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Post by elinterneb9 on Apr 12, 2020 18:21:03 GMT
, technical question ... we have to do something special when we finish coding with the OBDeleven to disconnect it from the car. I mean, yes, within the app there is an option to disconnect from the car or simply when we finish we remove it.
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Post by Deleted on Apr 12, 2020 21:09:34 GMT
Personally I leave my dongle plugged in full time (both old and new ones now) and do nothing and have no issues. Some people complained that if they left the dongle plugged in it would drain the battery flat and OBD11 Team advised that you should log off when you have finished coding forum.obdeleven.com/post/16445As I say personally I have never bothered (over the last 2 - 3 years) and had no problems but I suspect that newer cars with Stop Start rubbish have stronger batteries so its less of an issue (but that is just my guess)
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Post by dv52 (Australia) on Apr 13, 2020 22:41:40 GMT
^^^^ elinterneb9: I'm not sure about how OBD11 does stuff, but CAN networks operate by the modules going into hibernation when the T15 voltage isn't present. This is clearly obvious if you measure the electrical leakage current from the battery. What happens is that the amperage drops significantly and quickly to about 50 milliamps (it's called a quiescent current)as the modules go to sleep.
Normally, the quiescent current remains until the driver inserts the key and then turns-on the ignition, this wakes-up the modules on the CAN network as well as energizing the myriad of sensors and transducers in the car - this significantly increases the load drawn from the battery.
Clearly OBD11 needs the CAN network to be awake - so it can communicate with the CAN buses. When you normally plug-in the OBD11 dongle AND CONNECT to the software, the CAN network is already awake - because the ignition is usually turn-on. However, if you turn-off the ignition and withdraw the key WITH TO OBD11 CONNECTED, the dongle won't release the CAN bus and the modules won't be allowed to hibernate. Result: elevated electrical current will persist and the battery load will continue to be high.
So if you are going to leave the dongle plugged-into the OBD port in the car (I suggest that you don't)- make sure that it's not CONNECTed. For nextgen dongles - the color of the bezel indicates this (I think)
Don
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Post by Thirsty on Apr 14, 2020 8:09:04 GMT
I had it plugged in all the time and never had any battery drain issues. Most of the time i did disconnect via the app but sometimes i didn't and there was still no drain.
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Post by dv52 (Australia) on Apr 15, 2020 8:37:49 GMT
I had it plugged in all the time and never had any battery drain issues. Most of the time i did disconnect via the app but sometimes i didn't and there was still no drain. ^^^^Thirsty: OK - I measured the quiescent current in 3 x states - Ignition off - no nextgen dongle
- Ignition off - nextgen dongle plugged-in, but not CONNECTed (i.e. red bezel LED)
- Ignition off -nextgen dongle plugged-in and CONNECTed (i.e blue bezel LED)
Because I didn't want the hassle of lifting the negative battery lead off the battery-post to connect an ammeter on a real car - I used my test-bench which has a regulated power supply complete with digital ammeter and voltmeter (see below). My test-bench doesn't have a complete suite of modules and it has virtually no exterior sensors - but I was interested to see if there was an effect leaving the dongle plugged-in
Results: - 56 Milli-amps
- 64 Milli-amps
- 110 Milli-amps
I'm surprised it isn't a higher load with the dongle CONNECTed (perhaps due in part to the low module count and the fact that my test-bench has no sensors), and yes a healthy battery can sustain a 110 Milli-amp load. But I'm still not sure why you want to leave it plugged-in and CONNECTed?
Don
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Post by Thirsty on Apr 15, 2020 9:16:32 GMT
dv52 (Australia) Nice testing. Thumbs up I think we're not talking about the same states. When i wrote i sometimes don't disconnect i meant the following: I used OBDeleven and then switch off ignition and pull the key. Close the app and leave the vehicle. (Without disconnecting the app from the dongle before closing the app) Did you simulate pulling the key in your test aswell?
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Post by elinterneb9 on Apr 15, 2020 14:13:27 GMT
Thank you all for your answers!
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Post by dv52 (Australia) on Apr 15, 2020 23:24:00 GMT
dv52 (Australia) Nice testing. Thumbs up I think we're not talking about the same states. When i wrote i sometimes don't disconnect i meant the following: I used OBDeleven and then switch off ignition and pull the key. Close the app and leave the vehicle. (Without disconnecting the app from the dongle before closing the app) Did you simulate pulling the key in your test aswell? Thirsty: if you look at the picture of my test-bench, you will see what I have labelled as "C" -switch. This is the switch that makes contact when the ignition key is inserted into the barrel (in the steering column on MQB platform vehicles without KESSY). I've had to "externalize" the C-switch (it's normally inside the device that I label "ignition switch") on my test bench because I don't use a physical key to generate T15 voltage.
The measurements don't appear to vary with the electrical state of the C-switch - albeit it's difficult to make an accurate reading of electrical current because the major contribution to load seems to be the flashing LED on the nextgen housing.
Don
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