Re: Link10 (E-meter) keeps resetting--why?

["Mark" <mark@dodrill.net>]

This question of how the 12v wiring works keeps coming up, so I'll go into
more detail about how the car is wired.  I must confess that I don't have
a full understanding of why it is setup the way it is, so please don't ask
"Why did you do it that way?  That's stupid!"

My 120v DC pack is connected in the back to the Link10 amp meter, via a
500 amp shunt.  There is a knife switch right next to the emergency brake
inside the car, which breaks the pack circut (front to back).  In the front,
one side of the 120v DC connects to the contactor, and the other connects
to the Curtis 1231 controller.  The controller connects to the motor, and
the motor connects back to the contactor to complete the circut.  That's
the basics.

Now, there is an additional smaller (12 gauge or 10 gauge) wire that runs
from the contactor to the DC/DC converter 120v input (positive as I recall).
 There is also a wire (12 or 10 gauge again) that appears to go from the
main negative side of the controller to the DC/DC converter negative--there's
lots of shrink tubing on the controller connection, so it's hard to tell
for sure (but it makes sense).  This has the net effect that the DC/DC converter
is on whenever the 120v pack circut is complete (that is, when the knife
switch is engaged (the normal condition).

Ok, stay with me.  The 12v output of the DC/DC converter goes to a strip
connector (I think that's what it's called), and then is connected to both
the 12v accessory battery and the 12v system.  The way it is wired, the
12v system is powered by either the DC/DC converter, the 12v battery or
both, depending on the draw.  The DC/DC converter pumps out 13.8 v whenever
it is on, and the battery sits at the same voltage as what comes out of
the DC/DC converter and drops to a lower (12.8 or so) level when the DC/DC
converter is off.  This is how I know that the DC/DC converter feeds the
battery when on.

As far as I can tell, the Link10 is connected up to the main 12v system,
just like anything else--though I'm not sure if it has an isolator as Roy
talked about.

When I turn on the key, the power brake pump starts up for a bit, but that
only uses about 0.5 amps on the Link10 (at 120v), which is like 5 amps (at
12v).  There are no other loads that start at that time, unless you had
the brakes/lights/radio on.  No fans or pumps or whatever.  So, there isn't
a large startup inrush.

Given all this--the Link10 won't start flashing (low voltage condition)
unless the voltage is like 9v or less.  Wouldn't the car clock or radio
or blinkers start having trouble at that low of a voltage too?  Since I
don't see any effect on the other systems, it points to the problem being
related specifically to the Link10 or what's hooked up to it.

I'm a computer programmer, so I'm the most suspicious about the things I
know I've changed, rather than something else in the environment.

Thanks for any additional thoughts you have.

Mark

>-- Original Message --
>Date: Fri, 30 Aug 2002 09:07:03 -0700
>From: Lee Hart <leeahart@earthlink.net>
>Reply-To: ev@listproc.sjsu.edu
>To: ev@listproc.sjsu.edu
>Subject: Re: Link10 (E-meter) keeps resetting--why?
>
>
>Mark wrote:
>
>> I ordered a brand new Link10 from EVParts... The problem I'm having
>> is that the Link10 keeps resetting itself, clearing the amp/hours
>> used, and flashing, and seemingly random times.
>
>Since the Link 10 is resetting and flashing, it is somehow losing its
>12v power. The Sevcon and 7ah accessory battery are pretty small. I
>would expect them to momentarily sag below 10 volts when the headlights
>are turned on or a fan motor is started because they can't supply the
>50-100 amp inrush current.
>
>What are you using for the DC/DC converter between the Link 10 and the
>12v accessory battery? Maybe it is missing (dangerous!) or not adequate
>for the job.
>
>The Cruising Equipment E-meters had an "EV filter" option. This was a
>1000uf filter capacitor across the power input, so it would survive
>momentary voltage sags. Pehaps Xantex in their infinite wisdom has
>decided to eliminate it to save money. 
>-- 
>Lee A. Hart                Ring the bells that still can ring
>814 8th Ave. N.            Forget your perfect offering
>Sartell, MN 56377 USA      There is a crack in everything
>leeahart_at_earthlink.net  That's how the light gets in - Leonard Cohen
>

Mark
1985 Pulsar EV
* Love that EV grin! *