Interpreting Battery Charger Readings

[Larry M.]

I have just hooked up an old 6-amp battery charger to my battery because of a no-start, no power situation The battery appeared dead, which seems surprising as it isn't that old, and started the car fine 10 days or so ago.

The needle on the charger's amp gauge read zero when I plugged it in, and over several minutes, climbed to 4 amps (the gauge face reads to 8).

It's only been hooked up for about 10 minutes so far, but I'm interested in what the readings and needle movement might mean. Is the battery junk; is it charging?

Thanks in advance.

[Larry M.]

Re: Interpreting Battery Charger Readings

I found the reason for the dead battery - I had opened the center rear storage compartment to put my new insurance card inside, but didn't completely close the lid. The compartment lamp stayed on, draining the battery.

I'd still be interested in knowing how to interpret what the charger is telling me. The needle is up to 6 amps now.

[Patrick H.]

Re: Interpreting Battery Charger Readings

Normal charger activity, especially when starting from a "dead" battery.

[Larry M.]

Re: Interpreting Battery Charger Readings

Thanks, Patrick.

Would I be correct in assuming that if the gauge needle didn't move up the scale that the battery is junk? Or at least, a paperweight?

[Joe L.]

Re: Interpreting Battery Charger Readings

Thanks, Patrick.

Would I be correct in assuming that if the gauge needle didn't move up the scale that the battery is junk? Or at least, a paperweight?

Larry------


Yup. If after a period of time the charge meter doesn't move off zero, that means the battery is a "dead duck". Unlike Lazarus, it almost certainly cannot be brought back to life.

If the battery is good, but just discharged, it may start with a zero reading. Then, after awhile it will move to a positive reading. Then, when it's fully charged, it will move back to a zero reading.

[Edward J.]

Re: Interpreting Battery Charger Readings

Larry------


Yup. If after a period of time the charge meter doesn't move off zero, that means the battery is a "dead duck". Unlike Lazarus, it almost certainly cannot be brought back to life.

If the battery is good, but just discharged, it may start with a zero reading. Then, after awhile it will move to a positive reading. Then, when it's fully charged, it will move back to a zero reading.

Another reason it does not move of zero is, just a plain old bad connection on one of the cables ends

[Larry M.]

Re: Interpreting Battery Charger Readings

Joe,

Thanks. I've used that charger for years on a number of batteries, and other than the fact that some would take a charge and some wouldn't, I never knew how to 'read' the results on the meter.

Larry

[Duke W.]

Re: Interpreting Battery Charger Readings

I have a 2/6 amp charger that is about 25 years old. Siince I only drive my "daily driver" about once every week or two I always charge the battery the day before. Upon initially hooking it up at the 2 amp setting I switch to 6 amp and the meter goes to 6 or a little higher. After an hour or two the charge rate drops to 2 amps, and when I switch back to the 2 amp setting the meter goes to zero. That's when I know the 15-year old battery is fully charged. Avoiding cranking load with a partially discharged battery is why the battery has lasted so long. So if you meter goes to 2 or less after several hours, the battery is probably okay, but likely not as good as before it got fully discharged.

[Larry M.]

Re: Interpreting Battery Charger Readings

Duke,

Thank you for that information.