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    mrtrdrvr New Member

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    With a AGM battery what is the proper charging hertz to use. My charger I believe has 3 settings, 25 hertz, 50 hertz, and 100 hertz.
    I've been using 50 hertz, is that correct to use?
    I figured the battery guru's on here would know!
    Thanks:)
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    David Beale Senior Member

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    I doubt very much that it would make any difference you would notice to battery life. Your battery is going to die after at max. five years. If you fully discharge it that will happen much sooner.

    But I don't know the -correct- pulsing rate per the books.
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    jbrad4 Active Member

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    Any battery is a DC device. So, it doesn't matter what the frequency is going into the charger. The charger is going to convert it from Alternating Current (AC) to Direct Current (DC) to charge the battery. There may be a small ripple of AC coming out of the charger to the battery, but the frequency doesn't matter. I don't know why your charger has a frequency switch on it. I haven't seen that before. Someone else can ans. that one. The difference between a regular car battery and AGM is that the reg. car battery has a liquid electrolyte and the Absorbed Glass Mat battery has the electrolyte in gel form absorbed in fiber glass.
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    Britprius Senior Member

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    Not correct i'm afraid. A regular car battery is acid flooded An AGM battery has the acid absorbed in a glass matt between the plates but it is still liquid acid (often called staved lead acid). An AGM GEL battery has the acid mixed with silica gel and has know liquid acid.
    AGM batteries weather acid or gel tend to have deep cycle properties (they recover better from deep discharge, about 10volts for a 12volt battery)
    Gel perform better than liquid but must be charged more slowly or they may be damaged by bubbles forming in the gel against the plates reducing the area of plate in contact with acid.
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    qbee42 My other car is a boat

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    Your charger uses pulse width modulation (PWM) charging, which sends the charge to the battery in a series of rapid pulses. The frequency setting controls the speed of these pulses. All three frequencies should be fine for your battery, so leaving it on 50 should be good.

    PWM helps keep sulphate crystals from forming.

    Tom
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    nh7o Off grid since 1980

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    Yes. From my experiments with pulsers, it is the rise time of the pulse wave form that does the work. So a steep rise time is preferable, and the frequency is not so important. If one wants to attempt recovery of a sulfated battery, then 1kHz pulse rate or more is good. But for maintenance purposes, slower rates are OK and will probably generate much less RFI/ hash as well. (If that is a concern.)
    1 people like this.
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    David Beale Senior Member

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    On second thought, using that charger is a BAD IDEA. It -may not- cause problems with the many computer systems in the Prius, or it -may-. -I- wouldn't use anything that pulses constantly. My "Battery Tender" does pulse once in a while (when it switches modes) but it's rare.

    Those types of chargers/rejuvinators are intended to be used on a battery that is disconnected and placed in a place where "problems" won't result in corroded engine parts, and electrical "variances" won't result in confused or damaged microprocessors.
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    Britprius Senior Member

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    Im with you on this one. I put one of these chargers on a scope and found voltage spikes in excess of 40volts not good for ECU's

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