Hi Mark,
So I'm really confused how the Roadster is wired. My
own car (a 2.0
model) had its 12v battery replaced about 2 years ago.
When we did, I
brought along some wires and a PowerPole connector, and
asked the Tesla
tech if they could wire that in at the battery, so that
I could "jump"
the car if necessary. As a side effect, that's given me
a peek into the
battery's voltage without having to take half the car
apart.
The OVMS module is attached to the diagnostic connector
under the dash,
as usual. It tells me that the 12v supply is at about
13v when the car
is awake, and 11.4 when asleep. Uncalibrated, that
sounds about right.
But the battery (via the jumper cable) stays at 13.7,
regardless of the
car's sleep state.
At the last service I challenged the service folks to
explain what was
going on. They couldn't. We thought that when the car
was asleep, the
only systems alive were being powered by the battery
alone, and that the
DC-DC converter was only active when it was awake. That
would explain
the OVMS readings, but not that of the 12v battery. If
the DC-DC was
always active, that would explain the battery readings,
but not the OVMS.
How can they both be true?
Greg
Mark Webb-Johnson wrote:
Roadster doesn’t have a
12V battery. Ok, it does, but it is only used to power
emergency systems and not OVMS or the majority of the
car.
The 12V power for OVMS comes from the main first
sheets in 1.5 car, or a dc-dc converter in 2.x cars. I
haven’t worked out how to get a reliable 12v reference
for that, so disabled the alerts for the moment. If we
do manage to read the actual 12v voltage, it will be
from a can bus message and will have to be handled
specifically for Tesla Roadster.
Regards, Mark
On 20 May 2018, at
2:44 PM, Michael Balzer <dexter@expeedo.de>
wrote:
Greg,
if a car cannot provide the 12v charging flag it has
two options:
a) disable the 12v alert system by overriding the
methods (as Mark did)
b) provide a suitable reference value at startup.
Option b can be done by yourself / script:
metric set v.b.12v.voltage.ref 12.65
…or you can raise the threshold from 1.6 to whatever
fits your readings.
Maybe I'll add a config for the initial reference
voltage on startup, as that can also be wrong due to
12v noise.
Regards,
Michael
Am 20.05.2018 um
01:10 schrieb Greg D.:
Thanks for the overview, Michael. I have not
experienced the v2 module,
so didn't know how this worked.
If the reference is taken at boot, then plugging
the module in with the
car awake would give a too-high value vs when it's
asleep. I guess the
idea is that it should reset itself to a more
reasonable value after the
first charging session, yet I'm not seeing that.
It seems to be stuck
at 13v, which presumably was what it recorded at
the reboot when I was
playing with the SD card (car was awake and
apparently annoyed at the
time). I'm on the .005 code, which apparently
pre-dates Mark's commits,
though the commit was 30-April and the .005 build
is dated 1-May... {shrug}
The algorithm sounds like it is intended to detect
a weak battery by
observing its behavior after being charged, but is
this sensing
available on all cars? I'm guessing not, and that
the Roadster not one
of them. For those that aren't, couldn't we just
have a configured /
configurable threshold that would trigger the
alert? Regardless of
vehicle type, 12v battery health is an important
metric to watch.
Since I'm currently waiting for the modem issue to
repeat, I'll just
live with the alerts for now (vs resetting the
module to capture a lower
threshold value), and see what happens with the
.006 software. The car
just completed its periodic top-off, generating
another pair of events
(12 restored, followed by 12v alert).
Thanks again for the explanation,
Greg
Michael Balzer wrote:
Greg,
Mark disabled the 12V alerts on the roadster
firmware some commits ago.
Regarding the alert configuration:
commit 9c1a991a9a27de8afdc9fd408262a2fe0be7aef4
Author: Michael Balzer <balzer@expeedo.de>
Date: Mon Apr 30 22:39:05 2018 +0200
Vehicle: 12V battery monitoring & alert
New configs:
- vehicle [12v.alert] = 1.6 Voltage drop
alert threshold in V vs. reference
New metrics:
- v.b.12v.voltage.ref 12V
reference voltage [V]
- v.b.12v.voltage.alert Alert status
(bool)
This works like the old V2 12V monitoring, just
a bit improved. The reference voltage is taken
after max 15 minutes calmdown time after 12V
charging stops. The
initial reference is the first voltage measured
at boot.
Also, the AD conversion needs to be calibrated
for each module, to compensate component
tolerances. If you haven't done that for your
modules yet, their 12V
measurements will differ. To calibrate, measure
your real 12V level and change config system.adc
factor12v accordingly for each module.
Regards,
Michael
Am 19.05.2018
um 02:26 schrieb Greg D.:
Hi folks,
I'm getting alerts from OVMS that my 12v
battery is failing, as it's
dropped below the threshold, which is set to
13v for some reason. So I
get a notification every time the car
transitions from awake to asleep.
I don't see a configuration item, nor anything
in the OVMS v2 app.
Oddly, the threshold is 13.2 for my v3.0 proto
module, but I can't find
a config item there either.
How do I change the threshold?
Greg
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