EGO 7.5AH Battery degradation over time (3 year mark)

I log how much power it takes to charge my Ego batteries after I use them. I’m using this as a stand-in for how much capacity they retain over time. You should know that I have a large lawn (in Florida) and cycle these batteries at least once a week (more in the summer) so these batteries are getting more of a workout than if you had a small city lot that you could mow a few times before charging the battery.

I have two 7.5 AH batteries (one bought before the other). They took 410 watt hours to recharge when new.   My older battery has three years of use, and has 63% of it’s original capacity (260 w/h).     The drop from year 2 to year 3 was from 75->63% [The batteries have a 3 year warranty, so the first battery is now out of warranty.]

My second battery appears to be following the same general trajectory, although it’s capacity is just slightly less than the first battery (at the same years in service mark).

For the bar chart above I averaged the capacity of all measurements in a particular year, but if you graph all measurements you can see that they are generally decreasing over time (although the batteries do sometimes go “up” in capacity, possibly due to ambient temperatures).   The following graph is for my 2nd 7.5AH battery (manufacture date of 2018).

4 thoughts on “EGO 7.5AH Battery degradation over time (3 year mark)

  1. This is great work here. As an EGO owner of many tools, hitting the 4 year mark now.. I can see the drop of my 7.5Ah battery, lasts about as long as the 5.0Ah ones I switch off with while I mow my 0.5 acre lawn. Mine get discharged once to twice a week from April through September. I wonder how folks who take their electric cars looking 40% of their range on 3 years..

    • The (3) EV’s I’ve owned have not had this level of battery degradation. Mostly because people don’t run them down to zero every time they use them, but also because the chemistry of those cells is optimized for longevity, as opposed to maximizing energy storage/density). I think the EGO batteries are more accurately compared to laptop batteries (down to 50% after 2 years) than the larger EV batteries.

  2. Do your batteries have the “fuel gauge” (battery level indicator of 5 bars arranged in a circle)? Do they reflect the diminished capacity, e.g., do they now only show 4 solid bars when fully charged? Thanks for tracking and posting your findings.

    • No, all of my batteries (so far) are the older style with a single light ring (no fuel gauge). My understanding is that the new fuel gauge shows the “state of charge” and not the “state of health” of the batteries….so even if the battery is at half capacity, it will show “full charged” when fully charged. [This is how most battery gauges work, as they are typically based upon voltage, and not amp hours in/out. When fully charged the voltage is the same, even if the capacity drops faster.]

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