dave2001auto

I notice with the battery tender that a fully charged battery is really only about 60% to 70% charged with battery tender on a hundred AH battery. The really stange thing is when using a Fluke multi-meter on Amp setting, the charger will not work when connected to the amp meter in one direction (drawing 4A when charger is not powered) but will work when the polarity is reversed (no current draw when not powered and charging at 1.3A when powered). Why?

Also with only semi-smart Century charger (100/15/2 Amp charger) it will charge until about 70% charged and turn off due to high surface charge. If the head lighters are turned on for aobut 5 to 10 seconds, the charging will resume at 7A for about 5 minutes. How do I get the chargers to stay "On"?

Dave

whoover

How is the Fluke connected? Current readings are in series with the load, but if you're using the normal test leads they're way too small for the current with the charger working. If you have the Fluke in parallel, like you're reading voltage, who knows what kind of weird load the charger sees.

dave2001auto

The meter leads are in series

(+ of charger) (----Meter leads -----) to (+ of battery)


(- of charger) to (- of battery)

If the battery tender is not connected to the 120 VAC, the fluke meter reading can be either 4A or 0A, depending on the polarity of the connections.
When it's 4A, pluging in the 120 VAC will regrister a fault.
When it's 0A, pluging in the 120 VAC will give 1.3 A to charge the battery.
After a few hours, ithe Fluke reading will drop to 0.2A

My other 1.6 year old 40 AH battery (Kirkland) at rest is only 12.1V. Turning on the head lights for 1 minute, then off for 2 minutes, 11.5 V. Engine on 14.4V. Century charges at 7A for about 10 minutes before into fully charges mode. Looks like very bad sulfation or surface change. I can't seem to get a battery that will last more than 3 years in So. Cal now.

whoover

The Fluke leads just don't have the ampacity to allow proper charging. The charger is apt to see a weird load.

dave2001auto

The max. amp on my Fluke meter is 10 A wih an accurcy of +/- 2%. My charger are at 1.25 A for the Battery Tender and "15A" for the Century but I have never see it go above 9A on it's builted in Amp meter.

Dave

u001elg

Is this for a standard electrolyte filled battery or an Absorbed Glass Mat (AGM) battery.




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A "smart" charger not specifically designed for a AGM battery will not be able to fully charge an AGM battery.


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If this is the case, then you are needlessly fretting over a gremlin that simply does exist. Purchase a smart charger made to charge a AGM battery and you will be fine.

dave2001auto

I have both types of batteries 95AH and a 100 AH (2009 and 1984 model years plus other cars) . They are "smart charger" that claim to be both for FLD and AGM batteries. However, I really don't think the chargers, especially the "Battery Tender" has the capacity to charge these larger batteries, unless attached for over a week.

I am just curious why when the Fluke meter is attached between the BT and battery, the BT will draw a over 4 A and 0 A in the other direction.