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Good job on the "safety box" teardown video (I have a time machine...)

Those contactors are likely useless for your truck. Only rated at 120A...seem to be put zere by ze Germans to protect zat expensive 350A fuse 😂

Getting an ohm meter on that resistor will tell you how useful it is for precharging your inverter.

I didn't catch the part number of the precharge relay.
 

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Discussion Starter · #246 ·
so yeah I blew it all up to smitherenes and now feel way more comfortable understanding what the he11 is going on inside this black box, and here to share

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both the Panasonic "positive" and "negative" contactors appear to be identical Part # AEV140125 M25

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Discussion Starter · #247 · (Edited)
the BMW 530e Safety Box internal low voltage wire harness

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the BMW 530e Safety Box internal high voltage wire harness (orange wires)

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this is the OEM current shunt, aka current sensor, it does not appear to be removable from the green logic board

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how it looks from underneath

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Discussion Starter · #248 ·
so lets take a look at the negative circuit path from the battery Cell Module # 1 main negative lead into and through this black box


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sorry the orientation below is upside down (adding to the confusion I'm sure)

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Discussion Starter · #249 ·
here I isolate only the components needed to complete the negative "circuit" through this Safety Box

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close up of the negative contactor, the stud sticking up is where the current shunt mounts to to bridge that gap over this contactor in the pics above

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Discussion Starter · #253 ·
here is probably the most important circuit in the entire Safety Box the pre-charge circuit, it tickles the capacitor inside the inverter with gentle current before shooting all of it down it's throat, this keeps the capacitor from blowing up

it consists of a relay and a resistor and utilizes the same fuse as the positive contactor in the positive circuit mentioned above

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the white bar of soap looking block is a 15 ohm resistor


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The precharge circuit does not utilize the fuse, it is part of it. The actual fuse in the circuit is actually one of the orange wires, the resistor, or the relay, which seems reckless...

The precharge resistor, orange wires, and relay is, however, protected by inference by that circuit board you plan to discard because it simply opens the relay when a fault is detected in the circuit, which includes those capacitors the "safety box" is determined not to blow up....allegedly. Shows how ignorance and strict reliance on Google can set your car or truck ablaze by tossing out a critical circuit element.

The Panasonic relay AEC51012 is, from what I can tell, a 400V 5A relay, which means the precharge resistor must be at least 80 ohms. It's allegedly 15 ohms, which means a peak inrush current of 26 amps into the inverter and through the relay...
 

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Correction. The Arrow site as indexed is incorrect:

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The relay is 10A, which make the min resistor size 40ohms.

Found the datasheet. Contacts are rated for 30 seconds at 30A. Again, the board planned on being thrown out will time the charge/discharge cycles of the precharge to ensure the relay specs are not exceeded, since the 15 ohm relay will peak out at 26A. This is an abuse scenario, not expected operation that may need oversight by the controller.
 
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