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Thread: Testing a used Deka 8G4d - how to go about it?

  1. #1
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    Default Testing a used Deka 8G4d - how to go about it?

    I just got a used DEKA 8G4D GEL battery how do I test if its 183AH rate at c/20 as its spec suggests. do i plug a 9.15AH load for 20 hours or a 20 Ah load for 9.15 hours which one would be more accurate and for one test will the battery get damage if I recharge it right after the test
    Last edited by russ; 03-07-2012 at 02:07 AM. Reason: misleading title

  2. #2
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    For testing a battery capacity, you only want to pull out about 25% of the charge, that is enough to tell if it's good, and not deep enough to hurt it.

    Fully charge the battery
    Let rest 4 hours, then Measure the voltage.

    Use a light load, drain 25%-30% charge (calculated by amps & time)
    Let rest 4 hours, then Measure the voltage.

    Does the voltage match the curve according to the Mfg's voltage chart ?
    Battery_Volt_Chart.jpg
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  3. #3
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    Quote Originally Posted by Mike90250 View Post
    For testing a battery capacity, you only want to pull out about 25% of the charge, that is enough to tell if it's good, and not deep enough to hurt it.

    Fully charge the battery
    Let rest 4 hours, then Measure the voltage.

    Use a light load, drain 25%-30% charge (calculated by amps & time)
    Let rest 4 hours, then Measure the voltage.

    Does the voltage match the curve according to the Mfg's voltage chart ?
    Battery_Volt_Chart.jpg
    thanks Mike finished the load test and Battery is right on spec not bad for 100$
    quick question this is a 183 AH gel battery will this charger SC-1200A 2/8/12A 12V Automatic SpeedCharge Charger be good enough to charge it or will I damage it after reading most post 10% of AH capacity is recommended

    http://www.batterychargers.com/Produ...me=94026806ACP

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    The charger needs to be a 3 stage charger, with settings for the "flavor" of battery you have, GEL, AGM, Flooded..

    The sales sheet or manual says nothing about 3 stage charging, so while that charger might be good to top off the battery once in a while, I'd not leave it on charge for more than a day

  5. #5
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    Quote Originally Posted by Mike90250 View Post
    For testing a battery capacity, you only want to pull out about 25% of the charge
    Mike FWIW when load capacity testing is one time it is worth completely discharging the batteries. IEEE 455 procedure is to put th ebattery at the highest discharge rate practical for the battery, usually the 4 hour discharge rate, and apply the load until the batteries reach 1.75 volts per cell. It is the only way to accurately measure the real capacity.
    MSEE, PE

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    I admit to an abundance of caution. Test away!

  7. #7
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    Default thanks Guys for the great info as usual

    Quick Question for DEKA 8G4D: i have a 15 Watts Panel will it damage this Gel Cell battery if i connect it without a charge controler the spec on the PV says there is a no need for charge controler if i use one panel only but the Voltage peek at 15V and this GEl BT recomends no more than 14.10V i know this panel is too small to really do anything but since i have it there might as well use it right.

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