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Thread: How to measure true current coming from charger? (Sierra Electric JB5411 Charger)

  1. #1
    Enlightened 4tified's Avatar
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    Default How to measure true current coming from charger? (Sierra Electric JB5411 Charger)

    I know that most people here are not fans of recharging disposable alkaline cells, and I agree. Self discharge rate is high, batteries are WAY more prone to leak, and rechargeables are efficient more than ever before. I have lots of good LSD NiMH cells and a late generation Maha C9000 that I use everyday. Consider this question just for experimental purposes.

    I have a cheap, POS charger that does not have specs concerning voltage output or "charging finished" voltage termination for primary cells. In fact, it does not terminate at all when it thinks the battery is charged, the LED just goes from red to green. You've probably seen this charger before, it's the Sierra Electric JB5411 "Super Charger". RRIIIGHHHHTT.....

    http://www.amazon.com/Sierra-Electri.../dp/B002RT8ORS

    Notice the charing specs aren't listed....

    Now, this charger does have short-circut protection and individual cell charging, but the benefits ends there. The charging light turns green when an alkaline cell reaches 1.35 volts, which makes me think that the charging routine for alkaline and nimh/nicd cells is not all that different. My guess is constant current regardless of battery chemistry. I've heard from several people that charging primary cells requires slow pulse-charging and pole switching every 5 pulses (or something to that effect) to keep the excess gases from building up and rupturing the weak seals in alkaline and zinc-xxx clhoride/carbon cells.

    I want identify the charging rates of different cells in this charger to see what's really going on (ie: voltage, current, pulse vs constant charging, etc.). How would I go about measuring the voltage on the charger terminals? When a battery is not present, the AAA/AA/C/D bays measure 8 volts, but when a cell is inserted, the voltage drops. Taking the current change in consideration, how would I go about accurately measuring the voltage the charger puts out for certain cells without getting the cells voltage interfering with the measurement? Will I have to measure a component inside the charger while a battery is being charged?

    Hopefully this is not an overloaded question... I am happy to clarify if that is the case.

    Thanks for any input!

  2. #2
    HKJ's Avatar
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    Default Re: How to measure true current coming from charger? (Sierra Electric JB5411 Charger)

    I explain how in my DMM guide.
    You can also see how I test charges, there I uses a better methode.
    My website with flashlight, battery and charger information: lygte-info.
    More than 200 battery reviews and 80 charger reviews.
    Compare 18650 LiIon batteries or smaller (RCR123, 16340, 14500, 10450) LiIon batteries.

  3. #3
    Enlightened 4tified's Avatar
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    Default Re: How to measure true current coming from charger? (Sierra Electric JB5411 Charger)

    Quote Originally Posted by HKJ View Post
    I explain how in my DMM guide.
    You can also see how I test charges, there I uses a better methode.
    Those are very elaborate instructions, thanks for directing me there! I will have to get a better multimeter it seems for this to be accurate.

  4. #4
    Enlightened 4tified's Avatar
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    Default Re: How to measure true current coming from charger? (Sierra Electric JB5411 Charger)

    It seems termination voltage is 1.375 regardless if it's a rechargeable or alkaline battery. Haven't experimented to see what the current is for different chemistries, but the alkalines voltage climbs faster. This charger sucks. I don't even think there's a trickle charge mode because even after leaving the alkalines in the there for a 2-3 minutes after the lights turn green, the end voltage after removing the cells show no change in current. Guess this will be used to just revive aged NiMH cells.

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