[WIP] Mercedes 310E (310D campervan) - GS450H/GS300H

[Jacobsmess]

So having abandoned killed the Lexus BMS I'm looking at the leaf BMS. As I understand the 24kWh, 30kWh and 40kWh BMS use the same Comms but the 40kWh can be a little finicky with regards to its existing wiring.... So it's really good news that I picked up a 40kWh BMS and a bunch of associated cabling for cheap the other day ....

I'm looking to get a 24kWH BMS also as it might be an easier route. OR failing all that I'll go the 16 Channel 'Flying' BMS from Johu. The pack will need to be split (going under the van either side of the prop shaft) so the Leaf BMS might have an issue here, whereas with the 16 Channel BMS I can just run 3 BMS units in each pack with a Comms cable running from one to the other.

I'm also debating the pack ratio, ideally they'd be identical just mirrored making them cheaper, simpler and neater as well as having slightly better weight distribution but the original modules are 8no. 9s3p and 3no.8s3p...
One was around this is to break one of the 8s3p modules in half and put one half in each box which shouldn't be too difficult but does then require some mounting for the loose cells and also rearrange the cell taps. The nice thing however is a neat 3 BMS option in each pack.

Lastly, the original pack had a whopping 33 thermistors for the cells (and more for all the heating/cooling infrastructure)... With the leaf BMS I think there are only 3 or 4 temp sens lines or the Flying BMS I'd get 2 per board, so 12 total. I have been debating making some Arduino or similar code that would reconcile the remaining temp sens lines seeing as the wiring is already there which for a programmer would probably be no big thing, but for me, may not be quite so straightforward.

Other progress, the van spent the last week with the front end off and bothering the neighbours up until yesterday when I managed to find some time to reinstall the newly painted wings and grille, although the replacement grille was too small ( )... And I also made up a very basic sectional template of the battery box to make sure I can fit the batteries where I want them beneath the van.

[johu]

Since you'd be the first to deploy this on a larger pack I'd be willing to discount on that. Let me know

[Jacobsmess]

Let me know

I've pmd you

[Proton]

Since you'd be the first to deploy this on a larger pack I'd be willing to discount on that. Let me know

Can I get a discount too? lol

[johu]

Can I get a discount too? lol

Or cut a deal with Jacob, he's getting some made (if we only knew where he's from - please share your location )

EDIT: but yes if you buy 6 or more from the shop you can get a discount, too since you'd still be the first to buy that quantity

[Jacobsmess]

Or cut a deal with Jacob, he's getting some made (if we only knew where he's from - please share your location )

Added my location (UK) and pmd Proton

Johu, I've also messaged you about the CPL and BOM files.

[Jacobsmess]

So, whilst waiting on the 40kWh leaf BMS to turn up (that may not work due to split battery boxes and needing to extend cell tap lengths....) I've finally committed to a battery box design. I've got for a mirrored pair either side of the prop shaft. To do this I can keep all the battery modules as they are with one of the small 8S3P modules being split between into 2no. 4s3p modules.

This meant drilling out 8 rivets on the end plates which allowed the removal of the end plate and thus breaks the modules into separate 24no. cells

With a bit of cutting I've managed to make the original plastic routing and cell tap connectors work for both of the mini modules and if I can get someone to show me how to 3d scan the plastic end plates I can then 3d print those and fabricate the metal parts to mimic the existing setup with some metal bar rivetted or screwed in to tie the modules back together. It does make me consider breaking the modules down completely and trying to make them fit somewhere else but in order to keep things simple and move forward I'm going to stick with this arrangement.

The battery boxes will be made up of a separate bottom piece with structure to hold the modules in place. This will hold 3 long modules next to one another and the mini module to the rear at 90 degrees as the bottom layer, then an upper tier of 1 long module module and 1 short module next to one another. I think there should be enough room for a BMS, Shunt and contactors in the box in dead space. There will then be a lid that is comprised if the top and sides which will sit on top and be fastened around the bottom.

As I understand a minimum of 1 composite and 1 negative contactor is required, given I'll have two battery boxes I'll have 1 main and 1 pre change contactor in each.

I might add air cooling by means of reusing parts of the lexus UX300E with some external pipework and a fan on each box pushing air through the box and maybe a small radiator or air to water heat exchanger and I'll likely reuse the heating pads also, at least on the bottom layer.

Apologies for the stream of conscious post!

[Jacobsmess]

Oh and in addition, whilst perusing the lexus UX300E wiring diagram I noticed the safety service disconnect in the pack doesn't break the pack in two and instead just breaks the positive or negative (I can't remember which), which I found surprising. Anyway, if I can manage to mount the disconnect I'll reuse that. It contains a 350A fuse and I could place it between the two packs as a precaution.

[Jacobsmess]

On another note, current sensors. Are they easy to reverse engineer? I've got my hands on 3, one from the Lexus UX300E pack and another 2 from a random contactor setup I bought for cheap one of which is a low voltage LEM one. I don't know the parameters for any of them but it'd be nice if I could reuse them. Any guidance?

[johu]

The blue one is the LEM HTFS, 5V supply, output centered at 2.5V. The other ones I don't know. You need to figure out which are the supply voltage pins, e.g. with a 50 mA current limited 5V supply. When a third pins spits out around 2.5V you've nailed it. Some are asymmetrical centered at 3V or something. Some need 15V or even +/-15V. Search for the part number if readable

[Jacobsmess]

You need to figure out which are the supply voltage pins, e.g. with a 50 mA current limited 5V supply. When a third pins spits out around 2.5V you've nailed it.

Is this likely applicable to both sensors or just the LEM hall effect one? From the data sheet the LEM one is only suitable for 300V so no good for me but the other is the Lexus one, a Google of the number doesn't bring anything up unfortunately but I'll search further. It's also a 5 pin sensor, I've got the pin out from the lexus wiring diagram, pins are as follows...
1 - IBL
5 - IB1
3 - IB0
4 - GIB
5 - VIB

[nkiernan]

When you mention two battery boxes either side of the rear prop, I've gone that route and would suggest investigating if you could follow the BMW X5/530E/330E pack design route. You'll have seen their two main battery compartments either side of the prop, but connected either above or below the prop at some point. Means a single battery box, simplifies things. I'll be modifying mine like this

Also investigate the location of the safety disconnect in relatoin to the cells of the pack. Don't think it's an issue with the Leaf BMS, but with Orion for example, its critical you don't break the pack in certain locations...for example, you can't split a 96s pack with a 96s Orion 2 in the centre!!! Leaves a HV route through the Orion BMS and it goes pop

[Jacobsmess]

Thanks, I think for the leaf BMS it needs to be broken at cell 48 for reasons I don't understand but also to avoid 'popping'.

The single/double battery box (with a solid corridor above the prop) might be a good idea actually. It would protect all the cabling, keep the number of input and output connections to a minimum and provide a sensible place for the disconnect. I'll have to get under the van to ensure this can be accommodated thanks.

The only real issue is being able to install it simply, which I find the most difficult of things. KISS is always my downfall!

[Jacobsmess]

So I've been quiet on here but things have been slowly moving (although at more of a glacial pace)....
The Van failed it's MOT on some pretty major welding which I've been completing over the last month or so, which I'm happy to say it passed last Wednesday although in doing so I discovered more very suspect welding and tbh I may sell this van now and find another in better condition, which might be a blessing in that I've found a couple of motorhome versions that are build on Chassis Cab beds, which gives fat greater mounting options than my original panel van.

I'm currently rigging up some form of compressor to squeeze some cells back into their original packaging after disassembling one of the UX300E modules to explore alternative battery back options and in waiting on some threaded bar to turn up to do so.

Also, somewhat more excitingly my first 3d printer (Ender 3 V3 SE) turned up today (less than 12 hours from ordering?!)

AND!
10 of Johus finest 16 channel Flying BMS boards turned up from JLCPCB. I did need to tweak the manufacturing files a little bit as some components weren't placed correctly on the CPL file I had for some reason and I added male headers and a screw clamp to the board but they look pretty good I think.

Once I've got them all flashed and working I'll probably sell off the 4 I don't need if anyone is interested.

No idea when I'll get chance to mess with any of this stuff (funnily enough after spending a month welding the van my family are requesting more of my time?!?) but I'm sure I'll be updating you with my troubles and tribulations in due course!

[tom91]

Headers are quite shit connectors for automotive applications. No real way of retaining the connector and ensuring a good connection.

[Jacobsmess]

Headers are quite shit connectors for automotive applications. No real way of retaining the connector and ensuring a good connection.

Sure but for now they'll work, they cost very little and they won't be difficult to swap for something better. I was going round in circles trying to find something that had the right spacing, connection type and number of pins that was available from JLC. If you've any recommendations on options that would be great. Ideally I'd have something that wired direct to the board with the male receiving connector in the BMS housing or some sort of solid pin connection.