Battery voltage or Amps: My question is, Can a used battery that was 11.1 volts now fully recharged to 12.6 volts have an amperage problem and cause it not to work? Do batterys go bad...

Swayne

My question is, Can a used battery that was 11.1 volts now fully recharged to 12.6 volts have an amperage problem and cause it not to work? Do batterys go bad and show fully charged but the Amperage is still low or no good?

Dave R. Loc: PNW

If a battery is charged it is charged assuming all things are equal to when new. The amperage should not be affected assuming the battery does not have another fault of some kind which yes it could make a difference. It is a difficult subject to many but if you google ohms law and study it's content it should clarify. Ohms law is in many ways the same as aperture / ISO / and shutter speed. One affects the other when a change is made.

jerold222 Loc: Southern Minnesota

The quick answer is yes, it could be bad.

You don't give much information, I am assuming an automotive battery?

Is your battery truly fully charged?

If it is a lead acid car battery, a short charging period could create a "surface charge" of 12.6 volts, and still not have the amperage to start a car.

Charging a completely dead Car battery takes hours, up to a day even if you use a low amperage charger.

Mike D. Loc: Crowley County, CO.

Absolutely. The ability of a storage battery to either voltage or amperage diminishes over time. It's a chemical process that gradually stops working as it should.

I'm sure that modern battery tester can check for other things but the old-timers just did a load test which was a current draw to see how big the gap was between what it should be and what it is.

When you buy a car battery with a longer life span, what you are actually getting is more space between the lead plates and the case. This way, it takes longer for the inevitable flaking of the lead fron the plate to cease its usefull life.

Apaflo Loc: Anchorage, Alaska

Swayne wrote:

My question is, Can a used battery that was 11.1 volts now fully recharged to 12.6 volts have an amperage problem and cause it not to work? Do batterys go bad and show fully charged but the Amperage is still low or no good?

The only way to test a battery is to measure the voltage while pulling a full load (whatever amperage it is rated for).

You can measure the voltage without a load, but it doesn't mean just a whole lot unless you know positively that the battery is good.

The internal resistance of a battery should be very low, but if it isn't then even a small drain will result in a very low battery voltage under load, and a normal voltage with no load.

geezer7 Loc: Michigan

Swayne wrote:

My question is, Can a used battery that was 11.1 volts now fully recharged to 12.6 volts have an amperage problem and cause it not to work? Do batterys go bad and show fully charged but the Amperage is still low or no good?

A simple model for a dc power supply consists of an ideal voltage source (constant voltage for any current drawn) and an internal resistance (which increases as a battery ages and becomes less effective). Thus an aging battery must source current through greater resistance and as indicated by ohm's law becomes less capable of servicing loads. Open circuit voltage can still appear to be adequate. Note that batteries are chemical processes and this model only serves to explain the electrical behavior.

davefales Loc: Virginia

Expanding on Ohm's Law:

V(oltage) = I(amps) times R(esistance)

Hold voltage constant (12.6), increase resistance (failed cells) and Amperage goes down.

Dave R. Loc: PNW

davefales wrote:

Expanding on Ohm's Law:

V(oltage) = I(amps) times R(esistance)

Hold voltage constant (12.6), increase resistance (failed cells) and Amperage goes down.

Thank you. I seriously doubt anything has changed after 45 years plus as a licensed master electrician. :thumbup:

boberic Loc: Quiet Corner, Connecticut. Ex long Islander

Swayne wrote:

My question is, Can a used battery that was 11.1 volts now fully recharged to 12.6 volts have an amperage problem and cause it not to work? Do batterys go bad and show fully charged but the Amperage is still low or no good?

First of all, voltage and amperage are inextricably related relatively with resistance. Second and more importantly. ALL batteries regardless of chemistry will eventually fail, regardless of use. They constantly self deplete even if not used. A rechargeable battery is rated by number of recharge cycles. They are also rates by amp/hours- number of hours the batter will take to discharge when fully charged. I don't know if that answers your question, but performance of a given battery will vary and an occasional one will fail out of the box. Battery technology is a speciality unto itself, It can get very complicated depending upon the size and chemistry.

joer Loc: Colorado/Illinois

Swayne wrote:

My question is, Can a used battery that was 11.1 volts now fully recharged to 12.6 volts have an amperage problem and cause it not to work? Do batterys go bad and show fully charged but the Amperage is still low or no good?

If remember correctly a fully charged car battery with no load applied is 14v.

Swayne

Actually I did recharge it for several days it even came up to 14 point something. The battery is being used to power an inverter to use with my Dynalite strobe lights power pack, Tested inverter it works perfect. Thank you for the info.

Swayne

Thank you, Powerful good information.

Swayne

Actually I did recharge it for several days it even came up to 14 point something. The battery is being used to power an inverter to use with my Dynalite strobe lights power pack, Tested inverter it works perfect. The battery still showed more than 12 V under load but would not power up my power pack enough to get a flash. The inverter is 2500 watts
Thank you for the info

Swayne

great info thanks for getting me on the right track

PixelStan77 Loc: Vermont/Chicago

Sounds like you have a bad cell in that battery.

Swayne wrote:

Actually I did recharge it for several days it even came up to 14 point something. The battery is being used to power an inverter to use with my Dynalite strobe lights power pack, Tested inverter it works perfect. Thank you for the info.