Hart electric mower won’t start? Try this.

Last Updated on August 12, 2023 by Dave Farquhar

I’m seeing a lot of people complaining that their year-old Hart electric lawn mower won’t start anymore. I don’t think that’s a coincidence at all. If your Hart electric mower won’t start all of a sudden, here are some easy things to try. It’s frustrating, but not difficult to fix.

When your Hart electric mower won’t start, it’s usually one of three things. It’s often the battery, the handle not being fully extended or locked, or the discharge, all of which are fairly easy to fix.

Don’t forget the battery!

Don’t overlook the most obvious solution. If your battery is flat, or overheated, that could be the problem. Let the battery cool down and charge it. If the battery is freshly charged and tests good in the charger, it’s not the battery.

But if the mower was working and stopped suddenly, this is a very common reason. Let the battery cool down and then charge it.

One other possibility is that the mower deck is clogged and the battery doesn’t have quite enough juice to power through it. I ran into that this year. It had rained every day that week so the grass was tall. I had a few hours of dry time on Saturday and it was going to rain all day Sunday. And that wet grass under the deck was just too much for my batteries to power through once they dropped below three bars. When I thought to check under the deck, I found my problem. I pulled out the battery for safety’s sake, cleaned out the muck that had accumulated, then flipped the mower back over and replaced the battery. The mower roared to life.

Check the handle

The reason I don’t think it’s a coincidence that mowers give trouble after a year is the handle. You may have collapsed the handle to store the mower for the winter, or bumped the handle over the course of the winter. And either of those can become a problem.

The handle is supposed to be fully extended for the mower to run. You can lock the handle in a lower position. But the extensible handle is meant for storage, not to adjust the mower’s height. Frequently when a Hart electric mower won’t start, it’s the handle. Either the handle isn’t quite fully extended, or one of the levers that holds the handle in place isn’t locked in the right position. Or both. It’s very easy to bump one of the levers when you walk past the mower in the garage.

So it’s very much worth it to unlock the handle, extend it fully, and lock it in place on both sides. That’s frequently enough to make it start working again.

Just to be sure, lower the handle completely downward. Then I extend the handle completely, and lock it in place.

If your Hart mower won’t start, this may be the most frequent reason why.

Some Hart models have two positions they lock into and will run. If you want to adjust the height, I recommend you find the two positions and mark them with some paint or tape so you don’t accidentally lock it in an incorrect position and disable the mower.

Check the discharge

Another reason a Hart mower may refuse to start is because of the discharge. If you’ve changed between the discharge, mulching, or bagging anytime recently, or you’ve removed and replaced the bag to empty it, make sure the deflector, mulching plug, or bag is installed completely, and completely snapped into place. There is a sensor that detects when you don’t have one of those three things properly installed, since running the mower without one of them is a safety issue.

I almost always mulch, so this usually isn’t the issue for me. And these parts are designed to be really easy to change. But if you have the bag or deflector installed and the mower gets bumped, I could see the bar coming unsnapped and making the sensor unhappy.

It takes about a minute to check, regardless.

In my experience, the problem is one of those two things most of the time. Check one, try starting. Then check the other and try again. You’ll probably be back in business.

Check the incline

I got my hands on a Hart manual and found a subtle, easy-to-miss warning in it. A Hart electric mower won’t start if it’s on a 45-degree incline. So don’t try to start your mower on a hill, and when you mow a hill, mow along it, rather than up and down it. This is a safety feature, intended to keep you from losing control of the mower and having it run away on you.

Bad sensors

I have heard of the sensors going bad on Ryobi electric mowers. Hart mowers are close relatives, because TTI makes both brands. Hart and Ryobi differ just enough to allow TTI to give retailers an exclusive if they want it. If you’re old enough to remember Pontiac and Oldsmobile, the difference is along those lines. So it stands to reason that Hart sensors will behave just like Ryobi sensors do.

It took less than a year for YouTube videos showing how to bypass Ryobi sensors to appear. I have a couple of problems with this. The first being the high likelihood a mower affected by this is still under warranty. Bypassing the sensors voids the warranty.

If you’re good with a soldering iron, then bypassing the sensor probably is less work than taking the mower back to the store to get it fixed. And you can make the modification in an afternoon. An authorized repair will certainly take longer than that. Maybe a week, maybe multiple weeks.

So you will have to decide if voiding the warranty on your $300 piece of lawn equipment is worth that for you. I would certainly recommend calling the store where you bought it to find out what the warranty procedure is and how long it usually takes. It’s at least worth the phone call.

That’s the lesser of the two issues.

Safety issues

The second problem is, you are introducing a safety issue when you make these modifications. I know people have mixed feelings on that, and some people like to defeat the safety measures on their tools, thinking this somehow is sticking it to the man. But if there is one thing I have noticed in the course of doing my day job, it’s that people are not very good at calculating risk. I have seen the same person say that 30% is really high or really low in two different situations, and I’ve seen this more than once.

Safety features reduce the number of bad things that happen. They don’t completely eliminate them, and unfortunately, there is an element of society who believe that if you don’t eliminate the bad thing from happening, it’s not worth doing anything. But if your choice is between stopping the bad thing from happening 50 times out of 100 instead of allowing it 100 times out of 100, it’s worth doing. At least you stopped 50 bad things. And usually the effectiveness is much higher than that.

I probably don’t know you, but I’d still really rather you didn’t get hurt.

Two possible workarounds

My workaround has been to have two mowers. Personally, I live much closer to Home Depot than Wal-Mart, so Ryobi is my brand. But this works for Hart too. You can get a 20-inch mower that works how mowers should, and get the small, cheap 13-inch mower for backup.

If one of the mowers ever gives me trouble, I can use the other one. And the 13-inch mower is small and light enough that it doesn’t take a lot of space. Granted, it’s a $230 piece of equipment. For some people that’s a lot of money. And for other people that’s a trivial amount of money. I look at it as much cheaper than a trip to the emergency room, and also less money than I would get fined if a neighbor complained that I haven’t been mowing my lawn.

If that’s more money then you want to tie up and having a spare lawn mower, here’s another option. Maybe one of your neighbors would let you borrow their lawn mower long enough to finish the job. And then again the next time you need to mow if your Hart is still in the shop. Just a thought.

Final thoughts on Hart electric mowers not starting

As much talk as the sensors on electric mowers get, it’s usually not the sensor. It’s usually a simple, two minute fix to get up and running again. And while it can be annoying, when a gas mower won’t start, I usually spent more than two minutes pulling cords and begging the mower to finally start. Given a choice between pulling cords with all my might or snapping and unsnapping components and handles to lock them into proper position, I’d rather spend two minutes locking components back into position.

It’s a tradeoff, but I think the tradeoffs are more than worth it.