Curious on battery life

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Hello, I was wondering how long the lithium ion battery is expected to last before it needs to be replaced. Also how much do replacement batteries cost. I was looking at the 7.5 amp battery.
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Paul Partington

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Posted 3 years ago

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Blue Angel, Champion

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Official Response
Paul, Ego's 2.5, 5 and 7.5Ah batteries use Samsung 25R cells, a highly regarded high-drain cell designed for these applications.

They are officially rated at 250 cycles, but that is at a continuous drain of 20A, their maximum rating.

Even if the 1000W motor in the 21" SP mower was running continuously at full power (it never will), the mower would draw 20A from the battery. Since the 7.5Ah battery has three parallel strings of cells (3P), each string of cells (therefore each cell) will see only 1/3 of that, or about 6.6A.

Depleting the cells at 6.6A instead of the rated 20A will lengthen their cycle life considerably compared to the 250 cycle rating, and that's IF the mower was drawing 100% load at all times, which would never be the case.

Also, Ego's Battery Management System doesn't charge the cells to their full 4.2V 100% charge capacity, nor does it drain them to their minimum 2.5V 0% capacity, both of which also reduce the impact of cycling.

If you figure mowing once a week (50 times per year), you can conclude that for most people the batteries will age faster due to time than cycling.

My personal estimate is 5-10 years depending on conditions, but it could be longer for someone who doesn't need all of it's capacity to get the job done. If the battery is 10 years old and has fallen to 60% of its original capacity, the battery is still good if it has enough juice to get the job done.

Simple answer: It depends. :-)