charge rate on rechargable batteries

Discussion in 'General Electronics Chat' started by clintonb, Mar 6, 2011.

  1. clintonb

    Thread Starter Active Member

    Mar 6, 2011
    I read that overcharging a lead acid battery is harmful for the battery. I have a battery charger that has an ammeter that shows the charge rate but i cannot seem to find any information on how this works(inclusing the manual!). Can someone please explain how this charge rate tells the state of battery charge?

    thanks in advance
  2. debe

    AAC Fanatic!

    Sep 21, 2010
    Hi Clinton, The ampmeter doesnt tell you the state of the battery. you need to conect a voltmeter across the battery terminals while charging. The voltage will slowly rise while charging, if its a normal car battery i would stop charging when the voltage rises to about 14.5V no more than 15V.
  3. Adjuster

    Late Member

    Dec 26, 2010
    The ammeter mainly gives you confidence that charging is taking place, and at a reasonable rate. For instance, it would warn you if the current was nil or low because the battery clips were not making good contact. A persistent excessive current might indicate shorted cell(s).

    Depending on the charger design, you might see some falling off of the current as the battery approached full charge, but if it happened at all this would only be a vague indication, and anyhow might be masked by mains voltage variations.