How to Charge a Lawn Mower Battery: Easy Guide for Beginners

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One of the essential parts of your lawn mower is your battery. It is the bloodline of your mower since it powers up almost all parts of your zero turn mower except your deck blades and your engine. However, it’s a common issue for it to get discharged. And it’s also a common problem for many to think that a non-working z-turn is caused by a dead battery. 

Common times a battery gets discharged

There can only be two things that can discharge your mower’s battery: over usage or long storage. Other reasons why your battery is dead other than these two are signs that you need to inspect your battery for maintenance or a  possible change in battery.

Over usage

Since some mowers have keyless ignition, many forget to turn the mower off. Leaving your engine on idle and your battery still powering up most parts of your mower thus results in using your battery until it’s discharged.

Long storage

Long winter season storage causes your battery to discharge. Not only that but leaving your mower unused for at least 2 months can discharge your battery thus requiring you to recharge your battery before using it again.

When to charge your lawn mower’s battery

Your battery doesn’t easily get discharged. However, by routine, there are three instances when you need to charge your mower’s battery:

  • Before storing it up for winter or for a long time
  • Before using it in spring
  • When the battery gets discharged

Features of a modern lawn mower battery

Newer lawn mowers have better battery features. From 2018 models onwards, you’re guaranteed to have batteries that have the following features:

  • Trickle charge or fast charge with jump-start mode
  • Slow charge option
  • Overcharge protection (it has an auto-adjustment of amperage thus preventing your battery from getting overcharged)
  • Standard clamps size to fit both top-post or side-post battery terminals
  • Reverse hookup protection (even if you end up clasping the wrong clamps on the wrong terminal, your battery won’t get damaged.)
  • Float mode (keeps the battery from getting discharged quickly)
  • Timer

How to Charge a Lawn Mower Battery

Don’t just rush in and charge your battery without inspecting your battery. Here are five simple steps you need to do when charging your lawn mower battery.

Access Your Battery

Most riding lawn mowers have their battery right under the rider’s seat. Simply lift your seat to gain access to your battery.

Inspect the Connections

Oftentimes, a battery’s terminals are disrupted due to the constant vibration caused by the engine, the moving blades, and the mowing of your lawn mower. This often causes the connections of your battery to loosen up and get disconnected to some parts of your mower.

Try tugging on the wire connected to the battery terminals to see if they are loose. The wires should be tight on the battery to ensure a solid connection powering up your mower. If it is at all loose in any way, you must tighten the wires to create a reliable flow.

Charge Your Battery

Before you charge your battery, it’s always best to take precautions. Wear gloves and protective goggles. There are potential dangers to charging your battery like a sudden power surge.

  1. Prepare your charger and your terminal clamps
  2. Connect the red cable to the positive terminal

NOTE: Always connect the positive terminal first.

  1. Then, connect the black cable to the negative terminal
  2. Before plugging in the charger, adjust the voltage setting to 12 volts. (This is the standard charging voltage for lawn mower batteries) Unless mentioned otherwise by the manufacturer on your mower’s manual, charge your mower to the standard voltage.
  3.  Plugin your charger and wait until the battery is charged. You should leave your battery to charge for about 8 hours. If your battery still indicates low power, then it means that you need to have it replaced. No jumpstart will make it recharge either.
  4. To remove the clamps off your battery start with the black (negative clamp) and then the red one.
  5. Finally, turn off your charger.

Test your battery with a Digital Multi-meter

If your battery hasn’t charged well enough, you need to check the condition of your battery with a digital multi-meter. Before doing this make sure that your charger is not connected to your battery.

  1. Turn on your multimeter and switch it to ‘DC’. This is the setting to test your battery’s voltage.
  2. Set the meter value to 13 for a 12 volts battery.

NOTE: Check your battery’s voltage and always set the multimeter one digit higher than the actual voltage of your battery (i.e. if you have a 24 volts battery, set the meter to 25).

  1. Take the clamps and clip the red one to the positive terminal then the black clamp in the negative terminal.
  2. If the reading is lower than 85% of your battery’s charge, you need to replace your battery. For example, if your 12-volt battery reads 10.5, then it’s not giving you enough current to power up your mower.
  3. You can try to give your battery an extra hour of charging then test it with a multimeter again. If it still has the same reading, then you need to shop for a battery replacement.
  4. With further testing, you can try to turn on your mower. If you hear a clicking sound and your machine doesn’t start to rev, then you may really need to have it changed.

Inspect your water reservoir

Lawn mower batteries do not function well without enough fluid to power them up. Since they are the flooded type battery, your water reservoir needs to be filled up to the maximum. Anything less than that will prevent your battery from fulfilling its duty. Fill up the water reservoir with clean filtered water. Try to start your mower again and see if it works.

NOTE: Do not use tap water since it can contain debris or other chemicals that may not react well with your battery.

Your battery breathes life into your mower and without a properly functioning mower, you won’t be able to manicure your lawn as you want it. To properly maintain your battery’s health, I highly recommend that you do routine charging especially if you only mow your lawn once or twice a month. Lack of usage will eventually weaken your mower’s battery without proper maintenance.

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EL Mehdi (Medi), the founder and voice behind Desired Lawn Mower. He is a riding mower enthusiast who enjoys spending more time discussing and covering various ride-on mower topics. He has been active in the industry for years comparing models of different ZTR and lawn tractor brands.