Picture of solar lawn mower
this Instructable will show you how to mow you're grass using solar power to charge the mowers batteries
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Step 1: What you'll need

Picture of what you'll need
-battery operated lawn mower
-12 volt solar cell
-wire (red and black)
-multi meter
-multi tool (I used my leatherman)

Step 2: Wiring

Picture of wiring
you'll need to cut off the cigarette lighter plug in and then strip your wires .you will also need to cut two lengths of red wire and two of the black and strip both ends of those .when using stranded wire its best if you pull the insulation away slowly as you twist it to keep the wires neat

Step 3: Connecting the wires

Picture of connecting the wires
locate the positive and negative terminals on each battery and connect the wires accordingly .it uses two 12v batteries connected in series circuit and you have to undo that connection .and wire it in parallel circuit to charge .then you must undo that and reconnect it to mow

Step 4: Bring out the solar cell

Picture of bring out the solar cell
now that you have those connected you will need to connect the red wires together and connect the black wires together

be sure you disconect the the jumper wire so theres no short and the solar cell is able to charge the batteries

once thats done you'll need to connect the solar cell to leads

Step 5: Charging

Picture of charging
once you've hooked it all up all you need to do now is set it in the sun and let it do its thing .it doesn't have to be a cloudless day for your solar cells to work but they do work best in direct sun .it takes about 4-6 hours to charge depending on how clear the day is and position of the sun in reference to the solar cell .and it is about to cut thick grass for 20-30 minutes on the mulch setting so that time would be greater if you were collecting it in a bag

the solar cell does not stay connected for use of the mower (it is only for charging) .and the batteries have to be hooked back up to the manufacturer's specs .but for free power the 3 minutes it takes to do that is worth it

.it only took me about 45 minutes to complete this project since I had all of the stuff just laying around (my father is a "junk" collector)

I'm sure you will be able to locate a battery lawn mower online .my dad bought this one on clearance for somewhere around 75 dollars ,and you can purchase a 12 volt solar cell for around 65 dollars from harbor freight

I hope this is helpful and I would like any feedback and criticism you would like to offer as this my first instructable
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drumdude3 years ago
dang, when I saw the picture I thought it was a TV on the lawnmower! haha
Im glad im not the only one!
Great Instructable!!!! I do have a few questions, hopfully it is not in the comments below but; how long does the battery supposing it is fully charged support mowing? How long can a fully charged battery by any means cut what square meter or square foot of grass, how high, and how long? My family has many acres, my parents have about 4 acres(my father cuts). It would be interesting to mount more batteries on this unit, how many can it support? I wonder how much for a riding mower, and how much energy it would require? since the mower is moving at low speed I suppose weight does not have much of an effect. what horsepower is the lawn mower you are using? Again great job -Inductionmind
somebullcrap (author)  INDUCTION_MIND6 years ago
as it is now it will cut grass a thats about 4-5 inches tall on the muclh setting for about 30 minutes .in about a 20 by 30 foot lawn (my front yard) .and as for mounting more batteries on it .I'd not do that unless you were going to go the riding mower route .as is stands now it weighs more then a regular gas powered push mower and isn't to easy to push .especially in the higher grass
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somebullcrap (author)  INDUCTION_MIND5 years ago
you forgot a zero .its actually 600' sq.
Thank you!
Hmmm,,, Electric Solar Powered Riding Mower,,, Bigger, multiple motors,  More batteries, larger solar panel.... Interesting....
NOTE your questions do not really apply to his instructable. assume you ALREADY have an electric battery mower. Does it work for you now? this does not change that. It just changes WHAT charges the batteries. I have a battery electric mower. IT DOES have enough charge to cut my lawn. (unless its wet then it will only do about 75% of the yard :-) with that established all this does it use a solar panel to recharge instead of my wall outlet. SO determine if a battery electric mower WILL work for you IF YES then you can do this mod. if not then its not relevant since you won't be using a batteriy powered mower anyway.
Wow... sure my questions apply, it is simple mathematics.
Using push mower with a dc motor of (T)hp, a blade length of (U) a battery with (W) amount of joules is able to cut X meters of grass of w\ length by Y density =Y. all that has to be entered is the variables, and we can make good predictions of the area that could be mowed assuming the batteries are fully charged and the grass is as wet as the control condition, lets assume dry.
wogga3 years ago
@sbc (author):
You do know the amperage of a solar panel if you know the wattage and what kind of battery it was designed to charge. A 12v panel in the full sun will probably charge at about 16 volts. WATTS = VOLTS x AMPS, so 5watts = 16volts x AMPS. Solving for AMPS, you get about .3 or .35 amps from a 5 watt solar panel.

I'd recommend DIYers look at the voltage that goes into their mower from the wall AC adapter. If the adapter says DC out - something like 26 or up to 30v DC out, then you can simply put 2 '12v' solar panels together in series to double their voltage. (Think of how you put two AA batteries together to get 3 volts.) Then find the adapter plug that is identifcal to the one on your AC adapter and attach that to your solar panels. The website is very helpful in tracking down the odd adapter plugs used by Black and Decker and will let you order one free!

I'd also recommend when shopping for a used mower to start this project that you choose a single battery (12v) model. It removes the need to put the panels in series. I have a black and decker single battery model and have had a 5 watt panel (now 10w by connecting 2 identical panels in parallel to increase the wattage without changing the voltage) charging my mower for 3 years winter and summer. After buying the molex connector, I just plug the panels into the female receptacle in the exterior of the Black and Decker mower. It handles the power maintenance, though my panels both DO have blocking diodes to prevent power going the wrong way - if the mower doesn't do that itself.

In my case I was lucky. The battery is a 26amp hour battery and will run for about 50 minutes and was in great shape 3 years ago - and is still in 'okay' shape now. You should keep your lead acid based batteries on trickle/solar charge all the time, rather than charging them up and storing them till use. Also, try not to use up all of the charge ever - the battery will last a bit longer. Any body have any good 'This mower runs on SOLAR" stickers?!
I think most the comments were very constructive regarding this instructable. We need more of such maturity on this website. I was once told, "Those who do not fail are not trying hard enough". This by no means is a failure, I think it is great. It is great when someone has the courage to make an Instructable and others are helpful with suggestions and it continues to be "tuned". I will throw my two cents in as a trained horticulturist. As far as mowing, the average homeowner mows once a week, perhaps twice during peak growth, dependent on irrigation and season. (Allow the ignorant to dream) What if this idea could be combined with some others such as low power/high torque motors for propelling the mower? Removal of the solar panel(s) making a charging station. Combine that with the tech used in such as the "robot vacuums" or "invisible fence". I dream more, when the electric power reaches a near depleted level the "mowing unit" if you will, returns to the charging station until recharged yet only mows during a set time period. Finally, what if the charging station had a rain sensor as well as the mower. If it is raining it does not mow during the set times or if it starts it goes back to the station. IF these techs could be combined in one unit you would have a "robotic mower". I do not have the skill nor tech knowledge. I am just casting out an idea. Please be kind in your comments.
I'm dreaming of this too. I hate mowing my lawn!!

I've been tinkering for a while with the Arduino microcontrollers which will serve nicely as a 'brain'. I've also just started out with stepper motors coupled via an EasyDriver stepper driver, which as the name suggests, is VERY easy to hook up.

It'll likely be less of a mower, more of a 'grazer' I think. ;)
Beardy, Exactly, "Grazer" is the concept I was trying to explain. A solar powered robotic mwer that does not mow the whole lawn at once but continually grazes maitaining the grass continuously. The effect would be the grass never grow over the set mowing height, never giving that "needs to be mowed" look. I wish you luck and would love to hear about your progress.
I want to make something like this sooo badly but it would be stolen in days around here :-(
add a GPS to your micro-controller... :)
hey cobaltxxxfusion! It's been a while and the desire to build a lawn grazer hasn't gone away. Happily, I recently started teach electronics to a couple of teen boys at a local private school. They've really grabbed hold of my suggestion to build a robo-mower ;) so we're on our way. There's nothing to show for it yet - we're still exploring the design considerations - but I'll post something somewhere as we go. kr
yeah I think they do have them I seen it on a segment on a discovery science show can't remember the shows name but the segment was called tech toys it uses a magnetic wire to know where not to mo and has an alarm if someone tries to steal it its pretty cool Aaron
lar26 years ago
This looks like a great idea! Pretty cool for a first Instructable. Mowing later in the evening allows a full day for charging. You mentioned cutting up "the Cigarette lighter plug". It wasn't mentioned in your first step. Was it something else someone needs before this is attempted?
Marsh lar24 years ago
Something that was overlooked about that lighter plug was that there is a diode inside it to prevent the battery from discharging into the solar cell. When there's plenty of light out, the PV cell is making electricity and charging the battery. When it gets dark, what do you think happens? The battery has greater potential so it discharges into the solar cell. Using 2 of these (usually on sale at harbor freight for $20), one for each battery and with diodes installed to isolate the batteries from each other should make it so you just store the thing in the sun and it's ready to use any time you need it.
somebullcrap (author)  lar26 years ago
no .just how it came from the factory
I was thinking about doing something similar to this with my mower, but it seems someone beat me to it.
Don't let that stop you!
saites20016 years ago
This could stand to get a few more details, but it's a very cool project. I wish someone would post a guide on converting a gas mower to an electric solar powered mower. Nice project, man.
you don't you buy an electric mower and go from their :-) it would be crazy costly to "convert" a gas mower to gas. in fact you can't you would have to remove the gas engine and simple use the mower deck to MOUNT your electric motor and batteries too. I guess if you already have all the bits this makes sense but for those who don't just hit craigslist and get a cordless mower.
do you know that you can convert a car that runs on gasoline to run on natural gas? maybe someone comes up with a mower that runs on natural gas. it will only bee convenient if natural gas is cheaper that gasoline and you will get about the same horse power as gasoline. to fill the natural gas tank from the mover you can make a device to hook up to your gas outlet from behind the stove and on to your natural gas tank.
I just came back from Brazil where everyone is outfitting their cars with Natural Gas kits and just about every gas station has a natural gas pump as well. It's entirely possible... Brazil's ahead of the curve.
Mr. Rig It6 years ago
This could use more information in it. Like, how long will it run for? How long does it take to charge? What keeps it from over charging? How thick of grass will it cut? etc You are on the right track though, keep going.
Answers - Run time irrelevant determined by what mower you buy (he did not make a solar battery powered motor he bought a STOCK battery electric motor with its specifications from the manufacturer and ADDED what is simply a solar charger.

Time to charge depends on size of panel size of battery depth of discharge and available sunlight. HE is in texas he gets a lot more sun than for example ME in pennsylvania.

Assuming FULL depletion 3 weeks to recharge the batteries in PA 1 week in Texas. I assume he does NOT use 100% of the batt cap to cut his grass so probably 4-6 days to recharge which is fine since I assume he does it once a week.

Overcharging. he is only putting in 2.5 watts AT PEAK (sun directly overhead) at that charge rate its a virtual FLOAT charge and he has almost zero need to be concerned about over charging.

ask the manufacturer about how thick the grass it will cut he did not design or build the mower :-)

IF you can find a battery electric mower that WILL meet your demands what you do is GET that mower and then use his instructable to convert to solar charging.
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OK. Peace man. I was being a jerk and your reply was not nice either. I am sorry for how this has gone. It was my fault. Lets just chill out and enjoy the original post as it stands it really is a good one. Again sorry Mr. Rig
Sounds good to me, and I agree it is a really good one. Peace out and thank you.
I have voluntarily removed my hurtful posts. They were uncalled for and just plain stupid. You were of course asking a question that needed asking at the time it was asked.
willyb216 years ago
Anyone have a DIY to change a Corded Mower to Battery or Solar? Thanks
nerys willyb214 years ago
yeah hit craigslist and get a cordless mower. Worst case you get a dead one cheap and put 2 car batteries in it.
Besides the obvious method? That would be mounting a battery and an inverter (properly sized) to the mower base and plugging the mower into the inverter, then it's just mounting a 12V panel on top that's wired to the battery connections, with charge regulation as needed. For a fan cooled inverter you'd need filtering over the air intake. I'd go Project 2 route, make a portable panel/battery/inverter unit for go-anywhere power (battery in battery box with the rest mounted to the box), and construct a parking place for it on the mower, strap down, plug in, attack weeds. Otherwise, you'd be talking about needing a different motor, one working at battery voltage, and figure in cost, hassle, mechanical and maybe metal fabrication skills needed for the changeover... Plus minor safety concerns with spinning large chunks of sharp edged steel... Hey, that portable solar power station sure seems a good place to start!
Cool thanks I just bought the mower and this was just to get a rough idea on the difficulty in changing over. I will be waiting a while but will continue to research. thanks again forgesmith.
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