SP mower battery life?

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I had an electric SP Ryobi mower for over 20 years -- loved it, limped it along for years, but it finally fell apart and died.  I've been looking for a replacement for several years, and it sounds like the 21" SP is as solid and well-designed as my trusty old Ryobi.  Yay!

But:  the 7.5Ah battery costs about $350 !?!?  Eeeyowch!!  What is the expected lifespan?  If it's rated for e.g. 200 charge cycles, that would last me upwards of 10 years and I'd be satisfied with that.  If it lasts 4-5 years, not as happy.  Is the 3-year battery warranty pro-rated?
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Gary

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Posted 3 years ago

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Gary

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Hm, at https://community.egopowerplus.com/ego/topics/what-is-the-life-expectancy-of-the-battery-in-the-ego-... Blue Angel said lithium cells are good for 500-1000 cycles.  That would be fantastic.  

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries indicates depth of discharge is a big factor; for Li-ion batteries, they estimate 300-500 cycles for 100% discharge, 1200-1500 cycles for 50% discharge.  With my lawn I expect it won't go below 75% so that suggests somewhere around 750 cycles.

I mow roughly 6 months a year, about 20x/yr.  At that rate 500 charges should last me for 25 years!  Is that a realistic expectation for the 7.5Ah battery?  If so, it's a non-issue.  The mower will probably fall apart before the battery gives out.  
(Edited)
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Blue Angel, Champion

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Gary, it sounds like you're convincing yourself nicely!  :-)

I chose to put my money into the Ego ecosystem after researching their battery technology.  As far as I can tell, they have far and away the best Engineered battery/charger SYSTEM on the market.  The fact the tools are so well designed doesn't hurt either!

Lifespan of LiIon battery cells is dependent on MANY factors.  As you pointed out, depth of discharge per cycle plays a big role.  Another factor is peak charge voltage... if you watch the beginning of this video you can see how Ego charges their 14 cell battery packs to a slightly lower voltage than Echo charges their 14 cell packs:

https://www.youtube.com/watch?v=lRdBS9oFUXc

The more voltage you pack into the cells the more you tax them, shortening their expected life.

Having said all that, probably the biggest factor in shortening the useful life of LiIon cells is heat, and this is where Ego really shines.  With phase change cell wraps they are able to maintain the temperature of the cells during charging and discharging cycles MUCH better than the competition.

Here's another video that really shows this... taking hot battery packs right off the blowers and putting them right onto the chargers over and over, simulating what a commercial user might expect from a battery tool platform:

https://www.youtube.com/watch?v=8jPgrPtGH7o

(That guy has several interesting Ego vs. Echo battery videos on his channel)

Long story short, I expect my Ego tools to last a very long time!
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Kid Rock

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Trying not to be a fanboy here (neutral and unbiased)... Read this if you really want to analyze it. Otherwise, my points convince me it's still a great value!
___
It's $380 at Home Depot in California. If the battery lasts 10 years that's $40 a year (if you include tax). So you have a great question. Ego is positioned in the forums as a inexpensive option to gas. So this will be an interesting thread!

$40 a year buys a lot of gas. Some people don't spend a lot on gas mower maintenance (even though suggested). So this may be a good longterm cost figure. But there is the unexpected repair that I have encountered. (gas Echo string trimmer with a failed engine after warranty expired, lead acid (cheep) battery failure in a Lawn-Boy mower with Honda engine).

I would imagine Ego knows and is counting on battery sales in their revenue. Either people will buy a new tool (do to huge cost of 7.5 Ah battery) or buy a smaller battery with less power.

Important to consider...

» People buy electric to help environment.
» Ease of use, no old gas to deal with. Or trips to the gas station.
» Less smelly.
» The batteries can be used across the Ego lineup! Although, I wouldn't want use a 7.5 Ah battery in the handheld Ego tools. But capacity per pound will likely go down... Using higher Ah cells. And my 7.5 Ah battery mowes my 3 lawns 3x (new battery on thinner lawn). Still I would expect to get two mows at least for years to come. But as long as I get one with power to spare, I'm happy!

I think you should consider that the battery also runs all the tools in the Ego lineup. So the cost is across several tools and not just one.

Me, I'm still an Ego fan and it still makes a lot of sense to go cordless with Ego!
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Kid Rock

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Something more to add to my post above...

$40 a year for gas... Hmm not really a lot of gas. When gas was $4/gallon it would have been 4 gallons a year. Even if someone said they were adding 8 gallons a year to the amount of fuel your car uses, would that sound like a lot?

Plus...

If at many years (just very likely as you never know for sure) from now I had to replace my mower battery I would be fine with a 5 Ah battery as for me, it would still cut my lawns close to 2x.

Plus, with new products coming out I would just need to get one with a 5 Ah battery. Problem solved! Today it might be a chainsaw.
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Blue Angel, Champion

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Ah, that reminds me...

Gary, another thing to consider is how batteries are getting better and cheaper with time. 18650 Li-Ion and other "commodity" cells have been improving on their cost/performance ratio by about 7% per year. So if we estimate 7% for 10 years from now:

1.07 ^ 10 = 1.97

That means 10 years from now, the cost of cells for a given capacity will be roughly 1/2 (divided by 1.97) compared to the cost today. Since the raw cost of the cells is the large majority of the cost of building a battery pack, I would expect today's $350 battery pack to cost MUCH less than it does now.
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Gary

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This is dredging up an old thread, but... I think it will be much better than your example.  According to https://en.wikipedia.org/wiki/Electric_vehicle_battery the cost per kWh in automotive Li-ion batteries has dropped at 20-25% per year.  Other sources suggest rates as high as 30%.  Maybe E-Go can't match the cost efficiencies of car companies, but I'd bet their battery costs will drop at least 15% per year.  Which says the battery costs would drop by 50% or more in just five years.
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Exrace

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https://www.tesla.com/gigafactory Ego...source your batteries from Tesla!
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Blue Angel, Champion

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Gary, I believe some of those higher reduction figures are speaking to the cost of the entire battery pack as a whole component. A lot of that cost reduction is seen through volume manufacturing of the packs (economies of scale). Once labor intensive hand made items in 2008 (Tesla Roadster), EV battery packs are now benefitting from high volume production techniques.

The 7% I've seen referenced is speaking to the $/performance ratio of commodity cells like 18650's.

On that note, Ex, it's funny you bring up Tesla's Gigafactory. Their new commodity cell is a 21700, a larger cell than the 18650. By simply making the battery ~30% larger by volume they are increasing the $/performance ratio substantially in one step. Since the cost of the raw materials is only a small part of the cost, the price per kWh drops substantially... a key part of their strategy in launching the Model 3.

Samsung has also launched a similar larger cell for the same reasons. Something I didn't know about three months ago I guess.
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Julio Villanueva

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When you buy the 21" SP mower get the one with the 7.5 battery included. It will only cost you an extra $100. Only if you'd buy the battery by itself you would pay the $350
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Kid Rock

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$380 plus tax at Home Depot in Sacramento region. Worth the extra $100 especially if you have multiple Ego tools and more to come.
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Jennifer VandeWater, Community Manager

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Official Response
Just one quick reminder to chime in here as well. The batteries and chargers are covered by a 3 year warranty so you can, at least, rest easy knowing you're covered for 3 years without issue as long as you purchased from any of our authorized retailers.  Make sure you register all of your tools/batteries/chargers and keep a copy of your receipt.  We'll even store the receipt in your account for you to help!
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Gary

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Well I just took my new Tesla for a spin around the yard.  :-)

The grass was pretty light -- I just mowed 5 days ago.  But I wanted to mow before I left town for a week, and besides I needed to test out my new toy!  I mowed at full drive speed without noticeably loading the blade motor, so it wasn't a tough test.  But here are my thoughts:
  • Good lord this thing is light!!  It feels like a toy.  My old (vintage 1993) Ryobi SP electric was a TANK compared to this mower.  It's so light you almost don't need the self-propulsion.  Almost.  I still use it.  :-)
  • I much preferred the front-wheel drive of the Ryobi.  If I needed to stop suddenly or turn around, I just pushed down on the handle and the drive wheels were spinning in the air.  It worked very well for panic stops and 180° turns.  I'm learning to let go of the drive-engage lever in panic-stop situations, and for 180° turns.  I'm still refining the timing to re-engage the drive so I can take off again without waiting for the soft-start to spin up.
  • My lot is about 1/3 acre, with maybe about 5000 sq ft of grass.  I didn't time myself but it usually takes about 45 minutes to mow; probably less this time because I was mowing in Ludicrous Speed.  When I put the battery back on the charger only one light lit up, but within 10 seconds a 2nd and within 30 seconds a 3rd lit.  I didn't watch it but I think the 4th light started flashing after maybe 20 minutes.  So apparently I used something less than 1/2 charge?  So even with thicker grass it should have no trouble cutting the whole yard.
  • I wiped off the underside with a wet rag when I was done.  The grass seemed to stick -- I had to rub fairly hard to get it off.  Is that normal?

So, first impressions:  I like it.  I don't think I'm a fan-boy (yet?) but it works well.  I want to see how it handles mulching heavy grass.  But I've been looking for a good replacement for my Ryobi for almost 10 years (I found another Ryobi and used it as a parts mule to keep mine running for another 5-6 years) and I think this is finally it.
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Jacob

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The first few charges, i have noticed, are like learning charges. I dont know why but the same happened to me. My first run with my 20" mower was like 15 mins. I charged it too before that. 2nd mow was better, but the third charge is when it lasted as it should. Just my experience
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Jacob

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Sorry. You didnt deplete the battery all the way. I didnt see that. Yeah. That battery if its the 7.5 ah, will last over an hour i believe. Charge it every other time you mow or every 3rd mow.
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David Cline

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The 21" SP varies the power—and thus the run time—a lot more based on how dense the grass is. My first mow of the season used slightly less than half of the battery. My last mow (cutting on the lowest setting just before leaving on vacation) managed to completely deplete my fully charged 7.5Ah and then 85% of a 2.5Ah.

Turns out my "torture test" (cutting wet, overgrown grass on 2nd cutting height) wasn't the as taxing as cutting a few days later on the lowest cutting height! The 7.5Ah got through all of the cutting and still had enough charge left over for trimming and blowing without reaching the 15% remaining red warning light.

Anything that causes the mower to ramp up power and stay elevated is going to drain the battery much faster than typical mowing conditions. Very similar to blower run time difference between low and high power when running it continuously using the 7.5Ah battery.
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Gary

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After using the E-Go for several months, I still like it.  This is a great mower!

One complaint:  it doesn't mulch.  It doesn't chop the grass finely.  It's OK if the grass isn't very long, since the pieces it cuts off aren't very long.  But if the grass gets longer, so it's cutting off 3-5", it just leaves piles of 3-5" blades on the grass.

Am I doing something wrong?  I don't remember the manual specifying anything that had to be done to make it mulch properly, but I'm remodeling my house and I can't find the manual now.
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David Cline

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Sheesh! Since it's very bad for the grass to take off more than 1/3 of the blade, I assume you are cutting grass that is at least 9-15" high!?? Once per year mowing?
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Gary

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No, I was out of town for almost 2 weeks.  Some patches of grass got a bit long.  I cut at the highest setting but that was still about half the blade.
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Blue Angel, Champion

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In a situation like that it might not be unreasonable to have to go over it a second time. With the mower at its highest setting and only cutting half the blade is pretty long grass.

Do you find it works well when doing your weekly cutting?
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Gary

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Well as I said, with short grass the pieces it cuts off are already short.  I can't tell if it's chopping them up or not.  But it is definitely not chopping long grass.  At least it's not chopping all of it, since it's leaving lots of long blades behind.

FWIW my old Ryobi mulched everything like a champ, including long grass.  It never left anything visible behind -- all the mulched-up pieces disappeared into the turf.  So it is certainly possible.  If a vintage-1992 electric mower could do it, the E-Go oughta be able to do it too !!
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Blue Angel, Champion

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Gotta agree with you there! :-)
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Gary

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Blowing the dust off this thread...  FWIW 3 years ago @Blue Angel predicted 7%/yr decrease in E-Go battery prices.  7%/yr for 3 years should have dropped the 7.5A price from $350 to 0.93^3 = 80.4% or $281.  

And BA was being very conservative.  BloombergNEF (link) says LiIon batteries actually dropped 26% in 2016-2017 and 18% in 2017-2018.  If we guess the average and say they dropped 22% in 2018-2019, that says batteries "should" have dropped 1 - (1-26%)*(1-18%)*(1-22%) = 53%, dropping the 7.5A from $350 to $165.

In reality, the original 7.5A BA4200 battery price is unchanged after 3 years.  

I discovered there is a new BA4200T battery, which you might expect to benefit from new development, cheaper batteries, etc.  At HD it is still the same $349 price as the original BA4200.  

So while the underlying cost of batteries has certainly dropped in 3 years, E-Go does not seem to be in a hurry to lower the prices they charge us.
(Edited)