headers
Will Schmit | 1 Mar 2012 01:01
Picon
Favicon

Re: power supply?

I'm with you Jay,
I think my best 
choice is to be kind to my batteries, and hope the price of Lithium 
drops.  The fear I have is that most of the best battery technology has 
already been bought by the automakers.  The new technology will (most 
likely) not be used, or will go right into $20,000 cars, never entering 
the hobbyist market.  I see our best hope is the Chinese, who will see a market, and throw us a bone. 

Martin,
My conversion is a little bit bigger than and S10, it is a 1995 Dodge 
Dakota Sport (short cab).  I take off at 500 amps, and settle to 250 to 
300 at 35 mph.  This particular Trojan is a real pig.  They have 
terrible Peukert numbers, and have neither range or giddyup.  If I only had a few more inches of room, I
would use the T-145s, even if I had to drop to 132v to squeeze them in -- the numbers are like night and day.

Regarding Lithium...
$8000 in my book is real money.  It would be much more cost effective to 
replace the T-1275s with the same thing ($3000) and wait a few years for the miracle battery
breakthrough.  Luckily, my needs are limited, and I am patient.

________________________________
 From: Jay Summet <jay <at> summet.com>
To: Electric Vehicle Discussion List <ev <at> lists.sjsu.edu> 
Cc: Martin WINLOW <m.winlow <at> btopenworld.com>; Will Schmit <anchornm <at> yahoo.com> 
Sent: Wednesday, February 29, 2012 11:08 AM
Subject: Re: [EVDL] power supply?

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
(Continue reading)

Permalink | Reply | 0 comments |
headers
Roland Wiench | 1 Mar 2012 01:03
Picon
Favicon

Re: winning the amp-hour war in an older pack (long)

Hello Chuck,

I have been charging my US145XC's batteries as recommended by US Battery.  I 
thought the acceptance maximum acceptance voltage was too high, so I 
contacted US Battery and they kind of yell at me, that you SHALL charge 
these batteries during the bulk cycle at 25 amps at 7.75 volts per 6 volt 
battery.

The prior battery pack I had, was Trojans T145's which they recommended a 
maximum acceptance voltage of 7.4 volts and up to 50 amps during the bulk 
charging cycle.  So I did just that, and 6 of the batteries in 8.8 years 
with 6476 cycles fail.  The other 24 Trojans are now in another EV which a 
friend of my has.  Had to modified the low profile stud post which started 
to fail with auto post.

So I now have been charging the US145XC at the 25 amp rated at 7.75 volts at 
80F battery temperature.  I do not heat the batteries, as where there are in 
a super insulated double wall isolated battery box.

SUGGESTION:

Also when the charger is on, the battery pack is disconnected from the main 
contactor and control by means of two more contactors.  When the charger is 
off, the battery pack is disconnected from the battery charge by a AC 3 pole 
contactor where the 3-poles of the contactor are tie together which is 
control by the AC input power.

The self discharge was greatly reduce, by electrical isolated from the 
battery charger and the controller, plus a non-conductive battery box.
(Continue reading)

Permalink | Reply | 1 comment |
headers
tomw | 1 Mar 2012 01:57
Picon
Favicon

Re: The effects of cold weather on EVs

Donald,

My heaters are a total of 350W for 36 cells, so 10 hours would be 3.5kWh if
they ran continuously.  They held the cells a set point  of 55 F for two
successive nights of -5 F temperature.  A difference of 28 C between set
point and ambient.

--
View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/Re-The-effects-of-cold-weather-on-EVs-tp4429850p4433650.html
Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.
Permalink | Reply | 0 comments |
headers
Roger Stockton | 1 Mar 2012 01:55
Favicon

Re: The effects of cold weather on EVs

donald.dakin@... wrote:

> I took +10 deg C as a desired target temp to maintain a battery at (just a
> guess). I assume when Nissan says The car runs great at -10C the battery
> is more like at 10 Deg C because it's working. When it sits in -20 deg
> weather faithfully waiting to take you home I guess it should try and keep
> itself warm like +10 deg C I assume that it would take 1 KW of energy to
> keep the battery 30 Deg above ambient (-20 C) for about 10 hours. I guess
> I'm asking how well the car would do in a "cold soak" test. Or in this
> case how much energy does a 10 hour cold soak cost. I think it's slightly
> similar to an  accelerated version of the tesla battery brick issue.
> Similar types of concerns.

Totally different concerns.  The Leaf does not become unusable ("bricked") at -20C, the question is merely
whether its performance is reduced sufficiently to make it unable to satisfy your mission.

The difficulty with making estimates as you are attempting to do is that we don't actually know just how warm
the battery will be when you park the car, we don't know its specific heat capacity, we don't know how
well-insulated it is, and we don't know what sort of thermal management features the vehicle includes
that might already maintain the battery temp in an appropriate range.

Your numbers might appear perfectly reasonable, yet be completely unapplicable to this particular
vehicle ;^>

> I actually trust the (as long as it makes sense to me) people on the list
> more then the people at Nissan. At least until I make more in roads there.

Why thank you ;^>

I think I would look for a Leaf owners' group forum to ask your questions on instead.  If you can find a Leaf
(Continue reading)

Permalink | Reply | 0 comments |
headers
Larry Gales | 1 Mar 2012 03:21
Picon

Re: The effects of cold weather on EVs

Yes, I used efficiency in a loose sense.  The real reason is that one
gallon of gasoline/ethanol mixture holds 33.7 kWh of energy, which is much
more than the 24 kWh in the entire Leaf battery pack.  While 100% of the
energy in a gas burner is converted to heat, the actual efficiency of
getting it to where it is needed is something on the order of 85-90%, but
that is still way more than you get from the battery.

Even though heat pumps supposedly are 400% efficient, it still requires
about a 2-3 kw drain on the battery to provide enough heat in really cold
weather.

The real point I was making was responding to the note that even with
heated seats, the person stated that he was miserably cold when the
temperature was very low, so a small gas burner heater seems the best way
to go (of course more insulation and thermal glass would be a big help too)

-- Larry

On Tue, Feb 28, 2012 at 7:46 PM, Roger Stockton <rstockton@...>wrote:

> Larry Gales wrote:
>
> > About a year ago or so I reported some calculations in this email list
> > based in the fact that:
> >
> > (a) electricity is very efficient at running motors but very INEFFICIENT
> > at
> > creating heat
> > (b) gasoline is very inefficient at running motors but is almost 90%
> > EFFICIENT at creating heat
(Continue reading)

Permalink | Reply | 2 comments |
headers
Rod Hower | 1 Mar 2012 03:46
Picon

Re: EVLN: Corbin Motors wants a Sparrow 2 for 2013 market

I've been involved with contract engineering on the Myers Motors NMG in the past
and agree with your perception of this being a unique looking design that is 
pretty cool!
This definitely is not a vehicle for the vast majority of people, but it is 
really a cool and fun 
vehicle for those that have driven it.  I've had the pleasure of driving 4 
different Sparrow/NMG's
and can say they are very fun to drive!  I think there is a market for this 
vehicle even if it is
a slight percentage of the total vehicle market.  If prices are reasonable and 
much higher volume pricing
is available for manufacturing, I believe there would be many more NMG's on the 
road.
Hopefully Myers Motors or Corbin will eventually bring this to market at a 
reasonable price!
Rod
https://plus.google.com/photos/102124681118672255625/albums/5184373384887099057?banner=pwa

----- Original Message ----
From: Jamie K <Jamie <at> JamieKrutz.com>
To: Electric Vehicle Discussion List <ev <at> lists.sjsu.edu>
Sent: Wed, February 29, 2012 11:29:16 AM
Subject: Re: [EVDL] EVLN: Corbin Motors wants a Sparrow 2 for 2013 market

The Sparrow/NMG has some advantages. Compared to a motorcycle it gets 
the driver out of the wind and weather, drives like a car and adds 
enclosed cargo capacity. Compared to a car used by one person, it gets 
rid of wasted seats and weight.

I've never had the opportunity to drive one but it looks like it would
(Continue reading)

Permalink | Reply | 0 comments |
headers
Voltswagon | 1 Mar 2012 03:54
Picon
Favicon

Re: It?s A Brick? ? Tesla Motors?


Evan Tuer wrote
> why not complain about the number of transistors
> in your computer's CPU, it's about the same thing :)
> 

Do you know what a transistor is?  Essentially a tiny on-off switch.  Can
one big switch turn two circuits on and off?  No.  

Can one larger battery do the work of two in parallel?  Yes, yes they can.

--
View this message in context: http://electric-vehicle-discussion-list.413529.n4.nabble.com/It-s-A-Brick-Tesla-Motors-tp4425628p4433878.html
Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.
Permalink | Reply | 0 comments |
headers
Tom Keenan | 1 Mar 2012 03:59
Picon
Favicon

Motor Overheat Question

I recently converted my 48v Citicar to 64 volts.  evalbum.com/1196 

It is quite a bit more fun to drive - more power, higher speed, etc.  At 64 volts, it easily keeps up with (and
sometimes exceeds) 'regular' cars.  At 48v, it was somewhat of a struggle.  64v seems to be a good fit for the Citicar.

At any rate, the motor - a 6.7" GE series motor - is now heating up at a higher rate than it did at 48v.  I would
expect, based on what I understand of I2R improvements, that a higher voltage would decrease losses,
resulting in a cooler motor - At least as long as I kept the acceleration/speed about the same as it was at 48v.

For a test, I drove about 5 miles (10 miles round trip - normal commute to work) for a few days, approximating
the speed and acceleration I had at 48v.  At 48v, the motor would heat up at about 10 degrees F per mile.

At 64v, it heats up at 13 degrees F per mile.  The total amount of heating allowed in this motor (class 'F') is
221 degrees above ambient temperature.  In other words, the maximum range based on motor temp is now about
17 miles.

A couple of reference points - the brushes are advanced roughly 5 degrees, and there is no arcing apparent so
the amount of advance seems appropriate.  The commutator is an even brown/gold color.  The motor is
'closed' - no ventilation.  There are plastic plugs covering ventilation holes, and I could remove the
plugs, but there is no internal fan.  The plugs have always been installed.  The Citicar seems to coast about
as far as it used to, so it does not appear that anything is dragging (brakes, alignment, etc.)

Possible problems I can think of - 
Some sort of armature/field problem?
Bad bearings?  
Brush problems? 
Wrong transaxle oil (motor shaft seal excessive friction) - Presently running RedLine MTL)? 

Any thoughts as to what might be causing the overheat?
(Continue reading)

Permalink | Reply | 5 comments |
headers
Jay Summet | 1 Mar 2012 04:22

Re: Motor Overheat Question


On 02/29/2012 09:59 PM, Tom Keenan wrote:
> I recently converted my 48v Citicar to 64 volts.  evalbum.com/1196 

> Any thoughts as to what might be causing the overheat?
> 

Seeing as the only change you have mentioned is the voltage, I'd suspect
the higher voltage is doing it.

Did you add weight to go to 64 volts (more batteries)? If so, even
driving at the same speed/acceleration would take more power. More power
= more waste heat.

Do you have a way to measure watts? (either a dedicated watt meter,
voltage and amperage gauges that you could eyeball) to determine if your
motor is using more total power?

Jay
Permalink | Reply | 1 comment |
headers
Tom Keenan | 1 Mar 2012 04:43
Picon
Favicon

Re: Motor Overheat Question

There is a bit more weight in the Citicar now (about 110 pounds) but the terrain is generally flat, so other
than the short time accelerating I'd suspect the weight would not really have much of an effect on power
use.  Cruise speed to work is about 28 MPH, so aero losses are not significant.

The wh/mile went from about 230 wh/mile to about 275 or so wh/mile.  I am not confident in these numbers,
because the pack is ageing (about 4.5 years old) and when I changed to 64v I also changed to a different
charger (was an old Lester ferro resonant - now an Elcon 2500).  

One additional item - Just before changing to 64v, the motor had a catastrophic failure of the brush
crossover links.  They shorted against the frame of the motor, creating a large amount of copper snot.  At
the time, the 48v system was frame grounded, and could possibly(?) have 'spot welded' one or both of the
armature bearings?  I replaced the links with stock components and cleaned up the inside of the motor, and
(other than the heating issue) it seems to run as expected.

Tom Keenan

--- On Wed, 2/29/12, Jay Summet <jay@...> wrote:

> From: Jay Summet <jay@...>
> Subject: Re: [EVDL] Motor Overheat Question
> To: ev@...
> Date: Wednesday, February 29, 2012, 7:22 PM
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> 
> 
> On 02/29/2012 09:59 PM, Tom Keenan wrote:
> > I recently converted my 48v Citicar to 64 volts. 
> evalbum.com/1196
(Continue reading)

Permalink | Reply | 0 comments |

Gmane