[WIP] Leaf to VW Type 2 Campervan

[marcexec]

I'd start with the (chest-) freezer and a heat gun if you want to take it easy and have no time pressure.

[Romale]

[ianlighting]

Out with the old, in with the new…

That’s the motor in place with a nice fit on the coupler (ignore yesterday’s panic attack!)

PDM does fit, despite what I thought early on in the build. The challenge is the cables, but they can be adjusted to avoid hitting the inverter. I’ve modified the way they are held by brackets.

One of the tight points is the coolant hose, which isn’t visible but runs from the top right corner of the inverter and is fed from the right hand side of the PDM (im flowing back to front through the PDM in my arrangement). Tight, but ok.

Need to tighten up bolts on the Brat adaptor plates once I’m happy with it all. I also need to create a top box to manage the HV between inverter and PDM now they are separated.

Then the original support bar that held the back of the vw engine goes back, but now with lovely new rubber mounts to replace the decrepit old ones. Then need to create a bracket to go between motor and support bar. Then, then, then….etc.

[Bratitude]

I’m confused, the pdm dose not fit? Dose it collide with the shelf?

[ianlighting]

I’m confused, the pdm dose not fit? Dose it collide with the shelf?

You might have misread. I said is DOES fit. I was clarifying because early on in the build I was not sure there was enough space for the PDM in the fuel tank space once the motor and inverter were mounted aswell. In my disaster bus I ran the PDM from the passenger compartment.

[Bratitude]

You might have misread. I said is DOES fit. I was clarifying because early on in the build I was not sure there was enough space for the PDM in the fuel tank space once the motor and inverter were mounted aswell. In my disaster bus I ran the PDM from the passenger compartment.

Fit on the leaf motor stack? So a full leaf stack will bolt in as is in the back of the bus (with my adapter plate)

[ianlighting]

Fit on the leaf motor stack? So a full leaf stack will bolt in as is in the back of the bus (with my adapter plate)

No. That’s not what I’m saying.

The PDM is separate from the inverter/motor.

The PDM physically fits into the fuel tank space. It is orientated 90deg to normal.

But the height of the top of the inverter, when mounted with the motor, using your adaptor plates is very close.

The closeness is not due to the PDM ‘box’ itself, but there’s a potential for the cables that exit the PDM to clash with the top edge of the inverter.

Early on in my build I’d commented about this. The post yesterday was confirming my plan is possible.

But it requires some ‘tweaking’. All the cables still exit from the PDM standard locations, but I have adjusted the Nissan brackets and cable management to make them avoid the inverter with the way I’ve arranged it.

I’ll do a side photo soon, maybe later that should clarify.

[ianlighting]

Some more images to better explain what’s what…

(Still WIP, some loose ends)

Slight side angle. Shows the PDM sat on the shelf where the fuel tank was.

Top view through the engine hatch that later T2s have…

Photos above are with motor mounted to vw transmission, and all is fine. But this next one shows how close it is with a small gap before final mounting…

I’ll do more down below images once things are a bit tidier, but here’s one from the right hand side. Bottom 2 cables are heading off to the battery. Top 3 are the AC and DC charge cables. (Enlarge image if it’s showing the wrong way round)

Last one. Is it just me, or does this beasty look a bit ominous?

[Bratitude]

but dose the pdm fit on top in it original position on top of the inverter regardless of cables?

also why is your hv disconnect ontop of the motor?

[ianlighting]

but dose the pdm fit on top in it original position on top of the inverter regardless of cables?

also why is your hv disconnect ontop of the motor?

No the PDM does not fit on top of the inverter. If that was possible I wouldn’t have been doing all this juggling. The only way that I could come up with is what I’ve shown. By being placed in the fuel tank space it is actually slightly lower than if it was on top of the inverter.

The main service disconnect is still mid way in the battery pack. But it’s about as accessible as it is in a Leaf - not easy to get to in a hurry. In the event of a problem, I want something easy for me or emergency workers to break the circuit. That switch breaks the HV on the way to the battery from the PDM.

[ianlighting]

I need to ponder how to do my brake vacuum. Brake booster vs vacuum pump. There’s a decent write of up the options here, courtesy of Brat Industries…
https://bratindustries.net/electric-bra ... atsun-720/

If I had time, I’d investigate the quieter booster option, but I’m behind my ideal schedule and really want to get the bus on the road for summer. So I plan to go for the easier to implement vacuum pump. I can always come back to it the future.

So that decided, I need to think about where to position the new bits - pump, valves, sensors etc. There’s plenty of videos of people playing with this - think AliBro did one and a Bobby Come Lately, plus others I’m sure.

The thing with the VW is the brake servo and cylinder are located up front near the front wheels. Although I’m accepting the intermittent grinding whining noise of the pump every so often, I would prefer it if it was not under my seat! That noise would probably bug me after a while.

So can I make use of the existing vacuum line that runs back to the engine bay, about 2 meters away and hide the gubbins back there?

Any reason why that’s a bad idea? Does the 2m of vacuum line between the pump and the master cylinder introduce reduced performance?

Also need to think about whether I just need a pump and have that feed the existing vw brake servo (that’s separate to the master cylinder), or whether I need a separate vacuum reservoir aswell. If I need a separate reservoir that’s another thing I’d probably prefer to put at the back where the engine bay is.


Image is a bad picture up front showing the existing servo. Vacuum line runs 2m back behind the camera to the engine bay.

[J0hannes]

You are thinking my way I also did the minimum on the vacuum system just to minimize the time there and prioritizing other areas first. I took the Volvo vacuum switch and vag vacuum pump route.

1) the brake booster is a vacuum reservoir by itself already, I don't get why people add additional reservoirs, to have the pump running longer periods of time less frequently? Anyways, it shouldn't matter where in line you would have the reservoir. (With the assumption that you don't have flow restrictors in the system (i.e. changing hose diameters etc.)

2) Any length of hose between the pump and brake booster can be just considered as vacuum reservoir volume. In theory what the added length between the pump and booster is likely to give you is delay on vacuum pressure build up speed. Is that going to be noticeable in normal driving conditions, probably not.

3) Pressure switch/sensor should be as close as possible to the brake booster to minimize time delay for pressure signal.

Since you are not taking this to the track, the possible delays on the vacuum build up speed shouldn't really matter in normal driving conditions. And you can always move the pump closer to the booster then, if you don't jump the gun and go all in with the i-booster then

[ianlighting]

Thanks!

I’ve been looking at the MES / DEA 70/6E2. I like it because it seems to be completely self contained, it includes sensor and switch. I guess maybe that’s bad from the pov of view of points of failure possibly taking out the entire unit. But I like a plug and play device that is designed to work as a single unit instead of a mismatched set of stuff I source separately.

But I would be placing this in the engine bay, so that places it’s switch 2m from the VW brake booster (vw naming convention on this thing is ‘brake servo’). Which you suggest is not ideal, which I get. As you say it’s not a performance vehicle, perhaps it will be ok.

Where I live I certainly have a very good test environment because we live up a very steep private track. You need brakes on for several seconds because it’s rough ground as well as steep and you need to stay slow. If i consume my vacuum before even reaching the public road, I’ll know I need an extra vacuum tank.

Part of the decision making is about getting past the DVLA checks. So want to avoid bolting things to inappropriate places that the inspector may take offence to. Once it’s passed… things can return to SOP. The amount of random holes and bolts on a 50 year old bus is quite high!

[J0hannes]

Thanks!

I’ve been looking at the MES / DEA 70/6E2. I like it because it seems to be completely self contained, it includes sensor and switch. I guess maybe that’s bad from the pov of view of points of failure possibly taking out the entire unit. But I like a plug and play device that is designed to work as a single unit instead of a mismatched set of stuff I source separately.

But I would be placing this in the engine bay, so that places it’s switch 2m from the VW brake booster (vw naming convention on this thing is ‘brake servo’). Which you suggest is not ideal, which I get. As you say it’s not a performance vehicle, perhaps it will be ok.

Where I live I certainly have a very good test environment because we live up a very steep private track. You need brakes on for several seconds because it’s rough ground as well as steep and you need to stay slow. If i consume my vacuum before even reaching the public road, I’ll know I need an extra vacuum tank.

Oh, that MES pump looks nice! Really nicely packaged

Nevertheless, not ideal still doesn't mean that it wouldn't work. I don't see much difference in opting for a fully self contained unit like the MES you've been looking at or a vacuum pump setup made up of discrete components, without redundancy, a failure in either is likely to stop/prevent the pump from running.
So maybe I wouldn't worry about that aspect:)

If there isn't a leak, a vacuum brake booster doesn't consume constantly vacuum. Only when you press the pedal and then release --> pumping the brakes is what consumes vacuum the most. So a steep hill where you press on the brake intermittently would be a great to get a feel on the brakes and how the feeling changes
(if it is even noticeable, the fluctuation of the vacuum pressure)

[jrbe]

A booster without a leak should hold vacuum for a few brake presses. Past that it depends on how quick your vacuum pump is. You likely don't need a second reservoir.

[ianlighting]

Let the smoke out…

Not happy. Bad enough it happened at all, but I know a 60kWh Leaf BMS is going to be hard to find - unless the reverse engineering of Leaf BMSs is relevant here and I might be able to use a 24.

Will recap what I did wrong when I’ve wiped away the tears.

Edit - hilariously, this post has just elevated my status to ‘engineer’ according to the forum’s algorthym! I beg to differ.

[Jacobsmess]

I think the 24kwh bms has been reverse engineered and it's possibly to flash new firmware on it, so possible to work with a different pack. There has been some alluding to this on the forum.

[ianlighting]

I think the 24kwh bms has been reverse engineered and it's possibly to flash new firmware on it, so possible to work with a different pack. There has been some alluding to this on the forum.

I was following the thread where the work was happening a while back, but haven’t seen where it’s at for some time now.

It’s this one. More reading…!
https://mynissanleaf.com/threads/revers ... -bms.36627

[ianlighting]

Anyone know if swapping in a BMS from a 30kWh battery (I have a workong one, but low SOH) into my 60kWh pack (both leaf OEM batteries) would work enough to let me get the bus running? I wouldn’t expect accurate SOC, but if it allowed all the internal checks to be passed and the system start up and run ok, it would let me prove everything else is valid while I source a 60kWh BMS.

[Marat]

As a quick solution BMS30 will do, you can also unsolder 93S86 the unit will count SOH100%

[CorW]

Hi Ian,
I have a 62kWh BMS for sale on Ebay for $200, though I will sell it at half for a fellow EVer.
This is the model nr 293A0-5SF0A.
Let me know if you are interested.
I am in Silicon Valley.
Shipping as First Class package to UK would be $32 according to USPS.com

[ianlighting]

Hi Ian,
I have a 62kWh BMS for sale on Ebay for $200, though I will sell it at half for a fellow EVer.
This is the model nr 293A0-5SF0A.
Let me know if you are interested.
I am in Silicon Valley.
Shipping as First Class package to UK would be $32 according to USPS.com

Hi Cor, thank you, that’s great. I’ll switch over to DM if that’s ok. I’ll try to track it down on eBay, but if I don’t I’ll be in touch.

And I think I know who to thank for making this connection, so thanks to him aswell!

[ianlighting]

I would appreciate advice to confirm my understanding of the leaf BMS and HV paths.

My confidence took a bash when I stupidly messed up (plugging in BMS before HV wiring completed). But it’s leading me back to basics to make sure I understand before I repeat plugging in the replacement BMS.

Sanity check…
When we have a standard leaf battery, and with the service disconnect removed, there is no risk of HV causing an overload in the BMS. But why is this? The cell taps are running back to the BMS, so the HV positive (up to about 180 volts on each half) is potentially there. At what point does the BMS connect to the HV negative to create a circuit? The contactors make the circuit, and link the battery to the motor stack, by going to the PDM.

In my setup, it is physically a different shape to the Leaf battery, but logically the same, with all the original modules, service disconnect and contractor unit located as Nissan intended.

The voltages on each module, and cumulatively across each half of the battery (either side of the disconnect) are as I would expect (approx 180V each side currently) They match what I documented when the modules were all in situ in the leaf battery case before dissection.

What further test can I do before I go the final step and connect the BMS? How can I be sure I won’t create an unwanted circuit through the BMS? Could faulty contactors create an unwanted HV circuit through the BMS? How should I test that?

In normal operation, how does the BMS operate safely with the HV?

I know it is a mistake to have the service disconnect in a non-standard position. But I have not done this. As far as I can tell I have a logically correct setup.

I’m basically just really nervous having reached this stage. If anyone wants to correct anything I just said or point out something obvious I should or shouldn’t do, much appreciated.

[tom91]

Look at where your BMS blew up, check all the cell voltages on that connector to a known pinout. The negative stays in place while measuring all other voltages to find a missing wire or a break in your HV circuit.

This clearly looks to be a cell tap mix up to me form the photos of the damage.

The BMS is indeed the last thing you plug in. You need to wire up the HV between the modules before doing so.

[ianlighting]

This clearly looks to be a cell tap mix up to me form the photos of the damage.

The BMS is indeed the last thing you plug in. You need to wire up the HV between the modules before doing so.

Correct - I found I had plugged modules 15 and 16 (16 is the final one) back to front. The burnt area is the connector for them. But equally it was premature for me to have the BMS plugged in at all at that stage.

It is interesting that you can identify that from the image. What are you seeing?

…

Yes, all HV modules are now connected. I just need to be sure that no unwanted HV will go through the BMS. So I’m keen to make sure I understand how the BMS works safely in normal operation to make sure I’m recreating that correctly.