[KJSeller]

Hi guys,

Been busy working on my garage reno. Was looking at battery powered mowers. I don't have a large lot, so decided to sell my Ariens 21 self propelled gasser and buy a DeWalt 20v push mower. I don't need self propelled.

Ariens was bought new back in 2003 and never let me down.

I like how much more quiet the DeWalt is and it can be stored standing up.

Bonus is the batteries work on my power tools as well.

 

[Oneacer]

2 of my neighbors use battery mowers ... they have extra batteries to get them through a mow, as one runs out of charge, but they are whisper quiet and do a good job.

Enjoy

 

[KJSeller]

The batteries that came with the mower are 10ah. After I cut the grass the batteries still showed three bars. I should probably leave them and see how many times I can cut the grass before they are fully drained. The box says 75 min of run time.

 

[Oneacer]

I am not sure how those batteries want to be charged ... the manual should tell you ... i.e., I remember some types awhile back wanted to be pretty much drained before placing them in the charger?

I am pretty sure the current batteries of today should be capable of just placing on the charger when done each use.

 

[KJSeller]

I'm sure there are two schools of thought. One is to fully drain and the other is to recharge when you want. I have done both, but haven't had any issues with the batteries. Only issue I had was when I burned out a hammer drill and was trying to troubleshoot of the brushes were shot. I ended up frying a 2.0ah battery.

 

[tabora]

I am pretty sure the current batteries of today should be capable of just placing on the charger when done each use.

I'm sure there are two schools of thought. One is to fully drain and the other is to recharge when you want. I have done both, but haven't had any issues with the batteries.

According to the Dewalt manual: "You may charge a partially used pack whenever you desire with no adverse effect on the battery pack."
This has been my experience with the Greenworks 80V batteries as well.

https://images.thdstatic.com/catalog/pdfImages/d5/d50d81b3-4e7a-4e98-9e1f-ae2596dbdd2c.pdf

 

[jherbicide]

Somewhere along my time with LiPo hobby batteries I learned or was told they last X amount of cycles, regardless of how each cycle. A cycle is discharge-recharge, so in essence every time you connect the charger the lifespan is reduced by 1.

I don’t know if that translates to NiMH batteries, nor if it’s actually true. I also was told the above is generally speaking, as technically they slightly degrade every time they cycle, but at a certain cycle number (the cycles or lifespan from above) it really starts to degrade.

For example, and these are not actual numbers, just a demonstration of what I was told:
a battery may maintain 90% of its full charge rating for 100 cycles, then for the next 50 maintain 80%, then after that it may only take 10 cycles to be essentially useless.

 

[Oneacer]

And when does an electric car become useless?

 

[KJSeller]

Somewhere along my time with LiPo hobby batteries I learned or was told they last X amount of cycles, regardless of how each cycle. A cycle is discharge-recharge, so in essence every time you connect the charger the lifespan is reduced by 1.

I don’t know if that translates to NiMH batteries, nor if it’s actually true. I also was told the above is generally speaking, as technically they slightly degrade every time they cycle, but at a certain cycle number (the cycles or lifespan from above) it really starts to degrade.

For example, and these are not actual numbers, just a demonstration of what I was told:
a battery may maintain 90% of its full charge rating for 100 cycles, then for the next 50 maintain 80%, then after that it may only take 10 cycles to be essentially useless.

I've never had an issue with my DeWalt NiMH batteries. I only had one 2.0ah die when I burned out my hammer drill and tried to troubleshoot it. The oldest 20v batteries are from 2011 and they've been charged 100s of times.

Only time will tell. I'm not hard on my OPE so I'm sure this mower will last 5-10 years unless the design is poor and not reliable.

 

[jherbicide]

I've never had an issue with my DeWalt NiMH batteries. I only had one 2.0ah die when I burned out my hammer drill and tried to troubleshoot it. The oldest 20v batteries are from 2011 and they've been charged 100s of times.

Only time will tell. I'm not hard on my OPE so I'm sure this mower will last 5-10 years unless the design is poor and not reliable.

I’ve got a 4ah and a 5ah dewalt 20 batteries that are still good, but I know they aren’t “like new.” My heavy use is cutting (saws ‘em all) up shipping crates for work. They still work fine, but they don’t last as long as they used to.

My highly scientific “study:” When new the 5ah one could do about 8-9 of these crates, but now 4 years later it can manage about half that number. If I had to guess they’ve been thru about 50-100 charge cycles.

 

[tabora]

My highly scientific “study:” When new the 5ah one could do about 8-9 of these crates, but now 4 years later it can manage about half that number.

That was my experience with NiMH batteries, as well. I've converted all my NiMH tools over to lithium-ion batteries with much smarter chargers (they also take advantage of the smarts in the batteries themselves) and they monitor the voltage and temperatures of the cells during charging.

Lithium-ion is a low maintenance battery, an advantage that most other chemistries cannot claim. There is no memory and no scheduled cycling is required to prolong the battery's life. In addition, the self-discharge is less than half compared to nickel-cadmium, making lithium-ion well suited for modern fuel gauge applications. Lithium-ion cells cause little harm when disposed.​

​

Lithium-ion is fragile and requires a protection circuit to maintain safe operation. Built into each pack, the protection circuit limits the peak voltage of each cell during charge and prevents the cell voltage from dropping too low on discharge. In addition, the cell temperature is monitored to prevent temperature extremes. The maximum charge and discharge current on most packs are is limited to between 1C and 2C. With these precautions in place, the possibility of metallic lithium plating occurring due to overcharge is virtually eliminated.​

 

[jherbicide]

That was my experience with NiMH batteries, as well. I've converted all my NiMH tools over to lithium-ion batteries with much smarter chargers (they also take advantage of the smarts in the batteries themselves) and they monitor the voltage and temperatures of the cells during charging.

These are Lithium batteries I’m speaking about, the dewalt “20v” series.

 

[tabora]

These are Lithium batteries I’m speaking about, the dewalt “20v” series.

Confusing, because you quoted @KJSeller's comment: "I've never had an issue with my DeWalt NiMH batteries..."

 

[jherbicide]

Confusing, because you quoted @KJSeller's comment: "I've never had an issue with my DeWalt NiMH batteries..."

I can’t speak to his experiences, but I had a lot more issues with the older generation batteries (NiMH, or Nicad) than the new ones. IMO The only thing they have on the liPo technology is they make better paperweights…

Regarding LiPo degradation, I speculate the heavy use/amp draw of the sawzall application is one of the harder applications. My experience with said degradation was similar with LiPo with RC stuff too.

edit: found this, that somewhat debunks the “cycle theory” I posted above. It does agree with that heavy use (heat) can shorten a lifespan.

Whats Lifespan Lithium Ion Battery | Northeast Battery Blog

Today’s rechargeable batteries are better than ever before. Nearly every gadget has one, and you rely on its power for daily tasks. Most devices depend on lithium-ion technology. How long do lithium batteries last? It’s time to take a look at this simple product that has complex, internal...

northeastbattery.com

a more technical link with fancy charts and numbers:

https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries

 

[tabora]

Regarding LiPo degradation

LiPo lithium-ion polymer (light drone-type batteries) are different than Li-ion. They use a polymer electrolyte instead of a liquid electrolyte and provide higher specific energy than other lithium battery types and are used in applications where weight is a critical feature, such as mobile devices, radio-controlled aircraft and some electric vehicles. Tools use heavier Li-ion batteries which have a high energy density, no memory effect and low self-discharge.

 

[KJSeller]

My bad I meant lithium ion batteries. You can tell I'm getting old . I haven't used the NiMh in a long time.

 

[jherbicide]

LiPo lithium-ion polymer (light drone-type batteries) are different than Li-ion. They use a polymer electrolyte instead of a liquid electrolyte and provide higher specific energy than other lithium battery types and are used in applications where weight is a critical feature, such as mobile devices, radio-controlled aircraft and some electric vehicles. Tools use heavier Li-ion batteries which have a high energy density, no memory effect and low self-discharge.

Sorry, “lithium based batteries.”

 

[Tony-chicago]

I’ve got a 4ah and a 5ah dewalt 20 batteries th
My highly scientific “study:” When new the 5ah one could do about 8-9 of these crates, but now 4 years later it can manage about half that number. If I had to guess they’ve been thru about 50-100 charge cycles.

On or two per month?

 

[jherbicide]

Yeah it probably averages out to 1-2 of these uses per month. Some months more, sometimes a few months between uses.

 

[tabora]

I took my Greenworks 80V Pro 18" chainsaw out into the woods last weekend with three 2Ah batteries. I ran out of bar oil before I ran out of battery power.