Pros: Cordless, quiet and costs $.05 per 4,000 ft to operate.
Cons: Lead-acid batteries, weak battery charger.
Just like Sarah Palin is shaking up American politics, the Black & Decker Cordless Lawn Mower is changing the way we look at cutting grass. Silent operation that is quieter than a Dyson DC-07 Vaccum, quick startup controlled by an easy pull lever and zero emissions to congest your lungs while working makes the CMM1200 an attractive purchase for any yard enthusiast. Yet on the other hand a shortened battery life and long recharge time quickly push several potential buyers out of the market. The good news is that this mower does work and I even have made a few discoveries that will yield much longer mowing times!
Shipping And Setup
I ordered my cordless lawn mower from Amazon because no one in the greater Louisiana area offers the mower for sale. The problem with ordering heavy items online is the enormous shipping costs. Amazon has a special shipping program called Amazon Prime. With Prime you can ship anything 2nd Day UPS for free if you submit a $79 annual fee to them once a year. The shipping for the mower was $150 for standard freight and 2nd Day UPS was $400. I only paid $79 to ship my mower and had the benefit of using their shipping service the remainder of the year for free!
The mower came in on a Monday afternoon. Like a child on Christmas morning, I was so excited about getting my lawn mower I called in sick! The mower came in a large cardboard box partially assembled. I pulled the mower out, attached the handle, put the safety key and it started up right away. The only other setup you will need to do is to pull the battery charger out of its box and find a place for it in your garage that it close to a 120VAC outlet. While the box was damaged, the mower is very well built so you can be confident that it will survive UPS drop, pound and roll shipping.
Appearance And Weight
The deck of the lawn mower is bright orange and a large plastic cap that covers the motor and batteries is black. The mower has a lever mechanism above the right rear wheel which you press to adjust the mower deck height for all wheels. The feature is very easy to use and is another extra feature that makes mowing a joy rather than a pain. While standing on a bathroom scale with the mower hanging from my stained arms, the whole mower weighs about 72lbs. For comparison, another mulching gas mower in my garage must weigh over 100lbs because I could not pick it up for longer than a few seconds.
At the core of it all is mowing, you must blindly push a 60lb, bright orange, four wheeled box around your yard to get the job done. For exercise, you cannot find a better motivator than this cordless mower. The gas fumes are gone and you will find that after mowing 20 minutes you are still breathing from your nose. The majority of the weight, the batteries, are mounted over the rear wheels which make pivoting and turning the mower a snap when compared to a traditional front heavy lawn mower.
In stock form, the mower can run for about 30 minutes on heavy St. Augustine grass. To help extend the battery life, I will take a break every ten minutes and drink some water, much like running or working out in the gym. As you use the mower, you will learn that the strongest side is on the left. The mower can chomp its way through a full deck with little problem at 25% charge on the left side. The weak side is the right. I strongly suggest only mowing a line even with the left recessed bolt so that it will consume less power. Later when the cordless mower is at 25% charge, you will have to only mow half a strip on the right side to keep the mower from stalling.
The mower is very safe because you do not have to lift tilt it very high to make a 180 degree turn at the end of a row of grass. Even better, the quick release handle instantly shuts down the mower in the case of an emergency.
The CMM1200 does a tremendous job of mulching my yard. The grass is so finely cut that it falls beneath the cut grass blades providing an insulating blanket for the root system beneath. In Lake Charles, Louisiana the dominant species of grass is the thick, fast growing variety called, St. Augustine grass. Mulching mowers have a hard time reducing the grass down because it is so heavy that it will fall to the ground before the blades have time to fully chop it up. Push mowers like my gasoline lawn mower need a 6.5HP or greater engine to handle the increased strain of mulching which also increases the overall weight that you have to handle. Even worse, mulching lawn mowers require more gasoline to feed the larger engine. The Black & Decker 19" Cordless chops up the grass so well that I now mow the lawn barefoot again!
Batteries, Charging And Power Consumption
The cordless lawn mower uses two 12Volt, 17Amp Hour, and sealed lead acid batteries measuring 7" L x 3 "W x 6.5" H. They are charged with a Black & Decker Model @@@@@@ that utilizes 1960's style, transformer based technology. I feel a switching power supply would have been a better choice because of its higher efficiency rating but we take what we can get! Charging the mower takes 10 hours if the batteries are completely drained. After the charger shows a green light, I would use my P3 International P4400 Kill-A-Watt meter to record the number of kilowatt hours consumed to fill the batteries.
Here in chronological order, is the CMM1200's performance on a thick lawn that grows in the almost rainforest like atmosphere of Lake Charles, Louisiana:
8/30/2008 .42Kwh, 4305 Sqft, mower ran down to the point of barely spinning blade in high grass with 1/2 of yard to go.
9/7/2008 .45Kwh 4550 Sqft, mower ran down again to the point of barely spinning the blade in high grass with 1/2 of yard to go. I let the mower sit 15 minutes while I used my gas mower to finish 1/4 of yard. I turned on the mower again and to my surprise was able to cuts another 250 Sqft of area with no problem. I removed a tie down bolt for the rear section of the black cover and felt the batteries. They were over 120F from touch on the outside of the plastic battery case. Allowing the batteries to cool for 15 minutes gave the electrolyte a chance to cool off and provide more electrons.
9/15/2008 .43Kwh 4600 Sqft, mower rand down again to the point of barely spinning the blade. I cycled the mower through several cooling periods but never was able to finish the front yard.
9/22/2008 .13Kwh 2000 Sqft, ran the mower for the first time in Live Plug Mode in a 2,000 Sqft section of the backyard for about 25 minutes. Consumed no noticeable power while plugged in.
9/23/2008 .34Kwh 3500 Sqft, ran the mower again in Live Plug Mode in the largest section of the backyard for over 35 minutes. Consumed .01Kwh while plugged in. The mower never ran low on power while mowing the thick grass and pieces of palm tree leaves.
9/24/2008 .43Kwh 9375 Sqft, ran the mower again in Live Plug Mode in the front yard. The neighborhood peanut gallery was out in force today. They have all been watching with keen interest and were surprised to see an extension cord this time. The mower quickly finished half the yard with no problems at all. The cord was a little troublesome but you can get used to it after a few minutes of operation. After the neighbors saw I was over half way done they came over and started asking questions about what I had done. Of course, offers to use their large lawn tractors were made and they wanted to see me finish the lawn without the cord. I caved into their demands and disconnected the cord with 25% of the lawn remaining. We were all surprised that I was able to finish on battery power from this point.
Before you over analyze the Sqft totals, I based these figures off of the size of my front yard: 125Ft x 75Ft and then marked a mid way point on my driveway at 35Ft. I always reached this point while mowing the front yard but with just a little juice to go maybe another 50Ft.
For comparison to these power consumption figures, the Cuisinart DGB-550BK Auto-Grind 12-Cup Coffee Maker requires .12Kwh just to make a pot of coffee!
I am currently conducting research on three fronts: battery cooling, battery alternatives and live plug operation. My goal is to eventually mow the entire front yard with as little investment as possible.
After removing the black plastic top cover, I found two 12Volt batteries, a permanent magnet DC motor and a blocking diode that is serving as a junction box for the mower. You will not find any complicated control circuitry on the platform of the mower. For the overclockers out there, this mower is truly an open book. You can literally do anything you want with little fear of damaging the components.
Motor And Battery Cooling
Battery cooling is essential to pulling out all the juice possible from any battery operated device. The batteries and motor in this lawn mower reach temperatures of over 120F during normal operation. The heat reduces the lead acid battery's ability to draw electricity and as a result give us the impression they are empty. Overheating electric motors can bake off their protective enamel and eventually short circuit, requiring costly replacement. To fix the perceived problem, I drilled five, 1 1/4" vent holes on top of the black case and placed a coffee filter underneath secured with four sheet metal screws to allow clean air to circulate out of the mower. Then, I put one 80MM fan in front of the DC motor to cycle the hot air rising off the motor and batteries. The fan was able to handle the 24 volts because it had a three way fan speed selector that I put on low. While it may not increase your run time, I feel better knowing that the internal components are not overheating which can cause rapid premature breakdown in the humid Louisiana heat.
The electric motor is a solid unit complete with spring loaded contacts and heavy guage feed wiring. The permanent magnet is 1/2" thick and stands approximately 7" high! The armature wiring appears to be at least 14 Guage or better and has a thick enamel coating to protect from overheating conditions. I feel that the motor can easily handle 30 Volts if you decide to boost the battery voltage. A slight increase in voltage will go a long way towards increasing your mowing time.
I found a Power Sonic, PSH-12180FR, 21Amp Hour, AGM battery on the internet for $51. The item is on backorder and I have only received on so far. You will also need a stronger battery charger, lucky for us, private aircraft have 24 Volt battery banks so there are several aftermarket chargers available on the internet. You should get an additional 300 sq. ft. with this battery upgrade.
Live Plug Operation
The safety key on this mower can easily be modified to allow plug-in of the battery charger while mowing. First, to test whether this modification works, I had to use a Dremel tool to remove 3/4" of plastic starting at the end of the key where the plastic hole resides. I then plugged in the battery charger and started the mower. Right away, the red light on the charger came on! I then read the voltage of the batteries while the mower was running with the charger connected and got a reading of 24.71 VDC. Next, I removed the charger plug and my voltage reading dropped to 24.63 VDC. The charger light and voltage readings prove that the mower can be run with the charger connected! While inconvenient, you could then finish an entire yard without worry of running low on battery power. My biggest reason for doing this was that I do not like dragging 100ft cords around my yard. Once, you reach the end of your electric cord, just unplug and run on battery power.
To mount the charger on your mower simply wedge the charger on the inside of the left push frame rail and resting on the bagging hinge. Then wrap the AC cord around the left frame and end at the middle brace with 1ft of cord so that you can tie off to your extension cord. You can then add a professional touch by using black zip ties to secure the cord in place. I ran the mower for 25 minutes on a lazy romp around bushes, rock gardens and trees in my back yard. The mower never ran low on power and still had plenty of zoom when I finally disconnected from the cord to finish some corners. My first trial yielded no measurable kilowatt hours while mowing and a scant .13Kwh to recharge.
For the cost of a full size 6.5HP gasoline mower, you can get one of these and never buy gasoline or oil again. Ok, I admit the CMM1200 was not designed to mow the LSU football field in 24 hours. The exercise potential, fresh carbon monoxide free air, cordless operation and the seemingly free source of energy attracted me to this unique mower. I will be happy for years to come with this but the typical heavy large yard user will become frustrated if they forget to plug it in. The battery charger is rather weak, but using the Live Plug modification you can mow while plugged in which will give you much more bang for the buck. I agree that plugging in a cordless mower is pointless because I should have just bought a corded mower, but I run with the cord for the first 1,000 Sqft and unplug. Since, I can unplug at anytime or never plug in at all the convience far outweighs the lower cost of a traditional plugged electric mower.
2010, the year of the American electric vehicle was just to far away for me. My purchase of this mower was born out of frustration and a need to take conservation matters into my own hands. Since mowing is a somewhat public event, my neighbors now watch me and cheer me on as the mower slowly dies as I mow my massive front yard. Yes, it has changed me and as the infamous characters on South Park would say, I have become SMUG. I just hope my review does not combine with Hillary Clinton's democratic convention speech and cause a SMUG STORM!