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How to Tell if Your Battery is Bad in 3 Easy Steps

 Tech Tips & Tricks

Having battery troubles? Yeah, we hear you. Almost everyday, we receive calls and comments about batteries that "won't hold a charge" any more. Maybe you've been in that boat before. To clear up a misconception: a battery isn't like a water bottle. You can't use up half now, and then wait and use half later. It's not a tank of electricity. Also, batteries don't "leak" power like water can. What we're dealing with here with a lead acid battery is a plastic box that encases a delicate balance of chemicals which are ready to interact with each other to produce electricity when the load is applied.

If your battery is having trouble producing electricity, chances are, it's a chemical issue.

Here are some ways to test your battery at home, and determine if it's bad

1) Inspect the Battery

Bent TerminalSometimes you can tell if your battery is bad by simply taking a good look. There are a few things to inspect, such as: a broken terminal, bulge or bump in the case, crack or rupture of the plastic, excessive leaking, and discoloration. Broken or loose terminals are dangerous, and can cause a short circuit. If a short did occur, there would be some indication of burning or melting. When a battery short circuits, all of the power is unloaded in an instant. That produces a lot of heat, and sometimes even causes the battery to explode (no joke). If the battery is still intact, but there is a bulge in the case, this is usually a result of being overcharged. Others signs such as physical openings in the case are often caused by mishandling. Cracks, splits, and holes will not cause a battery to stop working, but for safety reasons the battery should be labeled unsafe to use.

With wet-cel (flooded) batteries, water levels have to be maintained. If they are low, usually re-filling them with distilled water will help. But if the battery has been dry for a long time, it can cause a problem. When the plates in the cells are exposed to oxygen, it rapidly causes sulfation to build up. Sulfation is the number 1 cause of early battery failure. Plus, charging a dry battery will burn it up. If your battery has plenty of fluid in the cells, but the color is dark, or brownish, this is also an indication of a bad battery. Even if one cell is brown, it is rendered useless and therefore the entire battery is, too. Time to replace!

2) Take a Voltage Reading

The voltage of a battery is a good way to determine the state of charge. Here's a handy table with the breakdown:

State of Charge Voltage
100% 12.7 - 13.2
75% 12.4
50% 12.2
25% 12.0
Discharged 0 - 11.9

If your battery is reading 0 volts, chances are the battery experienced a short circuit. If the battery cannot reach higher than 10.5 volts when being charged, then the battery has a dead cell. If the battery is fully charged (according to the battery charger) but the voltage is 12.4 or less, the battery is sulfated. Sulfation is the natural byproduct when the battery discharges. Naturally, re-charging the battery will reverse the sulfation crystals and turn it back into electrolyte, ready to produce power again. But if a battery sat, uncharged, severely discharged, and/or drained for extended periods of time, the sulfation will increase in size and harden onto the plates. This covers the surface area of the plates, removing the chemicals needed to produce power. Sulfation decreases the potential to reach a full charge, and it self-discharges the battery quicker than normal. Charging a sulfated battery is like trying to wash your hands while wearing gloves. At this point, charging alone will not restore the battery to a healthy condition. The majority of replacement battery purchases occur when the original battery has reached this point.

3) Load Test the Battery

Your local automotive shop is more than able to load test your battery for you. But it's quite easy to do at home. All you need is a digital voltmeter. For any load test to be accurate, the battery must be fully charged. Let's use a motorcycle battery for an example. Remove the seat and expose the battery in your bike so that you have access to the terminals. Do not disconnect the battery because you will attempt to start the bike. Hold the prongs of your voltmeter to the correct terminals on the battery. Now push the starter button and watch what the voltage drops to. It doesn't matter if the bike starts or not, what you're looking for is a voltage reading.

DC VoltageA healthy 12 volt motorcycle battery should maintain a range from 9.5 - 10.5 volts under the load for a good 30 seconds straight. If the battery begins to hold and then steadily drops in voltage, there is a problem. If the voltage instantly drops to 0 volts, that is also a problem. We call this the open cell. On a new battery, this can be a result of manufacturing flaws, but it also may be caused by sulfate crystal buildup. Under the intense heat of the load, one or more of the weld pieces connecting the cells is coming loose and separating. This will cut the current, and voltage will drop. When the battery cools off, the pieces will touch, barely giving a complete connection. This gives you a false voltage reading. Batteries with open cells may read fully charged in idle, but they fail under a load test every time. Once a battery reaches this point, there is no going back. The best thing to do is recycle the thing.

 


 

These 3 steps will help you determine if your battery is truly bad or getting there. Sometimes it's obvious if there is a failure, but other times it's not. Flooded batteries make it possible to simply look inside the cells and determine if the battery has a physical defect. But for sealed AGM and Gel batteries, it requires testing. The only tools you really need are a battery charger and a digital voltmeter. If your battery experiences any of the symptoms described in the steps above, then maybe it's time to replace the battery.

Look no further. We've got a wide selection of powersports batteries for your motorcycle, ATV, scooter, Jet Ski, or snow mobile. But we also carry batteries for lawn mowers, wheelchairs, UPS systems, RVs, and Marine applications. Whether you need a starting battery or a deep cycle battery, we have the stuff. And all of our replacement batteries come with warranties to ensure that you won't have any of these problems with your new battery.

Having battery troubles? Yeah, we hear you. Almost everyday, we receive calls and comments about batteries that simply "won't hold a charge" any more. Maybe you've been in that boat before. Now, a battery isn't like a water bottle. You can't use up half now, and then wait and use half later. Also, electricity doesn't "leak" like water can. What we're dealing with here is a plastic box that encases a delicate balance of chemicals which are ready to interact with each other to produce electricity when the load is applied.

If your battery is having trouble producing electricity, chances are, it's a chemical issue.

Here are some ways to test your battery, and determine if it's bad

1) Inspect the Battery

There are some sure ways you can tell if your battery is bad by simply taking a good look. There are a few things to inspect, such as: a broken terminal, bulge or bump in the case, crack or rupture of the case, excessive leaking, and discoloration. Broken or loose terminals are dangerous, and can cause a short circuit. If a short did occur, there would be some indication of burning or melting. When a battery short circuits, all of the power is unloaded in an instant. That produces a lot of heat, and sometimes even causes the battery to explode (no joke). If the battery is still intact, but there is a bulge in the case, this is usually a result of being overcharged. Physical openings in the case are caused by mishandling. Cracks, splits, and holes will not prevent a battery from working properly, but for safety reasons the battery should be labeled unsafe to use.

With wet-cel (flooded) batteries, water levels have to be maintained. If they are low, usually re-filling them with distilled water will help. But if the battery has been dry for a long time, it would have rapidly caused sulfation to build on the plates in the cells. Sulfation is the number 1 cause of early battery failure. Plus, charging a dry battery will burn it up. If your battery has plenty of fluid in the cells, but the color is dark, or brownish, this is also an indication of a bad battery. Even if one cell is brown, it is rendered useless and therefore the entire battery is, too. Time to replace!

2) Take a Voltage Reading

The voltage of a battery is a good way to determine the state of charge. Here's a handy table with the breakdown:

State of Charge

Voltage

100%

12.7 - 13.2

75%

12.4

50%

12.2

25%

12.0

Discharged

0 - 11.9

If your battery is reading 0 volts, chances are the battery experienced a short circuit. If the battery cannot reach higher than 10.5 volts when being charged, then the battery has a dead cell. If the battery is fully charged (according to the battery charger) but the voltage is 12.5 or less, the battery is sulfated. Sulfation is the natural byproduct when the battery discharged. Naturally, charging the battery back up will reverse the sulfation crystals and turn it back into electrolyte, ready to produce power again. But if a battery has sat, uncharged, and drained for extended periods of time, the sulfation will increase and harden onto the plates. This covers the surface area available for power. It decreases the potential to fully charge, and it self-discharges the battery quicker. Charging a sulfated battery is like trying to wash your hands while wearing gloves. It's not very effective. If your battery cannot even reach a full charge, consider it bad.

3) Load Test the Battery

Mechanic and automotive shops are more than able to load test your battery for you. But It's quite easy to do at home. All you need is a digital voltmeter. For any load test to be accurate, the battery must be at fully charge. For our example, let's test a motorcycle battery. Expose the battery in your bike so that you have access to the terminals. Do not disconnect the battery because you will attempt to start the bike. Hold the prongs of your voltmeter to the correct terminals on the battery. Now, push the starter button, and watch what the voltage drops to. It doesn't matter if the bike starts or not, what you're looking for is a voltage reading.

A healthy 12 volt motorcycle battery should maintain a range from 9.5 - 10.5 volts under the load, for a good 30 seconds straight. If the battery begins to hold and then steadily declines, there is a problem. If the voltage drops to 0 volts, there is a problem. We call this, the open cell. This is typically a result of poor manufacturing at the factory, but it can be caused by sulfate crystal buildup as well. Under the intense heat of the load, one or more of the weld pieces connecting the cells is coming loose and separating. This will cut the current, and voltage will drop. When the battery cools off, the pieces will touch, barely giving a complete connection. This gives you a false indication of a true voltage reading. Batteries with open cells may read fully charged in idle, but they fail under a load test.

 


 

These 3 steps will help you determine if your battery is bad or not. Sometimes it's obvious if there is a failure, but other times it's not. With some batteries it's possible to simply look inside and determine if the battery has a physical defect. But for the sealed AGM and Gel batteries, it requires testing. The only tools you really need are a battery charger and a digital voltmeter. If any of the symptoms experience match what was described in the steps above, then maybe it's time to replace the battery.

 

Look no further. We've got a wide selection of powersports batteries for your motorcycle, ATV, scooter, Jet Ski, or snow mobile. But we also carry batteries for lawn mowers, wheelchairs, UPS systems, RVs, and Marine applications. If you need a starting battery, or a deep cycle, we've got the stuff. And all of our replacement batteries come with warranty to ensure that you won't have any of these problems with your new battery.

 


 
10 Responses

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  • I enjoy your information on batters. Don‘t drop me from your list. Thanks Gerald .
    Gerald Robinson
    August 11, 2012 a 4:31 pm
    • As HST said – “Give ‘em Hell” – loved your video. Do you folk make batteries for use with solar panels?

      Blessings to you all Pete
      Pete
      August 13, 2012 a 10:25 am
      • We do! You can see all of the batteries that are designed for solar use at www.batterystuff.com/batteries/pv-solar/

        Jeremy Fear
        August 15, 2012 a 11:07 am
      • Hay, thanks for the tip, yup that‘s what I thought brown water indicates loosened rust particles floating around, also can short between plates! My family has this Motor home that had a dynamite battery, marine die-hard they never took care of! Well, it died hard alright, last two cells were dry to the bone! Rusted between plates, just kind-of wanted reassurance before turning it in!

        Mr Dennis B. Zwolle
        May 9, 2013 a 1:50 pm
        • Yeah, when cells are not equally drained there is indication that one or more cells is defective, causing all the others to be pulled down with it. I would recommend replacing the battery. Thanks

          Jeremy Fear
          May 20, 2013 a 7:59 am
        • Great read Ty for the refresher course.

          J. Craig Hembree
          October 20, 2013 a 9:20 am
          • Nice blog for Automotive.

            Cameron Jolie
            November 22, 2013 a 1:26 am
            • You guys should give lessons to our local Advanced Auto Parts store. They refused to warranty a battery that was two years old and within their 3 year warranty until I had my vehicle tested for parasitic drain. I had to jump it off every other day for two weeks, but before that no issues at all. I finally made them test it WITHOUT me jumping it off first. It had 4.8 volts. They finally replaced it when I got District Management involved. The district manager was even ruder though. I will have to give you guys a try next time. Thanks for the valuable info and not being ashamed to publish it. Sounds like you guys might understand customer service a lot better than they do.

              David Netherland
              February 1, 2014 a 9:26 pm
              • Inspection of battery is essential before replacing Harley starter.

                Mabel Margaret
                April 11, 2014 a 3:21 am
                • Good post.
                  harley starters

                  Mabel Margaret
                  August 7, 2014 a 11:58 pm
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