Unusual battery issue

before buying a new battery, do this (experience talking here...will save you some money possibly and more importantly help you determine the problems/root cause)

1. take battery off mower. Clean those posts ...vinegar and water works fine.
2. with multi-meter test dc volts. write this value down on paper
3. connect a battery charger to the battery. but don't plug in just yet.
4 connect multi-meter to test dc volt, use clamps so it doesn't move.
5. now turn on battery charger and notice test dc volts change.
6. what you are looking for is an initial inrush of current, when first apply battery charge power to the battery..you will see this as volts above 12...probably as high as 14.5 for a battery that is taking a charge. But it can be as low as 12.8- 12.5 for a battery that is already charged (the range is provided for batteries that are still "good" but have worn down a little bit. If the battery charge is above 12.8 and into the range of 14.5 let that go until the battery is fully charged. This might take as long as several hours. If you battery charged has an overprotection circuit, great let it go unattended. But if your battery charger is ancient it might not have overcharge protection and you want to watch it carefully until the charge normalizes in the 12.8 to 12.5 range. Then after that take it off battery charger and let it rest for 1 hour.
7. test dc volts again with multi-meter. volts should not drop by more than .2 volts. If it does drops more than .2 volts, then you probably have a bad battery (or you could have a poor or bad battery charger!!! it happens)
8. if you want to know for sure about your battery health, then find another battery charger that is good, and do the recharge again..now compare the results from the original charger. Any improvement? IF YES, then your original battery charger is no good or working poorly.
9. and finally, dc volts will NOT TELL YOU the actual state of charge health of a battery. The correct and reliable way to determine the health and state of charge of a battery is to performed loaded test. And for that the process is simple: charge the battery until it reaches a fully charged state. Using a good battery charger. If that battery cannot sit for an hour and maintain 12.8 - 12.6 dc volts, it's probably not a good battery. But it might still have some life left regardless. Take this fully charged battery to autozone and have them do a load test. The amount of load applied will be according to the rated cold cranking specs of the battery. For instance if your mower battery is rated for 200 cold cranking amps, the load tester will probably be 200 amps...at that load, there is a "decay rate" that is used by the load meter to determine if the battery discharges at that load at that rate. If it discharges faster than the decay rate range, the battery is deemed inop. If it discharges within the range of decay rate, then it is a good battery.

as you can see, there are many factors involved doing a proper battery test. Many people just assume the battery is dead for instance, when the real problem is that the charger is junk. And yes, there are many junk chargers sold! I like the old school analog gauge ..not the led. The chargers swing a needle and that really helps to SEE the inrush of current in real time and it's extremely helpful to diagnose a battery. Some of these old school chargers also have built in load testers, and that can be very helpful in diagnosing not just state of charge, but if you apply that to a battery attached to the alternator or stator charging circuit, you can witness if the stator is providing proper charging circuit power!?

obviously, the battery is not the only issue here, so before you reattach ANYTHING to the mower, get that mower circuit back to a negative ground and make sure your diode isn't blown and you can test the stator too. university youtube is helpful on how to do that.

Firstly, in the pic, the red cable is not tight to the post. Second, you indicated you tried to measure continuity, of the cables to ground, with the battery connected. That's a no-no as there is voltage present. an Ohm Meter supplies its own voltage to make measurements. Remove the cables from the battery to do the test. Disconnect the red battery wire from the starter and turn the key and watch the battery voltage. Does it drop in the run position, in the start position? Reconnect the starter and if it drops the voltage under 10vdc, then the starter is sucking all the juice. It could be an internal short or a mechanical issue with the engine or starter being too tight.

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and please rotate your positive cable so it is not so close to the battery box (chassis ground) edge.

I replaced the battery with the same size (340cca), but had a strange thing happen. When starting, sometimes, the engine spins very quickly and starts right up. Most times, it struggles to turn at all and is very hard to start. I cleaned every connection point from the battery to the starter, and back to ground at the battery, but still have the same thing. Could the contactor be worn out?

Try jumping the battery positive directly to the starter red terminal. If it always turns well, it may be the solinoid or bad connection somewhere. If it still struggles, try will no spaerk plug. should always trun fast. I have seen very many starters that are tight due to bad internal bearings or just worn out. If you lower the starter from the flywheel, you should be able to turn, not only the bendix gear, but the whole motor easily. If starter is good, then you may need to adjust the valves as the compression release may not be functioning correctly.

donb108 said:

replaced the battery with the same size (340cca), but had a strange thing happen

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Might wanna load test the new battery as well.. Rule out every possibility..

Freddie21 said:

Firstly, in the pic, the red cable is not tight to the post.

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Yes, I just set it there for the picture, it was bolted down before.

Freddie21 said:

Second, you indicated you tried to measure continuity, of the cables to ground, with the battery connected. That's a no-no as there is voltage present.

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I don't recall how I did the original reading, but you're right, that would be a no-no. I traced the wires and concluded it was a normal 12V-negative ground; not sure how I got it wrong in the first place.

Freddie21 said:

Try jumping the battery positive directly to the starter red terminal.

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Good idea, that could rule out the solenoid. Sounds like the starter may also be the culprit, I'll try to check it too. I already returned the mower to my neighbor, so might be a while to get it back for testing.

Cajun power said:

before buying a new battery, do this

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Sorry, I didn't see your post in time and exchanged the battery when I bought the new one. Excellent write-up, I'll use it on the next one.

donb108 said:

I'm working on a Craftsman 42" riding mower (917.270622). I'm trying to replace the battery. It doesn't have the original battery, so I checked some youtubes. It looks like the battery is installed with the positive connected to ground; i.e. 12Vdc-positive ground. I've never seen one setup this way. Is this correct, or did someone goof something up?

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Donb108: I seen where someone stated that they had never seen a Positive to ground, well that was the only way that the older farm equipment, cars, trucks and lawnmowers worked, that is when they used Generators, on the mowers it was a starter and generator that was a one-piece unit, I still have some antiques that have that and yes, the positive did go to ground but for yours what probably happened it just that the post on the batter were on a different side or just switched the cables, Joe