battery terminal corrosion

redka

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May 5, 2010
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what causes the battery terminals to corrode so soon after being cleaned? Like within a couple weeks.
And what can be done to prevent it?
Thanks
 

jhwentworth

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what causes the battery terminals to corrode so soon after being cleaned? Like within a couple weeks.
And what can be done to prevent it?
Thanks

Battery terminal corrosion (lead sulphate) is more common with vented batteries; is this what you have? The vapors released from the battery during the charge/discharge process are acidic, and attack the battery terminals. Vented batteries should have a plastic tube connected to the vent that directs the vapors away from the battery.

Sealed batteries are better able to avoid terminal corrosion, but a bad connection at the terminal can accelerate corrosion.

Remember that the corrosion is caused by current flow during charging/discharging, so if there were a current draw on the battery when the mower was not in use the corrosion would continue. Most riders have a solenoid on the carb to shut off fuel when the ignition switch is turned off. You'll hear it click when the switch is turned on. If you leave the switch on while the mower is parked the solenoid will continue to draw about 300-400 mlliamps of current. This current flow will speed up the corrosion.

Clean the terminals with a wire brush and baking soda. Examine the battery cables for damage, and make sure the cable connector is able to connect tightly to the battery terminal. Battery cables are cheap and easy to replace. After cleaning, apply petroleum jelly to the terminals.

Corrosion can be an indicator that the battery is on the way out, or that the alternator/regulator isn't working properly. If cleaning and repairing the battery cable connections and battery terminals doesn't fix the problem, and the mower doesn't sit with the ignition key on, then it's time to do a battery load test and meter check of the charging system.

Some riding mowers don't have a sophisticated charging/regulator system, and rely on the battery to provide voltage regulation. I've seen these systems producing 17 volts at the battery at 3 amps. Poor regulation can increase battery corrosion.

If you have a multimeter (DVM), a quick check is to measure the voltage between the battery terminals with the engine shut off and again with it running. Shut off you should read 12v-12.5v; running at full rpm you should read something over 13v. If you mower has a regulated charging system the upper voltage level will be 14v-15v. An unregulated charging system will give you a much wider range of voltages.
 

redka

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Thanks. It's not a sealed battery. I'll check the vent tube. It's my son's machine, at his house. Will check the voltage too.
Not sure on the age of this battery. I'll ask him.
 

Manny

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I don't know - could be moisture. I just make sure I keep my lawnmower covered up at all times, when not in use.
 

indypower

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I put a thin coate of greases on the battery teminals. It keep corrosion from forming on them.
 

lizard

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Petroleum Jelly.....or Vaseline........this will stop this problem happening.....make sure terminals are tight.:smile:
 

touree

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I would also attribute it to moisture too. Keep the ends lubricated at all times and covered too. That way it will work well for you and last longer.
 

Nasty135

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Once you get the terminals clean give them a thin coating of vaseline with a Q-tip to get in all the NOOKS & Crannies (what's a cranny??) :cool:
 
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