[ausev] Technical Considerations; Battery Pack Replacement 98 Ranger

[michael]

Based on all of this, it brought me to a new question…. 
 
In cars with engines, heat is the major killer of batteries, I don’t
know how many “swelled” batteries I replaced during my grease
monkey/tire jockey days.  Is this a concern for Electric cars or is the
heat not as much of an issue since it only is sun heat and not engine
and sun heat?  
 
(I hope that last sentence made sense)
 
Thanks!
 
Michael Ringer
Administrative Manager
GCE, Inc
512-528-0908
512-528-9293 FAX
Your Passport to education and employment
Member of NACES
HYPERLINK "http://www.naces.org"http://www.naces.org
-----Original Message-----
From: ausev-bounces at austinev.org [mailto:ausev-bounces at austinev.org] On
Behalf Of jtp
Sent: Thursday, August 10, 2006 11:46 AM
To: AustinEV News Announcements and General Discussion
Subject: [ausev] Technical Considerations; Battery Pack Replacement 98
Ranger
 
Additional technical aspects worth considering in the battery pack
replacement may relate to some of the new advanced electrical controls
on '99 and later IC's.
  '99 and later DC alternators on GM vehicles, for example, use a
computerized all-silicon voltage regulator, which requires a specific
sequence in reconnecting the harness, high amp output, and ground, in
order to properly "bias" the charging system for it to work.   
   Consideration might be given to the possibility that components of
the '98 Electric Drive Ranger may not only have a reconnection sequence
as well, but possibly, the question ought to be answered as to the
potential need for a disconnection sequence also.  
   When inspecting the Ranger at the "Who Killed the Electric Car"
event,  I noticed that the drive motor was manufactured by Siemens.  It
might be a good idea to see if Siemens Engineering could provide
guidelines about  this
or anything else in the wiring and controlling.
   Since there is apparently  a very substantial undertaking in the
replacement of the batteries,  I recommend that a very high level of
working precision be required here.  For example,  an "Inch-ounce"
torque wrench in order to record the removal torque required for all
bolts and clamps at the batteries, and making a carful decision as to
minimal and maximal torque specification at battery connections.  Torque
should be rechecked at least three times at differing temperatures (as
if you were working on the Space Shuttle).
Recording torque readings at removal for the main tray bolts also would
be important with a foot-pounds torque wrench.
  Since the "Sprung-weight" of the batteries would be off of the
suspension, and, an anticipated spring travel will reposition front
steering and suspension geometries, then, it may be a good idea to
lubricate any available grease fittings in the "extended-travel"
positions of the lubricated joints.  This in anticipation of dried-out
or thickened lubricants at all of the suspension points. 
  I am very opposed to the use of any kind of grease coating at any
battery connection, since grease is an insulator and can melt down
between critical contact areas.  While for  IC automotive (easy to
access) battery sitiations I use clear acrylic spray paint which keeps
corrosion at bay for at least 5 years (and is also of some value in
reducing the chance of accidental shorts as it has slight, low voltage
insulating value),  I can not say I could recommend that for higher
voltage packs at all, but only for the auxiliary voltages at a 12 volt
auxiliary battery only. 
   Another consideration which comes to mind, given the difficulty in
this endeavor, is to test cycle ALL the batteries at least a minimal
number of times in a similar application.  This may sound like a lot of
work, but actually using the batteries in a similar load-scenario may be
wise, such as installing them (if they will fit), into an EV where the
batteries could be performance tested.  Then, if there is one or more
which seem unable to perform as well as the rest, then there ought to be
an exchange requested for the underperformers. 
   Optional items.  Diamler-Chysler utilizes a datastream called
"Battery Temperature".  There is a sensor placed in the tray underneath
the battery which provides battery temperature as a function of
"reference voltage" whereby temperature of the battery influences its
internal resistance.
(Allowing for a very nicely accurate decision as to which mixture ratio
schedule to process).   This may be a really nice way to remotely
monitor battery temperatures, but maybe on an analog basis.   Also,
performing bench testing of cell temps during recharging each battery
after a calibrated discharge (of several discharge rates) may be helpful
in preventing inadvertent installation of a weak battery. 
 
 Dan Petit. 
   
   
  

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