Battery Powered Lawn Mowers - All Junk - Why?

Electronics has been my hobby and
profession for most of my life.
I use a lot of high quality battery
powered shop and garden tools.

When I was kid I learned how repair
and rebuild small gas engines, so
I was very skeptical when weak and
poorly made battery powered tools
became available several years ago.

These days, I save myself countless
hours of maintenance by using every
type of battery powered equipment
I can afford.

I would love to buy or build a high
quality battery powered lawn mower.
Most of the manufacturers that briefly
entered this market got out real quick!
There were a few 36 volt models that
had all sorts of problems. The only
one left is Black & Decker. They've
got a 24 volt unit that runs off a heavy
lead-acid battery. The power to weight
ratio is terrible. Also, they used
a lot of flimsy plastic parts which
forced a recall a couple of years ago.

Are there any folks out here (on the
web, that is) that build there own
battery powered mowers? With lithium-
ion battery technology it should be
possible to build a powerful mower.
I'm not that concerned about the cost.
I would gladly pay two or three times
the price of a deluxe model push mower
if I knew that I could buy or build a
battery-electric mower that had none
of the grease, grim, and maintenance
headaches associated with gas engines.

Holophote

On 26 Apr 2005 08:32:46 -0700, "Holophote" <h_markston@hotmail.com>
wrote:

Electronics has been my hobby and
profession for most of my life.
I use a lot of high quality battery
powered shop and garden tools.

When I was kid I learned how repair
and rebuild small gas engines, so
I was very skeptical when weak and
poorly made battery powered tools
became available several years ago.

These days, I save myself countless
hours of maintenance by using every
type of battery powered equipment
I can afford.

I would love to buy or build a high
quality battery powered lawn mower.
Most of the manufacturers that briefly
entered this market got out real quick!
There were a few 36 volt models that
had all sorts of problems. The only
one left is Black & Decker. They've
got a 24 volt unit that runs off a heavy
lead-acid battery. The power to weight
ratio is terrible. Also, they used
a lot of flimsy plastic parts which
forced a recall a couple of years ago.

Are there any folks out here (on the
web, that is) that build there own
battery powered mowers? With lithium-
ion battery technology it should be
possible to build a powerful mower.
I'm not that concerned about the cost.
I would gladly pay two or three times
the price of a deluxe model push mower
if I knew that I could buy or build a
battery-electric mower that had none
of the grease, grim, and maintenance
headaches associated with gas engines.

Holophote

What will, say, 5 hp-hour worth of batteries weigh? Or cost?

John

On Tue, 26 Apr 2005 08:44:28 -0700, the renowned John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On 26 Apr 2005 08:32:46 -0700, "Holophote" <h_markston@hotmail.com
wrote:

Electronics has been my hobby and
profession for most of my life.
I use a lot of high quality battery
powered shop and garden tools.

When I was kid I learned how repair
and rebuild small gas engines, so
I was very skeptical when weak and
poorly made battery powered tools
became available several years ago.

These days, I save myself countless
hours of maintenance by using every
type of battery powered equipment
I can afford.

I would love to buy or build a high
quality battery powered lawn mower.
Most of the manufacturers that briefly
entered this market got out real quick!
There were a few 36 volt models that
had all sorts of problems. The only
one left is Black & Decker. They've
got a 24 volt unit that runs off a heavy
lead-acid battery. The power to weight
ratio is terrible. Also, they used
a lot of flimsy plastic parts which
forced a recall a couple of years ago.

Are there any folks out here (on the
web, that is) that build there own
battery powered mowers? With lithium-
ion battery technology it should be
possible to build a powerful mower.
I'm not that concerned about the cost.
I would gladly pay two or three times
the price of a deluxe model push mower
if I knew that I could buy or build a
battery-electric mower that had none
of the grease, grim, and maintenance
headaches associated with gas engines.

Holophote

What will, say, 5 hp-hour worth of batteries weigh? Or cost?

John

I figure about $2K and 30kg, assuming the density is the same as NiMH
AA cells. More cost and less weight for Li cells.

But maybe it could be 1/5 or 1/10 of that, I'm not sure about your
assumption. A 1/2 HP DC motor for 2 hours should be fine- and maybe
then it's only putting out full power 1/2 the time. At $200-$400 and
3-6kg it's starting to look interesting as a boutique item.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

In article <2dos619ehhhvos598fc80nlve86j007l54@4ax.com>,
jjlarkin@highNOTlandTHIStechnologyPART.com says...

On 26 Apr 2005 08:32:46 -0700, "Holophote" <h_markston@hotmail.com
wrote:

Electronics has been my hobby and
profession for most of my life.
I use a lot of high quality battery
powered shop and garden tools.

When I was kid I learned how repair
and rebuild small gas engines, so
I was very skeptical when weak and
poorly made battery powered tools
became available several years ago.

These days, I save myself countless
hours of maintenance by using every
type of battery powered equipment
I can afford.

I would love to buy or build a high
quality battery powered lawn mower.
Most of the manufacturers that briefly
entered this market got out real quick!
There were a few 36 volt models that
had all sorts of problems. The only
one left is Black & Decker. They've
got a 24 volt unit that runs off a heavy
lead-acid battery. The power to weight
ratio is terrible. Also, they used
a lot of flimsy plastic parts which
forced a recall a couple of years ago.

Are there any folks out here (on the
web, that is) that build there own
battery powered mowers? With lithium-
ion battery technology it should be
possible to build a powerful mower.
I'm not that concerned about the cost.
I would gladly pay two or three times
the price of a deluxe model push mower
if I knew that I could buy or build a
battery-electric mower that had none
of the grease, grim, and maintenance
headaches associated with gas engines.

Holophote

What will, say, 5 hp-hour worth of batteries weigh? Or cost?

Lessee. 5HP-hr is what, 3750WH or optimistically (1.2V/cell) 3125AH.
Batteries America has AA 2.3AH NiMH batteries for $2.50ea, so that's
about 1360 'AA' batteries, cost $3400 and weigh 40.8kg. ;-)

--
Keith

"Spehro Pefhany" <speffSNIP@interlogDOTyou.knowwhat> wrote in message
news:p9ps61lq070cl663hi3cupi06f9b6vicmv@4ax.com...

But maybe it could be 1/5 or 1/10 of that, I'm not sure about your
assumption.

I think you're onto something here -- presumably grass is effectively cut with
the blade spinning a certain minimal speed, so with a feedback control system
the power delivered by the motor could be increased or decreased as needed to
maintain the cutting speed, and in 'light' grass probably nothing near 5HP
would be needed.

Panasonic makes electric razors that use this principle (the cutting speed is
kept constant regardless of beard thickness).

---Joel Kolstad

Holophote wrote:

Electronics has been my hobby and
profession for most of my life.
I use a lot of high quality battery
powered shop and garden tools.

When I was kid I learned how repair
and rebuild small gas engines, so
I was very skeptical when weak and
poorly made battery powered tools
became available several years ago.

These days, I save myself countless
hours of maintenance by using every
type of battery powered equipment
I can afford.

I would love to buy or build a high
quality battery powered lawn mower.
Most of the manufacturers that briefly
entered this market got out real quick!
There were a few 36 volt models that
had all sorts of problems. The only
one left is Black & Decker. They've
got a 24 volt unit that runs off a heavy
lead-acid battery. The power to weight
ratio is terrible. Also, they used
a lot of flimsy plastic parts which
forced a recall a couple of years ago.

Another aspect beside battery capacity is the
safety aspect. While a petrol powered engine
stops when encountering a root or a stone or such,
an electric engine starts drawing much more power
when braked. Thus a normal motor is inherently safer.

Rene
--
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

On Tue, 26 Apr 2005 12:02:45 -0400, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

On Tue, 26 Apr 2005 08:44:28 -0700, the renowned John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

[snip]

What will, say, 5 hp-hour worth of batteries weigh? Or cost?

John

I figure about $2K and 30kg, assuming the density is the same as NiMH
AA cells. More cost and less weight for Li cells.

But maybe it could be 1/5 or 1/10 of that, I'm not sure about your
assumption. A 1/2 HP DC motor for 2 hours should be fine- and maybe
then it's only putting out full power 1/2 the time. At $200-$400 and
3-6kg it's starting to look interesting as a boutique item.


Best regards,
Spehro Pefhany

Naaah! Why waste your time. Around here you can get a free electric
(with a cord) mower by turning in your gasoline-powered version to the
Salt River Project (one of the major power companies here in Phoenix).

Me, I don't own either, my yard/garden maintenance man uses all
gasoline-powered tools ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On Tue, 26 Apr 2005 18:36:38 +0200, Rene Tschaggelar <none@none.net>
wrote:

Holophote wrote:

Electronics has been my hobby and
profession for most of my life.
I use a lot of high quality battery
powered shop and garden tools.

When I was kid I learned how repair
and rebuild small gas engines, so
I was very skeptical when weak and
poorly made battery powered tools
became available several years ago.

These days, I save myself countless
hours of maintenance by using every
type of battery powered equipment
I can afford.

I would love to buy or build a high
quality battery powered lawn mower.
Most of the manufacturers that briefly
entered this market got out real quick!
There were a few 36 volt models that
had all sorts of problems. The only
one left is Black & Decker. They've
got a 24 volt unit that runs off a heavy
lead-acid battery. The power to weight
ratio is terrible. Also, they used
a lot of flimsy plastic parts which
forced a recall a couple of years ago.

Another aspect beside battery capacity is the
safety aspect. While a petrol powered engine
stops when encountering a root or a stone or such,
an electric engine starts drawing much more power
when braked. Thus a normal motor is inherently safer.

Controls, or even a circuit breaker, would take care of that. An
electric motor has, potentially, less moment of inertia, which would
make it safer in lots of situations.

John

On Tue, 26 Apr 2005 09:51:03 -0700, the renowned Jim Thompson
<thegreatone@example.com> wrote:

On Tue, 26 Apr 2005 12:02:45 -0400, Spehro Pefhany
speffSNIP@interlogDOTyou.knowwhat> wrote:

On Tue, 26 Apr 2005 08:44:28 -0700, the renowned John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

[snip]

What will, say, 5 hp-hour worth of batteries weigh? Or cost?

John

I figure about $2K and 30kg, assuming the density is the same as NiMH
AA cells. More cost and less weight for Li cells.

But maybe it could be 1/5 or 1/10 of that, I'm not sure about your
assumption. A 1/2 HP DC motor for 2 hours should be fine- and maybe
then it's only putting out full power 1/2 the time. At $200-$400 and
3-6kg it's starting to look interesting as a boutique item.


Best regards,
Spehro Pefhany

Naaah! Why waste your time. Around here you can get a free electric
(with a cord) mower by turning in your gasoline-powered version to the
Salt River Project (one of the major power companies here in Phoenix).

Me, I don't own either, my yard/garden maintenance man uses all
gasoline-powered tools ;-)

...Jim Thompson

So did ours, but I decided the exercise was worth the -$600/year it
cost to get rid of him. Got rid of the electric mower at the same time
and got a midrange gas mower. When it starts to show trouble, it will
end up and the end of the driveway and a new one will be bought. Those
little IC engines are just too much trouble to fool with, IMHO.

But.. I bet top quality electric mowers would sell well to a certain
set. The same kind who were sanctimoniously using Gardena push mowers
20 years ago.



Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

John Larkin wrote:

On Tue, 26 Apr 2005 18:36:38 +0200, Rene Tschaggelar <none@none.net
wrote:

[snip]

Another aspect beside battery capacity is the
safety aspect. While a petrol powered engine
stops when encountering a root or a stone or such,
an electric engine starts drawing much more power
when braked. Thus a normal motor is inherently safer.



Controls, or even a circuit breaker, would take care of that. An
electric motor has, potentially, less moment of inertia, which would
make it safer in lots of situations.

John,
Are you sure that a 1 or 2 HP electric engine has
less inertia than a 1 or 2HP petrol powered machine ?
While the pseudothreephase asynchroneous machine with
a 90degree cap delivers torque moreless constantly,
a twostroke engine delivers torque only downwards,
requires a flywheel to keep it going plus the balanced
pistons.

Rene