish permutations refer to a thermal/voltage graph.

Someone commented on a 4 ampere constant charge rate for a 10-ampere AGM battery. Snide comments. Ignorant comments. I know of NO absorbed glass mat battery that cannot safely accept a 40% of total amp hour charge amperage that does not exceed 14.4 @ 25c temperature compensated volts. God almighty, the Lifeline group 31 safely accepts NINETY AMPS charge rate. All font on a forum looks the same - beware.

Gotta love those AGM's. I wish I knew at what percentage state of charge they start to taper.

This morning
Load 2 amps
Over night use 113 amp hrs
SOC 83.6%
Voltage 12.74

Over night use Sunday night to Monday morning
136 AmpHrs , SOC 78.6 percent,
Loving the new batteries

I reset the capacity at 674 amphrs instead of 600,
600 was to much reduction about 12 percent

MrWizard wrote:
Too bad you could not use yours in your shave ice machine

I wish! It would run forever! But they are much too big for the compartment, and much too heavy. Is hard enough to get that thing in and out of the van :).

Too bad you could not use yours in your shave ice machine