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by DBMandrake
Sat Mar 07, 2020 1:26 pm
Forum: General Technical Discussions
Topic: MCU 20A 450VDC fuse investigation
Replies: 31
Views: 8599

Re: MCU 20A 450VDC fuse investigation

2.4kV ?

So the original 2kV caps would probably suffer a failure while my 6kV caps would survive in this scenario ?
by DBMandrake
Sat Mar 07, 2020 1:48 am
Forum: Batteries and Battery Management
Topic: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter
Replies: 477
Views: 114549

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Here is a simplified functional schematic of the OBC, MCU and Pack, showing details of the HV DC Output section with the snubber caps and MCU fuse that seems to blow. The snubber caps in my OBC were definitely 2kV not 3kV as shown in your diagram - one was undamaged and easy to read. I fitted 6kV r...
by DBMandrake
Sun Mar 01, 2020 11:51 am
Forum: General Technical Discussions
Topic: Under the Cover--an Inside Look at a 2018 On-Board Charger (OBC2)
Replies: 5
Views: 1336

Re: Under the Cover--an Inside Look at a 2018 On-Board Charger (OBC2)

i think if you were to proactively replace the 20A MCU fuse as a maintenance item, then your old OBC would work just fine for a good long time. i'm still doing research on the failure modes. i'm struggling to understand how the MCU fuse could experience an over-current condition and blow, without t...
by DBMandrake
Fri Feb 28, 2020 8:50 am
Forum: Batteries and Battery Management
Topic: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter
Replies: 477
Views: 114549

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Hi DBMandrake, Glad to hear you're up and running again, Can you tell me what potting compound you used or even better provide a link for it? Think my board is a bit worse off than your one but again with the help of the great guys in this forum it should be sorted soon, Sure no problem. It's not a...
by DBMandrake
Thu Feb 27, 2020 12:32 pm
Forum: Batteries and Battery Management
Topic: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter
Replies: 477
Views: 114549

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Good news. :) The fuse finally arrived today and the rest was a bit of an anti-climax! I fitted the fuse, put the cover back on the MCU, refitted the traction battery safety link, reconnected the 12v battery, plugged the car into charge listening for a bang but all I got was charging. :D I checked t...
by DBMandrake
Wed Feb 26, 2020 9:52 am
Forum: Batteries and Battery Management
Topic: Fuel gauge vs tortoise
Replies: 33
Views: 3486

Re: Fuel gauge vs tortoise

Hi, You can check my blog over on frenchcarforum.co.uk, starting at this post: https://www.frenchcarforum.co.uk/forum/viewtopic.php?p=624171#p624171 You'll need to register on the forum to read threads in the blog section. One mistake I made during my cell swap was to attempt the swap when the pack ...
by DBMandrake
Wed Feb 26, 2020 6:13 am
Forum: Batteries and Battery Management
Topic: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter
Replies: 477
Views: 114549

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Looks like the fuse is finally arriving tomorrow after paying customs charges... in the meantime here is a picture of the potted caps that I meant to post earlier: https://drive.google.com/uc?export=download&id=1dF6n-iTmpeVmSO0Y7Lw6_RU5baNSd5j1 This is neutral cure high voltage high temperature ...
by DBMandrake
Wed Feb 26, 2020 2:59 am
Forum: Batteries and Battery Management
Topic: Fuel gauge vs tortoise
Replies: 33
Views: 3486

Re: Fuel gauge vs tortoise

For what it's worth, I ran battery down to 0 bars and when the turtle came on the bad cell was down to 3.48V, the rest were still at 4.0V. So it seems that the bmu software sets the charge gauge based on the weakest cell, but controls the charger based on the strongest cell. This is essentially cor...
by DBMandrake
Wed Feb 26, 2020 2:40 am
Forum: Batteries and Battery Management
Topic: No Ready and Yellow Light after new 12V?
Replies: 3
Views: 663

Re: No Ready and Yellow Light after new 12V?

The car definitely won't go into ready unless the RFID tag in the key has been programmed to the car. So if you just bought a random blank key with blank not yet programmed RFID chip and only had the key mechanically cut to fit the lock, that is one of your problems right there. When getting a repla...
by DBMandrake
Tue Feb 25, 2020 9:41 am
Forum: Batteries and Battery Management
Topic: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter
Replies: 477
Views: 114549

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Simon and Kenny, thank you both for such wonderfully detailed information about fixing the OBC and thus making it easier for those of us who will have to face this in the future. :ugeek: Wishing you all the best as the moment of truth arrives today when you fire up the car :!: .... My fuse (I actua...

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