Search found 2350 matches

by jonescg
Yesterday, 20:39
Forum: General EV Discussion
Topic: EV Importing, Urgent Help, advice or recommendations please
Replies: 7
Views: 76

Re: EV Importing, Urgent Help, advice or recommendations please

Yeah so long as you can prove you weren't going to ride it on the road you might have a chance. But you'll definitely need a customs broker.
by jonescg
Mon, 19 Nov 2018, 15:13
Forum: Members Machines
Topic: Francisco's Electric Pajero
Replies: 59
Views: 1612

Re: Francisco's Electric Pajero

134 Termination cooling of pouch cells.pdf The cell tab is the highest resistance point in the cell, and it's typically the hottest single point in the circuit. A solid buslink here is critical to ensuring the cells don't get too hot. The paper attached above looks into cooling the cell termination...
by jonescg
Mon, 19 Nov 2018, 06:31
Forum: Technical and conversion discussion
Topic: Prelude conversion project - some questions
Replies: 79
Views: 5583

Re: Prelude conversion project - some questions

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.
by jonescg
Sun, 18 Nov 2018, 21:17
Forum: Technical and conversion discussion
Topic: Prelude conversion project - some questions
Replies: 79
Views: 5583

Re: Prelude conversion project - some questions

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 Module assembly3.jpg I assembled another two enclosures this afternoon (^on the lower shelf of the workbench). I seem to have a system down now. With...
by jonescg
Sat, 17 Nov 2018, 18:54
Forum: Technical and conversion discussion
Topic: Prelude conversion project - some questions
Replies: 79
Views: 5583

Re: Prelude conversion project - some questions

Starting to put the battery modules together now. I reckon i can make two modules a week working only evenings and weekends...
Module assembly.jpg
Module assembly.jpg (122.43 KiB) Viewed 165 times
I picked up some thermostats too - might be worth using these to only turn the fan on, since the pumps should be fairly quiet by comparison.
by jonescg
Sat, 17 Nov 2018, 18:23
Forum: General EV Discussion
Topic: Bring on the BERM please
Replies: 5
Views: 100

Re: Bring on the BERM please

Oh but making your own would be a hoot!
I know Husqvarna make a very solid electric ride on mower.
by jonescg
Fri, 16 Nov 2018, 18:26
Forum: Technical and conversion discussion
Topic: Prelude conversion project - some questions
Replies: 79
Views: 5583

Re: Prelude conversion project - some questions

Yeah I think I might leave the aircon set to 100% PWM and leave it as an on-off switch. Those NO thermostats - you stick them to the base or side of the charger? I figure if you drive up a steep hill and park on a warm afternoon, the motor and inverter will still be rather warm, and the coolant in t...
by jonescg
Fri, 16 Nov 2018, 16:16
Forum: Technical and conversion discussion
Topic: Prelude conversion project - some questions
Replies: 79
Views: 5583

Re: Prelude conversion project - some questions

As I put the battery together I started to map out the plumbing. Apologies in advance for the potato-camera. As the battery modules will be in parallel for inlet and outlet I want to ensure they all get the same flow, so that means making sure the flow path for all 8 modules is the same length. Frus...
by jonescg
Thu, 15 Nov 2018, 06:42
Forum: General EV Discussion
Topic: DO HYDROGEN FUEL CELL PHEVS QUALIFY?
Replies: 3
Views: 70

Re: DO HYDROGEN FUEL CELL PHEVS QUALIFY?

I'd argue they are more like a conventional series hybrid. It's not an EV unless you can plug it in and charge it from renewable electricity. Can the HFCV be charged at home? If they increased the size of the buffer battery and treated it like a PHEV then maybe.
by jonescg
Thu, 15 Nov 2018, 06:38
Forum: Batteries, charging, management and monitoring
Topic: Cell compression?
Replies: 7
Views: 120

Re: Cell compression?

I have pouch cell stacks which aren't compressed still working well with a few lines of Kapton tape. I think your efforts will be fine.
by jonescg
Wed, 14 Nov 2018, 20:06
Forum: Batteries, charging, management and monitoring
Topic: Cell compression?
Replies: 7
Views: 120

Re: Cell compression?

Yes the equivalent of 14 kg per square centimetre, or about 1 ton per pouch cell :o
by jonescg
Wed, 14 Nov 2018, 14:36
Forum: Batteries, charging, management and monitoring
Topic: Cell compression?
Replies: 7
Views: 120

Cell compression?

Some recently published research on the impact of cell compression on charge retention and internal resistance.
226 Effect of compression on Li Ion cells.pdf
(1.24 MiB) Downloaded 13 times
Conclusion: Some compression is good, but it's possible to overdo it. 1.4 MPa was ideal in this instance.
by jonescg
Tue, 13 Nov 2018, 10:43
Forum: Members Machines
Topic: Francisco's Electric Pajero
Replies: 59
Views: 1612

Re: Francisco's Electric Pajero

I have some data on Tesla packs somewhere I can share, and I also have the mass flow calculations for heat flux out of the battery. I will see if I can get them into an easily shared format first.
Chris
by jonescg
Thu, 08 Nov 2018, 10:34
Forum: General EV Discussion
Topic: All about the money :)
Replies: 13
Views: 244

Re: All about the money :)

Jon wrote:
Thu, 08 Nov 2018, 09:17
For sure if I buy it :) ... I get the feeling though that the battery assembly isn't standard practice?
Most of us don't have the patience to put thousands of cells together like this, so I'm keen to see how it was done.
by jonescg
Thu, 08 Nov 2018, 08:41
Forum: General EV Discussion
Topic: All about the money :)
Replies: 13
Views: 244

Re: All about the money :)

Jon wrote:
Thu, 08 Nov 2018, 07:21
Hey thanks! The batteries are units composed of Samsung 25R cells. 3000 of them.
I gotta see a picture of this...
by jonescg
Wed, 07 Nov 2018, 09:48
Forum: The Lounge
Topic: which power specification is correct?
Replies: 13
Views: 167

Re: which power specification is correct?

Sometimes they refer to the 'cooling power' or the rate of heat removal. That would be closer to 1.8 kW I'd think.
by jonescg
Wed, 07 Nov 2018, 08:43
Forum: Technical and conversion discussion
Topic: Prelude conversion project - some questions
Replies: 79
Views: 5583

Re: Prelude conversion project - some questions

The cells are standing on top of the flat cooling plate, and the thermal epoxy fills the air gaps between the base of the cells and the plate. Since the electrodes inside the pouch cells stand upright, most of the plates will have a short thermal path to the cooling plate. Sure, it goes via the poly...
by jonescg
Tue, 06 Nov 2018, 21:37
Forum: Members Machines
Topic: Francisco's Electric Pajero
Replies: 59
Views: 1612

Re: Francisco's Electric Pajero

I'm working with 44 volt modules of 72 Ah, so they too would need some hefty testing equipment. Although I would never expect to see more than 2C peaks (140 amps).
by jonescg
Tue, 06 Nov 2018, 14:44
Forum: Members Machines
Topic: Francisco's Electric Pajero
Replies: 59
Views: 1612

Re: Francisco's Electric Pajero

You will only need to produce a 315 amp current. A coil of MIG wire around a ceramic support, submerged in water will work.
by jonescg
Tue, 06 Nov 2018, 13:15
Forum: Technical and conversion discussion
Topic: Prelude conversion project - some questions
Replies: 79
Views: 5583

Re: Prelude conversion project - some questions

No - I'm filling that gap with a thermally conductive (electrically insulating) filled epoxy. There are silicon encapsulants out there too, but they are all in the 1.0 to 2.0 W/m.K range. Generous application is the key though, as you're aiming for a uniform temperature gradient from cell to sink.
by jonescg
Tue, 06 Nov 2018, 13:13
Forum: Nissan Leaf
Topic: Non OEM Leaf battery upgrade?
Replies: 22
Views: 1226

Re: Non OEM Leaf battery upgrade?

If I was to replace a Leaf battery with a home-brew battery, I'd aim to increased the capacity by as much as feasible.
by jonescg
Tue, 06 Nov 2018, 13:02
Forum: Members Machines
Topic: Francisco's Electric Pajero
Replies: 59
Views: 1612

Re: Francisco's Electric Pajero

Richo if the cells have a very low DCIR it's probably OK without a cooling system, or at least a fairly simple one will work. But the high energy density pouch cells are typically in the 20 mOhm range, so a 25 kWh battery is likely to dish out ~4 kW of waste heat at 2C. A sealed battery would warm ...
by jonescg
Tue, 06 Nov 2018, 12:55
Forum: Members Machines
Topic: Francisco's Electric Pajero
Replies: 59
Views: 1612

Re: Francisco's Electric Pajero

Good effort on the cooling channels. I'd advise you cover the cells in some kind of contact plastic so the foil can't rub against the cooling surface. Kapton would be expensive but polyethylene is possibly OK.
by jonescg
Tue, 06 Nov 2018, 11:52
Forum: Technical and conversion discussion
Topic: Prelude conversion project - some questions
Replies: 79
Views: 5583

Re: Prelude conversion project - some questions

Yes, some pressure to ensure they can't swell further than their originally manufactured thickness. The internal resistance will increase if the cell is allowed to expand considerably. Over time they will soften up as the electrolyte is able to off-gas (generating CO2) but this is normally accelerat...