Less run time on a charge

  • 2
  • Question
  • Updated 2 years ago
  • Answered
Have had the LM2000-S mower/battery about a year.  Used to get about 45 minutes per charge, now I get 20-25.  Used to do my whole yard on one charge, now it takes two.  Is my battery defective?
Photo of Bill Nowak

Bill Nowak

  • 140 Points 100 badge 2x thumb

Posted 2 years ago

  • 2
Photo of charlie hepler

charlie hepler

  • 1,338 Points 1k badge 2x thumb

Bill there is a couple of threads going on about this very subject.  I have seen my run time down this year but my yard is quite large and the grass is exceptionally thick and damp this year.  Could be just the good spring conditions or possibly the battery may be losing a little runtime in it's life cycle.  Would need more info about the battery size and any other info you can supply to get a better read on the issue.



Photo of Bill Nowak

Bill Nowak

  • 140 Points 100 badge 2x thumb
The battery is the standard 56v 4.0Ah BA2240 that came with the mower.  I did over seed the yard this past fall, so it's a tad thicker. But I have a hard time believing that could account for the battery holding half the run time it used to. 
Photo of Jacob

Jacob

  • 64,144 Points 50k badge 2x thumb
Sharpen your blade. Its almost always a dull blade that causes the 20" mower issues related to run time, mulching, and general performance.
Photo of Jacob

Jacob

  • 64,144 Points 50k badge 2x thumb
I have had cases where a dull blade gave me less than half the normal run time.
Photo of (a)Typical Engineer

(a)Typical Engineer

  • 26,412 Points 20k badge 2x thumb
Summary: "Less run time is subjective and dependent on many factors... so we need DATA"

The only real way to measure the remaining capacity of your battery is to measure the "approximate" power required to refill it.  You'd start with a fully charged battery, and then run it down to RED, and the measure how many kilo-watts were required to re-fill it.

After you have a baseline reading for your battery, you can compare month to month and see if it is changing.  This is very much an approximation, as there will be variables, such as: blade sharpness, thickness of grass, length of grass, height of grass being removed, etc.  Just like the miles per gallon (MPG) on a vehicle, it is going to vary a little between tanks.  What you're really looking for is a significant drop off in performance.

Let's consider a quick example, 5.0 AH battery (any mower).  Say it usually takes you 1-1/2 charges to mow your lawn.  A 5.0 battery has about 280 Watt-Hours (WH) of power (5.0 amps x 56 volts).  And when you recharge your battery, your watt meter tells you it took 0.250 (kilo-watts, which equals 250 watts); and the other half charge took 0.125 kW (or 125 W).  So basically, the work was mowing your yard, and the total power consumed was 0.375 kW (or 375W).

Now months down the road, you haven't sharpened your blade, and you noticed it now takes two complete charges to mow your lawn.  But when you measure the power to recharge, it still takes 0.500 kW (or 500 W); or 250 W per charge.  So you could conclude that your battery "capacity" has not changed, but something has changed which is using more power from the mower.

Last scenario, you diligently sharpen your blade; but you find that it takes 4x complete charges (I'm using round numbers to make the math easy); however, when you recharge, you notice the charger only takes 0.125 kW (125W) to top off the battery, all FOUR times.  So when you compare that the battery used to hold 250 W before going RED, and now only takes 125 W to top it back off; you have lost 50% of your capacity (125 / 250).

That's when you ring up Ego CS, give them your performance data, and ask them if your battery is still performing up to expectations.

Note: couple assumptions, the power conversion isn't going to be exact, there will be conversion losses.  And conditions WILL change.  What is important is to measure the performance over time.

STRETCH GOAL: Someone (in another post) mentioned an Ego Online Database; it would be great if Ego would setup a database to track customer's real world performance of individual batteries.
Photo of (a)Typical Engineer

(a)Typical Engineer

  • 26,412 Points 20k badge 2x thumb
Photo of Amber F.

Amber F., Official EGO Rep

  • 67,814 Points 50k badge 2x thumb
Official Response
Bill, there’s no way that your battery should be producing half of the run time, unless something is wrong with it. Please call us and we’ll get this sorted out: 1-855-346-5656
Photo of Bill Nowak

Bill Nowak

  • 140 Points 100 badge 2x thumb
Called today and got great response from EGO.  VERY impressed with the product and the customer service!

This conversation is no longer open for comments or replies.