Gemeinsame Masse | Posts 16+

Okay, if it goes through the AC cycle even when starting (which wasn't clear from your previous message), then my assumption is probably incorrect.

Some of my sentences seem to have been lost during the copy-pasting process. It's possible that the DC-to-AC converter, when starting up, loses synchronization due to a voltage drop – these devices are usually not particularly sophisticated – and as a result, the serial connection is no longer powered correctly. While the internal power supply of the computer might still prevent a crash for the board itself, the +/- 15V for the RS232 interface could already be outside the acceptable range.

According to the instructions, my DC-DC converter should definitely not remain in the ignition coil during startup.

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because I already have AC for crafting

Lucky you...

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It doesn't matter if it's up to a maximum of 10 amperes - it's probably going to be less.

Much less, in fact. As a general rule of thumb, you can roughly estimate the DC voltage by looking at the rating on the bottom of the laptop or its power adapter. Even though this refers to a higher voltage level, my measurements show that it's quite accurate, even when the battery is removed – and that includes accounting for conversion losses. Mine consumes 1 amp in idle mode, but even with the hard drive and screen active, it only uses 1 amp.

Hi,

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According to the instructions, my DC-DC converter should definitely not remain in the ignition coil during startup.

It's good to know... I think my laptop battery can still handle those 10 seconds – I just bought an adapter like the one you have.

Of course, I also tried to activate the whole thing only after it had been started, but that resulted in the same outcome.

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Lucky you...

Not really... there's always some maneuvering involved in the backyard to position the car so that the power cord reaches. Most of the time, I do it at my parents' place, where it's much easier because they have a carport.

That's also why I've been considering using 12V, especially since I've always wanted to log data, which hasn't been possible since the end of 2002 because the battery is too weak.

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Much less, in fact. As a general rule of thumb, you can roughly estimate the DC voltage by looking at the rating on the bottom of the laptop or its power adapter. Even though this refers to a higher voltage level, my measurements show that it's quite accurate, even when the battery is removed – and that includes accounting for conversion losses. Mine only needs 1 amp in idle mode, but even with the hard drive and screen active, it only uses 1 amp.

The Thinkpad requires a maximum of 3.3 amps at 16 volts, but typically uses significantly less. At its best, it could run for about an hour on the 11 Wh 12-volt battery. It will likely draw a maximum of 1.5 to 2 amps from a 12V DC source, considering the conversion losses without a "Powersafe" device.

My 8.10 A were the worst-case scenario for the 12->230->16 conversion path via the AC adapter, assuming a very low efficiency.

I'm definitely curious to see how everything works out with the new adapter.

Best regards,

Jan.

@Jan: Double galvanic separation? Let it be triple-glazed, it doesn't matter!
What's even more important is what you write further down: How does the diagnostic interface or laptop obtain its ground potential? (Jan, I don't think you need to explain to me again the difference between ground potential and 'ground'). Even in my case, electrons occasionally wander along paths they're not supposed to. Although my current strengths are nowhere near as spectacular as yours. I already notice it when some pA are wandering around, and I don't have to wait until it starts smoking ) .

Read what I wrote above: (regarding the diagnostic interface, circuit diagrams, errors, and so on...).
And then there's the possibility that the decreasing voltage during starting can lead to certain 'effects.'

Regards,
Sure, here is the translation of the text from German to English:

'Micha'

@Bee:

I think you're talking to me, not Jan.
And if you're starting with a car that has a ground potential, I have to explain things a bit more .

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In this case, I wouldn't know how the manufacturer could obtain a "CE" mark, which they need in order to be allowed to sell their product in Germany at all.

It's very simple: Any manufacturer can affix the marking themselves - without any measurements whatsoever. He only needs to be able to demonstrate compliance in the event of a dispute.

Hi,

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Read what I wrote above: (regarding the diagnostic interface, circuit diagrams, errors, and so on...). And then there's the possibility that the decreasing voltage during starting can lead to certain "effects."

I did read that... and I explained why I'm quite sure the interface is okay.

From a potential perspective, it doesn't make a difference whether you power the laptop (with double galvanic isolation) from the on-board network via the path 12->230->16, or whether you power it from AC via the path 230->16 with single isolation. A defect in the device would likely manifest in both versions.

The on-board voltage AFTER starting is higher than it was before. As I mentioned earlier, it doesn't matter whether you start with the adapter connected or plug it in afterwards; in either case, the converter will start at 14.4 volts instead of 12 volts, then drop to slightly above 10 volts, and then rise to 14.4 volts.

The error is therefore almost certainly NOT caused by voltage drops during startup, and NOT by grounding issues in the interface.

EMI is still my suspicion, possibly due to unfavorable superposition of the switching frequencies of the converter and the notebook power supply.

Best regards,

Jan.

Hi,

EMI problem? Then the diagnostic interface could also be a factor. For example, a capacitor used for filtering in the level shifter might be 'forgotten' during assembly and come loose due to vibration.
Okay, I only fire when I've measured and confirmed that everything is okay. I only know about simply swapping parts and trying them out from VW .

Regards,
Sure, here is the translation of the text from German to English:

'Micha'

Hi,

@Bee: I wonder if you're reading my posts...

I can't really test the part because I can't get it apart without damaging it. Measuring only the pins on the outside serves no purpose whatsoever.

Furthermore, considering the fact that the interface...

- Turn off AC and the motor.
- Turn on AC and motor.
- Notebook battery (when it was still working) and engine off.
- Turn on the notebook battery and motor.
- DC to AC conversion, and motor off.

It works perfectly fine under normal conditions, but it only malfunctions when connected to a DC-to-AC converter and a motor, suggesting that the problem lies in the interaction between the DC-to-AC converter and the motor when both are operating.

Consequently, testing with a different power supply is a significantly cheaper alternative to attempting disassembly and measurement at the interface, especially since I need a 12V power supply anyway, and using AC power for that purpose is anything but practical. If there are still problems, I can try disassembling it again, or I could sell it on [website name] and buy something proper from Rainer (as I've already mentioned, Rainer's shop didn't exist back then).

This thread has shown that using DC/DC converters in conjunction with an interface without galvanic isolation is not a problem, so there's nothing more standing in the way of trying it out (as long as the postal service cooperates and delivers the adapter).

Best regards,

Jan.

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provided the postal service cooperates and delivers the adapter

It took three days for them to process my order with that provider, but it should arrive tomorrow.

Hi,

It was there last night, and I just tested it outside in the cold car.

What can I say... amazing!

"Everything works, even with the engine running - I had the interface connected while the engine was idling for about 10 minutes and tried all sorts of things - no communication interruptions, no problems (and the ASV vibrates quite a bit at idle when it's cold, so any cold solder joints would definitely cause issues there)."

The potential difference was 0.08 volts, which is negligible.

I have no idea how much power the Thinkpad 240 draws through the adapter, but it's definitely significantly less than the maximum possible 3.5 amps (the maximum is 3.36 amps for the TP240), and the adapter doesn't even get warm to the touch.

This suggests that the electromagnetic compatibility (EMC) issues related to the DC-to-AC converter might be exacerbated, possibly due to interference effects between the two power supplies (the converter and the laptop power adapter).

Best regards and many thanks to you, Roger, for the link to the device.

Jan.

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Everything is possible, even with the engine running.

Glad to hear it!

I personally haven't had the thing in the car since last weekend due to the freezing cold - a chronic lack of motivation, even though I still wanted to try a few more things .

@Jan6K: Yes, I read your posts. (And I read them quite thoroughly ). I have therefore clearly read that you are unable to access the interface. (And: I haven't even forgotten ).
Okay, let me try to explain what I was trying to say in my last post, but in a shorter and clearer way:
Two devices, A and B, are being used together, and there are issues. Replacing device A with device C improves the situation. However, this doesn't necessarily mean that the problem lies with device A. The following scenario is also possible: Device A is functioning within its specifications, while device B is defective (outside of its specifications). The replacement device C also functions within its specifications and offers an additional 10% margin. These 10% reserves are necessary to ensure that device B continues to function even in the event of a fault.

This experience is extremely helpful when troubleshooting issues involving multiple devices, and it is unfortunately often overlooked. 'This results in faulty devices being labeled as 'good' during testing, while good devices are labeled as 'defective'.'

Anyway, your diagnosis is working again, which is really great.
Jan, I hope you didn't take my posts as a personal attack; that was not my intention. Sometimes I just express myself forcefully, without meaning to.

Regards,
Sure, here is the translation of the text from German to English:

'Micha'

Hi,

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Jan, I hope you didn't take my posts as a personal attack; that was not my intention. Sometimes I just express myself forcefully, without meaning to.

Don't worry, I'm not.

I'm very familiar with the concepts of tolerances and mutual overlap, and that's precisely why I've been so meticulous in outlining what each part does and what it doesn't.

It's possible, and even likely, that the interface bears some responsibility in this situation, because the computer continues to run while only one function fails. However, given that the motor and AC are working, a loose connection is very unlikely, so it's probably more likely a design flaw that becomes apparent when the two converters are used in series (which is, strictly speaking, an extreme use case).

"However, buying the converter for 15 euros is significantly cheaper than buying a new interface or attempting complex troubleshooting on this device, which is sealed internally and covered by a warranty."

Best regards,

Jan.