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Summary
  • Jump-starting the battery and cleaning the terminals with household items like Epsom salt and aspirin can help recondition a battery that won’t hold charge.
  • Jump-starting is a generic process that you can perform on any vehicle, but keep in mind that there might be some additional precautions to observe, depending on the year, make, and model.
  • Conducting a battery load test, voltage test, and conductance test can help you determine if you should replace your battery.

Caution: Never work around any car battery without good eye protection (better than your prescription glasses). A full face mask is best.

There are very few things more frustrating than discovering you have a dead battery when you need start your car.

Imagine being late for an important appointment only to find out that the engine won’t turn because of a dead battery. This issue can happen to anyone, and there are times when new batteries fall victim to this kind of problem.

So how exactly can you fix it?

First, Check the Terminal Connections

battery terminal connections corroded
If your battery terminal connections look like the ones pictured here, take care of this problem before doing anything else. | Image Source: Richard McCuistian

How to Recondition a Car Battery That Won’t Hold Charge

There are some instances where your car battery might need a little push to get going. Here are some simple ways to recondition a car battery that won’t hold charge.

Important note: These methods apply if you have time and are in a financial situation where you can’t afford a new battery at the moment. This isn’t 100%, but it won’t hurt to try. Of course, some batteries are purposely designed in such a way that you can’t open the cells. These methods won’t work on batteries of this type or on “gel” batteries.

Jump-Starting

Jump-starting is a simple process that can breathe some life into your car’s battery. You’ll only need jumper cables and another working vehicle.

jump starting battery illustration
Make the connections as shown in the illustration, with the last connection being made to the engine block of the vehicle with the dead battery. Since the last connection will likely make a spark, you don’t need to take the chance of igniting the flammable gasses that can be present above the battery. | Image Source: Richard McCuistian

Make sure to use high-quality copper cables when jump-starting a dead battery. When it comes to jumper cables, you get what you pay for; some jumper cables can look good and still not do the job. Again, it’s important that you make the last connection as far away from the working battery as possible to mitigate the possibility of a battery explosion (they do happen.

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Create at least a little distance between your vehicle and the one you’ll be drawing charge from. How much distance you can put will be determined by how long your cables. 

, How to Fix a Car Battery That Doesn’t Hold Charge

Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with CarParts.com, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.

Pro Tip: Some old timers used to park the jump vehicle so that its chrome bumper touched the dead vehicle’s chrome bumper and just used the positive jumper cable, but this is not a good practice. It won’t work on today’s vehicles anyway, because bumpers are plastic.

It’s normal for the cables to spark once they complete the jumping circuit and, again, this is why you make the last connection on the dead vehicle’s engine block. For some new vehicles, you might notice a special ground or a positive power connection located away from the battery for jump-starting purposes and these will sometimes be plainly marked. 

Note: Jump-starting is a generic process that you can perform on any vehicle, but keep in mind that there might be some additional precautions to observe, depending on the year, make, and model. Some of the newest vehicles advise against it, so be careful, and don’t connect the cables backwards either. This can ruin a lot of parts.

Always consult the appropriate manual when performing such procedures. 

Use an Epsom Salt and Distilled Water Solution

Using Epsom salt is another way to recondition a battery that won’t hold charge. Epsom salt or magnesium sulfate can help dissolve solid salts that have formed around the battery plates over time. 

Simply mix one part Epsom salt with three parts distilled water, and pour the solution over the battery cells. After that, you’ll need to charge the battery for about 12 to 24 hours before conducting a load test.

Try Using an Aspirin Solution

Aspirin has acidic properties that can alter a battery’s electrolyte composition.

Crush 12 aspirin tablets into a fine powder, and add about 180 ml of warm water to create the solution. Pour the solution over the positive and negative battery terminals, and add more water to cover all the plates if necessary.

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Knowing When to Replace an Old Battery

When your car battery is too far gone, the only thing you can do is replace it with a new one. This is the best way to handle a worn-out battery once you’ve determined that enough of its cold cranking amps are depleted to make it undependable.

But before you do, here are some tests you might want to perform on your battery to know whether or not a replacement is absolutely necessary.

Battery Electrical (Parasitic) Drain Test

A battery electrical drain test determines if there’s a component or circuit that’s draining the battery even when the ignition is off.

Electronically tuned radios, computers, and controllers are some components that draw a slight but continuous amount of current from the battery when the ignition is off.

diagram showing how to conduct a parasitic drain test
Diagram showing how to conduct a parasitic drain test | Image Source: Richard McCuistian
test using an inductive amp meter illustration
Using an inductive amp meter is actually better if the vehicle has already been sitting for a couple of hours because all the modules will be asleep and you can get an immediate reading. | Image Source: Richard McCuistian

An inductive DC ammeter and a digital multimeter that’s set to read milliamperes are some tools that are used to conduct a drain test (see illustrations).

To find the source of the drain, check to make sure the underhood light, glove compartment light, and trunk light aren’t illuminated when they shouldn’t be. Check interior lights, like map lights kids may have turned on when you weren’t looking. Disconnect fuses one at the time from the underhood junction box and then the inside fuse panels, but make sure you don’t have the door open so that the dome light is on while removing the fuses or you’ll get a false positive result.

If the drain stops after one fuse is disconnected, the source of the drain is located in that particular circuit.

But if the battery drain still exists, check the alternator, starter solenoid, or nearby wiring for any issues. If you don’t know how to do this, take your car to a mechanic.

Battery Load Testing

A battery load test determines the condition of any battery. This method requires a load tester that uses a carbon pile to create an electrical load on the battery.

To perform this test, it’s important to determine the battery’s CCA rating before anything else.

The proper electrical load to be used on the battery should be half of its CCA rating or three times the ampere-hour rating. Once you’ve determined the CCA rating, you can proceed with connecting the load tester to the battery. Apply the load for a full 15 seconds.

During the load testing, the battery should have a reading of above 9.6V. Repeat the test at least one more time to get a more accurate battery condition.

See also  How to Tell Positive and Negative Terminals on a Car Battery

Battery Voltage Test

A battery voltage test can determine the state of charge of any battery.

Also referred to as an open circuit battery voltage test, this procedure is conducted with an open circuit, no current flowing, and no load applied to the battery.

Before attaching a voltmeter to the battery terminals, always make sure that the surface charge has been removed. To do this, turn the headlights on high beam for one minute, turn them off, and wait for at least two minutes.

From there, connect the voltmeter to the battery posts. Read the voltmeter, and compare the results with the state of charge. A negative meter reading could mean two things: an incorrect voltmeter connection or the battery needs to be replaced.

This test should be followed by watching the battery voltage (with eye protection) while attempting to start the vehicle. Check at the battery post, and if the voltage stays steady, move your probe to the battery terminal. Do this first on the positive side and then on the negative side.

diagram showing how to watch battery voltage while attempting to start the vehicle
Diagram showing how to watch battery voltage while attempting to start the vehicle | Image Source: Richard McCuistian

Check at the battery post, and if the voltage stays steady, move your probe to the battery terminal. Do this first on the positive side and then on the negative side.

– Richard McCuistian, ASE Certified Master Automobile Technician

Electronic Conductance Testing

Electronic conductance testing measures how well a battery can create current. It’s usually done on batteries that are under factory warranty and can be performed on test flooded or absorbed glass-type batteries.

A conductance tester sends a small signal through the battery and measures a part of the AC response.

This method isn’t designed to accurately determine the state of charge of a new battery. It should only be used to test batteries that have been in service.

A conductance tester usually displays two results: ”good battery” or “charge and retest.”

However, keep in mind that improper connections to the battery can produce inaccurate results. Also, make sure to turn off all accessories and the ignition switch before conducting the test.

About The Authors
Written By Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Technical Reviewer at CarParts.com

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

File Under : Electrical System , DIY Tagged With :
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Wrip

Thanks, I’m going to try these, I have a fairly new battery that won’t hold a charge & my charger isn’t giving a full charge for some reason.

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