MacFormat 1994 November/macformat-018.iso/Utility Spectacular/Utilities/EVDesign 1.1/MiscInfo/Battery.Txt

Text File | 1994-05-20 | 45.0 KB | 986 lines | [TEXT/MSWD]

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Miscellaneous battery info gleaned from the EV mailing list on the Internet
Thanks to all who contribute to that group!

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Date: Sun, 11 Jul 1993 20:00:28 PDT
From: Peter Jacobs <[e-mail]>
To: Multiple recipients of list EV <[e-mail]>
Subject: Battery Info #2

As promised, here is another article by Bill Glazier on batteries from
VEVA newsletters. There are 2 more follow-up articles which I will
post as time permits.

"LEAD ACID BATTERIES #2
Today a few comments on REVERSE POLARITY and EOUALIZING.

These terms are quite familiar to persons having to
do with fork lift batteries but are readily misunderstood by others.
However, both occur in every size of Lead Acid battery with the
same effect. Reverse Polarity means simply that the positive plates
have become negative charged and the negative plates have
become positive charged. This applies only to the plates of the
battery, not to the battery as a whole. There may be only one plate
reverse charged or there may be a considerable number. There
would never be a situation where all plates were reversed unless the
battery was initially charged backwards. This can occur, the battery
will still work if hooked up backwards, but with diminished
capacity. That would be a no-excuse error in production.

       To understand why a plate reverses polarity you must first
understand that the positive plate carrying a positive charge is
shown as a plus (+). The negative plate carrying a negative charge
is shown as a minus (-). Now the tricky part! If you think back to
your high school algebra you will recall that when you add a plus
to a minus you get a plus. Therefore when you add the fully
charged voltage of a positive plate (2 volts) to the fully charged
voltage of a negative plate (.1 volts) you get 2.1 volts. Because the
plates in any cell are welded in parallel the voltage for that cell
never changes and we tend to say the voltage of a fully charged 12
volt battery will be 12.6 volts. The batteries we are most interested
in for electric auto use are 6 volt and their nominal voltage is 6.3
volts. If you refer to my last notes on charging and voltage
regulators you will recall that the condition of the battery dictated
the maximum voltage required to fully charge the battery and that a
new battery could require as high as 2.75 volts per cell to fully
charge. Because the negative plate tends to discharge at a
proportionate rate to the positive both plates should go to their
usable state of discharge at the same time. However, this does not
always happen and it is quite common for the negative plates to go
dead before the positives, and because they carry such a relatively
small amount of the energy the battery continues working with
little if any noticeable loss of capacity. At that point reversing of
polarity starts to take place.

          During the discharge process the current is flowing in
one direction, for purposes of explanation we say out the positive
terminal, through the motor and back to the negative. During the
charging process we then say the current enters through the positive
terminal and grounds back to the charger through the negative
terminal. If by chance a negative plate reaches zero state of charge
while the battery is still operating the current does not cease to pass
through that plate. It continues to flow through the plate in the
wrong direction, the direction it should flow in while being
charged. In this manner the negative plate becomes charged
positive. In a large fork lift battery with 18 or more cells there is so
much capacity that several cells may go dead while the battery is
still operating. Not only the negatives, but some positives as well
except that the positives become negative charged. Now, the
battery is put back on charge and the current starts to pass from
positive to negative and all the plates should return to a fully
charged state. But they don't!.

      What happens now is that the plates that still have their correct
polarity will charge normally but the reversed polarity cells must
first be returned to zero before they will charge correctly. This
takes place as the charging current passes through them and when
they have reached zero they start to charge in the correct manner.
This would be great if the other cells were not nearing the full
charge state and will soon need to go into a low
finish rate. Now, because of the low cells the voltage needed to cut
the charger back to the finish rate is not reached and the charge rate
remains high, so high that the charged cells begin to heat and gas
excessively. This results in damage to these cells if not corrected.

      Specific gravity readings taken while a battery is being charged
will quickly show up this condition and action must be taken to
correct the situation. Voltage readings can also be used. If the
battery is only slightly out of balance a few overcharges will bring
the plates back in balance. By overcharging I am stating what an
equalizing charge does. In order to bring the last cell up to full
charge it is necessary to overcharge every other cell in the battery
while at the same time making sure the charged cells do not receive
any damage. That means the temperature of the battery should not
exceed 110 degrees F. When the battery gets hotter than that
charging should be discontinued until it cools off .

In one meat packing plant we had a number of fork lift batteries
that were continuously abused. There were exchange batteries for
each of three shifts and it was the responsibility of the new shift
operator to change batteries immediately he came on shift. If a
large truck was almost loaded there would be great screaming
going on to finish the load and then change the battery- - the fork
lift was running fine so why not. The batteries had good excess
capacity so this form of abuse would take place until suddenly the
battery could not finish the shift. Then we had to explain why our
battery couldn't put in the shift. Some of these batteries would have
as many as a third of their plates with reversed polarity. Because of
their size equalizing could not be carried out in the normal manner
so a different process was used-- and this you can also use. The
battery must be discharged until every plate is dead, zero: a wire
across the terminals will not cause the faintest spark. Then the
battery is put back on charge and all plates will come up to full
charge together. This charge may take several days because the
plates may still need some equalizing charges at the end of
charging. It is also a good idea to start the charge with a very high
rate of charge so that all plates get started together. Have you ever
put a dead battery on a charger and after several days nothing
happened so you threw the battery away? Chances are that you
could have taken the battery to a battery shop where they would
have put it on charge for about one minute at 40 or 50 amps and the
current would have started flowing. You could then have put it on
your 6 amp charger and it would have charged fine.

     The point in all this is that you may think you are not doing
any harm to your batteries because they are working fine and
giving you more range than you expected. Watch your overall
voltage carefully, do not discharge below 1.75 volts per cell except
in an emergency. If you do, on a regular basis, you can expect the
troubles mentioned earlier. Next month I will explain how a
cadmium stick tester is used to tell the condition of plates, how it
can tell you that your negatives are still positive even while being
charged correctly."

reproduced with permission from W.J. (Battery Bill) Glazier,
                                Glazier Inovations Ltd.,
                                Vancouver, B.C., Canada.




--
Peter Jacobs
Victoria, B.C.
[phone]                                   [e-mail]

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Date: Thu, 22 Jul 1993 08:34:37 PDT
From: Peter Jacobs <[e-mail]>
To: Multiple recipients of list EV <[e-mail]>
Subject: Battery Article #3

I submit article 3 on batteries, by Bill Glazier
(printed with permission)


LEAD ACID BATTERIES-#3-
 - Last month I talked about reverse polarity and the problems encountered
with equalizing a battery in that condition. I have since been asked how to
bring a battery to zero voltage so that a correcting charging can commence.
This is easily done with a small battery such as in a car, simply leave the
headlights on overnight and the battery will be dead in the morning. However,
in the case of a large battery it is another story.

You must always first make sure that any discharging connection is made away
from the top of the battery where the explosive gases occur. A recently
charged battery will have a high concentration of gas while a battery that
has not been charged for several days will have less. Remove the cap from
the cell and look carefully to see if any bubbles are still visible in tbe
fluid. If there are still bubbles visible then explosive gas is still being
generated. In that case add water to the maximum fill mark to reduce the
space available for gas. We would normally use a squeeze bulb or an air hose
to blow all gases out of all cells on a battery before working near the top
of any traction battery. Never do anything to create a spark near the top of
any lead acid battery.

Now, to discharge a large battery we would attach a heavy jumper cable to
each terminal of the battery, or series of batteries, being careful the ends
do not touch. The free ends of the jumpers were then attached to bars that
were usually bars of solder or plain lead. These bars were inserted in a
large plastic bucket of water to which a small amount of battery acid had
been added. The bars are on opposite sides of the bucket but the current will
flow through the water/acid solution and create a short circuit until the
battery is dead. Remember that the fumes coming off this bucket are explosive
so make sure there is plenty of ventilation. At the very least the fumes will
clean out your plugged sinuses. In this manner it is possible to control the
discharge rate of very large batteries such as used in large fork lifts.

In one case where we were cycling a submersible battery several times to bring
it up to capacity we used a coil made from 1 inch aluminum tubing through
which we could pass cooling water. The capacity of the battery was 1500
amps at 240 volts DC so the current was very high. The coil was about 6
feet in diameter wound around a wooden frame and had about 50 or more
turns. The connectors from the battery could be bolted on to the tubing at
various positions to continue the discharge at a controlled rate. This was
a very low cost device and worked like a charm. Last I heard that
submersible was still seeking lost treasure in the caribbean. Use common
sense when discharging, just can't put the car up on blocks and run it till
it quits. You will destroy your motor first.

Now back to the cadmium stick test. Cadmium is a neutral metal and therefore a
very good conductor when submerged in battery acid for test
purposes.The tester used is quite sensitive to low voltage readings and in
addition it has either graduations on both ends of the dial or has two
terminals, one for positive and one for negative.The battery must be on
charge when this test is made, usuallyat a rate about 10% of the battery rated c
apacity. Place the tester prod
on the
negative terminal of the battery and insert the cadmium stick into the
acid of
the cell. You should get a reading on the dial that indicates the voltage of
the negative plate. If this reading is positive you have reverse polarity in
that cell. Continue to charge taking readings regularly to determine if the
voltage is changing. Continue to charge until no more change occurs always
being careful not to overheat. By doing the same on the positive terminal you
will be able to add the two readings together for a check on the condition of
the battery.

This Cadmium test is not commonly done outside of battery manufacturing plants
but if you are really serious about that extra mile (it could win the race)
then look a little deeper.The following addresses are quite old but if you
write
to either I am sure they would send you some information on meters and
test procedures.

Boyt Electrical Instruments
19 Linden Street,
Penacook, NH. 03303

Standard Electric Co. Inc.
PRO. Box 6356,
San Antonio, TX.

(article: Batteries #3, from V.E.V.A. newsletter, By Bill Glazier)

--
Peter Jacobs
Victoria, B.C.
[phone]                             [e-mail]

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Date: Thu, 2 Sep 1993 10:44:00 EDT
From: Greg Geyer <[e-mail]>
To: Multiple recipients of list EV <[e-mail]>
Subject: Horizon Press Release

Here is a BDM press release dated 6/2/93.  Dated, yes, but
should answer some questions I've received.  Forgive the
typos.

BDM AND ELECTROSOURCE FORM NEW COMPANY
TO PRODUCE ADVANCED LEAD ACID BATTERIES

BDM Technologies, Inc. and Electrosource, Inc. have jointly
formed a new company, Horizon Battery Technologies, Inc.
(HBTI), to produce in limited quantities a high performance
lead acid battery known as the Horizon, intended to power
electric vehicles (EVs) in the US and overseas.

The new company grew out of a strategic partnership
announced early this year by BDM, a technology services
company, and Electrosource, a pioneer in the development
of advanced lead acid battery technology.  They will
share equally in the ownership of HBTI.

BDM Technologies President John A. Corsiglia explained
that a typical compact EV will require a 20 kw/hour
battery pack, while vans require larger battery packs,
and motorcycles and very small cars require smaller
packs.  He said that HBTI has a target of manufacturing
50 battery packs each month for compact EVs by the
end of 1993.  By late 1994, HBTI is expected to be
capable of producing 250 battery packs per month.

Horizon battery packs are already beginning to be used
in testing and evaluation programs by manufacturers
preparing to respond to federal and state laws
mandating the widespread use of EVs in the coming years.

HBTI is currently seeking to license other companies
and establish joint ventures to manufacture the battery
in the US and in other countries.  Negotiations are already
underway with several US and international
manufacturers.

As a partner in HBTI, BDM's role is to design advanced
manufacturing systems and integrate the plants that will
produce the Horizon battery.  In addition, BDM will
provide marketing support and help negotiate joint
venture arrangements on a worldwide basis.

For its part, ELSI will provide research and development
services aimed at further improving the Horizon
battery.  Electrosource developed the technology on
which the Horizon battery is based using funds
raised as a public company.  In addition, the Horizon
development program was supported by the Electric
Power Research Insititute (EPRI), the research and
development organization of the US electric utility
industry.

According to Electrosource CEO Benny Jay, the Horizon
battery represents one of the most effective and
promising technologies currently available.  Jay
explained the that the Horizon battery:
 - Has the greatest peak power of any known EV
   battery candidate: over 550 watts/kilogram;
 - Can travel more than 100 miles (in EV usage)
   between charges;
 - Can be recharged to 50% in 8 minutes and 99% in
   30 minutes;
 - Can sustain more than 900 deep charge/recharge
   cycles, which, according to tests, means the battery
   will last approximately 80,000 miles;
 - Has significantly higher storage capacity to weight
   ratio than previous batteries and delivers more than
   52 watt-hours per kilogram specific energy; and
 - Can be manufactured for significantly less than
   other advanced batteries and potentially for even
   less than traditionally designed lead acid batteries.

The Horizon advantages come from its use of a grid
woven from lead wire co-extruded onto a fiberglass
core.  This material, along with the horizontal layout
of the battery's electrical plates, makes the Horizon
lighter, stronger, and able to withstand more charge/
discharge cycles than traditional lead acid batteries.

Corsiglia said, "Reaction to the Horizon battery in the
US, Europe, and the Pacific Rim has been
outstanding.  We believe the Horizon battery will be
the power source of choice for many of the electric
vehicles of the future."

"As its benefits and advantages become better
known," he continued, "BDM is looking forward to
utilizing our substantial experience in designing and
installing advanced manufacturing systems to
assist companies here and abroad to develop
modern facilities to produce Horizon batteries."

There's more, but that's more than enough PR at
one time....:)

Greg

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Date: Wed, 3 Nov 1993 18:00:30 U
From: Kevin Scoles <[e-mail]>
To: Multiple recipients of list EV <[e-mail]>
Subject: Re: Battery Efficiency

        Reply to:   RE>Battery Efficiency
Harjeet,

The data you need on batteries, in a table of the form you desire, can be found
in a paper recently published by C.C. Chan (Electrical & Electronic
Engineering, U. Hong Kong) in the Proceedings of the IEEE (Vol. 81, No. 9, Sept
'93, pp. 1202-1213). Eight battery types are included and compared in terms of
cycles life, calendar life, energy density, power density and cost per kWh, now
and with predictions for the year 2000.

Kevin Scoles
Electrical & Computer Engineering
and SunDragon Race Team
Drexel University

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Date: Fri, 3 Dec 1993 20:45:49 EST
From: Jim Mc Mullen <[e-mail]>
To: Multiple recipients of list HYDROGEN
     <[e-mail]>
Subject: Re: Batteries

Greg:
      There is a company in Troy, Michigan called Energy Conversion Devices
       (ECD) that manufactures a nickel hydrid battery.  Their phone number
      voice is - 313-280-1900, fax [phone]. That's hydride not hydrid.


                                       Jim Mc Mullen
                                        [e-mail]
"Politicians like diapers must be changed often - for the same reason"

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Date: Wed, 22 Dec 1993 16:53:25 -0500
From: Jeff A. Kester <[e-mail]>
To: Multiple recipients of list EV <[e-mail]>
Subject: Re: batteries/controllers

   Stan Witherspoon asked:

>What batteries have people chosen and why?

>I am trying to decide on a 120V string of 6V or two 120V strings of 12V
>in parallel. The car is a '73 914. I have heard that the parallel
>strings give you more performance at slightly less range, but I am
>wondering about how to keep the strings matched, otherwise there can be
>large currents flowing from one string to the other.
>
>     [controller comment deleted]

  The best price/performance recommendation I can make is to
stick with lead-acid batts. Now, now, take it easy with the flames
everybody...I said *price/performance*.  I refuse to use or recommend
NiCads because of the prohibitive cost as well as the difficulty of
recycling them.  The same is true of other "near-term" batteries (except
Ni-Metal Hydride, recycle yes, cost EEK!).  I know Mike Brown at Electro-
Automotive has supurvised a few 914 conversions and they all used 6v lead-
acids with varying success.

I use 16 6v Trojan T-145 batts in series for a 96v system.  The Trojans
cost about $70 per batt when bought in bulk, and they require watering
about once a month.  C/20 discharge rate is 244Ah.

Your information about parallel range problems sounds a little off.  If
you *only* use 12v batteries in series, you will get good pick-up
(I hope this is what you mean by performance) but reduced range.  If you
go for two sets of 12v batts, again get good pick-up and the range is
better than a single set (of either 12`s or 6`s).  The trade-off comes
from the extra weight of an additional set of batts.  I can't build
vehicles with dual 12v sets because I'll blow the GVWR out of the water,
once I do that I'd need to crash test the vehicle in order to comply
with FMVSS.  Not possible as a small manufacturer.

All this is becoming rather academic however, there are a few goodies
coming out this spring that will change everything (sorry Dodge:-) ).

First, there are the Horizon batteries.  I'm new to this list and I don't
know if you've already discussed them so I'll be brief. (Yea, I know--
why start now?:-) ).

Horizon batteries are advanced lead-acid batteries using extruded,
lead impregenated, fiberglass strands instead of traditional plates
inside the battery.  The strands are woven into a screen and the screens
sandwiched between fiberglass mats.  The sandwiches are layered horizontally
inside the battery case.  What this yields is: max surface area, light
weight and, because of the horz. layers and `glass mats for electrolyte
absorbtion, a maintenance free battery (it's leak-proof too).

They will be available in 6, 12 and hi-volt monoblocks.
How much? 12v cell=about $540. (Sorry folks, that's for bulk orders
to EV vendors [me], I don't know about sales to the public.)   The good
news is they promise 130+ mile range and should last over 5 years.

I'll post more specs and apples to apples compares if asked.

Second goodie is a new controller from Curtis.  It's still a MOSFET
unit but it'll handle 144VDC and it's limited to 500a `stead of 400.

I hope this helps.


        ----------------------------------------------------------------
        | Jeff Kester                  | "The only time I open my      |
        | Product Development          |  mouth is when I have to      |
        | GreenWheels Electric Car Co. |  change feet."                |
        | 181 Elliott St., #605        |                               |
        | Beverly, MA 01915  USA       | Internet:                     |
        | Voice: [phone]        | [e-mail] |
        ----------------------------------------------------------------

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Date: Thu, 23 Dec 1993 14:16:46 -0500
From: Jeff A. Kester <[e-mail]>
To: Multiple recipients of list EV <[e-mail]>
Subject: Battery Info

 Okay, here's what I've got for battery specs.  Most of
 these numbers are from HBTI and the NiCd EV info center.

 Conventional flooded-cell lead-acid:

        Energy Density (77F, 100% chgd)         31Wh/kg
        Power Density                            90w/kg
        Expected Life (EV applications)       103,000 km
        Mass Production Cost       $50 to $200* per kwh
             * Trojan T-145 in NE USA = ~$105/kwh
             I checked the rest of these specs for
             the T-145 batts and they're good.

 Conventional NiCads (SAFTs, the ones that are available):

        Energy Densisty                         40Wh/kg
        Power Densisty                          110w/kg
        Expected Life                        224,000 km
        Mass Production Cost     $1000 to $2000 per kwh

 Fibre Recom (sealed) NiCads (Daug-Hoppecke, not avail. yet)

        Energy Density                          50Wh/kg
        Power Density                           185w/kg
        Expected Life                   Nobody's saying
        Mass Production Cost   Their not saying that either

 HBTI sealed lead-acid (Beta test available in March `94, regular
        sales by end of `94)

        Energy Density                          45Wh/kg
        Power Density                           500w/kg
        Expected Life                        160,000 km
        Mass Production Cost       $150 to $300 per kwh

 Nickle Metal Hydride  (Supposed to be available by end of `94)

        Energy Density                          55Wh/kg
        Power Density                    200 to 250w/kg
        Expected Life          not demonstrated for EVs
        Mass Production Cost            about $1000/kWh

 Sodium Sulfer (Operates at over 300C, how's that for a heat
        problem?  There's also this little problem of water:-)

        Energy Density                        150+Wh/kg
        Power Density                           130w/kg
        Expected Life                   nobody's saying
        Mass Production Cost                    unknown

 Lithium Polymer (est. not available for at least 10 years)

        Energy Density                         200Wh/kg
        Power Density                          unproven
        Expected Life                  not demonstrated
        Mass Production Cost                    unknown

 Zinc Air (n/a)

        Energy Density                        ~100Wh/kg
        Power Density                          ~130w/kg
        No further info available

 Zinc Bromide (n/a)

        Energy Density                         ~60Wh/kg
        Power Density                           ~90w/kg
        no further info available

 Additional HBTI stuff:
        LxWxH   30x5x5.25 in., 762x127x133 mm
        Weight  59.4 lbs., 27 kg
                12 volt, 112 Ah, 1.35kWh

 Well, you asked for it!  As you can see, there are a few promising
 technologies but I need good batts now!  Ni-MHx will be my choice
 because they can be recycled within the existing Pb-acid infrastructure
 and they should last quite a bit longer than NiCads and Pb-acids.
 Since they're not avail. yet. I'll opt for advanced lead-acids.

 Hope this info answers some questions and please don't flame...these
 aren't my numbers, I'm just passing them along :-)


        ----------------------------------------------------------------
        | Jeff Kester                  | "The only time I open my      |
        | Product Development          |  mouth is when I have to      |
        | GreenWheels Electric Car Co. |  change feet."                |
        | 181 Elliott St., #605        |                               |
        | Beverly, MA 01915  USA       | Internet:                     |
        | Voice: [phone]        | [e-mail] |
        ----------------------------------------------------------------

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Date: Thu, 23 Dec 1993 22:57:32 +0200
From: Tuomas Koskinen <[e-mail]>
To: Multiple recipients of list EV <[e-mail]>
Subject: Re: Battery Info

>  Okay, here's what I've got for battery specs.  Most of
>  these numbers are from HBTI and the NiCd EV info center.
>
 ...
>
>  Zinc Bromide (n/a)
>
>         Energy Density                         ~60Wh/kg
>         Power Density                           ~90w/kg
>         no further info available

I`ve some info for ZnBr: Energy density=70-80Wh/kg, cost \S10000/kWh =
about $900/kWh (sold in 5kWh modules, price for small quantities), cycle life
about 600, max. temp about 50C. Available from SEA, 5-6 months delivery time.
Recycling is quite easy.

>  Additional HBTI stuff:
>         LxWxH   30x5x5.25 in., 762x127x133 mm
>         Weight  59.4 lbs., 27 kg
>                 12 volt, 112 Ah, 1.35kWh

Who makes these batteries? I mean, do you know where to get more info?

>  Well, you asked for it!  As you can see, there are a few promising
>  technologies but I need good batts now!  Ni-MHx will be my choice
>  because they can be recycled within the existing Pb-acid infrastructure
>  and they should last quite a bit longer than NiCads and Pb-acids.
>  Since they're not avail. yet. I'll opt for advanced lead-acids.
>
>  Hope this info answers some questions and please don't flame...these
>  aren't my numbers, I'm just passing them along :-)

Thank you for the data. How did you get the "expected life" figure in
kms? Also with energy density numbers it would be nice to see at what
discharge rate they are achieved. If you have that data, please post it.

 -- --
Tuomas Koskinen
[e-mail]

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Date: Thu, 23 Dec 1993 18:10:33 -0500
From: Jeff A. Kester <[e-mail]>
To: Multiple recipients of list EV <[e-mail]>
Subject: Re: Battery Info

Thanks for the response!

Tuomas K and others have asked for more info on HBTI. Here `tis:

        Horizon Battery Technologies, Inc.
        2809 Interstate 35 South
        San Marcos, TX 78666   USA

        Voice: [phone]
        FAX: [phone]

        Contact Michael Dodge, Director Sales/Marketing and he should be
        able to point you in the right direction.  Good luck.  BTW, I'm
        not affiliated with HBTI in any way, I just think they're moving
        in the right direction for EV development.


  I've been trying to find out about their Internet access abilities
  but all the folks I need to talk to are on vacation `til next year.
  The people I did get through to this afternoon believe that they
  have a FTP site for tech data but they're not sure.  Oh well, I'll
  post as soon as I find out. (won't they be happy :-) )

T.K. also asked:
>... How did you get the "expected life" figure in kms? Also with energy
> density numbers it would be nice to see at what discharge rate they
> are achieved. If you have that data, please post it.

Okay, as for the "Expected Life" specs (I thought that was a little weird
too.  Like I said, not my numbers and I'd promised apples vs. apples.),
what it looks like they (HBTI) did was to take the average range of an EV
with a pack of whatever type of battery, whether theoretical or actual, and
multiply by cycle life to get expected life.  Yep, that's the figure with
lotsa variation.  I'll hazard a guess at cycle lives as follows:
        Pb-acid         800     6v batts in series for 120v
        NiCd           1500     2v batts in series for 120v
        HBTI Pb-acid   1000    12v batts in series for 120v

I'm assuming that's to 80% DOD.  For "energy density" specs, most numbers
look like they were derived from a C/2 or C/3 discharge rate @ 80 or 90F to
1.75 volts/cell.

        ----------------------------------------------------------------
        | Jeff Kester                  | "The only time I open my      |
        | Product Development          |  mouth is when I have to      |
        | GreenWheels Electric Car Co. |  change feet."                |
        | 181 Elliott St., #605        |                               |
        | Beverly, MA 01915  USA       | Internet:                     |
        | Voice: [phone]        | [e-mail] |
        ----------------------------------------------------------------

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Date: Thu, 6 Jan 1994 19:13:47 -0500
From: Jeff A. Kester <[e-mail]>
To: Multiple recipients of list EV <[e-mail]>
Subject: C-C-Cold B-B-Batteries

In ref. to Richard Minner, Andy Nourse wrote:

>In cold climates, EVs are at several disadvantages:  heating (lack thereof)
>is certainly one of them [...]

  We've probably covered this point pretty well.  With Peter in BC, me in
coastal Massachusetts and others as far north as Finland driving all winter,
the viability of a heated EV (as a commuter car) is a proven point.  (As far
as A/C....nope!)

>[...] and you have a major loss in capacity of batteries at low
>temperatures.  The batteries that easily get you to work in warm weather
>may only get you halfway there before they run down. [...] if you
>don't charge them immediately, the batteries will freeze and burst,[...]

  True enough. But...
(Disclaimer 1: If this has been addressed in Yoder's FAQ, I'm sorry, I
haven't seen it)
(Disclaimer 2: I'll assume we're discussing flooded cell lead-acid
batteries.)  "Charging" a battery causes an electro-chemical reaction to
take place inside the battery that places the chemical elements within the
battery into a state which allows the potential of those chemical elements
to be "used" via an inverse electro-chemical reaction, i.e. "discharging".

A result of this electro-chemical reaction is heat.  The faster the reaction
takes place, the more heat is released.  Charging a battery usually causes it
to warm-up, and if it is charged too quickly, an essential chemical (H2) is
lost to "boiling" and the battery capacity may be damaged if it is not
replaced (with H20).  This heating and boiling phenomena is usually only
noticed during charging because we try to do it as quickly as possible
without damaging the battery.  However, the same thing happens when a
battery is discharged--heat is released and the battery warms-up.  The faster
it's discharged, the warmer it gets.  When romping the pedal in an EV, the
batteries get warm.  If the batteries are kept in some kind of insulated
container, they'll produce enough heat during the discharge/charge cycle
to cause no significant loss of range down to about 40F.  The thermal mass
of an 800lb. battery pack is substantial if insulated.

The winter range problem rears it's ugly head when the temps fall below
40F and the batteries start to cool (usually during the day when the car's
not as easily plugged in).  So, heat the batteries and the problem's solved.

(Disclaimer 3: This may be considered by some to be a blatant pitch of
a GreenWheels product.  That is not my intention.  I have not posted
anything in an attempt to sell my products to this list although as some
of you know, individual requests will be answered privately.)

We came up with a method of building very lightweight, acid-proof,
environmentally benign, insulated battery boxes as well as a method
of efficiently heating the batteries.  The battery heating is provided
by the 12v system (22.5 amps draw when they're going full bore) and
thermostatically controlled to provide 70F in a 0F ambient.  Basically,
the car can sit un-plugged in a parking lot all day in the winter with
no change in battery capacity.  Once the batteries are warm (from the
summer/fall) the thermal mass of the pack is maintained by charge/discharge
cycles and the battery heaters.  I've experienced a minor drop in range
with the onset of winter snows and temps in the 5F-15F range, which I
attribute to the road conditions.  I have a max/min recording thermometer
installed in one of the underhood battery boxes and the lowest temp recorded
so far is 70F.  It works for me!

>It may also take more energy to turn shafts and wheels when the oil
>lubricating them has turned to molasses.

Mobil makes synthetic gear oil and chassis grease for Artic use which
eliminate the "molasses" problem.


        ----------------------------------------------------------------
        | Jeff Kester                  | "The only time I open my      |
        | Product Development          |  mouth is when I have to      |
        | GreenWheels Electric Car Co. |  change feet."                |
        | 181 Elliott St., #605        |                               |
        | Beverly, MA 01915  USA       | Internet:                     |
        | Voice: [phone]        | [e-mail] |
        ----------------------------------------------------------------

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Date: Wed, 23 Feb 1994 00:45:53 -0500
From: editor of the EAA newsletter, Current EVents <[e-mail]>
To: Multiple recipients of list EV <[e-mail]>
Subject: GNB Battery Curves

Re: Mark Steven Burns' comment on data given by battery manufacturers:

Yes, you are quite right, Mark, and that is why I'd prefer to get discharge
data on these batteries from an independent source, if possible. Actually
I want these to compare with some other battery discharge curves generated
by an EAA member who has been testing capacity of several 12 Volt batteries.
I got him one each of a
ears DieHard Gold Group 29 and a West Marine Sea
Volt. He bought one of the new EverReady RV/EV batteries, so we are cycling
and testing all three. All the batteries are new, so it will take some
cycles to break them in. The DieHard Gold is looking quite good at this point,
with a 75-100 Amp discharge rate giving 50-60 min of life. I calculate capacity
 based on this as about 0.9 kWhrs after only 3 or 4 cycles.

If anyone else has experience with the above batteries, please let me know.
I think Solectria is using the DieHard Gold in its Force vehicles.
robably due to lightness -- the battery is about 56 lbs.
CB

[e-mail]
    GNB Battery Curves

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Date: Tue, 22 Feb 1994 22:29:27 -0800
From: Otmar Ebenhoech <[e-mail]>
To: Multiple recipients of list EV <[e-mail]>
Subject: DieHard Gold Group 29

Bob Schneevies uses the DieHard Gold Group 29 in his boat. (electrathon)
and claims 80 amps for 1 hour. Definatly very good. I thought he said they
were 62 Lbs. but I could be wrong.

Dave cloud got less than 100 cycles out of a set in his fiat before they
died. I understand that these are basically glorified starting batteries
and they seem to act this way too.

   -----------------------------------------------------------------------
     Otmar Ebenhoech         The Electric Speed Shop     [e-mail]
           People say life is strange.....But compared to what?
   -----------------------------------------------------------------------

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Date: Tue, 22 Feb 1994 22:29:24 -0800
From: Otmar Ebenhoech <[e-mail]>
To: Multiple recipients of list EV <[e-mail]>
Subject: Re: manfg. battery specs.

>Have most other poeple found this to be the case as well?
>

I have not.

Trojan regularly overstates their specs and US battery publishes 1450 specs
which are a insult to the intelligence of anyone using them. I remember
their 1 hour capacity was over 100 Ah. Actual is under 80 Ah.

   -----------------------------------------------------------------------
     Otmar Ebenhoech         The Electric Speed Shop     [e-mail]
           People say life is strange.....But compared to what?
   -----------------------------------------------------------------------

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Date: Wed, 23 Feb 1994 09:07:00 -0600
From: Arlen P. Walker <[e-mail]>
To: Multiple recipients of list EV <[e-mail]>
Subject: Re: GNB Battery Discharge Curves

>Prehaps I'm just a sceptic but I wouldn't believe any data that
>battery manufacturers provide.  Maybe just my bad experience but
>inside info suggests maybe not.  Has anyone else done
>comprehensive testing of battery capacities? I'm sure the combined
>experience of this group might persuade me that the manufacturers
>data is really not fiction if thats been the common experience.
>Recent GNB experience anyone.....

Mark,
  I'm wounded to the quick!! :{>}

   Since we're direct competitors of GNB anything I say about them should
be viewed with much skepticism, so I won't comment on our own experiences
with GNB batteries. But Ross Laboratories is an independent testing lab
whose numbers are extremely reliable, we've found (not just on our own
batteries, but those of our competitors). And for the skeptics out there, I
feel honor-bound to include that we feel that way, even though our
batteries don't always come out on top in his tests. Your local library may
have copies of his reports.

Have Fun,
Arlen

---------------------------------------------------
This mail message contains 100% recycled electrons
---------------------------------------------------

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Date: Fri, 1 Apr 1994 13:21:00 CST
From: Hart, Lee <[e-mail]>
To: Multiple recipients of list EV <[e-mail]>
Subject: Battery Question

>GNB ACTION PACK 220 6v batteries at Pace / Sam's Club, $38.93.
>
>Dave Robinson <robbo@hprdstl0>

I bought a set of 12 of them last year for my EV. So far, they have
been fine. It's rated at 75 amps for 105 minutes, so its capacity is
middle-range (other 6v batteries range from 80-145 minutes at 75 amps).

By the way, I got a coupon with purchase good for a "free" battery
state-of-charge gauge and T-shirt (for only $9.95 shipping and handling).
The gauge turns out to be a nice little expanded-scale voltmeter for 12v
batteries. The scale is calibrated from 0% charge (11.7v) to 100% charge
(12.7v).

Lee Hart <[e-mail]>

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Date: Thu, 19 May 1994 13:26:32 PDT
From: Charlie Panek <[e-mail]>
To: Multiple recipients of list EV <[e-mail]>
Subject: Horizon Batts: How 'bout them numbers?

In a recent posting, Clare Bell reported:

  Wescon 93 Highlights:

    Electrosource's Bill Craven described the beta-test model of the
  repackaged lead-acid Horizon battery.  This preproduction Horizon,
  specially developed "as a stake in the ground for EVs" will be 12 V
  112 Amphr at 3 hr rate of discharge, weighing 27 kg (59 lbs ) with
  dimensions of 30" X 5" X 5".  It will be going out to selected
  beta-test participants in early '94.  Data from 4V test cells
  indicate that the current Horizon design has 3x the power delivery
  capacity of standard lead-acid (440 Watt/kg as opposed to 145
  Watt/kg).  The high power acceptance capability enables the battery
  to accept rapid recharge, (50% of capacity in less than 10 min).

These being the first hard numbers on the Horizon battery I've seen,
I decided to do my own comparison.  The following numbers are taken from
Bob Brant's book (p 233).  I've extrapolated a W-H capacity number from
what is given above for the Horizon, though I'm a little confused as
how the numbers for the Trojans were generated:

                        Trojan 27TMH    T-125   Horizon
3C (A-hours)                 87          174      112
Weight (lbs)                 60           66       59
Volume (cu ft)             0.48         0.48     0.43
Energy Density (Wh/lb)     15.2         15.6     22.4
Vol. Eng. Den (W-h/cu.in.) 1900        2145      3069

(For the T-125, Energy density is very nearly = 174A-h  * 6V / 66 lbs
but for the 27TMH, it's much less than this.  Are they saying that the
output voltage drops much more with the Trojan 12V battery? hmm.)

Bottom line: Energy Density: 43% better than T-125.
             Volumetric Energy Density: 43% better than T-125.

Yet in the WSJ article, and the announcement at Wescon, Electrosource
talks about "powering a vehicle twice as far as any rivals commercially
available battery" and "..producing a.. ..pack that weighs 800 pounds -
which the company estimates is about half the weight of similar packs."

I'm sorry, but the above numbers just don't bear that out.  43% improvement
is great, but its not a "doubling" of capacity or a halving of weight.

Am I missing something, or is this just marketing exaggeration?

--
Charlie Panek                   Hewlett Packard Company
[e-mail]            Lake Stevens Instrument Division
                                Everett, Washington

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Date: Thu, 19 May 1994 17:22:00 CDT
From: Scott Mcbroom <[e-mail]>
To: Multiple recipients of list EV <[e-mail]>
Subject: Re: Horizon Batts Defense

Forwarded to:      smtp[[e-mail]]
          cc:
Comments by:       SMcBroom@VehRes@swri03

   -------------------------- [Original Message] -------------------------
This mail is in response to the message from the gentleman at HP.


Preface

I'm not in the business of marketing for Horizon.  I pursue Science and hence
expect not to gain any perks.


The HBTI batteries should effectively at least double the range if the
systems being compared have the same system voltage.  Granted while the
energy density isn't "double" nor is the weight "half," the effect of the
design will demonstrate its superiority in the driving schedule environment.
Because the battery has less of a voltage drop effect as its state of charge
is reduced, less IR losses occur from controller compensation for power.
These losses occur in both the battery pack and motor when the voltage is
lowered.  Also, since the vehicle now weighs less there are reductions in
losses from acceleration and rolling resistance.

The more steady state the comparison and the longer the time of comparison
the margain will decrease but the Horizons are still the winner.  I think
they do fit a wide market need.  With the short recharge period, high power
density, and eventual low cost for the life makes them extremely attractive
compared with more maintenance intensive and costly systems.  This is simply
a well engineered product that works!  Try one out later this year and see
for yourself.

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