Gas mowers are a drag - the gas .. the oil, .. the spark plug .. the air filter, the noise .. the stink, the carburator clogging, the pull-start action on your aching shoulder joint -- etc etc --- for a little more than what a new push mower costs and some patience and know-how, you can be off the gas-pump and gas mower roller coaster and coasting into a smile in the sun, mowing your lawn by the power of the sun. Photon collection, electron conversion and storage ----
Step 1: Gather Supplies
Mower: (in this case, Greenworks) - prior to a battery mower I had a B&D 'corded' mower, and it worked well but the cord kept getting wrapped around trees and run over and cut - too many obstacles in the lawn ...
I was able to get the GW's 3-in-1 mower off Craigslist - I got the guy down to about $60 or so , a/c charger, bagging attachment, instructions - the batteries were so consumed it only held charge less than 30 seconds. The battery level meter is one of the most inaccurate ones, you can see you-tube videos confirming this, Red,Yellow, and 3 greens (when 'full'). I then had to order new 12v batteries from the big box store - this mower is no longer carried - must be something to do with being green and lead acid incompatibility - only the corded version is in the local store anymore.
These batteries are 20 amp - hours 12 volt each. There are 2 of them. Together they give 480 Watt-hours of power; this is considerable - though heat and heavy load will kill them fast - I like this mower for light duty and for the bagging capabilities (picking up leaves/twigs) and for mulching.
Solar panel(s): 50W, preferrably up to 200W or more, esp. in northern climates of less sunshine. One 50W 'mono' panel is about 4 square feet. Mono and Poly give the higher longevity and energy efficiency, whereas the cheap harbor freight style are 'amorphis' type (to be avoided). I got my 4 x 50 watt panels at $1/watt from a hobby reseller.
Battery bank: I have 2 6 volt golf cart batteries (60 pounds each!), but you could have a simple 12v car battery, though not ideal.
Charge Controller: (optional, though very desireable, esp. with >30W of panels) A cheap $10 controller works but a $50 one that shows amps in , volts, amps out and settings for regulations can be purchased as your system grows and you use it more.
Cables/ wires: (old extensions cords work great too!),
Terminal connectors: (not absolutely necessary but makes life a lot easier)
Step 2: Collect Your Energy , Store It , Send It to the Mower Battery (recharge)
Collect energy from the sun with solar panels, store it in batteries (since this is probably not a 'portable' system, there is no need to purchase high $ lithium batteries to do this but lead acid 'SLA' or deep cycle batteries are best for this as they can be deeply discharged without the same kind of problems that occurr in 'starter' Lead acid batteries, NiCd , NiMh and Lithium Polymers) --
If you can get some kind of tracking device on your panels you can increase collected energy 20% to more than 40% ! This can be rocker style, rotation type or fancy linear actuated. The most bang (energy for your efforts) is from tracking the sun across the sky - the next best improvement comes from tracking the sun's azimuth, or angle of inclination.
The charger is typically a 110v a/c unit that plugs into the battery bank of the lawn mower. You can run an a/c invertor from your 12v /24v battery source, or you can grid tie power into your house run off grid and then just plug into any a/c outlet(about 90% eff) Since mine charger and mower are kept outside, even under roof, the rain in the south in the summer time or a careless misplacement of the charger allowing water penetration destroyed mine ) - Greenworks did send a replacement, however, IT DIDNT WORK !
Greenworks kept giving me he 'in 2weeks' business .. after about many of those kinds of responses and many, many calls, i gave up and tried my own charging system in deep frustration -
The GW's charger took about 2-4 hours to bring the mower to 'full charge' and consumed about 50 watts - Trying to run this 'offgrid' was difficult, peak sun to keep the invertor going to supply necessary voltage for the charger was needed - with the R/C charger, I can put in .1amps at 25-26 volts and leave it all night which is very gentle to the batteries giving them long life. (Solar panels almost never give the rated output: ie (my 50W panel typ. puts out 20 watts, at high noon maybe 30W). Without tracking it is difficult getting the precise angle up to the sun as well as sideways at it).
I so happened to have an old 'diamond' R/C battery charger for NiCd/NiMh - these can also be used to charge Pb (Lead Acid) batteries - the connector on the mower is a standard audio RCA type. I was able to use an old audio cable that had the plug end that fit the mower and the other end stripped so I could clip onto the output of the Diamond charger - wallah -- back in business AND with more efficiency ! (No DC - AC - DC conversion losses) - straight DC - DC voltage conversion, saving as many precious electrons the sun donates as possible.
Step 3: MOW , Without the Pains Associated With a Gas Mower !!!!
Disconnect the charging cable to the mower and mow ! In my case, I can get at least 15 minutes of mowing before I start to hear noticeable reduction in blade speed - I usually go shorter runs to pick up leaves / twigs with the bagging attachment, making sure the level is up enough that I am not cutting grass. It is nice not having to pull your shoulder out starting an internal combustion engine. Not having to go make a 'gas run' with the stinky gas can, having to smell the gas dribbles from the gas pump, the smelly dribbles from pouring gas into an ICE gas tank, and getting gas on your skin (carcinogenic) --- Not having to buy spark plugs, engine oil and fooling with an engine air filter and cleaning all of them every month or so in season. Aside from the loudness and exhaust fumes coming from a gas mower, the worst part of an ICE mower is when they have been sitting over a couple months or so and the carb gums up and it wont start without starting fluid, wont stay running or idle because the needle jet has been clogged by stale gas .. that is why most people throw their gas mower to the curb every couple years... they dont have time for the hastle.