Is my Lawn Mower Battery Bad?

[Charles Wiggins]

I've got a Honda 4013 that I got used at a good price and I had to replace the battery in June. Recently I ran into some electrical trouble and it won't start. I started troubleshooting with the battery and it seems that it will not hold a full charge. Most 12V batteries I have had generally hold more than 13V when new. It is a U1 type rated at 365A/300CCA, so it's not bottom of the line.

When I hook mine up to the truck to charge, after 15-20 minutes it seems to top out at around 12.4-12.8V. As soon as I remove it from the jumpers and put the meter on it I can watch it drop 0.01V per second. To be clear, that's just sitting on the ground with no load. Sometimes the drain slows down, but it finally settles in at around 11.9V, and holds there, even after a couple of days. I've done this test three times.

I took it back to the shop where I bought it and explained my attempts to charge it to the owner. He took it in the back to "have it tested" and brought it back and said it was fine but it just needed to be charged because it was only showing 11.9V (which I had just told him. Duh!). I don't really trust him. His employees are nice, but he reminds me of several salesmen I have worked with over the years who will say anything to make a sale, and say anything to keep from have to do warranty work or exchanges. I have not had the chance to take it to any of the auto parts stores that do battery testing.

Am I not charging it long enough or do I likely have a bad cell? I have to get this settled before I can do any more troubleshooting. (I suspect the starter, but we'll see.)

[Myk Rian]

Have you tested to see if the mower isn't dis-charging the battery?

[George Bokros]

Take it to an independent source for a test, AutoZone, Advanced or NAPA and let them test it and also test it under load.

[Matt Meiser]

When I hook mine up to the truck to charge, after 15-20 minutes

You'd probably have a lot better luck charging with a proper battery charger.

And why isn't it charging on the mower?

[Bill Orbine]

Sounds like the battery is bad. A new battery should hold at 12.6 volts or more for a long time. HOWEVER, I wonder if testing the battery on the ground is not such a good idea. Get it off the ground and place it in the tractor without the cables and test it from there. On the other hand, the tractor should be charging at around 13.6 volts. When battery is connected, it is important to check for any voltage resistance such as what voltage you read at battery as compared to voltage you see at ground (positive at battery/ground at tractor(not battery)). Your mower is 23-24 years old, I believe and sometimes the cables and connections needs cleaning up.....especially the ground!

[Lee Schierer]

Sometimes the drain slows down, but it finally settles in at around 11.9V, and holds there, even after a couple of days I've done this three times.

It sounds like you have one bad cell. As others have suggested take it to Autozone and they will test it for you. If you have a hygrometer you can check the charge in each cell. Most likely one of them will show low specific gravity. While you are at it check the water level in each cell. If they are low, the battery cannot reach full charge.

[Jason Roehl]

You can check for a bad cell with a voltmeter--just measure the voltage between adjacent cells (just stick the voltmeter probes directly into the battery acid, take all the appropriate precautions, etc). You should get about 2.1V between each pair. If you get a reading that's significantly different than the others, you have a bad cell. Make sure you rinse the acid off the probes when you're done.

[Joe Tilson]

I found out a couple of years ago, batteries are have different applications as do a lot of things we use these days. We had a Troybilt and had to buy a battery for it. The guy at Wally world gave me one which was under amp for my mower. The starting drained the battery significantly. Therefore low voltage even after running for a good while. We went to Auto Zone and they helped us get a proper battery, and after that had no problems.

[Steve Baumgartner]

I agree with the posts suggesting you have a bad cell in the battery, but if it is a modern sealed type you won't be able to follow the suggestions to stick probes into the cells, check the specific gravity, etc. However, any decent battery shop will have a tester that can detect a bad cell very reliably.

[Charles Wiggins]

And why isn't it charging on the mower?

The mower won't start. On the first attempt I hear the click-click-click, then nothing. That's what started all this. I don't have the money to take it too the shop right now.

[Jason Roehl]

I agree with the posts suggesting you have a bad cell in the battery, but if it is a modern sealed type you won't be able to follow the suggestions to stick probes into the cells, check the specific gravity, etc. However, any decent battery shop will have a tester that can detect a bad cell very reliably.

If it's anything like this:

http://www.walmart.com/ip/EverStart-...ttery/21984263

...then those two quasi-rectangular caps can be pried off easily, giving access to the cells, even though this type is considered "maintenance-free". Every car battery I've seen is similar.

[Dan Hunkele]

Put the battery in the mower and jump start it with the truck. Should start and run even if battery is bad.

[Rod Sheridan]

The charging voltage should be about 14 volts, sounds like your truck has a problem.

Hook the battery up to a small charger ( around 2 amperes) and leave it for 8 to 12 hours. You cannot charge a battery in a few minutes................Rod.

[Matt Meiser]

The mower won't start. On the first attempt I hear the click-click-click, then nothing. That's what started all this. I don't have the money to take it too the shop right now.

That's the symptom of a dead battery. Doesn't tell you why its dead. Your mower may well have an electrical issue that's killing batteries--could be overcharging for example. Check the voltage while the tractor is running. Or it my be physically killing them due to vibration, especially a cheaper battery.

The first step is to try to charge the one you've got with a proper charger. Back in the 90's when I was in high school/college and working at a local chain auto parts store that's the first thing we did before testing any battery that didn't show a full charge. And we charged them for more than 15 minutes even with a proper charger. We had a smart charger that would charge them until "full" then shut itself off. THEN we'd do a load test. I see they have an automated system at that store's successor (O'Reilly) now.

There's probably a clause in the warranty that allows them to deny warranty if your vehicle is the problem. I know ours did back then. Hard to say on the first, but if they replace it and you kill another in a couple months don't be surprised.

If you want a simple out for now, do as Dan said. My dad did that for years on a lawn tractor that killed batteries due to vibration. He kept a battery that was marginal in a car sitting near where the mower was parked--if you needed to start it out somewhere, you used the wheelbarrow to move the battery . You could use one of the jumper boxes--they work pretty good. I got ours at Autozone for about $50. However, if you got a bad regulator be aware you could also be killing things like electronics, fuel solenoids and electric clutches.

[Art Mann]

12V batteries using lead/acid chemistry have an inherent maximum charge of 12.7 or 12.8. When a battery is charged to a higher voltage than that, it does not imply any increase in energy content over that which is available at 12.7V. Some people refer to it as "surface charge". The voltage will settle back to the inherent charge on its own after a while due to self discharge properties. Even a modest load will bleed down this charge voltage in a few minutes. After that, the voltage decline will be much, much slower.

An automobile is a very bad tool to charge a small capacity battery. A typical charging circuit on a car will deliver a several times the recommended charging current and can damage the battery or boil away the water. It isn't really possible to safely charge a battery to anything like its maximum potential in 20 minutes. The most you can hope for is enough stored energy to crank the engine and start getting a real charge by running the engine for a few hours. The charge you think you are getting is a very temporary condition. Do yourself a favor and go buy an inexpensive charger that will shut off automatically after a full charge is achieved and has a low ~5A current setting.