Cordless lawn mower briefly starts then cuts out

Question

I have an Echo CLM-58v cordless electric push lawnmower. It's worked fine for ~1.5 years, however when I took it out of storage this spring it stopped working. When I start it, it gets a brief burst of power, less than a second, then cuts out completely. The burst of power is enough to get the blade spinning, but it slows to a stop shortly after the power cuts out.

I've checked the wiring harness, everything seems intact. I've checked the circuitboard that handles voltage regulation and the switches and it looks intact as best I can tell (the housing doesn't come off so it's hard to see). I checked the battery and it reports as fully charged and the multimeter says it is at 57.1 volts out of the supposed 58 volts, which seems fine to me. I also checked both the power switches and they have continuity when pressed, so I don't think it is them cutting out. There is a third safety switch I haven't tested for continuity, but when it isn't pressed and I try to start nothing happens.

Has anyone else experienced this issue or have any idea what might be up with it?

Answer 1

I have had 5+ batteries brought to me that show full charge to no charge but do similar or slightly less.

In all of them they had been heavily discharged according to the owners.

All of them had melted a solder joint connecting to the battery pack. I was able to reflow the solder and save the packs in all of the cases.

2 of them showed no charge but it was the same as the others that showed full charge once properly connected they worked fine.

note these were all OEM battery packs and from 2 different manufacturers so it’s not an aftermarket issue. I would check the internal contacts first unless the mower has other troubleshooting guides like an unbalanced blade that shuts down for safety or an excessive current because of built up grass.

Answer 2

I checked the battery and it reports as fully charged and the multimeter says it is at 57.1 volts out of the supposed 58 volts, which seems fine to me

Is that the voltage checked right after charging? Or did you check the voltage only after attempting to run the tool and it stopped?

I don't know the exact specs for the Echo batteries, but fully-charged 57.1 V for a 58 V battery is not "fine". A fully-charged battery will have higher voltage than nominal. Even after being used briefly, it should. So, it seems likely your battery has failed.

There is a small chance that the tool itself has some kind of fault that's leading to excessive drain on the battery, such as a short. But the fact that it runs briefly suggests that this is probably not the case. It's much more likely that the battery simply cannot hold enough charge to run the motor for any useful amount of time.

Maybe you can fix the battery as the other answer suggests. Though frankly, it's not really clear in that post what electrical connection it is they are actually talking about. A photo should have been provided, or at the very least a more specific description.

The fact is, without having the mower in hand and being able to perform specific diagnostic steps on it, it would not be possible for random people on the Internet to tell you for sure what's wrong.

Answer 3

I have the same mower. I solved this exact same problem today. That safety switch (the one you said that you haven't tested yet), THAT'S the culprit. It's a deadman switch, if it loses contact for even a second, the mower will die. The switch connections are not well protected from the elements, and prone to dust, corrosion, etc.

You need:

1. a small wire brush
2. dielectric grease

Remove the connections of the deadman safety switch. Clean the spades with the wire brush. Then slather the spades with dielectric grease. Pictures included below.

Answer 4

I have been frustrated with this same issue for months and finally found the fault! The battery has a tiny bit of play with it, ie it’s not locking 100% into place! Open your battery compartment and HOLD your battery firmly into place by pushing it all the way in. Then whilst still holding it start the mower and I guarantee you it works and stays on…but if you let go of the battery or knock it ever so slightly the battery is coming out ever so slightly and it dies straight away. I fixed this with a fudge…the locking mechanism on mine slots into the back of the battery, I made the slot it goes into on the battery not as deep by 1-2mm by putting some superglue in it. It padded it out and now locks in fully. Not the best fix but I have now emailed Bosch about mine to see what they say as the glue will eventually wear off. But atleast you know the problem now!

Answer 5

I'd like to describe the "adventures" I had with an Ozito which I picked up after it was put out on the nature strip without its batteries. I decided I had nothing to lose, so "inspected it". Looked good. I thought the construction was fairly good. Everything was easy to remove and quite solid. Motor seemed good.

Next, I thought I'd try my two 18v drill batteries (probably 2 amp hour) and I made an adapter for them which I attached to the mower. I found what the original poster described - motor would run fine for about 15 minutes, then start cutting out increasingly. I found the battery voltage fell to just below 19v, indicating insufficient charge. But even after recharging, the cut outs would start much sooner.

To try to eliminate everything other than the batteries I bypassed the solid state overload protector, the motor being now directly connected to the batteries via the on off switch. No change - the cutting out continued.

I then purchased two Milwaukee 6 amp hour batteries via eBay (at less than half the price you'd pay for batteries at a shop or from a posh manufacturer) The result was spectacular! Having a medium sized front and backyard, I have now mowed them both, and the nature strip, more than twice over, and the batteries are still not flat!

I have not yet tried it on tall grass, but was impressed on how long the motor runs without discharging the batteries. Basically, using 6 amp hour batteries transformed this lawn mower into something very much better.

My opinion (based on my personal experience, but I acknowledge I could be wrong) is that if the batteries are less than 6 amp hour (maybe even 4 amp hour), it is not only how long they retain a charge, but rather how much current can go through them. As well as their age, of course.