Thanks to an astute poster in this forum from two years ago, I located a cooperative US distributor for the orange 22-pin Yazaki 7382-6100 connector in the battery management computer. This connector corrodes due to gases coming from the battery pack. I'm curious why the corrosion appears worst around pins #19, 20, and 21 of this connector. In the example below these pins are literally missing from the connector: Does anyone have access to schematics for the battery management computer and could say what voltages appear on pins 19-22? I'm betting that pin #22 is the bottom of the battery stack voltage-wise and pins 19-22 are (probably due to a design error at Toyota in the early 2000s) the opposite end of the battery stack with the highest voltages relative to pin #22. But on further examination there's a 400V electrolytic cap tied to pin #22 so it might be the opposite of what I describe: pin #22 is the top of the battery stack and pins 19-21 are at or near the bottom of the stack. My guess is that someone forgot to sequence the connector's pin-out so that adjacent pins never have more than one block voltage (14VDC) between them. The 2.5mm pin-to-pin spacing in this connector could not long tolerate 200VDC between pins. Nor could the PCB underneath the connector, even with conformal coating on it. I turned the magnification up on my microscope and can see that the skinny copper PCB tracks exiting pins #21 and #22 have served as electrical fuses and blown open as part of this failure mode. The battery block voltages from the Yazaki connector are fed to a group of 7 dual-channel Matsushita/Panasonic linear optocouplers.
Thanks, Chap. It looks like I was reinventing the wheel on my Yazaki connector study. Seems that others have pursued the matter to its conclusion. The photos of totally blown-up Yazaki connectors the posting you suggested are concerning. It would be difficult to sustain a pin-to-pin arc with only one block voltage between the pins. So that suggests that T's supplier didn't sequence his connector pins with adjacent battery blocks between adjacent connector pins.
Didn't realize that there'd been an entire book of postings about it some time ago. Everyone who works on Prii should read that series of postings. Sobering... Matt, the Texas BMS rebuilder, in his responses to Chap's comments a while ago, answered my question above about how much voltage appears between pins 21 and 22 of the orange connector. Matt's answer was 30VDC. Given that the voltage is DC, it's sufficient to sustain an arc in a narrow space. My guess is T's BMS vendor contaminated his Yazaki connector with rinsed-off reflow solder flux which has a ton of ionic crap in it. Subsequently, moisture in the air driven by the voltage differential between adjacent pins, will get the corrosion rolling.
So, to avoid it, what? Dunk the whole unit in distilled water, agitate for half an hour, and then dry thoroughly, perhaps in front of a fan? I recall trying to open that case and it had some peculiar sort of Japanese screw like fasteners in it that looked like Phillips but weren't. When none of my screwdrivers fit well and they wouldn't budge with moderate force I gave up. Because it would of course be better to pull the board out and clean it rather than to dunk the whole assembly.
That sounds like it would be a PITA to fix. Is the board still relatively flat there or did the heat pit it?
