I purchased the mower last year and all was well. This year during the third time mowing there was an incident where my tire slipped off the grass edge into the garden causing the deck height to drop and bogged the mower down for a second. Once recovered from the bog-down, the RPM was instantly higher. I thought initially that it sensed the need for more power and entered a turbo mode. However, the RPM never returned to normal even after future uses and charge cycles. This is a problem since it drastically shortened run time which before was 40+ minutes dropping down to 22 minutes at best.
See the video for a side by side comparison of the old and new mowers.
I contacted customer support and was told they had never heard of this condition. They sent me a new mower and charger (sans a new battery). I was able to compare the two mowers using the same battery and the new mower very clearly runs at a slower RPM and it's cutting and run time performance is as it should be.
I could not find anyone else claiming to have this experience but perhaps it is happening to others and they are not really noticing the RPM difference. I do see where folks are having trouble with run time being shortened though so maybe the higher RPM issue could be the cause in some cases. It certainly was in mine.
The units are just over a year old and have been well used but I guess I will see about getting the faulty one replaced because of the safety issue and getting the handle clamps replaced with the new improved versions. I just don't have the ability to operate with one at the repair shop and only one in service so a shipped replacement sounds great.
From the start of this mow season, I've noticed both of my batteries had 50% decreased running time; approximately 10 to 15 minutes on the 2.0 and about 20 minutes on the 4.0. I called EGO and they sent me 2 new batteries in early May, but this made no difference in the run time. I've continued to mow with the new batteries and requiring multiple charges on both just to finish my lawn. I have approximately 1/2 acre of lawn. I thought maybe it was due to my lawn having grown thicker this year but also thought it may be an issue with the mower itself. I'm not sure about the RPM issue. After watching the video above, I haven't noticed the RPMs running fast like that. I have maybe 1 or 2 mows left for this season. I think I may need to give EGO a call.
I am sure that ego knows what is going on here and they are concealing some type of major defect that possibly could result in a recall. I find it extremely unlikely that I have had this same problem with two consecutive mowers and I am the only one having this issue. My guess is that most EGO customers are not tuned into this kind of thing and can't tell the difference. I noticed it the first time because it happened in the middle of a mowing session and it was obvious. Plus, I am kind of a gear head and pick up on these things. I would guess that most of Ego customers are enviro-natzis and not really the gear-head type that would pick up on this so this somewhat subtle issue.
I am not suggesting that they are covering anything up but rather more likely ignoring it. Are you so naive that you think this does not go on? Recent examples are all over the place in the automotive industry. GM ignition switch. Takata airbags. VW diesel emissions.
From what I have read, shortened battery life is a common problem for the Ego mowers. Given my experience with the only two Ego mowers I have ever owned, yes, I am suspicious that some of these shortened battery life issues may be related to the too high RPM issue I have personally experienced with two mowers in less than two years. I can see a battery depleting early when it gets some age and use on it. But I am talking about batteries that are only months old and only used once per week in a northern climate (6 mo mowing season).
I read about the sharp blade solution and tried this. It did nothing for me.
Now that I have cut my lawn recently with position 2 I observed this working correctly on my 21" as the mower worked harder to cut/mulch. I would like to understand how the mower detects load but I assume this has to do with the AMP draw and rotational speed.
I am curious about your comment "I understand this rpm issue has to do with load detection circuitry". What information do you have about this? Did this come from EGO? Are you speculating that there is internal RPM regulation circuitry that could be malfunctioning? I have never had the mower apart.
1) The mower running with the handles in the collapsed position, seems like an unrelated issue, e.g. there could be another mower with the high RPM issue, and it may or may not exhibit the safety symptom of running with the handle collapsed. Both the load sensing circuit and the safety cut-offs go to the motor controller (well of course they do, the safety circuit is a sub-system to the controller).
2) The load sensing could be based on two methods: a) hall effect sensor, or b) current sensing. I am pretty sure it's a hall effect sensor setup because there appears to be a magnet on the top end of the armature shaft, which sits in close proximity to other electronic gizmos above the brush assembly.
For Michael's case, but guess is that the motor controller is the issue, not the speed sensor, since the controller is the common piece that could cause both issues.
I have also noticed that when the motor senses the blade slowing down due to increased load (e.g. when I hit a patch of thick grass), the mower will attempt to compensate by increasing the RPM (ramps up quite quickly), and then when it sense the load is no longer there, it coasts back down to normal RPM (ramps down slowly). This has only happened a few times (maybe 1 in 5 times mowing).
In the picture below: a) the motor controller is right below the rear wheel, and it sits on top of the motor, b) the white block is a ceramic enclosed resistor, c) the red/blue/black connect to the battery, d) the hanging black plastic is the RH pivot, which contains the safety switch to ensure the handles are in the raised position.
See this post on why I had to tear this apart. =)
20" Mower "field" repair of the MOTOR