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1) I found the April 1st ad hilarious, but don't get me started because I have ideas ;)
2) I tend to know more about batteries than I ever wanted.
The 30 minute (and longer charger) that comes with the mower should have two modes to maximize the life and capacity of the battery. You are actually costing yourselves quite a bit of potential money due to warranty replacements because this was not properly implemented. The charger should have two buttons/options when a battery is docked 1) maintenance charge and 2) run charge.
1) "Maintenance charge" (or storage charge) should be for after the battery is used for the day.
2) Just before use, you would activate the "run charge", doing a full battery load. If you set your cutoff for the maint change at about 50%, this would only take 15 minute to do, roughly the time most people probably spend doing a quick trim job or something like that.
As you should be aware, optimal battery storage for this type of battery is around 35-50% charge, the cooler the better. Storing them drained after use or charging them to full is actually quite hard on the battery long term.
So I'm basically left with a situation where after I run, I need to put the battery on the charger for probably 5-10 minutes and them remember to go pull it off before it fully charges. This is the only way to properly and safely optimize the life of the battery with your system today.
I just picked up the mower last night and look forward to hopefully a blower, trimmer, and bladed edger in the future... but this seems like a pretty big "oops" in the design department for something that is this technically advanced.
So some quick research on li-ion, li-po, etc battery storage temperatures/voltage/capacity and you will see what I mean.
I fly electric radio control planes for a hobby and totally agree with the OP. Planes have slowly been making the transision from gas to electric ofer the last few years. I been charging my Ego packs when I am done for the week until I see the 50% light flash and then pull them off. Just something people theat are used to working lithium batteries hard are used to doing.
To the OP.
You are correct, but from my reading you will get best battery results if you do not drain the battery all the way, store inside in a cool place, and charge the battery to roughly 50%. Check out this link, the number of charge cycles falls drastically with temperature and full charge drain cycles.
It's a good read. I would love to see an option on the charger that automatically trickle's a battery down or up to 50% when it's in the holster for more than 48 hours.
Thanks for the good read.
I just came across this older thread and wanted to shed some light on the battery maintenance issue.
Eric, you are correct; lithium cells do not automatically discharge to a proper storage voltage. However, the Ego battery PACK is designed to discharge its cells to a proper storage voltage after a sedentary period of one month. It is not the CELL that performs this action, it is the pack electronics that do. It is a very sophisticated system, one that earned my business after researching.
Knowing, like you, that cells are better stored in a semi-depleted state, my personal approach is to charge the pack just before cutting the lawn and not recharge it immediately afterwards. In my case, this drains the pack to roughly 50% capacity before storage and the pack only sees a full charge level for a short while before mowing.
While you are correct about optimizing battery life by setting the charge voltage after use, I'm sure if you plotted the benefits of different battery maintenance and cell optimization methods, you would see a "bell curve" type of distribution that would indicate, for the average user, the Ego "1 month" method gets you most of the way there compared to the alternative of leaving your packs fully charged for the whole winter.
Ego have done a pretty remarkable job of Engineering this battery system. I'm sure one of their goals is to make it as simple and convenient for the average consumer as possible. Part of that would include a "fool proof" battery charging regimen.
While you can technically argue that the system isn't 100% optimized, you must also admit to the reality of a customer base who know little to nothing about battery cells and cannot be trusted to maintain them. Your two-mode charger idea IS a good one, I agree, but it would add cost, complexity, and maybe not much ROI (Return On Investment)? I trust the Ego team have done their homework.
Off topic, I was into RC when the "good" packs were the ones with the yellow 1500 mAh Sanyos... yeah, the 1.2V sub-C's. How times have changed! A single 18650 can pack as much juice now as a six cell pack back then.
If you encounter tall or wet grass that taxes the mower, just do what people with motorized lawn mowers have been doing for thousands of years – just go slower.
I will say, however, that Ego has done a fantastic job managing heat. Heat during high discharge is one of the main things that damages cells. Ego has a pack that goes far beyond what any other power tool company has done with regards to thermal management, as far as I know anyway.
Their "Keep Cool" technology is actually an individual cell wrap consisting of phase-change material. In a nutshell, this material absorbs immense amounts of heat while maintaining a stable temperature. This is why I can use the small 2.0Ah battery to cut my lawn and the pack is not even warm to the touch when I pull it from the mower. In that application the pack goes from fully charged to fully depleted in less than 25 minutes of steady mowing.
When I saw that I was very impressed, and gained a lot of confidence in the Ego packs. True, using the blower on Turbo will drain that pack even faster, but unless you hit the turbo button and don't let off until the pack is dead I'm sure you have nothing to worry about. The blower moves lots of air on High, Turbo is only for those situations where you've got a pile of heavy material to move.
The Teslas are not really relevant here because their battery packs are so large that the average person doesn't deplete them on a regular basis, rather they use a small portion of the capacity every day and may or may not charge the car every night.
The Leaf, on the other hand, offers some relevant insight. Nissan guarantees the battery will have 70% of its capacity left after five years or 60,000 miles. For a car with a relatively small battery capacity, being depleted and charged on a daily basis, that's promising.
Using the Leaf duty cycle as a comparison, consider mowing your lawn every day, year round, for five years straight. That's enough grass cutting for the average joe like me to keep their lawn trimmed for 14 years! I cut the lawn about six months/year, once a week.
Sure it's not an accurate apples to apples example, but it proves a point. No, the Leaf doesn't deplete its pack as quickly as the Ego mower does, but the Leaf doesn't have cell thermal regulation like the Ego packs do, either, and high ambient temperatures have caused lots of Leaf battery failures. If my Ego packs still have 70% capacity after even 5 years I'll be thrilled.
Just some food for thought. :)
Well, since some didn't believe me, I ran some tests. Note, there are some variables here including amount of moisture in the grass, age of the battery, height and thickness of the lawn, sharpness of the blade, etc. However, my conditions are quite consistent and the results are clear enough that these variables are clearly not part of the discussion. So the information:
I maintained the battery scientifically the correct way last season and the first month of this season. That means maintaining proper temperature. Never letting it sit at full or discharged state (prefer 40-50% roughly). etc. Over this period, the discharge curve (occasional voltage check as the battery is discharging) remained the same. As well, total capacity was decreased about maybe 2-3%. This is about normal and within tolerances of a lithium battery.
The last few months, I have been following the "normal user" and EGO formal or informal recommendations for battery maintenance. Letting it fully charge on the charger and letting it sit, allowing it to remain partially discharged (sub 40%). Storing in the greater temperatures than I typically would, etc. As a result, I have lost about 15-17% of the capacity of the pack, and the power curve has changed quite a bit as well. The output voltage now drops quicker, resulting in much more frequent yellow alarms as I mow. I have a video of a stretch of about 30' of grass, where the battery is at about 40%, the grass has already been mowed, where i go over it again and the yellow kicks off 5 times.
So the result, do your research on proper battery maintenance or face the scientifically expected results. I hate to say told ya so, but told ya so. Hopefully EGO updates their chargers and documentation to reflect the correct way to deal with these cells. The rest of their design is fantastic down to the way they laid out the cells inside the battery, why they ignored the obvious I still do not know.
Just curious, how are you measuring the capacity of the pack? Are you just measuring voltage before/after mowing, or do you actually have a discharge bench rig set up?
I've often considered hooking up a volt meter to my mower so I can see what's going on while mowing.
Just a comment regarding the power curve of the cells. I believe all Ego tools have regulated supplies which keep power supply to the tool constant as the battery voltage drops, pulling more current from the battery as the pack discharges.
I have noticed that my mower's performance doesn't change one bit until the red light comes on indicating the battery is getting low. At that point I believe the pack's voltage drop under load is great enough that it can no longer maintain the motor's output.
However, I can take that same battery and put it in my blower and the battery light is green again due to the lower power draw in that application.
Regarding battery charge monitoring for ideal daily storage, how hard would it be to adjust the programming on (an improved) pack's charge indicator that now blinks red, orange, green, so that it signals in only orange at 50% when charging (and also when the test button is pressed) to indicate that this Smart Cell has reached (or dropped to) an ideal storage and recharge point of 50% charge?
This would be a great, green way to extend battery life and keep more heavy metals out of landfills. Informed consumers could choose the Twin Pack Smart Cell option to always keep each cell at an ideal 50% charge, thus maximizing their product investment.
Ideal recharge/re-store timing also effectively cuts battery charge time...by half!
EGO would see an increase in pack sales as existing customers upgrade to the SCTP system.
Offer an EGO-ECO Recycle/ Replacement program where everyone who drops off an old pack for recycle at a Home Depot receives the EGO-ECO coupon on a new Smart Cell Twin Pack at a deep discount. EGO-ECO is a win, win, win that rewards customers who recycle 1 unit of proto-tech for the option of purchasing 2 longer lasting units of smarter tech.
This, I believe, would need to be done through Ego and only honored for those turning in packs which they had bought new from an Authorized Retailer and registered with Ego. This would be an AWESOME incentive plan to keep loyal customers over the years, something like 50% off replacement packs once your pack is out of warranty.
I should add some relevant comments too... I have FOUR 2.0 and 2.5 packs (have a 5.0 in route, but will take a while to cross the Pacific). So they way I used them in the 20" mower is that I run either 2.0/2.5 for about 15 minutes, then change it out before it goes RED. And I always let my packs cool back to room temperature before re-charging. And having read this thread, I'm boxing up the fast charger, and using the slow ones instead!
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