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Ha-ha, I missed the elephant in the room- the stock sensor will be powered off with the vehicle!
@AZBean your setup is good enough for the intended purposes. If the van is going to malfunction and draw an excessive current you will notice it. Your results are surprisingly good. The TI page on INA226 says that with a 0.15mOhm shunt it is accurate to 10%@1Amp and 25%@0.3Amp.
Twisting the shunt wires might help to reduce the external noise.
 

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In any case none of them physically look like the PacHy's sensor and for that matter, LIN bus or CAN bus, nothing could be read unless the car is powered on, whereas my gadget can collect data while the car is off.
The IBS is mounted to the neg post and is supplied constant power from F12 (5a).. it never turns off. It sleeps until the data request is made on the LIN. See wiring shots.

Your module could tap into the LIN and send those same data requests and listen for the respond like demonstrated in your first document from Vishay - Ie: broacast the HEX “3D” on the LIN. This should not wake the BDC because the BDC is the master. Typically the master has to wake to update and goes back to sleep. :)

But it would be more helpful to have the info for the exact make of IBS.
 

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Discussion Starter #23
The IBS is mounted to the neg post and is supplied constant power from F12 (5a).. it never turns off. It sleeps until the data request is made on the LIN. See wiring shots.
Oooh, that is good information. Maybe I should attach my cheapie USB logic analyzer and see if I can make heads or tails of what is being transmitted.
 

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On a second thought, it maybe not be such a good idea. There is a good chance that the sensor primarily detects the voltage drops under load, and may not be sensitive enough to measure the standby current. Also, if it reads the battery only on requests from BCM, it is not going to send anything while the vehicle is off.
 

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Where can I get instructions and a BOM for building this marvelous device? I have a phantom current drain in my wife's 2008 Miata that I would like to monitor and track down.
 

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Where can I get instructions and a BOM for building this marvelous device? I have a phantom current drain in my wife's 2008 Miata that I would like to monitor and track down.
I'm not quite ready to publish the details, but I am working on it. The feature that recharges its little LiPo battery doesn't work since it causes the sensor readings to go awry. Also the software is not up to my (former) professional standards.

Be aware that if you put the battery monitor in the engine compartment of the Miata alongside the 12v battery then the WiFi uploading feature might not work since it would be shielded by the metal of the hood and the engine. The Pacifica Hybrid is a little unusual in that the 12 volt battery is in the passenger compartment, way back on the left side where the spare tire goes for the gas version of the Pacifica. If the WiFi fails to connect then you would have to remove the SD card from the battery monitor in order to get access to the data.
 

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Where can I get instructions and a BOM for building this marvelous device? I have a phantom current drain in my wife's 2008 Miata that I would like to monitor and track down.
Your Miata is a bit harder. It probably doesn't have the factory monitor, so you'll need to install your own shunt and make sure it can withstand the starting current. Pachy doesn't have a conventional starter, its battery maximum load is just a fraction of the usual.
 

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On a second thought, it maybe not be such a good idea. There is a good chance that the sensor primarily detects the voltage drops under load, and may not be sensitive enough to measure the standby current. Also, if it reads the battery only on requests from BCM, it is not going to send anything while the vehicle is off.
BMW uses IBS primarily for closed current draw monitoring along with cranking load/voltage. In a BMW the DME wakes every 15min for 40ms to collect this info and is sleep again.. so there is no reason our Pachy cant.

The worst that I can see is that AZBeans device pulls data and overlaps the BCM request which may set a communication fault.

But that data would speak for itself whether its useful or not.
 

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Discussion Starter #30
I imagined that the AZBean's monitor would be a passive device on the LIN bus. Seems safer and easier to program.
Me too. But since we don't know exactly what sort of commands the IBS responds to, then the first step would be to put a logic analyzer on it while the van was powered on to try and decode the existing LIN bus traffic. I have one of these which should be just the ticket for that purpose: https://www.amazon.com/gp/product/B077LSG5P2
 

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Discussion Starter #32
Yes, you would think so. You are quite right in that it is really a dumb device. But there are a very nice pair of open source software packages called SigRok and PulseView that will accept the data from that little USB logical analyzer and decode it for you. The CAN and LIN protocols are both supported: https://sigrok.org/wiki/Protocol_decoders. It is just the thing for exploring a LIN bus that is using an unknown command set.
 

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Discussion Starter #35
Any updates on the data collected @AZBean?
I spent some time reorganizing the software on the data collector to make it more flexible and less like a one-off prototype. I can now configure things like the reporting interval and the network name and password using a configuration file on the SD card instead of having that stuff hard coded in the program.

I can now say with good confidence that the average discharge when the van is sitting idle is 23 milliamps. This figure was obtained by averaging the readings over a full 24 hour period when the van was not used at all and no doors were opened. The actual reported discharge varies between 17 milliamps and 34 milliamps due to the step effect of the INA226 chip which reads the shunt voltage at increments of 2.5 microvolts, but by averaging all of the readings at 15 second intervals over 24 hours I came up with the 23 milliamp figure.

I did notice one unusual spike of a 46 amp discharge right after the completion of a short trip. This lasted for less than 15 seconds. I am not sure what was going on. I guess what I need to do now is to start keeping a diary of what I was doing, what doors I opened and stuff like that so that I can correlate the battery readings with my actions. Are there any particular events that you would like to see a record of?
 

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Are there any particular events that you would like to see a record of?
Not really.

So whats the end goal for this tool? are you hoping to identify trends or just data log whats going on?

Also, Any plans to share the software eventually with a hardware list so others can install the same? If so will you collect all the data?

:nerd:
 

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Discussion Starter #37
So whats the end goal for this tool? are you hoping to identify trends or just data log whats going on?

Also, Any plans to share the software eventually with a hardware list so others can install the same? If so will you collect all the data?
The is basically a hobby project that let me learn a bit more about electronics and make use of my programming skills which are getting further and further behind the times. At the same time it will let me keep an eye on my 12v battery so that with any luck I can see that its health is declining before it leaves me stranded somewhere. I will probably get around to publishing the software and a bill of materials. I definitely do not want to collect other people's data!
 

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Discussion Starter #38
This week we went on a camping trip. For three days the van sat at the camp site without being driven, but the lift gate and sliding doors were opened and closed frequently as we needed to store our food inside the van to keep it away from critters. Each time a door is opened the van woke up and drew a current of 15 amps or more which then tapered down to a fraction of an amp as the van went back to sleep. As you might imagine, doing this repeatedly over a long period of time gradually draws down the 12 volt battery. By the time we were ready to leave this morning the voltage was down to 12.0 volts when the van was idle and 11.7 volts when it was awake. When we were finally ready to leave and turned on the van the 12 volt battery started charging at the rate of 86 amps! This seems like a very high charging current to me, but maybe somebody else has better knowledge about how much charging current these batteries can withstand. We made two stops during the trip home, which you can see in the chart as dips in the voltage and current. When we got home and after the van got unloaded and went back to sleep the idle voltage was back up to 12.86 volts.

I think the lesson to be learned from this is that if you go camping and need to open and close doors frequently, then once every day or two you should turn on the van for 15 minutes or more to replenish the 12 volt battery. If we had continued several more days without turning on the van I think we might have needed to jump start it.
 

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