Why Your Car Battery Won’t Hold a Charge

Wondering why your car battery won’t hold a charge?

car battery won't hold a chargeOr why do you need to replace your vehicle’s battery often?

Well, the number one culprit is something called battery sulfation.
Sulfation is the number one killer of lead acid batteries.

It is estimated that 80% of all battery failures is do to the process of sulfation.

So, in this post I am going to outline some steps that you can take to minimize or even reverse sulfation. I’m also going to take a look at what goes on in a battery and see why sulfation occurs in the first place.

Before we get into it though, let me just say this isn’t just theory for me. Sulfation is a real world situation that I deal with personally and professionally.

Let me tell you briefly what I am currently dealing with.

I am trying to save 27 6-volt batteries in an inverter for an outpatient surgery center. These batteries were not properly maintained by the maintenance contractor. Consequently, they have sulfated badly.

To replace all these batteries would run around $8,000. So, needless to say they want me to try and save them first. I’ll update this post when I have successfully desulfated these batteries and let you know my results.

In the meantime, let’s look at what goes on in a battery.

Lead Acid Battery Operation and the Process of Sulfation

lead acid batteryThe lead acid battery or flooded battery produces electrical power for your vehicle through a chemical process.

The battery is made up of lead plates immersed in a bath of sulfuric acid. The sulfuric acid is also called the electrolyte. The lead plate acid combination is where lead-acid battery is derived.

When we apply voltage to the battery as with a battery charger or your vehicles alternator, a chemical reaction occurs between the lead plates and sulfuric acid.

The reaction causes a build up of free electrons on the negative side of the battery that we can use for power. During the process of using the battery, the sulfate in the electrolyte breaks away from the acid and adheres to the active part of the  lead plates, forming lead-sulfate.  When the battery is recharged the process is reversed and the sulfate recombines with the acid.

There are three main condition which allows for excessive build up of lead-sulfate on the lead plates which leads to a condition known as sulfation.

Hope that wasn’t too boring!

Now, on to what can be done to prevent excessive sulfation. If preventive steps are taken a battery can be made to last twice as long as the manufacturers’ warranty suggests.

Watch this here for a step by step procedure on how to find a parasitic draw.



The main culprits of parasitic draws are trunk lights, glove compartment lights, after market radios amps and woofers.

What You Can Do When Your Car Battery Won’t Hold a Charge

The best way to prolong your battery and to keep it from sulfating is to prevent it from happening.  As I have already stated above about the causes of sulfation and what you can do, preventing it would be the easiest and just would be a matter of taking the appropriate steps.

1.  Avoid excessive deep discharges until the battery goes flat.  Immediately recharge if allowed to go dead.

2.  Keep a quality [easyazon_link asin=”B004LWVEKS” locale=”US” new_window=”default” nofollow=”default” tag=”carbattery0e-20″ add_to_cart=”default” cloaking=”default” localization=”default” popups=”default”]trickle/float charger[/easyazon_link] on the battery when storing the vehicle longer then a few days.

3.  If at all possible park your vehicle in the shade or in a covered garage or carport if you live in an area where outdoor temps reach up and past 80 degrees F.

4.  Maintain the battery.  Clean terminals, and fill electrolyte levels with only distilled water.

5.  If you have the skills you can test the battery with a battery load tester and volt meter to determine if the battery is fully charged.  If not put it on a charger.

What to do if Your Battery is Already Sulfated.

When your battery will no longer hold a charge your options are limited.

1.  Replace the battery

2.  Place on a [easyazon_link asin=”B004LX14Z2″ locale=”US” new_window=”default” nofollow=”default” tag=”carbattery0e-20″ add_to_cart=”default” cloaking=”default” localization=”default” popups=”default”]special charger with boost mode[/easyazon_link] and that has desufating capabilities.

How does a desulfator work?

It’s pretty simple actually.  It begins with a higher voltage then what your battery is.

For example if you have a 12 volt battery the desulfation charger will usually charge at 16 volts.

This higher voltage is an attempt to break down the lead-sulfate that has hardened on the lead plates.  Hopefully, the sulfate recombines in the electrolyte.

If I sound a bit skeptical of the process it’s because batteries can go beyond the point of no repair.  But, if you have spent alot of money replacing batteries a [easyazon_link asin=”B004LX14Z2″ locale=”US” new_window=”default” nofollow=”default” tag=”carbattery0e-20″ add_to_cart=”default” cloaking=”default” localization=”default” popups=”default”]desulfator[/easyazon_link] might be a worthwhile investment.

Desulfation works best on batteries that have only recently been deeply discharged, although I have seen batteries desulfated and brought back to life after months of sitting on the garage floor.

In Conclusion

With lead-acid batteries an ounce of prevention is truly worth a pound of cure.  In this case preventing the build up of lead-sulfate on the lead plates.

There are steps one could do to reverse sulfated batteries, but proper maintenance and keeping the battery fully charged as much as possible can double the life of your vehicle’s battery.


Thanks For Visiting!

Edward Verheyden

Edward Verheyden is the founder of CarBatteryHelp.com. He has a 30+ year mechanical background and is the main reviewer here. He lives in San Diego CA with is wife and two daughters.

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