RPM too high shotening run time

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  • Updated 2 years ago
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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.

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Michael

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Posted 5 years ago

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Blue Angel, Champion

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Curious problem you have there, for sure! Even more curious is why the old mower runs with the handle in the collapsed position?
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Denise C

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Official Response
Hello Michael! Thank you for your post and for taking the time to document the comparison of the RPMs between your old mower and your new mower. You are right in suggesting that this problem would affect the run time of the battery. The noticeably high RPMs and the mower running without the bail handles being fully extended are not normal functions, and so we'd like to get it back for further inspection. Upon looking into your account, I see that we sent you a pre-paid return label on 5/14 to your email address. If you could please send back the original mower and charger using that label so that we can further inspect them, we would greatly appreciate it.
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Rhys Wiremu Arama

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Have you figured what to do about this problem being two years ago now i bought an ego lawnmower beginning of this year 2017 with the same problem occuring RPM too high no variation from start to finish. I am from New Zealand. What do I do to repair this problem thanks.
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Blue Angel, Champion

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Rhys, you'll have to call Ego in New Zealand, I don't think there's a user fix for this issue.

Here's their contact page:

https://egopowerplus.com.au/pages/contact-us

They should be able to get you back on track.
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Michael

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I packaged the old mower in the box that you sent the new mower in and dropped it off at FedEx this morning so it is on the way.  The new charger came in a separate box from the mower and since you provided only one return label, I assumed that you only wanted the mower and not the charger.  If you want the old charger as well, please send a separate return label.  There is no way I could get the old charger to fit in with the mower as there is no empty space large enough.
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Denise C

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Hello again Michael! No worries about sending us back the original charger. Please feel free to keep it as a back up if it is working properly for you now; -or- recycle it if it is giving you issues as indicated in your original call.
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Steve Valdes

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I have the exact same issue with one of my mowers. I use two for my zero emission lawn care company. I love these mowers and they perform great. In a way I find the higher RPM to provide a better cutting condition with the get up and go. The other unit is much slower to get up to speed. This high rev seems to happen when the safety stop is not working as the handle is in the collapsed position. The only other problem is with the handle clamps coming loose regularly on both mowers. I deal with this by using some straps to hold them in place.
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.
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Michael

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OK.  Here we go again!  About 1/2 way through this mowing season an almost exactly 1 year after receiving my replacement mower, the RPMs are now running high again.  This is the exact same condition as I originally documented in the video above.  There is obviously a fundamental design flaw.  I never heard back from EGO about what is causing this.  Even tough it is kind of a feature because with the higher RPM, it does cut very tall, thick grass quite well, over the longer term, I would suspect this may cause premature motor failure. So, I am on the fence about what I should do.  Is there anyone else that has had this problem that is now seeing their motors failing? 
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Rhys Wiremu Arama

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Hi there. I am from New Zealand and I too have the same problem as you. I bought my lawnmower near the beginning of this year. I Just wish someone out there can give us a fix or perhaps a reset method or something that lets us control the RPM ourselves.
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Jacob

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Agreed. A rpm control is a must have. Sad that they don't have this.......
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(a)Typical Engineer

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The excessively high speed is a problem, and the fix is to have it repaired, and the part being replaced is likely the control board or speed sensor.  There is no other "reset", other than removing all power, e.g. the battery from the mower.
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Jacob

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Control board it is. Speed sensor is on the board. Assuming it's the same as the 20"
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Dave .

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Would gladly give up about 20% or so runtime, to have the RPM go up to the "tough grass RPM" speed.  That way, I presume that once I get the high lift blade in the spring of 2017, the mower would perform more like I expected it to (given the grandiose claims on the 21SP's box) and like I WANT it to.  Granted, I already know that the HL blade won't improve the pathetic mulching performance--but at least it should vacuum little debris/grass clippings off of the grass and sidewalk better that what it currently does.
(Edited)
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Michael

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Unfortunately, the runtime reduction is more like 50%.  However, I sprung for an additional battery this year so with two batteries, runtime is much less of an issue.
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Dave .

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that would be too much of a reduction in runtime for me.  :)
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SueLW

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I also think it's my lawn mower and not the battery causing the decreased run time, but I haven't noticed  a change in the RPM.

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.
(Edited)
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Jacob

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Sharpen your blade. Problem solved. Sharpen it to a very sharp point. NIght and day difference. Sharpen it more than a new blade comes. So sharp you could carve prime rib with it.
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SueLW

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Did that 2 days ago. cutting performance better but mow time still reduced. 
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Exrace

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Ninja Sharp. :)
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Michael

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Here is the test that I believe determines if you have to too high RPM problem.  Lower your handlebar as if you are going to store it, then try to start the mower.  If the mower starts and runs, then you probably have the too-high RPM issue.  Notice in the video the one running with too high of RPM has the handlebars in storage position.  You should not be able to do this in a properly functioning mower.  But hey, if you have multiple batteries, then run-time is no longer an issue and the higher RPM actually gives you the ability to more quickly cut thick grass.  I now have two batteries (had to buy the second one myself) but I am currently not in a hurry to resolve my high RPM issue.
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Michael

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Additional thought...
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.
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Jacob

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I dont know how true those comments are. I used to work on f15 fighter jets. Not an enviro-nazi. I havent had this issue on 2 mowers. Also implying that ego is covering things up is quite a bold statement. I think your asumptions are rediculous.
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Dave .

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A37's, F100's, and F-106's here.
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Jacob

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Airforce too. I was stationed at Elmendorf AFB, AK. Cool dave.
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Steve breech

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Michael--Hooray for you! My comments exactly....these folks love these mowers that just don't cut very well, don't mulch very well...but they have those little useless headlights. They defend them to a fault.

I would love to get my mower to step up the RPMs

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Art Zasadny

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I'm an IT professional and brew beer/mead, repair guns and reload my ammo, etc... so I tend to notice mechanical things and I have not experienced this issue but I appreciate you making us aware of it.
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Michael

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And I am sure if you had this problem you would recognize it immediately.  

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.
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Jacob

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Hm. Interesting observation about the shortened battery life. I wonder if this could be true. Like there are a bunch of high performance mowers out there. Like hot rod mowers. I want one. But your comment may be correct. I understand what you are saying now.
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Steve breech

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I 2nd that too!
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Exrace

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I understand this rpm issue has to do with the load detection circuitry.
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.
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Steve breech

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I continue to fight the low rom issue with no proper cutting, losey bagging and almost no mulching. 

 I bought the 2 battery deal, got a 2a and a 7a battery. My 7A was dead so while it charged I used the 2a. With the 2A in the mower and it ran at all high RPMs, it worked like my old Honda. But when 2A went dead, the 7 was charged, so I put it in.  Then back the old start fast rpms then drop off to low speed and crummy mowing...but "the" little dinky headlights worked great.

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Exrace

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That is interesting. Do you have another 7a and does that behave the same way?
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Steve breech

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Yes, I have a 2nd 7a.  I will try both again this week end to see happens
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Michael

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Exrace,

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.
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Exrace

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Speculation only.
If I was troubleshooting this myself the first thing I would check would be all wire connections for high resistance connections by inspecting all wires connectors.
I understand the "controller" is not accessible as it is incased in plastic like the batteries controllers are. I would like to learn more how it works myself...I am curious that way. :)
(Edited)
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(a)Typical Engineer

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Couple thoughts on the matter:

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