Contactors in series....

[Jacobsmess]

I'm pulling apart a Lexus UX300E battery pack and noticed it contains 8 contactors. There are 2 pre-charge relays, 2 main positive contactors, two main negative contactors and 2 other contactors. The main contactors (positive and negative) are placed in series, what could the reason be for this?

[MattsAwesomeStuff]

Redundancy?

Double their voltage handling?

[tom91]

Please draw it out for us. I am a bit confused by what you mean. Did you review the information I provided from Lexus on the car in your build thread?

The charging system has contactors on the HV bus the set for DC fast charge and one set for the charger itself these are direct to the battery. Must have been something their safety analysis required.

[Jacobsmess]

Please draw it out for us. I am a bit confused by what you mean. Did you review the information I provided from Lexus on the car in your build thread?

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The charging system has contactors on the HV bus the set for DC fast charge and one set for the charger itself these are direct to the battery. Must have been something their safety analysis required.

Hopefully this is clear....
So there's two relay boxes.
One with 4 large relays. 2x Main relays and 2x "DCR" relays.

Then the 2nd with 2x precharge relays (one "AC precharge relay" and one "precharge relay") and 2x "AC charge relays"...

I think you are correct that charging is the reason for the extra large relays but I'm not entirely sure why.
I've downloaded the HV battery pack diagrams with the relevant information attached below and referenced in the above...

[tom91]

I think you made a mistake identifiying the Charge Contactor connections.

DCR are the DC fast charge relays, thus they connecto to the Fast Charge port, which in your drawing you labeled pos and neg.

The Battery connection is actually CB and CB

The diagram is very chaotic so quite stupid to follow. Also does not help things to the precharge relays are ofcourse also connected to the battery positive and negative.

[Jacobsmess]

Let me double check I understand and also add a little more information to make sure I understand.
The top + and - on my first drawing connect to the battery modules. The Pos3 and Neg3 and CBI and CEI (using the Lexus naming convention) have external connections.
Double checking my understanding of what you have written, the two DCR contactors connect to Pos3 and Neg3 and are coming from the DC fast charging port/controller whatever then the CBI and CEI are the main connectons to the inverter.
Which charge contactor connections have I misidentified?

[tom91]

Never mind, I have no clue what is going on. I would need to work it out for myself and no real point to that.

In the end it does not matter as you can use them how you need them to work. Just makes sure you work out their ratings and how to drive them.

[Jacobsmess]

Never mind, I have no clue what is going on. I would need to work it out for myself and no real point to that.

In the end it does not matter as you can use them how you need them to work. Just makes sure you work out their ratings and how to drive them.

Fair enough and that makes sense. The UX300E is rated for 150kw driving so I'm confident I'll be ok with the GS450H. I'm not sure on the charging and the AC charge contractors are smaller so I'll need to look into their ratings but suspect I'll be ok for my current charging plans if 11kw.