said by karlaijklm:
I have a 97 Ford Expedition and we can't pin point why the battery keeps draining. In November it broke down. We replaced the fuel pump, then the alternator went out, then we had to get a new battery cause the old one went bad. Now the battery keeps draining. We charge the battery and it does fine for a day or two and then it starts rapidly draining. My husband has checked everything he thinks it might be but nothing is working! Please help!
Draining a battery all the way dead damages the plates and reduces the batteries reserves and shortens its life dramatically.
4. At what voltage is a battery dead?
· Its important to understand that, although batteries are described as 12-volt, in reality a fully charged battery measures 12.6 volts after 24 hours of rest. A battery with a voltage of about 12.2 volt is only 50% charged and one reading 11.7 volts is, to all intents and purposes, fully discharged or dead.
6. Do I need to completely discharge my lead acid battery before recharging it?
· No, in fact you should never discharge your lead acid battery below 80% of its rated capacity. Discharging below 10.5 volts can damage the battery and cause the battery to die.
Or you can test it if you have a DMM - Digital Multimeter (or Analog voltmeter) by looking at the voltage with the engine running. If it shows 12.6 to 12.9 then the alternator is not charging, but if it shows 13 to 14 volts then it is charging and you have a parasitic drain to find instead.
»What's Killing my Batteries?
Parasitic Current Drain
Thexton Manufacturing T431 Parasitic Battery Drain Test Adapter
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