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

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

Bad Battery Bent TerminalSometimes you can tell if your battery is bad by simply taking a good look. There are a few things to inspect:

  •  
    •  
      •  
        •  
          • Broken terminal
          • Bulge or bump in the case
          • Crack or rupture of the plastic
          • Excessive leaking
          • 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.

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-cell (flooded) batteries, water levels have to be maintained. If they are low, usually refilling 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 your battery!

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
  • Cannot reach higher than 10.5 volts when being charged, then the battery has a dead cell
  • 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:

  1. 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.
  2. Hold the prongs of you voltmeter to the correct terminals on the battery.
  3. Now push the start 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 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.

DC Voltage

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 snowmobile. 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.

 


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38 Responses

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  • Been working for a parts store for about 17 years. Cant always teach you the things you need to know, while your working. You have to look for the knowleadge of others if you are willing to learn. So you can pass it on to your customers and employees . The reason I read this article is because it was my very own battery giving me problems.
    Thank you. Now I know what to look for and test it or at home.

    Lori Hanger
    December 27, 2016 a 8:21 am
    • thanks for the article, really helpful.

      Just a question about dry cells. How long for an idle battery with a dry cell before it gets damaged? just a rough idea? 6 weeks? 6 months?

      Thanks for sharing your knowledge.

      Manny
      November 4, 2016 a 2:23 am
      • AGM and GEL cell batteries have a slower discharge rate than wet cells. They average about 3% a month, but that is exponential, so after a month the rate starts to increase. In general we recommend that if you are not going to use a battery put it on a maintainer. However, if you are not able to I wouldn’t recommend just letting it sit more than a couple of months, or the sulfation that is building up in the battery will start to harden.

        Tech
        January 16, 2017 a 1:50 pm
      • Quite simple and informative….

        Rajesh Kumar
        October 21, 2016 a 2:56 pm
        • I had a battery that got submerged, the poles were covered in water, for a week and the battery drained down to 3 volts. There is no visual damage to the battery. Any chance this battery can be used again?

          Gerry
          October 17, 2016 a 2:25 pm
          • Unfortunately, the electrolyte most likely mixed with the water and was highly diluted. This is the reason why the voltage dropped so much, and unfortunately you cannot get the acid back. In a situation like this we recommend replacing the battery.

            Tech
            January 16, 2017 a 12:59 pm
          • When my computer ups in battery mode it will turn off after 4 beep sound what i do?

            Anandaraj
            October 15, 2016 a 4:23 am
            • I would consult with the manual of the UPS, but it sounds like it is no longer able to hold under load when using the batteries. If in fact it is time for the batteries to be replaced you can view our replacement UPS Batteries.

              Tech
              January 16, 2017 a 12:42 pm
            • Thanks for all the info. It was just the things I was wondering so I could determine what to do next.

              Angie Hunt
              October 13, 2016 a 2:48 am
              • I have a 2009 Yamaha Nytro snowmobile that worked great until I replaced the six year old battery. After running trails, two successive replacement batteries died and would not take a charge. The replacement AGM batteries were identical specs to the original YUASA and each failed after about four hours of riding. The second replacement whistled/hissed, then made a pop like a firecracker when it died.

                Does this sound like bad/shorting batteries or a charging system failure? Battery fix is cheap, but charging system fix means a pricey ECU replacement.

                Pete
                October 6, 2016 a 5:53 am
                • With both failures happening about 4hrs into a ride… It sounds like a charging system failure sending too much charge to the batteries. I would have your charging system checked out.

                  Tech
                  January 16, 2017 a 1:51 pm
                • Helpful information there!

                  A small question for the experts here:
                  I have a 150cc motorcycle whose battery charging system consists of a Rectifier-Regulator that partly supplies the power for the headlight(35W) as well as performing the battery charging simultaneously. Hence, my headlight flickers (which is expected from AC supply).
                  I wished to connect the headlight directly to the battery supply and use a LED headlight(20W – low/30W -high). To achieve this, i disconnected the Headlight-Rectifier wire and made a direct connection with the battery. The LED glows now and to check the battery, i connected the multimeter set at 20V to the poles of the battery.

                  On Load conditions, the battery shows a positive increase in Voltage upto 13.4 – 13.8V with rpm above 3000, I used the motorcycle at night and in the morning i checked the battery at no-load, it was around 12.42V. My battery is okay, isnt it?

                  Sam
                  October 2, 2016 a 12:58 am
                  • Your battery is starting ito enter the weak range, so I would replace when you start to notice. Anything less that 12.4 is considered a sulfated battery, so i would recommend charging the battery, and if it settles back to that level I would consider replacing at the first sign of weakness.

                    Tech
                    January 16, 2017 a 10:54 am
                  • Very useful article! Thank you for sharing!

                    Richard Peter
                    September 21, 2016 a 4:01 am
                    • My gsr600 battery was over charging so I replaced the rectifier but again it is showing overcharging, is there some thing wrong with the battery? I have already checked all the sockets and earth cable.

                      Ham
                      September 19, 2016 a 11:36 pm
                      • It definitely could be a weak battery! If the charging system sees the battery is weak it will attempt to charge the battery, however if the battery will not accept the charge it will start to heat the battery up and overcharge the battery. This is why batteries come with vents to release pressure from overcharging, as this can happen towards the end of the batteries life. I would suggest having your battery tested.

                        Tech
                        January 16, 2017 a 10:43 am
                      • So I tested my battery and its reading 12.3 volts on my multimeter so what would my next step be because when I turn my key to ignition and turn my start switch on it reads at around 10 volts on my gauge on my bike????

                        Scott
                        August 18, 2016 a 5:51 pm
                        • At 12.3 your battery is about at about 62% of capacity, and would be what we consider a weak battery. I would suggest charging, then let it sit off the charger for more than 12 hrs to see if your readings go up. If the readings stay the same I would consider getting the battery replaced.

                          Tech
                          January 16, 2017 a 10:11 am
                        • I have 30 SMF battery of 12V/100AH.The floating voltage of all battery is between 13V-13.80V but after testing with load the voltage drop down upto 10.50V.The 10.50v battery is considered weak battery .please reply us.

                          Shailendra Tripathi
                          July 13, 2016 a 12:46 am
                          • A battery under no load sitting at 10.5 would be considered a bad battery for a 12v battery. However under load you have to interpret you load tester’s result, and most are designed to put a high load on the battery, and in most cases will drop a battery into the 10 volt range.

                            Tech
                            January 16, 2017 a 10:02 am
                          • Really helpful, thanks. Battery full, but starting gave only ‘tick tick tick’ very quickly. Testing DC under load showed immediate drop to 4-5V….and then the battery came up to 10 V only.

                            Dim
                            June 7, 2016 a 5:03 am
                            • I have a 98 dodge ram 1500. I sorta put it in a mud hole and now it wont start. I put a new starter on it tonight cuz the old one went bad…. Ive tried jumping the truck but my battery gauge wont go over 11. And the motor wont turn…

                              Chad
                              June 3, 2016 a 7:33 pm
                              • I have a minnkota 30amp battery charger in my boat, I notice when I was charging the other day that one of the banks said check battery connection, does this mean the battery is bad, I looked at the battery and everything looked good. Any suggestions?

                                Tony E
                                May 19, 2016 a 9:52 pm
                                • It could be the charger, or the battery… In my experience it points to the battery if the charger is still alerting you that there is an issue, but every once in awhile it can be the charger as well. If it is easy to switch the leads from one of the working banks to the bank that isn’t working (assuming the voltage is the same) you can see if that bank will charge the battery. If you get the same result it is most likely the battery. However if that bank takes off charging it could be the charger. Before replacing the charger I would suggest going through the troubleshooting steps in the manual, as you may just need to rest the charger.

                                  Tech
                                  May 24, 2016 a 12:09 pm
                                • Thanks for the post. Really helpful post to knowing when battery goes dead.

                                  BatteryBhai
                                  May 19, 2016 a 3:25 am
                                  • Can i ask a question to you wonderful electrics experts. scenario:
                                    bike draining battery.
                                    so far i Put new battery on reading 13.3 volts.
                                    when bike running it showing 14.2 volts (this shows generator/stator and regulator are all working as should, yes?
                                    now bike turned off, keys removed:
                                    I have measured the Milliamps (draw on circuit) using the DCA Setting on 20m, with tester in circuit, and i’m getting a reading of 11.24?
                                    i disconnected every attachment from the harness and the 11.24 is made up of:
                                    3.00 from dash and 8.24 from the ECU.
                                    so,
                                    1. should the ECU have power when ignition off?
                                    2. is either of thoes my problem?
                                    thanks in advance!

                                    Josh
                                    May 2, 2016 a 2:43 pm
                                    • Josh,
                                      Your ECU definitely should not be drawing power when the bike and ignition are turned off. I am not quite clear on your test results though. You measure for milliamps when testing for draw, but the results you give me (11.24) is a voltage number. Can you please clarify. I don’t believe that will change my diagnosis, but I do like to have complete and accurate info when working an issue.

                                      Tech
                                      May 3, 2016 a 9:27 am
                                    • This is some great information, and I appreciate your point that a bulge in the case of a battery means it’s dead. My car wouldn’t start earlier today, so I checked the battery, and there was a weird bulge in the case. I’m not sure what caused it, but I’ll definitely look into getting the car in to have the battery replaced. Thanks for the great post!

                                      Lillian Schaeffer
                                      April 14, 2016 a 4:30 pm
                                      • Good post.
                                        harley starters

                                        Mabel Margaret
                                        August 7, 2014 a 11:58 pm
                                        • Inspection of battery is essential before replacing Harley starter.

                                          Mabel Margaret
                                          April 11, 2014 a 3:21 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
                                            • Nice blog for Automotive.

                                              Cameron Jolie
                                              November 22, 2013 a 1:26 am
                                              • Great read Ty for the refresher course.

                                                J. Craig Hembree
                                                October 20, 2013 a 9:20 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
                                                  • 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
                                                    • I enjoy your information on batters. Don‘t drop me from your list. Thanks Gerald .
                                                      Gerald Robinson
                                                      August 11, 2012 a 4:31 pm
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