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Discussion Starter · #1 ·
We're getting a lot of snow, and it's *heavy*. Although we normally
don't lose power (and the solar shed has about 5kw of battery power) we
might lose it someday.

So does anyone know about what the standby (spinning) load of a motor
generator would be? The Elec trak has a 2kw pack in it now, and a 9a
rotary inverter if needed. My main load would be the fireplace fans (40
watts) and a few lights (say another 60 watts for 4 15w CFLs). So about
100w.

Worst case I might find out since the E20 has a Link-20 on it... :)

Thanks
C

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Discussion Starter · #2 ·
What I've heard (haven't done the tests myself) is that full load efficiency
of a rotary inverter can be 70 to 80% or so, but that part load efficiency
is lousy, at least for the small ones (less than 50kW). Electronic
inverters tend to be pretty good above 10 to 15% of full load, whereas the
rotary ones need to be above 60% of full load... just what I've heard.
Another way of looking at this is the tare loss... about 20 watts for a 1000
watt electronic one, and more like 150 watts for a 1000 watt rotary one.
Again, these are not numbers I've measured or specs... just kind of vague
numbers I've heard.

Z

Chris Zach <[email protected]> wrote:

> We're getting a lot of snow, and it's *heavy*. Although we normally
> don't lose power (and the solar shed has about 5kw of battery power) we
> might lose it someday.
>
> So does anyone know about what the standby (spinning) load of a motor
> generator would be? The Elec trak has a 2kw pack in it now, and a 9a
> rotary inverter if needed. My main load would be the fireplace fans (40
> watts) and a few lights (say another 60 watts for 4 15w CFLs). So about
> 100w.
>
> Worst case I might find out since the E20 has a Link-20 on it... :)
>
> Thanks
> C
>
> _______________________________________________
> | REPLYING: address your message to [email protected] only.
> | Multiple-address or CCed messages may be rejected.
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Discussion Starter · #3 ·
I have a wind turbine with a 96v battery bank and a 2k inverter. The
inverter shuts off on safety before the amperage drw of my furnace fan
dropps ( 16= start, 6 run).
I have tried a PSC motor , a 5 speed motor and a super eficient fan motor
with no sucess. I'm looking for a 1/4 hp capacitor start motor to try.
Besides buying a 96 volt 3k inverter, does anyone have any ideas.
Other than that, my electric lawnmower (ev album-Nova Scotia) charged on
solar panels all summer and cut 75 hours of grass. My Suzuki Carry mini
truch sailed into Halifax yesterday and the conversion will soon begin.

Thanks:
John McManus

Lee Hart <[email protected]> wrote:

> On 1/26/2011 7:45 PM, Chris Zach wrote:
> > So does anyone know about what the standby (spinning) load of a motor
> > generator would be? The Elec trak has a 2kw pack in it now, and a 9a
> > rotary inverter if needed. My main load would be the fireplace fans (40
> > watts) and a few lights (say another 60 watts for 4 15w CFLs). So about
> > 100w.
>
> It's going to vary a lot, depending on the type and quality. The cheap
> ones are indeed a separate motor and generator. Their efficiency isn't
> all that good, as it's the product of the efficiency of the motor and
> the generator. 80% x 80% = 64% for example. At light loads it only gets
> worse.
>
> The other type is a rotary converter, which has a single armature with
> two sets of windings; one for input and one for output. They have about
> half the losses, so about 80% efficient at full load.
>
> Occasionally, you'll find an NON isolated rotary converter. It has just
> one winding, with taps for input and output. These work like an
> autotransformer, i.e. they are at their best when the input and output
> voltages are the same (120vdc in, 120vac out). Under these conditions,
> efficiency exceeds 90%.
>
> To guess at the light-load losses, assume you will still have about half
> of the full-load loss. For example, suppose it's 80% efficient at full
> load (1000w in, 800w out, 200w losses). At light load, assume the losses
> drop to 100w; so the no-load power consumption is still 100w. The 1/10th
> load efficiency is 80w out + 100w losses = 180w in, which is 100w/180w =
> 55% efficient.
>
> --
> Lee A. Hart | Ring the bells that still can ring
> 814 8th Ave N | Forget the perfect offering
> Sartell MN 56377 | There is a crack in everything
> leeahart earthlink.net | That's how the light gets in -- Leonard Cohen
>
> _______________________________________________
> | REPLYING: address your message to [email protected] only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev
>
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Discussion Starter · #4 ·
John,
Why don't you use a Universal (Brush type) or PM Direct Current motor
and run it from the battery pack directly? 96 volts is close enough to 100
for most simple DC motors to run very well with. Sure you will have to run
a separate pair of wires (size #12 or #10 if a long distance.) to the
battery and fuse it at 20 A with a slow blow fuse at the battery. (Or at the
input from the battery to the inverter if that is a more convenient location
to connect to.) A number of EV parts suppliers offer suitable motors and if
they are reading perhaps they will contact you with suggestions, prices, and
delivery availability. Similar to motors used to power power steering or an
Air Cond. Compressor, PM or shunt wound for good internal speed regulation
won't need a control except an on/off relay! Then without that heavy load
the Inverter can provide the service you need for everything else. I would
use the Battery directly for all the lighting with regular old incandescent
light bulbs to eliminate conversion losses in the inverter makes them more
efficient than compact florescent bulbs almost. you might want to be sure
of having a grid powered DC source to keep the heat working if the wind
turbine fails in a blizzard ? Or not?

Regards,
*Dennis Lee Miles* (Director) *E.V.T.I. inc*.
*www.E-V-T-I-Inc.COM <http://www.e-v-t-i-inc.com/> *(Adviser)*
EVTI-EVAEducation Chapter
*
++++++++++++++++++++++++++++++++
The "Stone Age" didn't end because they ran out of Stones;
It ended because they started using their Brains !
+++++++++++++++++++++++++++++++++++++++++++++
John McManus <[email protected]> wrote:

> I have a wind turbine with a 96v battery bank and a 2k inverter. The
> inverter shuts off on safety before the amperage drw of my furnace fan
> dropps ( 16= start, 6 run).
> I have tried a PSC motor , a 5 speed motor and a super eficient fan motor
> with no sucess. I'm looking for a 1/4 hp capacitor start motor to try.
> Besides buying a 96 volt 3k inverter, does anyone have any ideas.
> Other than that, my electric lawnmower (ev album-Nova Scotia) charged on
> solar panels all summer and cut 75 hours of grass. My Suzuki Carry mini
> truch sailed into Halifax yesterday and the conversion will soon begin.
>
> Thanks:
> John McManus
>
> On Thu, Jan 27, 2011 at 4:01 AM, Lee Hart <[email protected]> wrote:
>
> > On 1/26/2011 7:45 PM, Chris Zach wrote:
> > > So does anyone know about what the standby (spinning) load of a motor
> > > generator would be? The Elec trak has a 2kw pack in it now, and a 9a
> > > rotary inverter if needed. My main load would be the fireplace fans (40
> > > watts) and a few lights (say another 60 watts for 4 15w CFLs). So about
> > > 100w.
> >
> > It's going to vary a lot, depending on the type and quality. The cheap
> > ones are indeed a separate motor and generator. Their efficiency isn't
> > all that good, as it's the product of the efficiency of the motor and
> > the generator. 80% x 80% = 64% for example. At light loads it only gets
> > worse.
> >
> > The other type is a rotary converter, which has a single armature with
> > two sets of windings; one for input and one for output. They have about
> > half the losses, so about 80% efficient at full load.
> >
> > Occasionally, you'll find an NON isolated rotary converter. It has just
> > one winding, with taps for input and output. These work like an
> > autotransformer, i.e. they are at their best when the input and output
> > voltages are the same (120vdc in, 120vac out). Under these conditions,
> > efficiency exceeds 90%.
> >
> > To guess at the light-load losses, assume you will still have about half
> > of the full-load loss. For example, suppose it's 80% efficient at full
> > load (1000w in, 800w out, 200w losses). At light load, assume the losses
> > drop to 100w; so the no-load power consumption is still 100w. The 1/10th
> > load efficiency is 80w out + 100w losses = 180w in, which is 100w/180w =
> > 55% efficient.
> >
> > --
> > Lee A. Hart | Ring the bells that still can ring
> > 814 8th Ave N | Forget the perfect offering
> > Sartell MN 56377 | There is a crack in everything
> > leeahart earthlink.net | That's how the light gets in -- Leonard Cohen
> >
> > _______________________________________________
> > | REPLYING: address your message to [email protected] only.
> > | Multiple-address or CCed messages may be rejected.
> > | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> > | OTHER HELP: http://evdl.org/help/
> > | OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev
> >
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Discussion Starter · #5 ·
Just make sure that the furnace fan is not switched with an AC switch or
small relay
but *if* it is switched, to use a decent rated DC contactor.
Otherwise you will just create fireworks (arcs).

Success,

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 383 7626 VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040)23117400 x203 XoIP: +31877841130

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Dennis Miles
Sent: Thursday, January 27, 2011 10:44 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Efficiency of rotary inverters

John,
Why don't you use a Universal (Brush type) or PM Direct Current
motor and run it from the battery pack directly? 96 volts is close
enough to 100 for most simple DC motors to run very well with. Sure you
will have to run a separate pair of wires (size #12 or #10 if a long
distance.) to the battery and fuse it at 20 A with a slow blow fuse at
the battery. (Or at the input from the battery to the inverter if that
is a more convenient location to connect to.) A number of EV parts
suppliers offer suitable motors and if they are reading perhaps they
will contact you with suggestions, prices, and delivery availability.
Similar to motors used to power power steering or an Air Cond.
Compressor, PM or shunt wound for good internal speed regulation won't
need a control except an on/off relay! Then without that heavy load the
Inverter can provide the service you need for everything else. I would
use the Battery directly for all the lighting with regular old
incandescent light bulbs to eliminate conversion losses in the inverter
makes them more efficient than compact florescent bulbs almost. you
might want to be sure of having a grid powered DC source to keep the
heat working if the wind turbine fails in a blizzard ? Or not?

Regards,
*Dennis Lee Miles* (Director) *E.V.T.I. inc*.
*www.E-V-T-I-Inc.COM <http://www.e-v-t-i-inc.com/> *(Adviser)*
EVTI-EVAEducation Chapter
*
++++++++++++++++++++++++++++++++
The "Stone Age" didn't end because they ran out of Stones;
It ended because they started using their Brains !
+++++++++++++++++++++++++++++++++++++++++++++
On Thu, Jan 27, 2011 at 10:22 AM, John McManus <[email protected]>
wrote:

> I have a wind turbine with a 96v battery bank and a 2k inverter. The
> inverter shuts off on safety before the amperage drw of my furnace fan

> dropps ( 16= start, 6 run).
> I have tried a PSC motor , a 5 speed motor and a super eficient fan
> motor with no sucess. I'm looking for a 1/4 hp capacitor start motor
to try.
> Besides buying a 96 volt 3k inverter, does anyone have any ideas.
> Other than that, my electric lawnmower (ev album-Nova Scotia) charged
> on solar panels all summer and cut 75 hours of grass. My Suzuki Carry
> mini truch sailed into Halifax yesterday and the conversion will soon
begin.
>
> Thanks:
> John McManus
>
> On Thu, Jan 27, 2011 at 4:01 AM, Lee Hart <[email protected]>
wrote:
>
> > On 1/26/2011 7:45 PM, Chris Zach
wrote:
> > > So does anyone know about what the standby (spinning) load of a
> > > motor generator would be? The Elec trak has a 2kw pack in it now,
> > > and a 9a rotary inverter if needed. My main load would be the
> > > fireplace fans (40
> > > watts) and a few lights (say another 60 watts for 4 15w CFLs). So
> > > about 100w.
> >
> > It's going to vary a lot, depending on the type and quality. The
> > cheap ones are indeed a separate motor and generator. Their
> > efficiency isn't all that good, as it's the product of the
> > efficiency of the motor and the generator. 80% x 80% = 64% for
> > example. At light loads it only gets worse.
> >
> > The other type is a rotary converter, which has a single armature
> > with two sets of windings; one for input and one for output. They
> > have about half the losses, so about 80% efficient at full load.
> >
> > Occasionally, you'll find an NON isolated rotary converter. It has
> > just one winding, with taps for input and output. These work like an

> > autotransformer, i.e. they are at their best when the input and
> > output voltages are the same (120vdc in, 120vac out). Under these
> > conditions, efficiency exceeds 90%.
> >
> > To guess at the light-load losses, assume you will still have about
> > half of the full-load loss. For example, suppose it's 80% efficient
> > at full load (1000w in, 800w out, 200w losses). At light load,
> > assume the losses drop to 100w; so the no-load power consumption is
> > still 100w. The 1/10th load efficiency is 80w out + 100w losses =
> > 180w in, which is 100w/180w = 55% efficient.
> >
> > --
> > Lee A. Hart | Ring the bells that still can ring
> > 814 8th Ave N | Forget the perfect offering
> > Sartell MN 56377 | There is a crack in everything
> > leeahart earthlink.net | That's how the light gets in -- Leonard
> > Cohen
> >
> > _______________________________________________
> > | REPLYING: address your message to [email protected] only.
> > | Multiple-address or CCed messages may be rejected.
> > | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> > | OTHER HELP: http://evdl.org/help/
> > | OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev
> >
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> | Multiple-address or CCed messages may be rejected.
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_______________________________________________
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Registered
Joined
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70 Posts
Discussion Starter · #6 ·
OPS, I said use a relay but failed to mention the relay for the AC motor
would be inappropriate for interrupting the DC Current, so a DC rated motor
relay should be used. Thanks for pointing that out Cor.
Regards,
*Dennis Lee Miles*
-----------------------------------------------------------------------------
Cor van de Water <[email protected]> wrote:

> Just make sure that the furnace fan is not switched with an AC switch or
> small relay
> but *if* it is switched, to use a decent rated DC contactor.
> Otherwise you will just create fireworks (arcs).
>
> Success,
>
> Cor van de Water
> Director HW & Systems Architecture Group
> Proxim Wireless Corporation http://www.proxim.com
> Email: [email protected] Private: http://www.cvandewater.com
> Skype: cor_van_de_water IM: [email protected]
> Tel: +1 408 383 7626 VoIP: +31 20 3987567 FWD# 25925
> Tel: +91 (040)23117400 x203 XoIP: +31877841130
>
> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of Dennis Miles
> Sent: Thursday, January 27, 2011 10:44 PM
> To: Electric Vehicle Discussion List
> Subject: Re: [EVDL] Efficiency of rotary inverters
>
> John,
> Why don't you use a Universal (Brush type) or PM Direct Current
> motor and run it from the battery pack directly? 96 volts is close
> enough to 100 for most simple DC motors to run very well with. Sure you
> will have to run a separate pair of wires (size #12 or #10 if a long
> distance.) to the battery and fuse it at 20 A with a slow blow fuse at
> the battery. (Or at the input from the battery to the inverter if that
> is a more convenient location to connect to.) A number of EV parts
> suppliers offer suitable motors and if they are reading perhaps they
> will contact you with suggestions, prices, and delivery availability.
> Similar to motors used to power power steering or an Air Cond.
> Compressor, PM or shunt wound for good internal speed regulation won't
> need a control except an on/off relay! Then without that heavy load the
> Inverter can provide the service you need for everything else. I would
> use the Battery directly for all the lighting with regular old
> incandescent light bulbs to eliminate conversion losses in the inverter
> makes them more efficient than compact florescent bulbs almost. you
> might want to be sure of having a grid powered DC source to keep the
> heat working if the wind turbine fails in a blizzard ? Or not?
>
> Regards,
> *Dennis Lee Miles* (Director) *E.V.T.I. inc*.
> *www.E-V-T-I-Inc.COM <http://www.e-v-t-i-inc.com/> *(Adviser)*
> EVTI-EVAEducation Chapter
> *
> ++++++++++++++++++++++++++++++++
> The "Stone Age" didn't end because they ran out of Stones;
> It ended because they started using their Brains !
> +++++++++++++++++++++++++++++++++++++++++++++
> On Thu, Jan 27, 2011 at 10:22 AM, John McManus <[email protected]>
> wrote:
>
> > I have a wind turbine with a 96v battery bank and a 2k inverter. The
> > inverter shuts off on safety before the amperage drw of my furnace fan
>
> > dropps ( 16= start, 6 run).
> > I have tried a PSC motor , a 5 speed motor and a super eficient fan
> > motor with no sucess. I'm looking for a 1/4 hp capacitor start motor
> to try.
> > Besides buying a 96 volt 3k inverter, does anyone have any ideas.
> > Other than that, my electric lawnmower (ev album-Nova Scotia) charged
> > on solar panels all summer and cut 75 hours of grass. My Suzuki Carry
> > mini truch sailed into Halifax yesterday and the conversion will soon
> begin.
> >
> > Thanks:
> > John McManus
> >
> > On Thu, Jan 27, 2011 at 4:01 AM, Lee Hart <[email protected]>
> wrote:
> >
> > > On 1/26/2011 7:45 PM, Chris Zach wrote:
> > > > So does anyone know about what the standby (spinning) load of a
> > > > motor generator would be? The Elec trak has a 2kw pack in it now,
> > > > and a 9a rotary inverter if needed. My main load would be the
> > > > fireplace fans (40
> > > > watts) and a few lights (say another 60 watts for 4 15w CFLs). So
> > > > about 100w.
> > >
> > > It's going to vary a lot, depending on the type and quality. The
> > > cheap ones are indeed a separate motor and generator. Their
> > > efficiency isn't all that good, as it's the product of the
> > > efficiency of the motor and the generator. 80% x 80% = 64% for
> > > example. At light loads it only gets worse.
> > >
> > > The other type is a rotary converter, which has a single armature
> > > with two sets of windings; one for input and one for output. They
> > > have about half the losses, so about 80% efficient at full load.
> > >
> > > Occasionally, you'll find an NON isolated rotary converter. It has
> > > just one winding, with taps for input and output. These work like an
>
> > > autotransformer, i.e. they are at their best when the input and
> > > output voltages are the same (120vdc in, 120vac out). Under these
> > > conditions, efficiency exceeds 90%.
> > >
> > > To guess at the light-load losses, assume you will still have about
> > > half of the full-load loss. For example, suppose it's 80% efficient
> > > at full load (1000w in, 800w out, 200w losses). At light load,
> > > assume the losses drop to 100w; so the no-load power consumption is
> > > still 100w. The 1/10th load efficiency is 80w out + 100w losses =
> > > 180w in, which is 100w/180w = 55% efficient.
> > >
> > > --
> > > Lee A. Hart | Ring the bells that still can ring
> > > 814 8th Ave N | Forget the perfect offering
> > > Sartell MN 56377 | There is a crack in everything
> > > leeahart earthlink.net | That's how the light gets in -- Leonard
> > > Cohen
> > >
> > > _______________________________________________
> > > | REPLYING: address your message to [email protected] only.
> > > | Multiple-address or CCed messages may be rejected.
> > > | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> > > | OTHER HELP: http://evdl.org/help/
> > > | OPTIONS: http://lists.sjsu.edu/mailman/listinfo/ev
> > >
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> > | Multiple-address or CCed messages may be rejected.
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> >
>
>
>
> --
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Discussion Starter · #7 ·
Thank you for all your comments on this. After blowing the snow today
(and seriously taxing the E20's power bus) I charged up and plugged in
the rotary inverter to get some data. Here is what I found:

Elec-trak 36 volt single-shaft rotary inverter, fully charged pack, 300
watt halogen light load. All readings taken off a Link-20 E-meter on the
DC side and a P3 KiloWatt meter on the AC side.

With no load (inverter spinning)

Battery Voltage: 43.0 volts
Battery current: 3.1 a
Total wattage: 133 watts
AC voltage: 140.8 volts
AC current: 0 amps
AC frequency: 68.6 hz

----------------------------

With 300 watt halogen lamp:
Battery voltage: 40.4 volts
Battery current: 12.8 a
Total wattage: 517 watts

AC status:
AC voltage: 127.8
AC current: 2.54a
AC watts: 327.0
AC Frequency: 64.5 hz
Power factor: 1.0

So if we take away the 133 watts of no-load static cost, the efficiency
differential seems to be about 85%. The total overall efficiency for a
327 watt load is 63%.

Interesting.
C

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Discussion Starter · #8 ·
Thanks Lee:
I finally got an extra fan, 2 motors, 2 switches etc . together and tried
your idea. The unloaded motor started at about 6 amps and ran at 4+. With
this motor running the loaded fan motor drew 19 amps to start then down to
6. This is probably too much for my 2 k inverter .
I haven't tried DC as I haven't got the parts. I'm looking for a capacitor
start motor, I only need thye starting amperage to fall by about 4-5.

John

Lee Hart <[email protected]> wrote:

> On 1/27/2011 9:22 AM, John McManus wrote:
> > I have a wind turbine with a 96v battery bank and a 2k inverter. The
> > inverter shuts off on safety before the amperage drw of my furnace fan
> > dropps ( 16= start, 6 run).
> > I have tried a PSC motor , a 5 speed motor and a super eficient fan motor
> > with no sucess. I'm looking for a 1/4 hp capacitor start motor to try.
> > Besides buying a 96 volt 3k inverter, does anyone have any ideas.
> > Other than that, my electric lawnmower (ev album-Nova Scotia) charged on
> > solar panels all summer and cut 75 hours of grass. My Suzuki Carry mini
> > truch sailed into Halifax yesterday and the conversion will soon begin.
>
> Try connecting an induction motor with no load to the inverter first.
> Then connect your furnace motor. The motor that's already running
> momentarily becomes a generator, and supplies some of the starting
> current for the furnace motor.
>
> But the other problem you may be facing is that many inverters have
> highly inflated ratings. Your "2kw" inverter may in fact not be able to
> power any load that touches 2kw for even a fraction of a second.
>
> --
> Lee A. Hart | Ring the bells that still can ring
> 814 8th Ave N | Forget the perfect offering
> Sartell MN 56377 | There is a crack in everything
> leeahart earthlink.net | That's how the light gets in -- Leonard Cohen
>
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