Can You Jump A Lawn Mower Battery With A Car?

For bigger yards, riding lawn mowers are lifesavers. They chop up more grass at a significantly faster rate than a push mower, and, of course, you don't have to do all the pushing and pulling that walk-behind units require. For some yards, there's debate over whether a riding mower or lawn tractor is best, but overall, they're both huge aids in the lawn care department. In turn, though, they need to be taken care of, with routine cleaning, part replacements, and oil changes being necessities. Being mindful of the battery is also key, as is how you jump it (if necessary).

Say you get your lawn mower out after a long, cold winter and find that it won't start. It may just need to be jumped, not unlike a weak battery on a car or truck. Conveniently, you can actually use a car and its battery to jump a riding mower battery, and much of the process is similar to attempting to jump a car with another car. It should be noted that this is only possible with a 12-volt mower and a 12-volt car battery. If the voltages don't match — like if you're trying to jump an electric push mower with a 6-volt battery using a 12-volt car battery, for example — it won't work. If you attempt it anyway, you will likely wreck the smaller mower battery.

So long as you have the right hardware, the voltages match up, and your manual doesn't warn against it, jumping a riding mower isn't too hard. Here's how it's done.

Jumping a lawn mower with a car is pretty straightforward, and it only requires a handful of tools to pull off. The first thing to do is gather some safety equipment, specifically gloves and goggles — some of the many must-have pieces for home mechanics — to keep your eyes and hands safe. Naturally, jumper cables are necessary, too. Additionally, you want to ensure the car and mower are securely parked on level surfaces and are powered off. With that, you're good to go.

1. Connect one positive (red) clamp to the positive terminal of the mower's battery, and the other positive clamp to the positive terminal of the car battery. 
2. Connect one negative (black) clamp to the negative terminal of the car's battery.
3. Connect the other negative clamp to the mower's engine block via a bolt of your choosing. Alternatively, you can attach it to the frame away from the fuel tank. Regardless of placement, do not allow the clamp to touch any wiring.
4. Turn the key on the mower until it powers up.
5. Once the mower is powered, disconnect all of the jumper cables in reverse order: negative to mower, negative to car battery, positive to car battery, and positive to mower battery.

From here, you want to let the mower run for a bit; this way, the battery can recover its lost energy. If this doesn't do the trick, though, you might be looking at a bigger issue.

In many cases, jumping a weak lawn mower battery will get it up and running with no problems at all. However, if there's anything else wrong with the battery, then it won't be very effective. For one, there's a chance the battery may need to be replaced outright. If it's older than three to five years, it could just be on its way out. The battery may also have corroded or damaged terminals, cracks and swelling in the casing, or leakage, all of which are clear signs that the battery is at the end of its useful life.

If the battery isn't to blame, there is likely something wrong elsewhere inside your lawn mower. A common problem is the solenoid, which can prevent the starter motor from receiving enough electricity to power up the engine. There could also be an issue with the starter, the ignition switch, or a fuse. The engine could even be seized. If you're not comfortable attempting to diagnose and fix your mower, you can always take it in for repairs. If you're having trouble finding a mower repair service in your area, you can try consulting your local Home Depot or Lowe's. They don't do in-house repairs, but they can point you in the right direction.

Lawn mower maintenance can be a process, and neglecting it is a major mistake almost everyone makes with their mowers, but it's worth it in the end. The last thing you want is to have to jump your mower all the time or, worse yet, investigate why jumping it doesn't work.