Alibro said:

New box to go under the boot floor

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I like that idea Ali. It looks like a good solution.

kernowsvenski said:

You've forgotten the drain hole

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Lol, still time to get it sorted.

Your fabriucation is coming on leaps and bounds Ali, that box looks great, you should be proud of yourself. Does this new box mean there's no longer going to be batteries inside the cabin on the boot floor?

Jayridium said:

Your fabriucation is coming on leaps and bounds Ali, that box looks great, you should be proud of yourself. Does this new box mean there's no longer going to be batteries inside the cabin on the boot floor?

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Thanks mate but I'm afraid not.
This is the boot box.



And this is it with the modules where I think they will go. I need to be able to fit a HV socket, two contactors and a fuse somewhere hence the gap at the top right.
Also I will need a support for the lid down the middle so there will be some adjustment but this is close to the final layout.



And the lid which I made in two sections as I was getting short on steel. I still have to decide if I'm going to weld it or keep it in two parts and I have to grind the corners of the box so this isn't fitting as well as it will.

Making the battery boxes this way is so much easier, faster and more accurate than building a frame from angle and cladding it. I was able to make the box under the boot floor in just a few hours on Saturday and the boot box from scratch with a lid on Sunday.
I'll probably use rivnuts to hold the modules once I've decided on their final position.

I've been away from this for a few day but got back to it yesterday and made a discovery that pleases a lot.

The photo below shows the lower battery box in place with the tow bar refitted.



It occurred to me this might work but I'm really pleased to see it actually fits and I still have room to secure the tow bar side bolts. I'll never be using this car to tow a caravan but I want to be able to use it for trips to the dump etc so a tow bar is really useful.
Hopefully today I'll finish building the support bracket for the lower batt box tying into the rear two subframe bolts, the two middle tow bar bolts and the rear two fuel tank bolts.
Having the extra strength protecting the battery box in the event of a rear impact it a good thing too.

That looks really nice Ali.
You can put a lid on there too, so it can be separated from the cabin.

Nodge68 said:

That looks really nice Ali.
You can put a lid on there too, so it can be separated from the cabin.

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I don't need a lid on it as the boot battery box will cover it but I'll probably put a piece of timber over the hole to support the boot box. There will be holes in the floor and timber to let bms and power cables through.
Now I've been working on it today I think the fuel tank bolt holes and the two long tow bar bolts will be enough to hold this lower box.

New Vid

I've been working on the under boot floor battery box and after some cutting, hammering, grinding welding and more grinding it's gone from this



To This



If you look carefully the corners in the top picture are cut square. where in the bottom one they are rounded off.
When I first designed the box the towbar was not in the picture and the box fitted fine. With the towbar fitted it was a bit tight, so I rounded off the corners to allow it to slide past the subframe.
I'm still mulling over how to secure the modules in the box but it is looking likely I will need to secure them before raising the box into position. This means it needs to be an easy fit and as the towbar needs to be fitted before the battery box I needed more clearance.

This is the bracket I came up with to hold the box in place.



It has angle iron at the front held up by the fuel tank bolts and angle at the back held up by the two middle towbar bolts and straps going in between.



I tried making it in one piece but couldn't get the half in the lower part of the photo to go past the subframe due to the angle it needs to be at. That is also why I had to cut out 3/4 of the box section forming a triangle.
It is still plenty strong enough though, with it test fitted I stood on it and jumped up and down and it didn't budge. I usually start out massively over engineering my brackets then end up cutting them back to make things fit.

New vid.

Making progress bro... Welding's orders of magnitudes better since the start of this project, take some pride in that, as I don't dish out compliments lightly.

For the other batterybox, an easier way of securing the batteries to the box would be to invert that design of angle iron battery clamp I showed you a while ago for the 12v battery. As in one web of the angle goes horizontal across the bot of the battery, but this time, instead of the other web going vertical above the battery, it would go vertically down from horizontal plane of the first web, and reside between the batteries. On the floor of the box, weld up some channel with slots cut out of it, you'd then put studbar, nut and washer down till it hit the floor, slide it in so the stud comes up through the slot, slide the angle iron over the studbars and between the batteries, and put nuts on from the top of the studbar.

If you decide to stick with the same design for the top box's battery restraints, put two nuts on the end of the studbar, and tighten them one down, one up till they meet, you can then put a socket over the outer nut, to drive the threaded rods without the risk of damaging the threads with the check of the drill. To assemble it, put a drill to socket adapter bit in the chuck and run the studbar in with the drill driving the socket adapter driving the socket driving the double nuts, driving the studbar.

Jayridium said:

Making progress bro... Welding's orders of magnitudes better since the start of this project, take some pride in that, as I don't dish out compliments lightly.

For the other batterybox, an easier way of securing the batteries to the box would be to invert that design of angle iron battery clamp I showed you a while ago for the 12v battery. As in one web of the angle goes horizontal across the bot of the battery, but this time, instead of the other web going vertical above the battery, it would go vertically down from horizontal plane of the first web, and reside between the batteries. On the floor of the box, weld up some channel with slots cut out of it, you'd then put studbar, nut and washer down till it hit the floor, slide it in so the stud comes up through the slot, slide the angle iron over the studbars and between the batteries, and put nuts on from the top of the studbar.

If you decide to stick with the same design for the top box's battery restraints, put two nuts on the end of the studbar, and tighten them one down, one up till they meet, you can then put a socket over the outer nut, to drive the threaded rods without the risk of damaging the threads with the check of the drill. To assemble it, put a drill to socket adapter bit in the chuck and run the studbar in with the drill driving the socket adapter driving the socket driving the double nuts, driving the studbar.

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Thanks mate, I appreciate any compliments I get.
I think I understand what you are saying - vertical plates welded to the floor of the box rising between the batteries so the threaded bar can go through the batteries and the vertical plates clamping everything. It sounds like a good idea and if I ever need to change things in the lower box I'll consider doing it that way although because of the space constraints I'm not sure there would be room, the nuts either end of the threaded bar are pretty much touching both sides of the box.
For the upper battery box the modules will be upright so I won't need to worry about threaded bar but that is a good idea for feeding the threaded bar through. I have already drilled about 50 holes in the base of the upper box and am in the process of installing rivnuts to hold the modules down.
I decided to have the modules sitting upright for a couple of reasons, they sit lower so take up less height in the boot and they are much easier to link electrically.
The latter reason is a pretty major one as one of my biggest fears is a loose connection causing heat build up and fire risk. The easier it is access the screws in the modules the less likely that is.

Apologies guys for not updating this thread as often as I should, I've been tied up for the last week or so re-roofing a large shed but that only excuses me for the last week.
Anyway here are a few pics of the current progress in the rear battery box.
This is the rear upper battery box with the HV connector, contactors and fuse in place.


And today I got some of the HV connections made. As you can see I'm bringing the HV to the front of the car through the holes in the floor that were already there. This is all temporary and it will be tidied up with rubber grommets and orange conduit when installed in the proper car.
I'll also come up with some way to insulate/cover the fuse as I don't like so much live metal being exposed, especially in a metal box.
Note, it's only sitting at 7.5V now from a single module


The slot to the left of the HV connector is for BMS cables. I'm hoping to secure the BMS in this corner as most of the modules are here at the rear.


It's not easy to see but I also brought the two cables up from the lower box and connected them to the two large modules in the middle.
Every module is screwed down with the original VW screws using rivnuts in the bottom of the box. I haven't done it yet as this is only the test mule but I will weld some brackets to the outside of the box to bolt it down.


I couldn't decide if I should mark the cables coming up, pos and neg relating to the battery terminals they connect to, or the voltage in the cables but plumped for the terminals they are connected to as it's how I mark them when I can see both ends.
I'm using 35mm2 cable for the pack interconnects and 50mm2 cable for the two long routes to the front of the car. This might be overkill as VW only used 35mm2 but Nissan used 50mm2 cables for a less powerful car so I think it makes sense.
I still need to find a service disconnect switch for this pack but I think that plus some insulation for the box is the only thing missing regarding safety.

I've been in touch with Nodge for advise regarding the anti tamper connection in the HV connector. I plan to use it to kill the power to the contactors should the HV cable be disconnected while the car is turned on but I don't think the wires are heavy enough to take the current from the contactors so Nodge advised I use a miniature 12V relay that only draws 70mA.
I might even use this for the service disconnect as it will kill the 12V to the contactors both in the rear battery box and the front HV junction box ensuring that all cables and connectors are not live. Anybody any thoughts on this? As far as I can see it is how VW did it.

"Overkill is Underrated" That's looking good bud, picking up on what you said about exploring cable management options as your next moves, where the cables come up through the floor, via those significantly larger holes, you might need to go with blanking grommets, and cut an aperture to size, rather than just a conventional grommet. For insulating stuff in the box, are you aware of the spray on or paint on electrical insulation products? I've not used the spray stuff, but I've used the brush on stuff to great effect. These typically come in a copydex format, where the lid of the jar has a brush in it, the "product" contained therein is a dissolved polyurethane suspended in acetone by the smells of it, enter liquid insulating tape into amazon or ebay and you'll find stuff like this. like this:


For the apertures in the box, you also get rubber strip its like a round lace extrusion with a cross-section like this:


I've used it for protecting computer cables, as seen in this picture, to the right of the fan:


Those slots are where most of the cables coming off my motherboard come through in this build:


So it was getting pretty congested in there and I really didn't want to be running cables against bare sheet metal, and you've got a lot more angry pixies in your orange wires than I had to contend with. Maybe you'd want a bigger version of the pacman cord? Something like this: https://www.vital-parts.co.uk/u-channel-edging---edge032-5m-11995-p.asp

Jayridium said:

"Overkill is Underrated" That's looking good bud, picking up on what you said about exploring cable management options as your next moves, where the cables come up through the floor, via those significantly larger holes, you might need to go with blanking grommets, and cut an aperture to size, rather than just a conventional grommet. For insulating stuff in the box, are you aware of the spray on or paint on electrical insulation products? I've not used the spray stuff, but I've used the brush on stuff to great effect. These typically come in a copydex format, where the lid of the jar has a brush in it, the "product" contained therein is a dissolved polyurethane suspended in acetone by the smells of it, enter liquid insulating tape into amazon or ebay and you'll find stuff like this. like this:

For the apertures in the box, you also get rubber strip its like a round lace extrusion with a cross-section like this:
View attachment 276352

I've used it for protecting computer cables, as seen in this picture, to the right of the fan:

Those slots are where most of the cables coming off my motherboard come through in this build:

So it was getting pretty congested in there and I really didn't want to be running cables against bare sheet metal, and you've got a lot more angry pixies in your orange wires than I had to contend with. Maybe you'd want a bigger version of the pacman cord? Something like this: https://www.vital-parts.co.uk/u-channel-edging---edge032-5m-11995-p.asp

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Thanks for the links mate, I'll have a look for the insulating spray but do you think it would be much better than stone chip, I'm fairly certain it would not be certified to insulate 400V anyway.
I ordered some edge protector today already so will update when it arrives.
I've already orders some edge protector

Alibro said:

This might be overkill as VW only used 35mm2 but Nissan used 50mm2 cables for a less powerful car so I think it makes sense.

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Overkill is fine here. You want the fuse to be the fuse, not the cables.

Are you going to run the cables in trunking, maybe flexible trunking under the floor? That's the way I'd do it, which isn't too different to how manufacturers run the HV cables around the vehicle.

As for polarity at the battery box, I guess that's up to you, but make sure you mark the cables so you can't get it wrong.

Alibro said:

Thanks for the links mate, I'll have a look for the insulating spray but do you think it would be much better than stone chip, I'm fairly certain it would not be certified to insulate 400V anyway.
I ordered some edge protector today already so will update when it arrives.
I've already orders some edge protector

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Liquid insulation, even if rated for lower voltages than your EV's system operates will be far more appropriate than stone chip for this project.

Edit: the plasticote one is rated "Electrically insulates to over 1380volts/ml."

Nodge68 said:

Overkill is fine here. You want the fuse to be the fuse, not the cables.

Are you going to run the cables in trunking, maybe flexible trunking under the floor? That's the way I'd do it, which isn't too different to how manufacturers run the HV cables around the vehicle.

As for polarity at the battery box, I guess that's up to you, but make sure you mark the cables so you can't get it wrong.

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Yeah, I agree about the cables.
I have some orange flexible conduit for the job. Any cables external to the battery pack that carry HV need to be protected and coloured orange.

Jayridium said:

Liquid insulation, even if rated for lower voltages than your EV's system operates will be far more appropriate than stone chip for this project.

Edit: the plasticote one is rated "Electrically insulates to over 1380volts/ml."

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Brilliant thanks, I'll order some today but I also have thin foam to stick to the insides of the boxes plus will be painting them so it should be a bit safer.

Last night I spent an hour or so sorting the length of the 50mm2 cable I'm using to bring the battery power from the rear to the front.
Feeding them through the conduit was a mare of a job but a little brake clean squirted down the conduit helped.
You can see here I have already crimped ring terminals onto one end.


My back was kinda sore so I didn't mess about too much but tonight I went to chop some logs for the fire and suddenly felt a twinge in my lower back.
Looks like I'm going to be sore for a few days.
Getting older has nothing to recommend it.