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Discussion Starter #1
My TBS meter docs recommended installing the shunt near the negative
end of the battery. That was done and the meter worked well; it
correctly recorded 15 amps charging with the 3KW Zivan and then later 8
amps with the 1500 watt Elcon. During a re-configuration, the shunt
got moved to the motor bay, 6 or 8 feet from the battery negative. It
continued to record 8 amps from the Elcon but the Zivan shows erratic
readings, rarely more than 12 amps. I suspected the Zivan of being
broken but I recently noticed that, while using the Zivan for a few
hours and then switching to the Elcon, the battery became full before
the meter counted down to zero.

My next experiment will be to attempt a complete charge with the Zivan
and see if the charge is completed in the amount of time expected for
15 amp charging.

I have no reason to suspect that discharge current is being incorrectly
recorded.

Can anyone tell me what is going on here?

--
Willie, ONWARD! Through the fog!
http://counter.li.org Linux registered user #228836 since 1995
Debian3.1/GNU/Linux system uptime 23 days 3 hours 55 minutes

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Discussion Starter #2
Do you have the leads from the shunt twisted together and shielded? The
shield should be grounded at the end away from the shunt.
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Discussion Starter #3
Steven Ciciora wrote:
> But it is still electrically connected to the most negative battery terminal? In other words, it's not somewhere in the middle of the string?
>
> This is truely weird, and I'd love to hear what you figure out. How has the wiring from the shunt to the TBS meter changed? What is a TBS meter?

Yes, it certainly seems weird to me. The TBS instructions called for
the shunt to be installed near the battery negative; there must be a
reason. Initially, two years ago, the charger negative was install on
the wrong side of the shunt and no charging current was recorded; I had
to manually reset the TBS after every charge. But since then it has
worked well, all charge and discharge current seemed to be recorded
properly. Except when there were loose connections.

The car came back from it's most recent re-configuration with many
loose connections. Some symptoms were spurious BMS low voltage alarms
(loose cell connections) and apparently low discharge current recording
(loose shunt connections). For a while, before I located and tightened
the loose shunt connections, I was indicating 1.6 ah/mile while true
consumption was more like 1.8-2.0 ah/mile.

I guess I need to trace down the charger wiring, looking for more loose
connections.

TBS meter:
http://www.evworks.com.au/index.php?product=INS-TBS-PRO
Also re-branded and sold domestically as a Xantrex (I believe).

--
Willie, ONWARD! Through the fog!
http://counter.li.org Linux registered user #228836 since 1995
Debian3.1/GNU/Linux system uptime 23 days 12 hours 27 minutes

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Discussion Starter #4
olrowdy01 wrote:
>
> Do you have the leads from the shunt twisted together and shielded? The
> shield should be grounded at the end away from the shunt.

As I recall, the leads are twisted but not shielded. I'll look.
Thanks for the lead.

--
Willie, ONWARD! Through the fog!
http://counter.li.org Linux registered user #228836 since 1995
Debian3.1/GNU/Linux system uptime 23 days 12 hours 53 minutes

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Discussion Starter #5
As a quick check try wrapping tinfoil around the length of the twisted
leads and then grounding the tinfoil at only one end.

On 10/5/2010 5:50 PM, Willie McKemie wrote:
>
olrowdy01 wrote:
>> Do you have the leads from the shunt twisted together and shielded? The
>> shield should be grounded at the end away from the shunt.
> As I recall, the leads are twisted but not shielded. I'll look.
> Thanks for the lead.
>

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We weren't shooting at YOU." --Dave Barry
http://dmr-architect.com/~locouki/

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Discussion Starter #6
I've had shunt sensor wires go haywire before -- we were using about 40 feet
of cat5 cable, buried in the same trench as AC cable... it would work for a
while, then go haywire, and we'd have to switch pairs in the cat5 to get it
working again.... didn't make much sense, but I started using shielded cable
after that, and have never had other systems behave like that... it's
trying to sense a very small voltage relative to everything else going on
around it, so small stuff that would normally not have an effect, even on
other control wiring, can mess up shunt leads.

olrowdy01 <[email protected]> wrote:

> As a quick check try wrapping tinfoil around the length of the twisted
> leads and then grounding the tinfoil at only one end.
>
> On 10/5/2010 5:50 PM, Willie McKemie wrote:
> > On Tue, Oct 05, 2010 at 12:44:42PM -0700, olrowdy01 wrote:
> >> Do you have the leads from the shunt twisted together and shielded? The
> >> shield should be grounded at the end away from the shunt.
> > As I recall, the leads are twisted but not shielded. I'll look.
> > Thanks for the lead.
> >
>
> --
> "Come back to Miami!
> We weren't shooting at YOU." --Dave Barry
> http://dmr-architect.com/~locouki/
>
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Discussion Starter #7
olrowdy01 wrote:
> As a quick check try wrapping tinfoil around the length of the twisted
> leads and then grounding the tinfoil at only one end.

The shunt wires are twisted and not shielded. Unfortunately, they are
routed through some conduit for most of their length and not at all
convenient to access. I THINK the other wires in the conduit are 12v.

If I confirm that the Zivan is working (I've sent it off for "repair"
based on my assumption that my TBS was reading correctly), I guess I'll
just have to live with the charge mis-measurement. At least for a
while. Or, maybe I'll try to disconnect the meter end of the wires,
pull them from the conduit, and re-route.

Thanks to all for comments.

--
Willie, ONWARD! Through the fog!
http://counter.li.org Linux registered user #228836 since 1995
Debian3.1/GNU/Linux system uptime 23 days 14 hours 20 minutes

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Discussion Starter #8
Steven Ciciora wrote:

> This is truely weird, and I'd love to hear what you figure out. How has the wiring from the shunt to the TBS meter changed? What is a TBS meter?

This just in:

Yesterday, I charged my 45 LFP cells with the Zivan. The battery
became "full" at the time one would expect if the Zivan were charging
at 15 amps. The TBS indicated that the battery was about 25 ah short
of full; that's starting from about -45ah. Conclusion: the Zivan is
charging at the proper rate but the TBS is not properly recording the
current.

Yesterday, I received two of these chargers:
http://is.gd/eZ34E
They seem to work well. I am set up to charge with up to any three
of the following chargers:
a - Elcon 1500 watt
b - Chennic #1 from above
c - Chennic #2 from above
d - Zivan

Charging experiments; current readings from the TBS:
"a" alone reads 8.0-8.1 amps
"b" alone, 9.1 amps
"c" alone, 9.0 amps
"d" alone, 6-7 amps
"a" + "b" + "c", 26.3-26.6 amps
"b" + "c", 18.2 amps
"b" + "c" + "d", 34.5-34.9 amps
"b" + "d", 25.6 amps
"c" + "d", 25.6 amps
"a" + "d", 24.8 amps

The Zivan seems to read low on the TBS only when used alone and reads
correctly when used with any other charger(s).

The Chennic chargers are about $200 cheaper than the Elcon, charge at a
higher current, and have a very nice pack voltage display. If they
prove long-lived, I will be extremely pleased with them. About $900
for about 4500 watts worth of charging.

The Elcon is semi-permanently installed; it is the only dual AC voltage
charger in my inventory. I intend to continue to use it for most of my
charging but hook up one or two additional chargers when I want faster
charging. The Elcon is under the hood and the additional chargers will
sit temporarily on motor bay components only while the hood is open.

--
Willie, ONWARD! Through the fog!
http://counter.li.org Linux registered user #228836 since 1995
Debian3.1/GNU/Linux system uptime 25 days 12 hours 13 minutes

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