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Dales mobile battery bank and runabout - based on a dead lawn tractor.  RSS feed

 
Dale Hodgins
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Location: Victoria British Columbia-Canada
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I have decided that I need a battery bank and an electric runabout for the farm and for jobsites. Lawn tractors with a bad engine or rusted off lawn equipment,  are available cheap or free. All I need, is something with a decent frame,  steering and good tires. If the transmission were still intact,  that would be a bonus.

 I would add a chain drive or some other type of gearing mechanism,  to join to the existing transmission. With the proper gearing,  a very small engine could move the lawn tractor at a modest pace. My cordless chainsaw produces a little over one horsepower and I think that would be adequate.

With the weight of the grass cutter and engine gone,  we now have extra capacity to hold batteries. I would like to have 6 or 8 batteries along with a transformer to convert to regular 120 volt power. The former lawn tractor,  would not be able to carry any more weight,  due to the heavy load of batteries,  so we would tow a trailer when using it as a farm runabout.   There's plenty of power available for a 12 volt motor, if my chainsaw proves unsuitable.

This would allow me to have regular grid type power in every corner of the property,  simply by driving the lawn tractor to that location.

I will have one trailer that is meant for hauling rocks, firewood and that sort of thing, and another trailer which locks, that contains a wide range of power tools.

The trailer full of power tools would become my storage box on the back of the truck, and would be the one most likely to go to jobsites.

This is something I expect to be able to accomplish for $200.00 or less, plus the price of batteries. Lots of tinkering involved.
 
Rufus Laggren
Posts: 481
Location: Chicago/San Francisco
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You talking "walk beside" (or behind)? Or ride?

> transformer to convert...

I think you mean an "inverter"? DC to AC; input/output voltage as desired.

> tinkering...

Might want to check out what happens on the way DOWN hill. More than a couple batteries mean weight and with gravity and all it might accelerate pretty good. Some kind of moderately foolproof emergency brake could be worth it.


Cheers

Rufus
 
                    
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Location: AR ~ozark mountain range~zone7a
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Converting a gas rider to electric is fairly easy if your unit has a transaxle which are quite common in the junk yards. Because you expect to load it heavy + rough terrain, make sure your transaxle has heavy enough axles. You might be able to find an junk garden tractor, those typically have 1" diameter drive axles, often using a 5 bolt wheel hub, those garden tractors are better suited to heavy use because the size of the tires is larger than riding mowers {read as: small tires jumps down in pothole or rut & wants to get stuck, larger tires tend to roll over potholes & ruts... (easier on your back, remember these things have no suspension, other than low pressure tire cushion). I prefer the transaxle over any chain drive set-ups because the transmission, brake, & differential is integrated in one unit, you really need all 3 of those things for predictable performance. Typically a garden tractor has stronger steering components also, which on any junker, will already be well worn, try to find one with a cast iron front axle, or if it is rectangular/welded steel, make sure it is of heavy guage more than 1/8" thick. A garden tractor has a stronger hitch area, for pulling heavy trailers, and has thicker ply tires than a riding mower.

Now your probably thinking 'yeah... but, I want "moderate" top speed of walking fast'... So you could do what the lawnmower racers do, and that is change the (drive) engine pulley size to gain higher speed. Typically the input (driven) transaxle pulley is somewhere between 5"-10" diameter, and the (drive) engine pulley is around 3", which makes for a safe 'stock' speed in high gear, by increasing the (drive) engine pulley diameter, you will increase the top speed. However it will require more power, that is the tradeoff: for more ground speed, you need more torque at the (drive) engine pulley.

By utilizing the stock transaxle, you may be able to also utilize the stock clutch/belt set-up expecting some modifications if you change pulley sizes, or locate your electric motor closer to the transaxle.

Typically on a riding mower, I would say minimally about 5 hp (as the stock gasoline riding mower pulley size/gearing) is required to drive the thing like normal. All the horsepower above 5 hp is use to drive the mower attachment. {my only experiment for this was to retrofit an 8hp rider with a 5hp gas engine, and use no mowing deck as runaround only, 5 hp did just fine...I never experimented any lower, like with a 3.5 hp }

james beam

 
Dale Hodgins
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Posts: 6795
Location: Victoria British Columbia-Canada
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Hi, Rufus and James. Yes, it's an inverter that is required.

On horsepower - I know a guy who has made many electric bikes, scooters, go karts and such, that run on less than 1 hp. His bikes typically go 20 mph and go karts go 15 mph. His are on smooth pavement. Mine is on a gravel road. It's almost flat. I agree with Rufus about slopes. I will be happy with anything over 3 mph. That's 1/5 the speed of go karts that weigh 250 loaded. A fully loaded lawn tractor might weigh 1000 lb. with me aboard. I expect to reduce the gearing, so that low speed is just a crawl. My friend is confident that the guts from a mobility scooter could move 1000 lb at 4 mph. which is 1/3 the speed of the scooter.

I got this trailer for free today. It can carry 600 lb. I hope to find a small lawn tractor that will weigh that much complete.

Meanwhile, I may get the batteries and put them in the trailer for now. I make $25 per day by supplying power at remote locations for a part time employer. Typically, we need lights along with a Sawzall and circular saw. Saw time is less than 10 minutes a day. Right now, they idle a generator all day long. In 20 days of supplying power, I could recoup a $500 investment.
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John Pollard
Posts: 136
Location: Ozarks
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They actually made electric riding mowers back in the 70s-80s so you might do a web search on them and get some specs. Shame, that golf carts are probably not abundant where you are. Might be able to find an electric walk behind fork lift and get everything you need from it. Battery, electric controls, motor etc.
 
Dale Hodgins
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Location: Victoria British Columbia-Canada
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There plenty of golf carts here,  but many get shipped off to the smaller gulf islands, where they are used for transporting people around places too small for a car.

I've never seen an electric ride on  mower given away for free. I will change my advertising and include golf carts and ride on lawnmowers that are battery powered.
 
Dale Hodgins
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Location: Victoria British Columbia-Canada
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The E-go lawnmower puts out 600 watts continuously for 45 minutes. I could see mounting a lawnmower flat so that the headlight of the lawnmower becomes a headlight for the runabout. I don't need great speed since the distances aren't great. Five miles per hour would be just fine.
 
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