Prelude conversion project - some questions

Technical discussion on converting internal combustion to electric
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jonescg
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Re: Prelude conversion project - some questions

Post by jonescg » Sun, 18 Nov 2018, 21:17

The new jig spacer makes a much more convenient half-module assembly. The cordless driver with torque settings helps a lot too :)
Module assembly2.jpg
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Module assembly3.jpg
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I assembled another two enclosures this afternoon (^on the lower shelf of the workbench). I seem to have a system down now. With any luck I'll get the last one perfect :lol:
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Re: Prelude conversion project - some questions

Post by francisco.shi » Mon, 19 Nov 2018, 04:58

How much does the brick weigh and how many kwh do you have per brick?

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Re: Prelude conversion project - some questions

Post by jonescg » Mon, 19 Nov 2018, 06:31

The two row module weighs 18.6 kg and stores 3.2 kWh as a complete unit. So each brick of cells like the one above is about 9 kg.
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Re: Prelude conversion project - some questions

Post by tidalev » Mon, 19 Nov 2018, 16:53

4Springs wrote:
Fri, 16 Nov 2018, 17:43

I used an off-the-shelf controller for this, mine uses a 0-5V signal (from memory) to control the speed based on the temperature of the coolant.
Do you have any more info on this? I'm looking at a similar setup

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Re: Prelude conversion project - some questions

Post by 4Springs » Mon, 19 Nov 2018, 18:51

Controller info in this post.
viewtopic.php?f=18&t=5249#p64990
There are simpler controllers around if you just run the thing flat out.

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Re: Prelude conversion project - some questions

Post by jonescg » Wed, 28 Nov 2018, 10:11

Not exactly a gigafactory, maybe a kilofactory?
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Re: Prelude conversion project - some questions

Post by jonescg » Mon, 03 Dec 2018, 21:35

Managed to get a little help from Mike to bring the hoist up the hill. The Hyab truck they use to deliver and install wouldn't fit through the carport, so we had to unload it and roll it down to the shed. While we could have driven all the way back, we then wouldn't have a means to get it off the truck...

We can solve these minor issues :)
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Re: Prelude conversion project - some questions

Post by Richo » Tue, 04 Dec 2018, 12:20

I'm lost - what's that for
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Re: Prelude conversion project - some questions

Post by Johny » Tue, 04 Dec 2018, 12:29

Richo wrote:
Tue, 04 Dec 2018, 12:20
I'm lost - what's that for
Looks to me like Chris is going to lower the car onto the battery pack😄
It's awfully big😱

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Re: Prelude conversion project - some questions

Post by jonescg » Tue, 04 Dec 2018, 12:33

It's a car hoist. It will be installed in the workshop ahead of the Prelude conversion. Since the battery is going where the fuel tank used to be, the hoist will make the whole job a lot easier.

It's a clear-floor type, so they are taller than the regular 2-post hoists.
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Re: Prelude conversion project - some questions

Post by francisco.shi » Wed, 05 Dec 2018, 12:33

Have you done any measurements on the cooling system for the battery pack?

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Re: Prelude conversion project - some questions

Post by jonescg » Wed, 05 Dec 2018, 13:52

I've not yet set the modules up for testing, but I will have several tests to do by the weekend. The one module have already built is to be the 'spare' module, and it's just as well because the thermal epoxy doesn't have the sort of coverage I'd like it to have. It's probably 90 % as good as it needs to be.

However I found some Tesla pack data:
Tesla pack water temp graph.JPG
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So this is a 1.2 C discharge on a Tesla Model S module. The measured internal resistance is about 100 mOhm per cell (remembering there are 74 in parallel and 6 of these in series - so the overall internal impedance of the pack is 0.0081 Ohm. At 297 amps it was generating 715 W of heat - for the first 30 seconds anyway. It dropped off as the voltage dropped.

The heat generation is plotted, as is the delta T in the coolant. From the delta T in the coolant we can infer the heat absorbed by the coolant.
Tesla pack water heat flux.JPG
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It's rough, but should give some idea. Hope to have my data soon.
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Re: Prelude conversion project - some questions

Post by francisco.shi » Wed, 05 Dec 2018, 16:10

Where did you get the data from. I would like to read a bit more about what other tests they did.

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Re: Prelude conversion project - some questions

Post by jonescg » Thu, 06 Dec 2018, 09:26

I should add this was based on a measured DC IR of 100 mOhms per cell, which is probably higher than it really is. But not a lot higher. It's a used pack, so the DCIR has no doubt increased from new (which is supposed to be 60 mOhm).
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Re: Prelude conversion project - some questions

Post by jonescg » Thu, 06 Dec 2018, 09:29

Potted my first complete battery pack with thermal epoxy. Next step is to wire up the BMS and test it :)
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Re: Prelude conversion project - some questions

Post by jonescg » Fri, 07 Dec 2018, 09:09

And then there were two.
2nd module done.jpg
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Re: Prelude conversion project - some questions

Post by mikedufty » Fri, 07 Dec 2018, 17:41

Is that a zero motorcycle in the background?

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Re: Prelude conversion project - some questions

Post by jonescg » Fri, 07 Dec 2018, 18:10

Yes, Daniel Klemm's bike. Still has problems and we're trying to re-flash the firmware to make it go. Currently a 50 km/h limited bike with 5 km range and won't take a charge... :(
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Re: Prelude conversion project - some questions

Post by mikedufty » Fri, 07 Dec 2018, 22:06

Bummer

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Re: Prelude conversion project - some questions

Post by jonescg » Sat, 08 Dec 2018, 21:02

I seem to have about a one-a-day sort of productivity right now.
Prelude modules.jpg
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And now there are four (and a spare).
4 done and a spare.jpg
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Re: Prelude conversion project - some questions

Post by rhills » Sun, 09 Dec 2018, 00:30

Well, they look pretty professional IMHO.

How do you think those screws into perspex will hold up against vibration?
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Re: Prelude conversion project - some questions

Post by jonescg » Sun, 09 Dec 2018, 06:55

It's polycarbonate which is tougher than perspex. The screws are also glued in place by virtue of the seal it goes through. I reckon they will be okay.
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Re: Prelude conversion project - some questions

Post by francisco.shi » Sun, 09 Dec 2018, 08:34

Is the potting compound only on the bottom of the cells?

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Re: Prelude conversion project - some questions

Post by jonescg » Sun, 09 Dec 2018, 11:02

francisco.shi wrote:
Sun, 09 Dec 2018, 08:34
Is the potting compound only on the bottom of the cells?
Correct. The bottom face of the cell stack represents about 20% of the total surface area, and it's all in the plane of the electrodes, so thermal conductivity is at it's highest.

Screenshot from a video I'm preparing:
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Re: Prelude conversion project - some questions

Post by jonescg » Wed, 12 Dec 2018, 20:24

Almost ready to start work :D
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