Prelude conversion project - some questions

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jonescg
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Re: Prelude conversion project - some questions

Post by jonescg » Wed, 06 Feb 2019, 22:30

I think I have this right:
Charge control box.png
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The charger will draw 32 amps from the wall by default. Most public chargers are good for 32 A, and the home will have a 32 A charge point installed. But for lower power, you need to turn it down using the ZEVA EVMS. Or a rotary switch with a series of voltage dividers if that's how you roll.
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Re: Prelude conversion project - some questions

Post by reecho » Thu, 07 Feb 2019, 17:48

I'm not a fan of fuel door microswitches. It will be a weak point.

I'm thinking the ZEVA BMS Core has some functionality for inhibits you can use..??

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Re: Prelude conversion project - some questions

Post by reecho » Thu, 07 Feb 2019, 17:49

Is there a protective boot that could be used?

The fuel filler isn't known to be dry... :-)

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Re: Prelude conversion project - some questions

Post by jonescg » Thu, 07 Feb 2019, 18:41

reecho wrote:
Thu, 07 Feb 2019, 17:48

I'm thinking the ZEVA BMS Core has some functionality for inhibits you can use..??
Yes there is some functionality there. Will look it up.
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Re: Prelude conversion project - some questions

Post by jonescg » Thu, 07 Feb 2019, 22:20

Hmmm, turns out it needs a microswitch too.
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Re: Prelude conversion project - some questions

Post by jonescg » Sun, 10 Feb 2019, 20:03

Productive weekend all round. We had a whole bunch of kindling to remove from the back corner of the yard, so the green waste bin was filled in half a day. So that left an afternoon to get busy drilling out potted holes in the battery floor.
Module clamps.jpg
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The six rear battery modules will be held in position by several bits of polycarbonate placed around them to prevent them from moving sideways. To prevent them from moving fore and aft, the coupling nuts which are fixed through the potted sandwich panel are sufficiently strong to stop a module from moving should there be a sudden and rapid deceleration event. The modules are held down by aluminium brackets which are tightened down over the modules with M6 threaded rod, which is on the other end of the coupling nut.

The odd alignment of the bracket is because of the 4-wheel steering - I had to move them across about 25 mm, but forgot I'd already drilled and potted two of the holes at the other end. Shouldn't make a difference - they are purely to hold them down should you drive fast over any 'dippers'.
Module clamps2.jpg
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Now this is great, but there's not much clearance between the threaded rods and the battery cover which will eventually shroud the whole lot. The plumbing will go below the cables but the contactor probably could have been a bit further forwards. Oh well, I can make it work. The biggest clearance issue will be putting a decent draft taper on the cover. If it's too steep I will struggle to get the cover off the mould, but too shallow and I won't clear the cables :|
Tight cable clearance.jpg
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So that just needs a competent aluminium welder to finish. then I can take the modules off, drill holes for the BMS cabling and finally finish sealing the entire perimeter of the sandwich panel for waterproofing and a bit of delamination protection. The joining cable between the two rear modules will be another length of 50 mm2 cable with lugs to suit - it goes over the top where we have about an extra 100 mm of clearance. I hope to fit the pack fuse and service disconnect up there in this cavity.

So the next job was to fit the Type-2 charge inlet. If only all elements of an EV conversion were this straight-forward! I managed to fit three M5 Riv-nuts in position but the fourth one will be for purely for completeness; I couldn't accurately cut the hole out, so it was a bit lean on that corner. Plenty of Sikaflex will fix it though. I'm not sealing it up just yet as i need to run a microswitch and there's also a pair of positions for LEDs. Might run the TC Charger's LED leads out to this. It will tell you if it's charging or if there's a problem.
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Waterproof Type 2 cover.jpg
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These places are notoriously wet and rusty, so sealing it is a good idea.

Next job is to fibreglass up the battery cover and bench-test the BMS. Might lean on @zeva for that :)
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Re: Prelude conversion project - some questions

Post by francisco.shi » Mon, 11 Feb 2019, 10:34

The charge connector seems to be a tight fit.
I want to put a CCS 2 connector for my conversion but I am not sure that it will fit in where the petrol cap was.
I want to be able to use a DC fast charger. Not sure if it is necessary as it seems there are not that many DC chargers around at the moment.

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Re: Prelude conversion project - some questions

Post by jonescg » Mon, 11 Feb 2019, 11:03

Honestly, I don't think DC fast charging is necessary for the most part, especially on a conversion with limited capacity anyway. It's possible to fit 22 kW worth of on-board charger in most cases, and that's about as fast as a DC fast charge on a 24 kWh battery anyway, maybe 15 mins slower at the worst.
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Re: Prelude conversion project - some questions

Post by jonescg » Mon, 11 Feb 2019, 11:13

jonescg wrote:
Wed, 06 Feb 2019, 22:30
I think I have this right:
If you stare at it long enough you find a way :)
Charge control box2.png
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Saves me installing a microswitch.

Edit - just added a diode to prevent this from becoming a useless machine.
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Re: Prelude conversion project - some questions

Post by francisco.shi » Mon, 11 Feb 2019, 15:14

I will have a 70kwh battery capable of charging at over 150kw. So should be able to get to 80% in 20min if the charger can supply the power.
As far as I have been told the limit of how fast I can charge depends on keeping the batteries cool and do not over voltage them when they get close to full hence the 80% limit.

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Re: Prelude conversion project - some questions

Post by oudevolvo » Tue, 12 Feb 2019, 17:06

Looking forward to following further details on this project!
In particular around implementation of the airconditioning and active cooling for the batteries like we exchanged some info on on Facebook.

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Re: Prelude conversion project - some questions

Post by francisco.shi » Tue, 12 Feb 2019, 18:13

I do not use face book much. Are you in Brisbane?

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Re: Prelude conversion project - some questions

Post by jonescg » Thu, 14 Feb 2019, 10:36

Got the clamps welded up, and started to lay out the busbar. I wanted to put an isolator in the back, but it's probably just as easy to put the isolator up the front since I'm splitting the battery into a rear unit and front unit.

The HVSL connector from Amphenol has an interlock circuit which can be used to supply the main contactor. If the cable is unplugged, the contactor remains open. I think this is a suitable level of isolation, in addition to a master isolator under the bonnet.
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The busbar needs to be coated in fiberglass and resin for insulation and strength. I just don't like crossing conductive bits of metal where I can help it.
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Re: Prelude conversion project - some questions

Post by jonescg » Sun, 17 Feb 2019, 18:08

Today was a good day for progress on the Prelude - I have finished all the work on the inside as far as the rear seats are concerned. Also, the charge port (complete with LEDs) is installed.

I finished the charge port first - pretty straight forwards. I added a length of 4-core cable to the charge lead and used three of them for the two LED lights on the Type-2 inlet. I figure the green can be used to indicate it's charging, and red to indicate an error from the BMS. Unfortunately the new TC charger doesn't have a jumper for the LED error codes; that would make the most sense. I managed to tuck the 3-phase cable up out of the way for the most part, and so long as it can't fret against the 4WS rod it won't meed much more attention. The car will only have a single phase (32 amps at 240 volts AC) supply to the charger, but if we have room for another, we can install one.
3p charge lead installed.jpg
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SO after cutting the bum divots out, the next step was to cover the space with some flat sheet metal. I picked up some 1.15 mm galvanised steel sheet and cut it to shape as best IA could with a shifting spanner and an angle grinder. Since I never cut into any load bearing members, I was confident that Sikaflex and dozens of Tek-screws would do the job as required. All the screws are in tension and the surfaces are coated in a generous layer of polyurethane adhesive.
galv sheet glued and screwed.jpg
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The seat foam has been cut down to suit the new sitting height. It's certainly less comfortable than it used to be, but the number of times there will be more than two people in the car is limited.
Seat foam cut down.jpg
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On the underside, I pumped expandable foam into the recess created by the sheet metal. This both acts as an adhesive, keeps water out once painted with bitumen paint, and adds a little support.
Expandable foam in place.jpg
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Foan in place2.jpg
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But at least now the rear seat is back in position (minus a seatbelt clasp which needs to be replaced)
Like I was never here.jpg
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Battery assembly is next on the agenda. Then bench-testing the BMS, then making the fiberglass cover for the whole pack, and fitting it to the car.
That will conclude the rear end of the car's activities :)
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Re: Prelude conversion project - some questions

Post by mikedufty » Mon, 18 Feb 2019, 11:47

I hope they don't make you take all that apart for the licensing inspection.

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Re: Prelude conversion project - some questions

Post by jonescg » Mon, 18 Feb 2019, 11:55

mikedufty wrote:
Mon, 18 Feb 2019, 11:47
I hope they don't make you take all that apart for the licensing inspection.
That's what the photos are for :)
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Re: Prelude conversion project - some questions

Post by jonescg » Tue, 19 Feb 2019, 08:51

So I have a couple of options for plumbing the battery cooling loop.

I can run three in series and parallel these, along with the last two in series, paralleled. Or I can run two paralleled lots of three in series, and the other two in series, in parallel with the six. To borrow (and then butcher) a term from the electrical world, the battery would be cooled as (3s2p)//(2s1p) or (3p)//(3p)//(2s) :P

Pictures might help.
Cooling options.png
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Parallel on the left, series on the right.

The series option:
Cooling in series.jpg
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The Parallel option:
Cooling in parallel.jpg
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Noe the last two modules would need to be in parallel with either of these systems.

The pressure drop from one end of the series run to the other is significant, so to achieve any reasonable flow the pressures would be close to the limit of what the polyurethane glue can handle. The paralleled option means that there may be uneven flow through modules, but also, the plumbing takes up a fair bit of space.

I'm beginning to think that the paralleled is better and worth persevering with, but I need to make it more compact if I hope to fit it.
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Re: Prelude conversion project - some questions

Post by francisco.shi » Tue, 19 Feb 2019, 09:57

For the parallel option you would have to make all the hoses the same length on the in and the out to ensure the same flow thru each battery.
The other question is how much flow do you really need for the series to work?
If the a low flow is enough so the temperature difference between the cell and the water for the last cell is acceptable then the series may be good enough.

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Re: Prelude conversion project - some questions

Post by jonescg » Tue, 19 Feb 2019, 10:14

Yes it would be difficult to ensure the same flow. And making all hoses the same length would require me to run hoses around the back, where I definitely don't have the space.
I'm not opposed to the series runs, but I will need a better / bigger pump. The Bosch 12 V pumps with 19 mm fittings are great for flow but have lousy pressure performance. So a pair of them in series might have the oomph to push fluid through all 8 modules.
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Re: Prelude conversion project - some questions

Post by brendon_m » Tue, 19 Feb 2019, 10:34

I would think in parallel would be the way to go so you aren't making the pump work hard, having to deal with possible hoses popping off/bursting and pumping hot water into a pack you are trying to cool while the first pack is below freezing, Etc
If each pack gets a different flow rate because of different hose lengths/resistance, who cares, as long as the pack with the least flow has enough. Doubtful you are going to overcool a pack
You can possibly put a little tap on each pack (or group of packs) to drop flow on that bank if it really becomes an issue.
Being 19mm hose surely the retic isle at bunnings is going to be your friend. There's all sorts of pressure/flow regulators there

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Re: Prelude conversion project - some questions

Post by jonescg » Tue, 19 Feb 2019, 10:48

Agree about the flow rate - as long as it's moving, I don't think it matters. But pressure is an issue - less pressure is safer all round.
All the battery fittings and plumbing is 3/8 (or 9.5 mm) and that's the main source of flow restriction. I did run the test battery module at 3 l/min (about 6 times more than it needed to be) and it didn't leak, so I can afford a bit more pressure. I might even add a moisture sensor to the pack; t'besure t'besure.
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Re: Prelude conversion project - some questions

Post by francisco.shi » Tue, 19 Feb 2019, 10:52

Instead of putting two pumps in series would it be better to put say one pump pumping to the inlet of the pack and the other pump in the middle of the circuit so you can increase the pressure half way instead of trying to have higher pressure from the inlet.
Also the problem is not over cooling, the problem is if you have one pack that is not getting enough flow and it overheats.

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Re: Prelude conversion project - some questions

Post by jonescg » Tue, 19 Feb 2019, 21:34

Series wins.
Cooling loop installed.jpg
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So the diagram to the right is the working solution. I ran just a single string of three modules in series and measures about 2 lpm which is more than adequate. With two of these 3-series loops in parallel the flow is pretty close to 3 lpm. So adding two more in series as a loop in parallel with the main inlet and outlet shouldn't be an issue. It will drop the pressure a bit on the rear pack, but I can adjust that with restriction points if I need to.
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Re: Prelude conversion project - some questions

Post by jonescg » Sat, 23 Feb 2019, 18:40

I spent today wiring up the master contactor and it's precharge circuit, as well as fabricating the front panel where the main HV connection goes.
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Altronics stock a waterproof 18-way connector which is ideal - I can manage the TMS, BMS, contactors and power. The cable glands on the 3/8" hose is purely out of convenience - I can't find any purpose built 3/8" to 3/4" barbed reduction tubes with bulkheads, so I will just use brass fittings outside the battery pack.
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The pre-charge circuit here is to manage the capacitance on the air conditioning compressor (which is not insignificant). It will be driven by a simple 555 timer delay circuit inside the charge control box. Precharge of the main drive inverter is a separate beast which is managed by the inverter's own on-board components.

I will be ready to start to fiberglass the battery cover tomorrow evening, provided I can put enough hard surface around to stipple up against.
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Re: Prelude conversion project - some questions

Post by francisco.shi » Sat, 23 Feb 2019, 19:00

This is looking really good. 👍
What is the current rating on the orange connector?

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