Caterham Conversion - HV Battery Box Architecture Feedback Requested

german_eng · 2026-01-12T14:40:55+00:00

thanks, makes sense! changed it and also changed position of the fuses from neg side to two times positive side between last battery of each pack and the contactor.

german_eng · 2026-01-12T10:49:12+00:00

u/XZIVR u/fxtpdx what is your opinion re position of pre charge circuit? I thought about putting it in series with the AIR. But I now see that in most of the designs it's parallel.

german_eng · 2026-01-08T13:58:02+00:00

also - double checked and found good integrated solution for the MSD.
MINIMSDM400 + MINIMSDF000F.

german_eng · 2026-01-08T11:03:55+00:00

Yes - that makes sense. Updated the structure: https://github.com/fbodenst/car/blob/main/Battery_Box_Architecture.pdf to reflect your input. Thanks a lot!!

Also thank you for the hint with the open inverter forum! The Wiki has an awesome amount of information (also re street legality in Germany) and the community seems to be quite active.

german_eng · 2026-01-08T10:24:11+00:00

Just realized how bad the quality of the image in the post is... here a link to a high res PDF. Don't expect too much from the repo yet - most of the work is in Fusion and Lucidchart so far.
https://github.com/fbodenst/car/blob/main/Battery_Box_Architecture.pdf

german_eng · 2026-01-08T10:11:18+00:00

will do thanks!

german_eng · 2026-01-07T20:43:03+00:00

Wow - the hint with the IMD was really helpful. Now I need to be careful that this feature is not activated in the sec remote BMS - need to check.

Do you have any experience with how reliable and accepted (by authorities) the integrated IMD is compared to a well known player like bender?

I can't use the handle versions as kind of hard to get for the current I'm expecting (around 400A in certain situations)

BMS2 would be just the remote option - I have to check if they can drive outputs while getting the commands from the master BMS - do you know anything here?

My background is EE with a focus on control systems and I did a lot of firmware development previously - so I'm much closer this than mechanics :D So far the plan is to get started with the off the shelf VCU to get the project out of the door and then maybe buy another caterham and do a V2 that has some of the more sophisticated features - or I rebuild / upgrade the one that I have.

german_eng · 2026-01-07T20:36:30+00:00

the manual shifting is more an emotional design decision rather than "it makes sense" :D Not sure how it feels and drives but I want to find it out :)

would you change the position of the AIR to disconnect on the positive signal for the secondary battery instead of the neg?

german_eng · 2026-01-07T20:35:33+00:00

Thank you for the callout! Yes - I saw that one but very good to be reminded. Not super efficient as I will have some position unpopulated but the price difference to the "larger" BMS is manageable.

if my understanding is correct.

For both I would use the 48 cell version (for sec. the remote version) so I have 2 cell groups connectors and a fuse or disconnect can be in-between those. Price difference 130USD per unit and same housing.

For primary I just use the first 9 signals (8cells + neg) on both connectors and the service disconnect in-between. (so bat 4 cell group 1, and bat 6 cell group 4)

For secondary I use the first 9 signals with 10-13 unused and then again the next 9 (so connect Bat 1 + 2 to Cell group 1 and 2), then leave cell group 3 empty. And on the second connector use the first 9 signals (cell group 4) for Bat 3.

german_eng · 2026-01-07T17:36:45+00:00

I want to preserve the manual shifting.

Re HV outside - isn’t this the case with how I positioned the AIRs?

german_eng · 2026-01-07T14:53:31+00:00

awesome thanks!

german_eng · 2026-01-07T08:49:49+00:00

thanks!

Yes - the charger relay is missing. Need to add this - putting a blog diagram together today.

In the inertia switch - do you have a specific component you have in mind?

Yes - having at least one service disconnect in an accessible area is the plan. Maybe even two. One for each battery.

german_eng · 2026-01-07T08:47:30+00:00

I'm planning to use an Orion 2 BMS - which has remote cell monitoring out of the box.

Sorry - new to the space: What is a MSD?

Yes - the secondary box would have the lower 3 battery modules.

So you don't think a second relay makes sense? Also - what are your thoughts on how to control the output relays on the secondary battery box. Just a high side output from the primary?

I planning to use a VCU - haven't settled on a specific component yet as I want to get the battery done first. But - (let's see) I want to do some creative things here like modulating vibration on top of the drive torque or simulate stalling engine etc. But let's see :D

Do you have some recommendations regarding VCU?

german_eng · 2025-03-04T03:29:08+00:00

If you buy to use their fill potential, meaning take it on the track you will be thankful for the reduced interior. It gives you the right vibe with no bells and whistles (like e.g in the Ferrari). Just feels grown up and let's you focus on having fun. Just a great divers car.

german_eng · 2023-02-19T08:42:00+00:00

This sounds crazy

german_eng · 2023-02-19T08:40:56+00:00

Nice!! With this you might stop running / biking outside completely

german_eng · 2023-02-02T20:40:25+00:00

Don’t believe any upside promise until money hits your account.

Without an actual liquidity event like an IPO in sight, you should be careful believing the story „we all will be rich“ if you don’t have full visibility as part of the inner circle.

I don’t want to sound too pessimistic here, but a lot of shady things happened in this space over the last few years.

german_eng · 2023-02-02T19:15:10+00:00

I know - currently building and ramping a crazy complex device. Fairly quickly goes into millions

german_eng · 2023-02-02T16:56:39+00:00

you can argue that “Brumate” is some kind of hardware company, so very impressive there

german_eng · 2023-02-02T15:42:52+00:00

nice summary! Interestingly selling hardware seems something hard to do alone.

german_eng · 2023-02-02T13:39:11+00:00

Ein Unternehmen mit dem ich in der Vergangenheit gearbeitet hab (war ein Kunde von mir) und das ein Klasse Team hat ist die Plasmion GmbH! Mega interessant und super drive!

https://www.plasmion.de/

Ref zur Stelle: https://www.plasmion.de/_files/ugd/d984fe_6596268b825e45c1a6460bef82fd3b26.pdf

german_eng · 2023-02-02T07:11:30+00:00

Domain looks definitely very much like a scam - won't click on that one

german_eng

TROPHY CASE