• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

electric mower conversion?

Share this page

NutmegCT

NutmegCT

Great Pumpkin
Bronze
Offline
Is there a way ...

... to run a 6.5 amp 120v AC motor for a short time (like 15 minutes) using a 12v car battery?

Some kind of simple/affordable converter 12vDC -> 120vAC?

Trying to figure out how to strap on a car battery and run a push-type electric lawn mower for about 15 minutes without the cord. Only use the mower on a very small grassy area away from the house, once a week. Area is small and unsuitable for the riding mower. Then use a solar panel to recharge the car battery over the next six days.

T.
 
Tom:
I use a 12 v dc to 110 v ac inverter for my air matress pump and Some other electrical goodies when I`m camping. Weather it would run your motor or not is anyones guess. It says it is capable of 450 watts peak. The model is Vector Maxx SST, VECO 34, 225 watt dc to ac inverter. Bought it at AutoZone, can`t remember the price, I know for a fact that they have higher wattage ones too.
I can`t see why it wouldn`t run your mower, for how long before it drained your 12 v battery might be the question.
I always leave my truck running at idle while using mine so I can`t even guess as to what the battery drain might be.
Hope this helps somewhat
Kerry
 
Possibly. There are inverters that can deliver that kind of power, and I've seen them at Wal-Mart and Best Buy. You should be able to find them at RV stores too. Bear in mind to run that kind of motor you'll need something in the range of 1500 watts, because the starting current might be significantly more than 6.5 amps. Also, since a 1500 watt inverter can top out at 150 amps, you'll need BIG cables to connect it. A regular car battery doesn't take kindly to loads like that though; you might really want to invest in a deep cycle RV battery (or two in parallel) for running it, otherwise your car battery will be short lived. From a weight standpoint, you might be better off leaving the heavy battery and heavy inverter stationary and run the mower from an extension cord.
 
Vector makes a 3000 watt one but it IS pricy
On the bighter side, It could possibly run a fridge or freezer, household lamps for sure, during power outtages.
 
At first I thought this:

An 8d weighs about 132 pounds, add the inverter weight, and upgraded suspension, and of course wider wheels so this behemoth will not sink into the turf, should complete the mower conversion. The cost of the mule to pull it around can be offset by the sale of it's manure.

Perhaps goats, or astro turf, or the original extension cord would be cheaper.

Then I found this for "only" $500.

battery powered mower
 
T

You can eliminate the inverter if you have a universal motor, which will happily run on ac or dc. Remember that 1 hp = 746 watts at 100 percent efficiency. If you assume 85% efficiency for the motor, which is reasonable, you will need approx. 878 watts for 1 hp output. I think you can mow the average lawn with 1 HP without stalling, if you have a sharp blade. If you find a 12 volt dc universal motor, you will need 73 amps, per hp. At 120 volts ac you need approx 7.31 amps. The inverters sold for automotive are crap and do not have a 100 percent duty cycle. For our application you should double the required capacity or you will lose too much in the conversion. Better look for an inverter rated approx. 2000 watts. A brand new 12 volt battery might last you 15 - 20 minutes at 73 amps per hp. because of the inefficiencies involved, you will need closer to 85 - 90 amps on the 12 volt dc side to produce 1 hp.

good luck

p.s. my father retired from GE after 45 years and he got an ElecTrak garden tractor/mower as a retirement gift from the company. He was able to cut about 2/3 acre of relatively flat lawn on a full charge. BUT this thing was a big mother. It had 2 traction motors and 2 mower deck motors and 8 - golf cart type batteries. Sadly it sits in the corner of his garage now (he's 90 and stopped cutting his own lawn just last year)
 
T

I forgot to mention, most ac motors expect to see a reasonably good sine wave. However, the auto type inverters produce a square wave and it is very possible the the resulting harmonics will eventually fry the motor winding.

I might be able to provide better advice if you give me the nameplate information.
 
Thanks. It's a B&D M175.

But figuring volts*amps=watts ... that 6.5amp motor would be a huge draw. Over 7500 watts. That kind of "inverter" runs for several hundred bucks.

Maybe better to oil up the 1947 reel type push mower ... if I can ever figure out how to re-set the cutter blade! Gets jammed with the lightest bit of grass. Widen the gap, just gets jammed even more. Slightly narrow the gap, and it's nearly impossible to push, as the reel blades jam against the cutter.

argh.

T.
PS - I am really amazed that no one (yet?) has developed an adjustable converter so I could pull out the frozen B&S engine on a gas push mower, and drop in an electric motor/12v battery "kit".
 
NutmegCT said:
Thanks. It's a B&D M175.

But figuring volts*amps=watts ... that 6.5amp motor would be a huge draw. Over 7500 watts. That kind of "inverter" runs for several hundred bucks.

<span style="font-weight: bold">I think you need to check your math :laugh:
120 volts x 6.5 amps x pf (assume .8) = 624 watts. assume 85% motor efficiency gives you approx. 0.71 hp </span>
Maybe better to oil up the 1947 reel type push mower ... if I can ever figure out how to re-set the cutter blade! Gets jammed with the lightest bit of grass. Widen the gap, just gets jammed even more. Slightly narrow the gap, and it's nearly impossible to push, as the reel blades jam against the cutter.

<span style="font-weight: bold">Yes, they are a bugger. AND it's tough to find someone today who remembers how to adjust them. BUT, properly set up, they do a beautiful job. If you play golf, or know someone who does, the grounds crew would be able to give you advice. They still use them albeit larger ganged units for the fairways</span>
argh.

T.
PS - I am really amazed that no one (yet?) has developed an adjustable converter so I could pull out the frozen B&S engine on a gas push mower, and drop in an electric motor/12v battery "kit".

<span style="font-weight: bold">Well there aren't adjustable inverters really. When designing electrical equipment, you generally have to allow for the maximum possible connected load. For example, if you want to run a motor that requires 10 amps, the rating of your inverter needs to be 10 amps minimum. However, the same motor can be connected to an inverter rated for 20 amps, 40 amps , or anything larger than the required 10 amps. Except for a loss in efficiency the larger inverters are very happy to supply less than rated current.</span>
Click to expand...
 
LOL - check my math. No kidding! What's an extra zero mean anyway....

120*6.5=780
780*.8=624.

I have no idea what a power factor is. Where does the .8 come from?

So ... are we saying that a 700 watt 12vDC -> 120vAC inverter would do the job? Or are we saying it would do the job, but it'd take a Sherman tank to pull it? :laugh:

Funny - in all the websites I've visited where they show how to adjust a manual reel mower, they all have the same pictures and nebulous text. Those 'bots have been busy!

T.
 
I'm confused.
What's the point of all this trouble to get to a cordless electric mower when a gas push one is about $240 at HD et al?

Gas isn't THAT expensive - yet...
 
Alan - I already own the corded electric. But don't have an outlet where I need to mow now. Figured using an old car battery (I'm about to replace my three year old one in the Mazda) and a $50 inverter would be better than buying another gas mower.

and I have to admit, dragging the electric cord is a nuisance, but the electrics are low-maintenance as well as more neighbor-friendly!

T.
 
NutmegCT said:
LOL - check my math. No kidding! What's an extra zero mean anyway....

120*6.5=780
780*.8=624.

I have no idea what a power factor is. Where does the .8 come from?

<span style="font-style: italic">T: really I'm not kidding when I tell you that the power factor has to deal with real and imaginary power. Please take it on faith like I had to during that first year of EE at Villanova.</span>


So ... are we saying that a 700 watt 12vDC -> 120vAC inverter would do the job? Or are we saying it would do the job, but it'd take a Sherman tank to pull it? :laugh:

<span style="font-style: italic">No, I would recommend at least 1500 watts and no guarantee because of harmonics.</span>

Funny - in all the websites I've visited where they show how to adjust a manual reel mower, they all have the same pictures and nebulous text. Those 'bots have been busy!

<span style="font-style: italic">Isn't that annoying! Google is great, but sometime you might get several hundred hits that wind up with the same useless info</span>
T.
Click to expand...
 
JacksonMG said:
I found this when I Googled reel lawn mowers.

https://www.prisonmowers.com/
Click to expand...


Geez, my son just purchased one of those Scott's reel push mowers for his tiny back yard, works great. But that site says they are $900! He paid $140 for the exact same mower from Lowes. Go figure.
 
NutmegCT said:
Alan - I already own the corded electric. But don't have an outlet where I need to mow now. Figured using an old car battery (I'm about to replace my three year old one in the Mazda) and a $50 inverter would be better than buying another gas mower.

and I have to admit, dragging the electric cord is a nuisance, but the electrics are low-maintenance as well as more neighbor-friendly!

T.
Click to expand...

Dude, I'll help you out. Next time (or first) you come this far south, I'll GIVE you one of my gas mowers. I know it's not electric nor is it as neighbor friendly as the electric mower, but it would solve your problem. I usually have 3 or 4 around the house so I wouldn't miss one gone. They were "given" to me and I usually have little to no money in one. Now the $400 in gas it would take to get here, wellllll, your on your own there.
grin.gif
 
TR6BILL said:
JacksonMG said:
I found this when I Googled reel lawn mowers.

https://www.prisonmowers.com/
Click to expand...


Geez, my son just purchased one of those Scott's reel push mowers for his tiny back yard, works great. But that site says they are $900! He paid $140 for the exact same mower from Lowes. Go figure.
Click to expand...

Bill - minor detail. It's $900 for 10 of 'em.

Regardless, still can't figure why there's a dedicated "prison lawnmower wholesaler". Maybe he contracts with inmates' families, drives in with an order of ten mowers, then leaves the prison with ten "empty" boxes that now have airholes ....

T.
 
I've restored a couple of push-type reel mowers. the key is to properly sharpen the blades. they should cut like a pair of scissors. Also, they need to be used regularly. overgrown grass will clog even the best reel mowers.
Here's a link to a site on how to properly sharpen a reel mower. you can skip the special tool by finding a socket that will fit over the gear or axle, and use a speed wrench. and you can use valve lapping compound instead of thier "sharpening compound" it's the same thing.
Sharpening a reel mower
 
Back
Top