Prelude conversion project - some questions

Technical discussion on converting internal combustion to electric
Post Reply
User avatar
Richo
Senior Member
Posts: 3403
Joined: Mon, 16 Jun 2008, 00:19
Real Name: Richard
Location: Perth, WA

Re: Prelude conversion project - some questions

Post by Richo » Thu, 13 Dec 2018, 12:35

Nice Hoist - I'm there 8-)

What about the BMS?
Do you have to remove the lid of the battery modules to fit that?
Help prevent road rage - get outta my way! Blasphemy is a swear word. Magnetic North is a south Pole.

User avatar
jonescg
Senior Member
Posts: 2549
Joined: Thu, 21 Jan 2010, 23:05
Real Name: Chris Jones
Location: Perth, WA.

Re: Prelude conversion project - some questions

Post by jonescg » Thu, 13 Dec 2018, 14:24

Richo wrote:
Thu, 13 Dec 2018, 12:35
Nice Hoist - I'm there 8-)

What about the BMS?
Do you have to remove the lid of the battery modules to fit that?
Yeah I'll mount the BMS inside the modules and run the signal / CAN Bus wiring from one module to the next, probably via the sides but I'll have to wait and see how it all fits together first.
AEVA National Secretary, WA branch vice-chair

User avatar
jonescg
Senior Member
Posts: 2549
Joined: Thu, 21 Jan 2010, 23:05
Real Name: Chris Jones
Location: Perth, WA.

Re: Prelude conversion project - some questions

Post by jonescg » Sun, 16 Dec 2018, 08:45

It begins in earnest:
Bonnet off.jpg
Bonnet off.jpg (83.68 KiB) Viewed 1232 times
We drained the fuel tank, but the shed happened to have half a dozen seasoned EV drivers who complained bitterly about the smell...

We shan't get too carried away as we still need to weigh the car front and rear. I hope to get some cheap spring-balance bathroom scales and pair them up. 2 x 150 kg scales will do for each corner.
AEVA National Secretary, WA branch vice-chair

User avatar
brendon_m
Groupie
Posts: 164
Joined: Sat, 28 Oct 2017, 11:00
Real Name: Brendon McCarrol

Re: Prelude conversion project - some questions

Post by brendon_m » Sun, 16 Dec 2018, 09:36

You can use just 1 set of scales some blocks and a beam to weigh each corner. It takes longer but is cheaper and you should have all the stuff you need lying around the house

User avatar
jonescg
Senior Member
Posts: 2549
Joined: Thu, 21 Jan 2010, 23:05
Real Name: Chris Jones
Location: Perth, WA.

Re: Prelude conversion project - some questions

Post by jonescg » Sun, 16 Dec 2018, 10:18

I'm going to pick up a pair of 180 kg scales this morning. After all, we could use a set in the house :)
AEVA National Secretary, WA branch vice-chair

User avatar
jonescg
Senior Member
Posts: 2549
Joined: Thu, 21 Jan 2010, 23:05
Real Name: Chris Jones
Location: Perth, WA.

The Prelude Conversion begins!

Post by jonescg » Sun, 16 Dec 2018, 20:08

Technically it began when we started sourcing parts, but it's for reals now that the vehicle is immobilised.

I started by weighing the car using a fairly reliable method - two bathroom scales to evenly share the weight of a single corner of the car, while the other three corners were supported with blocks of the same height. The closer the two numbers the better, and after a few replicates I came down to a final weight of 1100 kg, give or take 10 kg.
Weighing the car.jpg
Weighing the car.jpg (145.66 KiB) Viewed 1202 times
This is including an estimated 50 kg of fuel in the positively massive tank. The front-rear bias is about 60:40. Adding 160 kg worth of battery just in front of the rear axle will mean a net increase of 110 kg on the rear, which can be taken up easily enough. That shifts the front rear bias to 52:48, assuming 110 kg net overshoot. I suspect we'll have a bit more weight come out from the front, so possibly approaching 50:50.

Very nice of @Mitchbiz to come and help today - not a lot of work involved in removing the tank and exhaust but it's always good to have company. The tank occupies the volume right where the 4-wheel steering rod goes, and it's really right in the way.
Tank space.jpg
Tank space.jpg (144.77 KiB) Viewed 1202 times
If we take the bum divots out of the rear seats (lets face it, it won't be any less uncomfortable than it already is) and do away with the 4WS, the whole battery pack will fit neatly in the space left by the tank, and it has a stack of mounting points around the place. I will build a bit of a sub frame for it anyway. Losing the 4WS isn't ideal, but unfortunately there isn't anywhere else to mount the modules. Also, it will be difficult to ensure they receive the same coolant flow as the others. The engine bay is going to be very tight, as there's little depth to work with. On the plus side, there's a nice little cavity where the muffler was where the charger can go, but it will need quite some length of plumbing. I think the weight up front will be appreciated.

We figure the 4WS won't cause a noticeable loss in turning circle if it can be locked out and the shaft removed.

Engine comes out tomorrow and heads down to Daniel at EV Shop for an adaptor plate to be fabricated. We're keeping the clutch since the terrain it drives in is mainly hilly, and dropping down to third will be handy.
AEVA National Secretary, WA branch vice-chair

User avatar
brendon_m
Groupie
Posts: 164
Joined: Sat, 28 Oct 2017, 11:00
Real Name: Brendon McCarrol

Re: Prelude conversion project - some questions

Post by brendon_m » Sun, 16 Dec 2018, 20:16

Could you ditch the rear seat entirely and keep the 4ws, make mounting your cell modules easier too.

User avatar
jonescg
Senior Member
Posts: 2549
Joined: Thu, 21 Jan 2010, 23:05
Real Name: Chris Jones
Location: Perth, WA.

Re: Prelude conversion project - some questions

Post by jonescg » Sun, 16 Dec 2018, 20:26

brendon_m wrote:
Sun, 16 Dec 2018, 20:16
Could you ditch the rear seat entirely and keep the 4ws, make mounting your cell modules easier too.
Unfortunately no - even with the rear seat gone, it won't fit in the remaining space. It's just in a really inconvenient location :/
AEVA National Secretary, WA branch vice-chair

User avatar
brendon_m
Groupie
Posts: 164
Joined: Sat, 28 Oct 2017, 11:00
Real Name: Brendon McCarrol

Re: Prelude conversion project - some questions

Post by brendon_m » Sun, 16 Dec 2018, 21:00

I was more going for plonking the cells in the back seat and stacking them up inside the cabin.

User avatar
jonescg
Senior Member
Posts: 2549
Joined: Thu, 21 Jan 2010, 23:05
Real Name: Chris Jones
Location: Perth, WA.

Re: Prelude conversion project - some questions

Post by jonescg » Sun, 16 Dec 2018, 21:10

Yeah trying to avoid that. I don't like the idea of having batteries anywhere inside the cabin because a) they might dislodge in a crash and become projectiles, and b) in the unlikely event of a fire, the cabin becomes smoke-filled very quickly. I built the modules with the preferred layout in mind, but we'll see how it goes. Re-registering a vehicle as a 2-seater is additional bureaucracy, whereas locking the 4WS (which was always a factory option) is much easier.
AEVA National Secretary, WA branch vice-chair

antiscab
Senior Member
Posts: 2262
Joined: Mon, 26 Nov 2007, 05:39
Real Name: Matthew Lacey
Location: Perth, WA

Re: Prelude conversion project - some questions

Post by antiscab » Sun, 16 Dec 2018, 23:12

Also, batteries in the cabin get cooked when parked in the sun
Matt
2017 Renault zoe
2007 vectrix - 145'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells

User avatar
brendon_m
Groupie
Posts: 164
Joined: Sat, 28 Oct 2017, 11:00
Real Name: Brendon McCarrol

Re: Prelude conversion project - some questions

Post by brendon_m » Mon, 17 Dec 2018, 07:04

antiscab wrote:
Sun, 16 Dec 2018, 23:12
Also, batteries in the cabin get cooked when parked in the sun
You would think I would have thought about that seeing as I'm currently battling that exact battle with the cells in my car
IMG_20181217_064909.jpg
IMG_20181217_064909.jpg (1.53 MiB) Viewed 1180 times
But cardboard and keeping the windows down works. Not very professional looking though...

User avatar
jonescg
Senior Member
Posts: 2549
Joined: Thu, 21 Jan 2010, 23:05
Real Name: Chris Jones
Location: Perth, WA.

Re: Prelude conversion project - some questions

Post by jonescg » Mon, 17 Dec 2018, 07:42

Full marks for innovation though.
AEVA National Secretary, WA branch vice-chair

User avatar
jonescg
Senior Member
Posts: 2549
Joined: Thu, 21 Jan 2010, 23:05
Real Name: Chris Jones
Location: Perth, WA.

Re: Prelude conversion project - some questions

Post by jonescg » Tue, 18 Dec 2018, 13:20

Engine came out this morning, and will head down to EV shop for an adaptor plate to be fabricated.
ICE Engine out.jpg
ICE Engine out.jpg (428.48 KiB) Viewed 1136 times
CV joints seems a little loose, but they never made any fuss while driving. Always worth giving them a spruce up later on anyway.
AEVA National Secretary, WA branch vice-chair

francisco.shi
Groupie
Posts: 128
Joined: Mon, 17 Sep 2018, 16:30
Real Name: Francisco
Location: Brisbane, Strathpine

Re: Prelude conversion project - some questions

Post by francisco.shi » Tue, 18 Dec 2018, 13:32

How much does the engine and gearbox weigh?

User avatar
jonescg
Senior Member
Posts: 2549
Joined: Thu, 21 Jan 2010, 23:05
Real Name: Chris Jones
Location: Perth, WA.

Re: Prelude conversion project - some questions

Post by jonescg » Tue, 18 Dec 2018, 13:34

According to the manual the engine is 126 kg wet. Not sure if that includes the transmission though. Will weigh it now.
AEVA National Secretary, WA branch vice-chair

User avatar
jonescg
Senior Member
Posts: 2549
Joined: Thu, 21 Jan 2010, 23:05
Real Name: Chris Jones
Location: Perth, WA.

Re: Prelude conversion project - some questions

Post by jonescg » Wed, 19 Dec 2018, 18:19

Well, I am sad, but it was somewhat inevitable.

I can't fit all 8 modules in the space at the back without substantial cutting of the chassis.
20181219_172832.jpg
20181219_172832.jpg (150.15 KiB) Viewed 1102 times
This is the minimum base size of the battery pack with all 8 modules. It's wide enough, but it's just not long enough. I have about 30 mm of flange around the outside perimeter of the 8 modules. So there are two options.

1. Put 6 modules back here and two up the front.
2. Go crazy with the grinder and make room for it.

Option one seems logical, however it comes with complications. The battery cooling loop for the rear cells will be running at a different pressure to the ones at the front. This could mean different flow rates and therefore different temperatures. It does mean we can probably retain the 4WS, but the seats will still need to be hacked to make way for the height of the modules (~200 mm including the floor of the box). In the end, it's two more boxes in under the bonnet, and space will still be rather tight.

Option two means losing the 4WS, and the seats will still need to be hacked, but it does mean the installation is nice and simple. The engineering required to hack into a chassis is serious, and will mean even less room in the footwell for the passengers.

So who here has hacked floor pans to make battery packs fit? Any tips?
AEVA National Secretary, WA branch vice-chair

User avatar
jonescg
Senior Member
Posts: 2549
Joined: Thu, 21 Jan 2010, 23:05
Real Name: Chris Jones
Location: Perth, WA.

Re: Prelude conversion project - some questions

Post by jonescg » Sun, 30 Dec 2018, 13:23

Back from a quick family visit to Queensland, I started to make room for the battery pack.
Divot cut.jpg
Divot cut.jpg (162.9 KiB) Viewed 987 times
First job is to carefully cut the bum divots out of the back seat metal. These will eventually be re-covered with sheet metal. Welding would be ideal, but I'm wondering if Sikaflex and Tek-screws will suffice...
Bum divots cut.jpg
Bum divots cut.jpg (186.54 KiB) Viewed 987 times
This provides a bit more height for the battery pack, so the rear seats get a bit less comfortable since there's less foam between your bum and the metal. I will now start building a sub-frame to which the battery pack is bolted to. Said sub-frame will be fixed to the chassis using Riv-nuts and existing pick-up points. I might even be able to retain the 4WS at this rate, but as always, I will no doubt learn more as I go along.
AEVA National Secretary, WA branch vice-chair

User avatar
brendon_m
Groupie
Posts: 164
Joined: Sat, 28 Oct 2017, 11:00
Real Name: Brendon McCarrol

Re: Prelude conversion project - some questions

Post by brendon_m » Sun, 30 Dec 2018, 14:54

Or skip the electric conversion and just go flintstone style

User avatar
jonescg
Senior Member
Posts: 2549
Joined: Thu, 21 Jan 2010, 23:05
Real Name: Chris Jones
Location: Perth, WA.

Re: Prelude conversion project - some questions

Post by jonescg » Mon, 31 Dec 2018, 19:30



I hope to set the temperature logging up at the end of the week and do a full discharge test. At 12 kW load (that's 5C) the module should be generating 760 W of heat. I'm keen to see how the thermal epoxy goes at transferring the heat across to the cooling plate, however this is the 'spare' module which was not built exactly as is was supposed to be (irregular thermal epoxy in places).
AEVA National Secretary, WA branch vice-chair

User avatar
jonescg
Senior Member
Posts: 2549
Joined: Thu, 21 Jan 2010, 23:05
Real Name: Chris Jones
Location: Perth, WA.

Re: Prelude conversion project - some questions

Post by jonescg » Wed, 02 Jan 2019, 20:10

Progress was made on the rear battery subframe.

I figured I would start with the 900 mm x 700 mm perimeter of the battery floor. I used 25 mm SHS (1.6 mm wall thickness) and welded it up using my trusty stick welder.
The next step was to affix hangers where I could use the existing M6 threaded holes in the chassis. I also put three new ones in using Riv-nuts. These ones are only going into 1 mm wall so I made sure there was several of them. I'm not completely done here as I need to make room for the contactors and HV connector, which will exist as a vestibule out the front of the pack. So once everything is lined up I'll mark it up and cut a section out where the tunnel goes. These fixtures are partly in shear, and partly in tension since they are at an angle.
Battery subframe1.jpg
Battery subframe1.jpg (178.02 KiB) Viewed 877 times
The back part was trickier, however there was also two slots where the original fuel tank hangers went. Since this will be above the 4WS rod, I can't make this part removable, so I figured I'd leave a section of SHS up there and bolt the lower part of the subframe to it. This consists of two M8 flanged bolts set in place and secured with a nut on the other side. I will weld this so it can't move. I have also put two more M6 Riv-nuts either side of these M8 hangers, and I can now bolt right through. So these guys are in shear for the most part.
Battery subframe2.jpg
Battery subframe2.jpg (181.34 KiB) Viewed 877 times
I'm not going to drill these holes until I have everything else lined up, clamped and ready for welding.

So that covers up and down movement, as well as some fore and aft, but I will also put a pair of hangers on the sides for improved fore and aft movement, as well as stabilising against left-right movement.

Once I have the subframe looking good I will either put M6 Riv-nits in the underside of the subframe, or drill right through and weld nuts on the topside. The latter is probably better for tension loads, but much more of a PITA. One every 150 mm should keep the battery floor secure, and add significant stiffness to the chassis.
AEVA National Secretary, WA branch vice-chair

User avatar
jonescg
Senior Member
Posts: 2549
Joined: Thu, 21 Jan 2010, 23:05
Real Name: Chris Jones
Location: Perth, WA.

Re: Prelude conversion project - some questions

Post by jonescg » Wed, 02 Jan 2019, 22:10

Hmm, change of plans - I will instead build two separate uprights using SHS. One for either side of the 4WS rod. Should make it easier to install too.
AEVA National Secretary, WA branch vice-chair

User avatar
jonescg
Senior Member
Posts: 2549
Joined: Thu, 21 Jan 2010, 23:05
Real Name: Chris Jones
Location: Perth, WA.

Re: Prelude conversion project - some questions

Post by jonescg » Thu, 03 Jan 2019, 14:55

Apologies for the shaky picture...
Subframe almost done.jpg
Subframe almost done.jpg (55.29 KiB) Viewed 855 times
Much better. I could gusset the back of the tubes with a piece of 3 mm flat bar, so now everything is skookum.
AEVA National Secretary, WA branch vice-chair

Geoffozz
Noobie
Posts: 7
Joined: Sat, 13 Oct 2018, 11:26

Re: Prelude conversion project - some questions

Post by Geoffozz » Thu, 03 Jan 2019, 21:00

G'day Chris
This is fascinating - you hit many of the same problems that any other car builder does and then you have to deal with contactors, pre-charge and fuses. Oh, and the small matter of battery construction!
"skookum" - I'm going to guess you watch AVE?
Thanks for the detail you put into these build diaries - it is helping me greatly to get my head around the electrics.

User avatar
jonescg
Senior Member
Posts: 2549
Joined: Thu, 21 Jan 2010, 23:05
Real Name: Chris Jones
Location: Perth, WA.

Re: Prelude conversion project - some questions

Post by jonescg » Thu, 03 Jan 2019, 21:06

Hehe, I spent a bit of time in Vancouver, so I learned the word there, but yes, AVE uses the word quite a lot :D
Honestly with this build the most complicated part is the motor adaptor plate and clutch fitment, which I will happily leave to Daniel Booth to work out for the most part. The Prelude has a huge under-tank space (but sadly not quite huge enough). Still, 19 kWh in the back and 6 kWh under the bonnet is doable.
AEVA National Secretary, WA branch vice-chair

Post Reply