Wire gauge for 48V lawn tractor/mower conversion: sanity check

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Wire gauge for 48V lawn tractor/mower conversion: sanity check

Michael K Johnson
I'm new to the list. I expect this has been discussed before but I
haven't found the right search terms. I apologize if so and would
appreciate a pointer.

I'm also entirely new to EV conversions. I've been scouring the net,
and have purchased most of the items to convert my lawn tractor to an
EV this winter. I'm using the ME1004 as a "drop-in" replacement for
the ICE in my existing hydrostatic-drive donor tractor, not doing
separate deck motors. I know several of the things I'll want to do to
reduce loss (belts, bearings, lube, new sharp blades, etc.) and I
understand the single motor/multi motor tradeoffs and already have the
ME1004... ☺

From what I've seen so far, ME1004 conversions on lawn tractors at 48V
consume 70-100 amps while actually mowing, and may momentarily consume
up to 200 amps while spinning up the mower deck.

I misread something somewhere (I don't even remember where anymore) as
indicating that since I expect to have 20 feet or shorter, I could use
4AWG fine-strand welding cable, so I bought some. Then I learned that
this might have been somewhat optimistic, so I'm expecting to chalk
that up in the "mistakes" column. I found the helpful articles at
engineeringtoolbox.com and a few references on resistance of copper
wire and am trying to calculate real voltage drop instead of following
rules of thumb. In particular, I'm looking at
http://en.wikipedia.org/wiki/American_wire_gauge and
http://www.engineeringtoolbox.com/copper-wire-d_1429.html which both
have similar numbers for ohms per thousand feet for copper wire.

I intend to fuse the conversion no larger than 400 amps and possibly
at 200 amps using an ANL fuse. So I've been calculating voltage drop
over 20 feet (and also, pessimistically, at 30 feet in case it takes
more cable than I expect) at 100 amps, 200 amps, and 400 amps.

My understanding is that I want to keep the voltage drop below 2%, so
with some room for error it seems like I want less than 0.9V drop in
normal operation, and not go much above it momentarily.

I'd like a sanity-check on my math, as well as the wisdom of the list
on recommended wire gauge...

For resistance per Kft, I am using:
1/0 awg: 0.09827
1 awg: 0.1239
4 awg: 0.2485

(I see no point in buying smaller than 1 awg if I replace the 4awg I
bought, so I'm ignoring 2 awg in my calculations.)

It looks to me like the voltage drop per 10 feet at 100 amps is the
same as ohms per Kft, since I divide by 100 to get the resistance of
10 feet, then multiply by 100 amps to get the voltage drop, so it
cancels out. Multiplying by 2 should give me voltage drop at 20 feet
at 100 A (my expected normal operation) and by 8 should give my
voltage drop at 20 feet at 400A.

Since 1/0 awg is more than twice as expensive as 1 awg as well as
harder to work, I'd prefer to use 1 awg. I calculate that 1 awg
(0.1239 Ohms/Kft) should drop about 1/4V at 100A at 20 feet (max
normal load) and about 1V at 400A at 20 feet (max momentary load).

Am I missing anything?

Thanks much!
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Re: Wire gauge for 48V lawn tractor/mower conversion: sanitycheck

Roland Wiench
Hello Michael,

Just leave the 4 gage in place and install another 4 gage in parallel with the existing wire.  We do this all the time in old and new installations.  Two 4 gages in parallel will run cooler than one 1 awg cable because of more surface area.

If you installing these wires in a conduit such as a water proof flexible plastic or metal conduit, it is best that the conduit is 60 percent larger than the wire to allow air flow.  Do not seal the end of the conduits, unless it is connected with seal tight box connectors to a ventilated enclosure.

The current capacity of the wire should at least 1.25% larger than the continuous current in the wire.  Example:  If you draw 100 amps continuous, then a wire good for 125 amps should be used.

Two 4 gage wires with a temperature rating of 75C is about 80 amps per wire or 160 amps total for a standard insulation wire in conduit.  Not in conduit suspended in air for 100 feet is closer to 200 amps allowing for a 3 percent voltage drop.

Roland
  ----- Original Message -----
  From: Michael K Johnson<mailto:[hidden email]>
  To: [hidden email]<mailto:[hidden email]>
  Sent: Saturday, November 02, 2013 9:06 AM
  Subject: [EVDL] Wire gauge for 48V lawn tractor/mower conversion: sanitycheck


  I'm new to the list. I expect this has been discussed before but I
  haven't found the right search terms. I apologize if so and would
  appreciate a pointer.

  I'm also entirely new to EV conversions. I've been scouring the net,
  and have purchased most of the items to convert my lawn tractor to an
  EV this winter. I'm using the ME1004 as a "drop-in" replacement for
  the ICE in my existing hydrostatic-drive donor tractor, not doing
  separate deck motors. I know several of the things I'll want to do to
  reduce loss (belts, bearings, lube, new sharp blades, etc.) and I
  understand the single motor/multi motor tradeoffs and already have the
  ME1004... ☺

  From what I've seen so far, ME1004 conversions on lawn tractors at 48V
  consume 70-100 amps while actually mowing, and may momentarily consume
  up to 200 amps while spinning up the mower deck.

  I misread something somewhere (I don't even remember where anymore) as
  indicating that since I expect to have 20 feet or shorter, I could use
  4AWG fine-strand welding cable, so I bought some. Then I learned that
  this might have been somewhat optimistic, so I'm expecting to chalk
  that up in the "mistakes" column. I found the helpful articles at
  engineeringtoolbox.com and a few references on resistance of copper
  wire and am trying to calculate real voltage drop instead of following
  rules of thumb. In particular, I'm looking at
  http://en.wikipedia.org/wiki/American_wire_gauge<http://en.wikipedia.org/wiki/American_wire_gauge> and
  http://www.engineeringtoolbox.com/copper-wire-d_1429.html<http://www.engineeringtoolbox.com/copper-wire-d_1429.html> which both
  have similar numbers for ohms per thousand feet for copper wire.

  I intend to fuse the conversion no larger than 400 amps and possibly
  at 200 amps using an ANL fuse. So I've been calculating voltage drop
  over 20 feet (and also, pessimistically, at 30 feet in case it takes
  more cable than I expect) at 100 amps, 200 amps, and 400 amps.

  My understanding is that I want to keep the voltage drop below 2%, so
  with some room for error it seems like I want less than 0.9V drop in
  normal operation, and not go much above it momentarily.

  I'd like a sanity-check on my math, as well as the wisdom of the list
  on recommended wire gauge...

  For resistance per Kft, I am using:
  1/0 awg: 0.09827
  1 awg: 0.1239
  4 awg: 0.2485

  (I see no point in buying smaller than 1 awg if I replace the 4awg I
  bought, so I'm ignoring 2 awg in my calculations.)

  It looks to me like the voltage drop per 10 feet at 100 amps is the
  same as ohms per Kft, since I divide by 100 to get the resistance of
  10 feet, then multiply by 100 amps to get the voltage drop, so it
  cancels out. Multiplying by 2 should give me voltage drop at 20 feet
  at 100 A (my expected normal operation) and by 8 should give my
  voltage drop at 20 feet at 400A.

  Since 1/0 awg is more than twice as expensive as 1 awg as well as
  harder to work, I'd prefer to use 1 awg. I calculate that 1 awg
  (0.1239 Ohms/Kft) should drop about 1/4V at 100A at 20 feet (max
  normal load) and about 1V at 400A at 20 feet (max momentary load).

  Am I missing anything?

  Thanks much!
  _______________________________________________
  UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub<http://www.evdl.org/help/index.html#usub>
  http://lists.evdl.org/listinfo.cgi/ev-evdl.org<http://lists.evdl.org/listinfo.cgi/ev-evdl.org>
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Re: Wire gauge for 48V lawn tractor/mower conversion: sanitycheck

Michael K Johnson
That's a really interesting idea. Thanks!

2 x 4 awg is the same cross-sectional area as 1 x 1 awg (42.4 mm²) so
I should be able to put 2 x 4 awg wire into a single 1 awg lug for my
connections. I'm using a pair of SB350 andersons for an emergency
disconnect; those lugs are sized for 1/0 awg but I was going to use a
pair of 10 awg solid pieces as core to ensure a snug fit in those
connectors; that would be even easier to do between two pieces of
stranded 4 awg than introducing them into a single 1 awg. I might need
to buy different heat shrink tubing but that's easy to check...

No conduit in my application, just grommets for any through-holes
required to route, and anchored cable ties to hold them in place. If I
route them not touching each other, that will keep them coolest.

(Leaving the 4 awg in place would involve letting it sit in the box; I
haven't started the conversion yet—need to keep using the ICE to
vacuum up leaves until the trees are bare; then I'll have enough time
to do the conversion as a novice... I had planned to re-purpose the 4
awg for welding purposes. But I can just buy more 4 awg instead.)


On Sat, Nov 2, 2013 at 12:38 PM, Roland Wiench <[hidden email]> wrote:

> Hello Michael,
>
> Just leave the 4 gage in place and install another 4 gage in parallel with the existing wire.  We do this all the time in old and new installations.  Two 4 gages in parallel will run cooler than one 1 awg cable because of more surface area.
>
> If you installing these wires in a conduit such as a water proof flexible plastic or metal conduit, it is best that the conduit is 60 percent larger than the wire to allow air flow.  Do not seal the end of the conduits, unless it is connected with seal tight box connectors to a ventilated enclosure.
>
> The current capacity of the wire should at least 1.25% larger than the continuous current in the wire.  Example:  If you draw 100 amps continuous, then a wire good for 125 amps should be used.
>
> Two 4 gage wires with a temperature rating of 75C is about 80 amps per wire or 160 amps total for a standard insulation wire in conduit.  Not in conduit suspended in air for 100 feet is closer to 200 amps allowing for a 3 percent voltage drop.
>
> Roland
>   ----- Original Message -----
>   From: Michael K Johnson<mailto:[hidden email]>
>   To: [hidden email]<mailto:[hidden email]>
>   Sent: Saturday, November 02, 2013 9:06 AM
>   Subject: [EVDL] Wire gauge for 48V lawn tractor/mower conversion: sanitycheck
>
>
>   I'm new to the list. I expect this has been discussed before but I
>   haven't found the right search terms. I apologize if so and would
>   appreciate a pointer.
>
>   I'm also entirely new to EV conversions. I've been scouring the net,
>   and have purchased most of the items to convert my lawn tractor to an
>   EV this winter. I'm using the ME1004 as a "drop-in" replacement for
>   the ICE in my existing hydrostatic-drive donor tractor, not doing
>   separate deck motors. I know several of the things I'll want to do to
>   reduce loss (belts, bearings, lube, new sharp blades, etc.) and I
>   understand the single motor/multi motor tradeoffs and already have the
>   ME1004... ☺
>
>   From what I've seen so far, ME1004 conversions on lawn tractors at 48V
>   consume 70-100 amps while actually mowing, and may momentarily consume
>   up to 200 amps while spinning up the mower deck.
>
>   I misread something somewhere (I don't even remember where anymore) as
>   indicating that since I expect to have 20 feet or shorter, I could use
>   4AWG fine-strand welding cable, so I bought some. Then I learned that
>   this might have been somewhat optimistic, so I'm expecting to chalk
>   that up in the "mistakes" column. I found the helpful articles at
>   engineeringtoolbox.com and a few references on resistance of copper
>   wire and am trying to calculate real voltage drop instead of following
>   rules of thumb. In particular, I'm looking at
>   http://en.wikipedia.org/wiki/American_wire_gauge<http://en.wikipedia.org/wiki/American_wire_gauge> and
>   http://www.engineeringtoolbox.com/copper-wire-d_1429.html<http://www.engineeringtoolbox.com/copper-wire-d_1429.html> which both
>   have similar numbers for ohms per thousand feet for copper wire.
>
>   I intend to fuse the conversion no larger than 400 amps and possibly
>   at 200 amps using an ANL fuse. So I've been calculating voltage drop
>   over 20 feet (and also, pessimistically, at 30 feet in case it takes
>   more cable than I expect) at 100 amps, 200 amps, and 400 amps.
>
>   My understanding is that I want to keep the voltage drop below 2%, so
>   with some room for error it seems like I want less than 0.9V drop in
>   normal operation, and not go much above it momentarily.
>
>   I'd like a sanity-check on my math, as well as the wisdom of the list
>   on recommended wire gauge...
>
>   For resistance per Kft, I am using:
>   1/0 awg: 0.09827
>   1 awg: 0.1239
>   4 awg: 0.2485
>
>   (I see no point in buying smaller than 1 awg if I replace the 4awg I
>   bought, so I'm ignoring 2 awg in my calculations.)
>
>   It looks to me like the voltage drop per 10 feet at 100 amps is the
>   same as ohms per Kft, since I divide by 100 to get the resistance of
>   10 feet, then multiply by 100 amps to get the voltage drop, so it
>   cancels out. Multiplying by 2 should give me voltage drop at 20 feet
>   at 100 A (my expected normal operation) and by 8 should give my
>   voltage drop at 20 feet at 400A.
>
>   Since 1/0 awg is more than twice as expensive as 1 awg as well as
>   harder to work, I'd prefer to use 1 awg. I calculate that 1 awg
>   (0.1239 Ohms/Kft) should drop about 1/4V at 100A at 20 feet (max
>   normal load) and about 1V at 400A at 20 feet (max momentary load).
>
>   Am I missing anything?
>
>   Thanks much!
>   _______________________________________________
>   UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub<http://www.evdl.org/help/index.html#usub>
>   http://lists.evdl.org/listinfo.cgi/ev-evdl.org<http://lists.evdl.org/listinfo.cgi/ev-evdl.org>
>   For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA<http://groups.yahoo.com/group/NEDRA>)
>
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Michael's 48V lawn tractor/mower conversion: sanity check

brucedp5
This post was updated on .
In reply to this post by Michael K Johnson
Welcome to the evdl Michael.

Others have already posted the answer to your initial question, and to
an EValbum page of a similar conversion.

We welcome more questions to help with your conversion, but it would be
wise to invest a little of your time to create a free EValbum.com page
of you own. It is free, simple, and you are not required to have
pictures right way (you can add them later). That way we can see/read
about your project and of what you are doing.

Speaking of which, I did not read from your first post, what your
project specifically is and what your use goals are (we are the people
who want the nitty-gritty details).
-Is it a from the ground up creation or are you using a donor ice model
(if so what brand, model, year).
The latter will give us an idea of what it will not only look like but
what the hp/performance needs are.

So, what are you going to do to personalize your conversion?
-Are you going to install a sound system like John Wayland's?
http://bp1.blogger.com/_ASjyUZYBmhk/RptniSwT3DI/AAAAAAAABPM/VRO9HHvhOPk/s1600-h/IMG_8500.JPG
http://evalbum.com/38

At 48V, I will assume you are not looking for Stig inspired performance
of Honda's Mean Mower ice with two e-motor driven cutting blades
http://www.themotorreport.com.au/content/image/h/o/honda_mean_mower_04-0718.jpg
http://www.octanefreaks.com/project-mean-mower-29711.html
http://www.autoblog.com/2013/07/17/honda-mean-mower-hits-60-mph-in-4-seconds-cuts-to-130-mph-w-vi/

Please post more details on your project and what your use-goals of
the completed conversion will be (how fast, how far, total cost, what
donor, how quick to recharge, etc.).


{brucedp.150m.com}
...
http://www.thefreedictionary.com/nitty-gritty
...
http://evalbum.com/evreg.php
Begin creating your own EValbum page



-
On Sat, Nov 2, 2013, at 08:06 AM, Michael K Johnson wrote:
> I'm new to the list. I expect this has been discussed before but I
> haven't found the right search terms. I apologize if so and would
> appreciate a pointer.
>
> I'm also entirely new to EV conversions. I've been scouring the net,
> and have purchased most of the items to convert my lawn tractor to an
> EV this winter. I'm using the ME1004 as a "drop-in" replacement for
> the ICE in my existing hydrostatic-drive donor tractor, not doing
> separate deck motors. I know several of the things I'll want to do to
> reduce loss (belts, bearings, lube, new sharp blades, etc.) and I
> understand the single motor/multi motor tradeoffs and already have the
> ME1004... ☺
>
> From what I've seen so far, ME1004 conversions on lawn tractors at 48V
> consume 70-100 amps while actually mowing, and may momentarily consume
> up to 200 amps while spinning up the mower deck.
>
> I misread something somewhere (I don't even remember where anymore) as
> indicating that since I expect to have 20 feet or shorter, I could use
> 4AWG fine-strand welding cable, so I bought some. Then I learned that
> this might have been somewhat optimistic, so I'm expecting to chalk
> that up in the "mistakes" column. I found the helpful articles at
> engineeringtoolbox.com and a few references on resistance of copper
> wire and am trying to calculate real voltage drop instead of following
> rules of thumb. In particular, I'm looking at
> http://en.wikipedia.org/wiki/American_wire_gauge and
> http://www.engineeringtoolbox.com/copper-wire-d_1429.html which both
> have similar numbers for ohms per thousand feet for copper wire.
>
> I intend to fuse the conversion no larger than 400 amps and possibly
> at 200 amps using an ANL fuse. So I've been calculating voltage drop
> over 20 feet (and also, pessimistically, at 30 feet in case it takes
> more cable than I expect) at 100 amps, 200 amps, and 400 amps.
>
> My understanding is that I want to keep the voltage drop below 2%, so
> with some room for error it seems like I want less than 0.9V drop in
> normal operation, and not go much above it momentarily.
>
> I'd like a sanity-check on my math, as well as the wisdom of the list
> on recommended wire gauge...
>
> For resistance per Kft, I am using:
> 1/0 awg: 0.09827
> 1 awg: 0.1239
> 4 awg: 0.2485
>
> (I see no point in buying smaller than 1 awg if I replace the 4awg I
> bought, so I'm ignoring 2 awg in my calculations.)
>
> It looks to me like the voltage drop per 10 feet at 100 amps is the
> same as ohms per Kft, since I divide by 100 to get the resistance of
> 10 feet, then multiply by 100 amps to get the voltage drop, so it
> cancels out. Multiplying by 2 should give me voltage drop at 20 feet
> at 100 A (my expected normal operation) and by 8 should give my
> voltage drop at 20 feet at 400A.
>
> Since 1/0 awg is more than twice as expensive as 1 awg as well as
> harder to work, I'd prefer to use 1 awg. I calculate that 1 awg
> (0.1239 Ohms/Kft) should drop about 1/4V at 100A at 20 feet (max
> normal load) and about 1V at 400A at 20 feet (max momentary load).
>
> Am I missing anything?
>
> Thanks much!
-
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Re: Michael's 48V lawn tractor/mower conversion: sanity check

Michael K Johnson
On Nov 2, 2013 1:45 PM, "Bruce EVangel Parmenter" <[hidden email]>
wrote:
> Others have already posted the answer to your initial question, and to
> an EValbum page of a similar conversion.

I could also have been clearer that I've viewed every EValbum page I could
find on any lawn tractor conversion. In particular Joe Lorenzi's beautiful
JD LA115 which is similar in nature but I suspect far more beautiful than
what I will accomplish. He very kindly answered several questions about his
conversion for me some months ago.

I do intend to document it much more fully; this initial question was a
very limited "hmm, have I put the right items in my online cart?"

It's good to know that an album makes sense early on... I will work on that
when I get a chance.

> Speaking of which, I did not read from your first post, what your
> project specifically is and what your use goals are (we care the people
> who want the nitty-gritty details).
> -Is it a from the ground up creation or are you using a donor ice model
> (if so what brand, model, year).
> The later will give us an idea of what it will not only look like but
> what the hp/performance needs are.

Donor ICE: 2005 MTD Troy-bilt Bronco. I'd pondered the conversion and the
need for a ring job pushed me over the edge. (My fault, don't ask...)

Use goals: mow about 1/3 acre (or a bit less; it is rather irregular and I
haven't measured exactly) once a week or so during the 8-9 month mowing
season. Occasional towing duties but the mowing is by far the most
significant requirement since running the mower deck will be more than half
the load. Mowing the whole thing on one charge normally. That's currently a
25-30 minute job so I expect to be able to do that on group 27 deep cycle
at about 60% DoD. (Also considering reducing lawn size a bit for unrelated
reasons which would give more room for error.)

Personalization: I go for vanilla as much as possible. No bumper stickers
on my cars. Muted paint colors. No bling. My goal is a good job without
frills.

I have purchased almost all the major parts. The lugs and additional cable
were the main remaining items to get started. I need to buy some angle to
weld into a battery support system, and the batteries themselves. Waiting
until the last moment to buy the batteries to not waste warranty. I do have
48V of UPS batteries available that I can use for idle testing and setting
the brushes before I buy the system batteries.

> At 48V, I will assume you are not looking for Stig inspired performance

Not remotely.

I'm not going to do any unbalanced pickoffs so I'll be able to use a single
48V charger (I got a Soneil constant current four stage). Planning to build
a set of four independent zener+LED DoD indicators, one for each battery.
I'm trying to keep the battery plant separate in the design on the theory
that when these die a completely different technology might be available...

What else?

Using the ME1004 and hydrostatic drive I'll use a 400A contactor and no
motor controller.

I'm going to use 48V muffin fans and an air filter to move extra air
through the motor and keep it clean to reduce wear. I bought a bank of four
fans but will use only many as I need to keep the motor cool. My plan is to
use 60 PPI reticulated foam for the air filter.
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Re: Wire gauge for 48V lawn tractor/mower conversion: sanitycheck

Michael K Johnson
In reply to this post by Michael K Johnson
I note that http://www.cloudelectric.com/product-p/pk-me1004.htm
includes 300A ANL fuses and 2 awg cable so 2x4 or 1 awg with 400A
ANL fuses seems vaguely in line, just as another sanity check from
something someone else may have done. ☺

On Sat, Nov 2, 2013 at 1:03 PM, Michael K Johnson <[hidden email]> wrote:

> That's a really interesting idea. Thanks!
>
> 2 x 4 awg is the same cross-sectional area as 1 x 1 awg (42.4 mm²) so
> I should be able to put 2 x 4 awg wire into a single 1 awg lug for my
> connections. I'm using a pair of SB350 andersons for an emergency
> disconnect; those lugs are sized for 1/0 awg but I was going to use a
> pair of 10 awg solid pieces as core to ensure a snug fit in those
> connectors; that would be even easier to do between two pieces of
> stranded 4 awg than introducing them into a single 1 awg. I might need
> to buy different heat shrink tubing but that's easy to check...
>
> No conduit in my application, just grommets for any through-holes
> required to route, and anchored cable ties to hold them in place. If I
> route them not touching each other, that will keep them coolest.
>
> (Leaving the 4 awg in place would involve letting it sit in the box; I
> haven't started the conversion yet—need to keep using the ICE to
> vacuum up leaves until the trees are bare; then I'll have enough time
> to do the conversion as a novice... I had planned to re-purpose the 4
> awg for welding purposes. But I can just buy more 4 awg instead.)
>
>
> On Sat, Nov 2, 2013 at 12:38 PM, Roland Wiench <[hidden email]> wrote:
>> Hello Michael,
>>
>> Just leave the 4 gage in place and install another 4 gage in parallel with the existing wire.  We do this all the time in old and new installations.  Two 4 gages in parallel will run cooler than one 1 awg cable because of more surface area.
>>
>> If you installing these wires in a conduit such as a water proof flexible plastic or metal conduit, it is best that the conduit is 60 percent larger than the wire to allow air flow.  Do not seal the end of the conduits, unless it is connected with seal tight box connectors to a ventilated enclosure.
>>
>> The current capacity of the wire should at least 1.25% larger than the continuous current in the wire.  Example:  If you draw 100 amps continuous, then a wire good for 125 amps should be used.
>>
>> Two 4 gage wires with a temperature rating of 75C is about 80 amps per wire or 160 amps total for a standard insulation wire in conduit.  Not in conduit suspended in air for 100 feet is closer to 200 amps allowing for a 3 percent voltage drop.
>>
>> Roland
>>   ----- Original Message -----
>>   From: Michael K Johnson<mailto:[hidden email]>
>>   To: [hidden email]<mailto:[hidden email]>
>>   Sent: Saturday, November 02, 2013 9:06 AM
>>   Subject: [EVDL] Wire gauge for 48V lawn tractor/mower conversion: sanitycheck
>>
>>
>>   I'm new to the list. I expect this has been discussed before but I
>>   haven't found the right search terms. I apologize if so and would
>>   appreciate a pointer.
>>
>>   I'm also entirely new to EV conversions. I've been scouring the net,
>>   and have purchased most of the items to convert my lawn tractor to an
>>   EV this winter. I'm using the ME1004 as a "drop-in" replacement for
>>   the ICE in my existing hydrostatic-drive donor tractor, not doing
>>   separate deck motors. I know several of the things I'll want to do to
>>   reduce loss (belts, bearings, lube, new sharp blades, etc.) and I
>>   understand the single motor/multi motor tradeoffs and already have the
>>   ME1004... ☺
>>
>>   From what I've seen so far, ME1004 conversions on lawn tractors at 48V
>>   consume 70-100 amps while actually mowing, and may momentarily consume
>>   up to 200 amps while spinning up the mower deck.
>>
>>   I misread something somewhere (I don't even remember where anymore) as
>>   indicating that since I expect to have 20 feet or shorter, I could use
>>   4AWG fine-strand welding cable, so I bought some. Then I learned that
>>   this might have been somewhat optimistic, so I'm expecting to chalk
>>   that up in the "mistakes" column. I found the helpful articles at
>>   engineeringtoolbox.com and a few references on resistance of copper
>>   wire and am trying to calculate real voltage drop instead of following
>>   rules of thumb. In particular, I'm looking at
>>   http://en.wikipedia.org/wiki/American_wire_gauge<http://en.wikipedia.org/wiki/American_wire_gauge> and
>>   http://www.engineeringtoolbox.com/copper-wire-d_1429.html<http://www.engineeringtoolbox.com/copper-wire-d_1429.html> which both
>>   have similar numbers for ohms per thousand feet for copper wire.
>>
>>   I intend to fuse the conversion no larger than 400 amps and possibly
>>   at 200 amps using an ANL fuse. So I've been calculating voltage drop
>>   over 20 feet (and also, pessimistically, at 30 feet in case it takes
>>   more cable than I expect) at 100 amps, 200 amps, and 400 amps.
>>
>>   My understanding is that I want to keep the voltage drop below 2%, so
>>   with some room for error it seems like I want less than 0.9V drop in
>>   normal operation, and not go much above it momentarily.
>>
>>   I'd like a sanity-check on my math, as well as the wisdom of the list
>>   on recommended wire gauge...
>>
>>   For resistance per Kft, I am using:
>>   1/0 awg: 0.09827
>>   1 awg: 0.1239
>>   4 awg: 0.2485
>>
>>   (I see no point in buying smaller than 1 awg if I replace the 4awg I
>>   bought, so I'm ignoring 2 awg in my calculations.)
>>
>>   It looks to me like the voltage drop per 10 feet at 100 amps is the
>>   same as ohms per Kft, since I divide by 100 to get the resistance of
>>   10 feet, then multiply by 100 amps to get the voltage drop, so it
>>   cancels out. Multiplying by 2 should give me voltage drop at 20 feet
>>   at 100 A (my expected normal operation) and by 8 should give my
>>   voltage drop at 20 feet at 400A.
>>
>>   Since 1/0 awg is more than twice as expensive as 1 awg as well as
>>   harder to work, I'd prefer to use 1 awg. I calculate that 1 awg
>>   (0.1239 Ohms/Kft) should drop about 1/4V at 100A at 20 feet (max
>>   normal load) and about 1V at 400A at 20 feet (max momentary load).
>>
>>   Am I missing anything?
>>
>>   Thanks much!
>>   _______________________________________________
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Re: Michael's 48V lawn tractor/mower conversion: sanity check

rodhower
In reply to this post by Michael K Johnson
I recommend using a motor control instead of a contactor.  I was going to reply with this suggestion, but thought $400 was more 
than you were thinking about spending for this idea.  A fellow Elec Trak user is selling one for a pretty good deal, $150
[hidden email]  , here's his post on the elec trak list,

Over the winter (2013) I replaced my ET E-20 motor with a D&D custom unit and needed to replace my ET 20-spec Alltrax with a standard Alltrax controller.  As a result I have a used ET E-20-spec Alltrax controller that I don't need.

It was in good operational condition when removed in early 2013.  I put it into service for the 2005 season, so it's had eight years of reliable use.  

Have pics (not that it's really that helpful) if desired.  $150 plus shipping cost.  Instructions, wiring pigtail.





________________________________
 From: Michael K Johnson <[hidden email]>
To: Electric Vehicle Discussion List <[hidden email]>
Sent: Saturday, November 2, 2013 5:20 PM
Subject: Re: [EVDL] Michael's 48V lawn tractor/mower conversion: sanity check
 

On Nov 2, 2013 1:45 PM, "Bruce EVangel Parmenter" <[hidden email]>
wrote:
> Others have already posted the answer to your initial question, and to
> an EValbum page of a similar conversion.

I could also have been clearer that I've viewed every EValbum page I could
find on any lawn tractor conversion. In particular Joe Lorenzi's beautiful
JD LA115 which is similar in nature but I suspect far more beautiful than
what I will accomplish. He very kindly answered several questions about his
conversion for me some months ago.

I do intend to document it much more fully; this initial question was a
very limited "hmm, have I put the right items in my online cart?"

It's good to know that an album makes sense early on... I will work on that
when I get a chance.

> Speaking of which, I did not read from your first post, what your
> project specifically is and what your use goals are (we care the people
> who want the nitty-gritty details).
> -Is it a from the ground up creation or are you using a donor ice model
> (if so what brand, model, year).
> The later will give us an idea of what it will not only look like but
> what the hp/performance needs are.

Donor ICE: 2005 MTD Troy-bilt Bronco. I'd pondered the conversion and the
need for a ring job pushed me over the edge. (My fault, don't ask...)

Use goals: mow about 1/3 acre (or a bit less; it is rather irregular and I
haven't measured exactly) once a week or so during the 8-9 month mowing
season. Occasional towing duties but the mowing is by far the most
significant requirement since running the mower deck will be more than half
the load. Mowing the whole thing on one charge normally. That's currently a
25-30 minute job so I expect to be able to do that on group 27 deep cycle
at about 60% DoD. (Also considering reducing lawn size a bit for unrelated
reasons which would give more room for error.)

Personalization: I go for vanilla as much as possible. No bumper stickers
on my cars. Muted paint colors. No bling. My goal is a good job without
frills.

I have purchased almost all the major parts. The lugs and additional cable
were the main remaining items to get started. I need to buy some angle to
weld into a battery support system, and the batteries themselves. Waiting
until the last moment to buy the batteries to not waste warranty. I do have
48V of UPS batteries available that I can use for idle testing and setting
the brushes before I buy the system batteries.

> At 48V, I will assume you are not looking for Stig inspired performance

Not remotely.

I'm not going to do any unbalanced pickoffs so I'll be able to use a single
48V charger (I got a Soneil constant current four stage). Planning to build
a set of four independent zener+LED DoD indicators, one for each battery.
I'm trying to keep the battery plant separate in the design on the theory
that when these die a completely different technology might be available...

What else?

Using the ME1004 and hydrostatic drive I'll use a 400A contactor and no
motor controller.

I'm going to use 48V muffin fans and an air filter to move extra air
through the motor and keep it clean to reduce wear. I bought a bank of four
fans but will use only many as I need to keep the motor cool. My plan is to
use 60 PPI reticulated foam for the air filter.
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Re: Michael's 48V lawn tractor/mower conversion: sanity check

Lee Hart
Rod Hower wrote:
> I recommend using a motor control instead of a contactor.

You'll want a contactor anyway, just as a reliable way to turn the darn
thing off (controllers tend to fail *on* i.e. a full throttle runaway).
But a controller certainly provides a lot smoother starting and speed
control.

--
"Obsolete" means nothing more than "the salesmen would prefer you buy
something else". -- Dave McGuire
--
Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm
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Re: Michael's 48V lawn tractor/mower conversion: sanity check

evdragracer
In reply to this post by brucedp5
Don't forget he has a hydrostatic transmission, so he can easily smoothly take off, and easily vary speed. Also the blades are being driven off the traction motor, slowing down via a controller will then slow the blades too much. A controller would be minimal benefit in this case.

-----Original message-----
Sent: Monday, 04 November 2013 at 07:03:23
From: "Lee Hart" <[hidden email]>
To: "Electric Vehicle Discussion List" <[hidden email]>
Subject: Re: [EVDL] Michael's 48V lawn tractor/mower conversion: sanity check
Rod Hower wrote:
> I recommend using a motor control instead of a contactor.

You'll want a contactor anyway, just as a reliable way to turn the darn
thing off (controllers tend to fail *on* i.e. a full throttle runaway).
But a controller certainly provides a lot smoother starting and speed
control.

--
"Obsolete" means nothing more than "the salesmen would prefer you buy
something else". -- Dave McGuire
--
Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm
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Re: Michael's 48V lawn tractor/mower conversion: sanity check

Michael K Johnson
The other potential benefit of a controller I understand would be
preventing overspeed, but this motor is supposed to be self-limiting.
I don't know how that is accomplished...

On Mon, Nov 4, 2013 at 12:28 PM,  <[hidden email]> wrote:

> Don't forget he has a hydrostatic transmission, so he can easily smoothly take off, and easily vary speed. Also the blades are being driven off the traction motor, slowing down via a controller will then slow the blades too much. A controller would be minimal benefit in this case.
>
> -----Original message-----
> Sent: Monday, 04 November 2013 at 07:03:23
> From: "Lee Hart" <[hidden email]>
> To: "Electric Vehicle Discussion List" <[hidden email]>
> Subject: Re: [EVDL] Michael's 48V lawn tractor/mower conversion: sanity check
> Rod Hower wrote:
>> I recommend using a motor control instead of a contactor.
>
> You'll want a contactor anyway, just as a reliable way to turn the darn
> thing off (controllers tend to fail *on* i.e. a full throttle runaway).
> But a controller certainly provides a lot smoother starting and speed
> control.
>
> --
> "Obsolete" means nothing more than "the salesmen would prefer you buy
> something else". -- Dave McGuire
> --
> Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm
> _______________________________________________
> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
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> _______________________________________________
> UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
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>
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Re: Michael's 48V lawn tractor/mower conversion: sanity check

evdragracer
In reply to this post by brucedp5
A low end controller won't protect against overspeed, but the good news is you don't need it. Your motor is a permanent magnet motor, so it'll want to spin one speed. Push it faster and it'll start generating electricity (regenerative braking) that will slow it down. On top of that the hydrostatic transmission will provide drag. My motor is similar in that the field is provided by a steady 12 volts, so it has a constant field like a permanent magnet motor does.. It regens down hills and overspeed is no worry even on steep grades. A sepex or permanent magnet motor makes a great tractor motor where you want to use its transmission designed to work with a constant speed motor. A series motor on a steep hill would be more prone to overspeed. -----Original message----- Sent: Monday, 04 November 2013 at 20:15:51 From: "Michael K Johnson" <[hidden email]> To: "Electric Vehicle Discussion List" <[hidden email]> Subject: Re: [EVDL] Michael's 48V lawn tractor/mower conversion: sa
 nity check The other potential benefit of a controller I understand would be preventing overspeed, but this motor is supposed to be self-limiting. I don't know how that is accomplished...
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