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A better answer than my first for this arrangement: Disconnecting the main at the chassis ground removes power from the vehicle electronics, except the IBS remains powered and doesn't reset (I think). Not resetting the IBS is a nice feature. I'm reluctant to disconnect my batteries in the name...

It was only ever an issue in your mind. The difference between the traces was always the voltage between N2 and N1. The scope could have been grounded anywhere in the circuit, even at MAIN+, and that still would have been true.

I never thought to wonder. I might guess that a single ground connection makes it easy to break the circuit connecting the batteries and vehicle. Do you know something about it?

I wrote that almost a year ago. It would be a slam dunk to anyone with a basic understanding of circuits. One does not simply declare 2V across a conductor. It takes a great deal of current to make that happen.

I agree with you 100%. This whole argument has been dumb. We've known what we needed to know for a year. We did get some new information from @J Sierra's efforts. Good stuff, IMO.

... and remains open for at least 150ms, contrary to the service manual. Edit: The trace in #224 shows it to be open for around 550ms.

Here's a chart showing the first 250 microseconds from the first cold start trace I posted last year. It shows detail that was not visible in the trace. This is less than one pixel in the original trace below, right when both voltages drop sharply. I think the initial load that pulls it...

200CCA means the battery can supply 200A at 0°F for 30 seconds without falling below 7.2V. It can supply a great deal more current at 70°F for 0.1 seconds when allowed to fall to near 0V, i.e., short-circuited.

I've seen scope ninjas who could capture a mouse fart in a hurricane. My scope-fu is second-rate.

Blowing quickly at 10x rated current is expected. The datasheet I linked shows both DMM fuses blowing within 0.1s at 1000% rated current. Both hold up for several minutes at 200%. Not a chance. To paraphrase a great author,

There's too much going on for me to follow. @J Sierra Could you add a math trace showing the difference between whichever channels you have on N2 and N1, at 500 mV/div?

It is indeed. It's common to exceed a fuse's rating for short periods. The engineers put a 150A fuse on the 200CCA AUX battery, with nothing to limit current. The Fluke 87V uses 440mA and 11A Bussmann fast-acting fuses (datasheet). Fluke's user manual says: For the 440mA circuit, For the...

Not to discourage new life in this old thread, but what are you guys hoping to discover? I measured the resistance between N1 and N2 at less than 3 milliohms in post 136. The trace of an ESS restart shows a sizeable voltage drop from N1 to N2, more than 2V for 100ms. If the PCR is conducting...

The only loop I need to consider has three legs: 1. Z to N1 (through the scope) 2. N1 to N2 (through the PCR) 3. N2 to Z (through the MAIN battery, IBS and ground connection) KVL says (voltage from Z to N1) + (voltage from N1 to N2) + (voltage from N2 to Z) = 0. Rearrange to get voltage...

I'm just upholdin' the law sir. Ohm's Law.

It takes awhile to blow a fuse. We're only talking about a few milliseconds. Fuse manufacturers provide charts or graphs showing blow time vs overcurrent. One might be surprised how long a typical fuse can endure 2x rated current. Several seconds, even minutes.

Busted. I suppose you'll be taking my badge and IR gun.

A real nerd should know the resistance across N1 and N2 on the PDC. The only path for current from N1 to N2 goes through the PCR, which is normally closed (conducting). Let's put some current through it and check the voltage drop: Apply Ohm's law: 22.39mV / 7.997A = 2.8 millohms. The voltage...

I have some trouble understanding exactly where the measurement is taken. With no AUX and no connection to the negative battery terminal, and the positive side connected normally, you should see 12V from the negative terminal to the chassis ground. I know that may seem weird.

@jebiruph Ridicule might be the best way to deal with this guy, who is totally not you. Well it was at the time. You've since topped it. The vehicle electronics are a load on the battery, not a source holding the voltage up. Wanna see? Here's my main battery, 1 full minute after disconnecting...