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Roadster battery pack specs?

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Starting at 3:00 mark
This is basically what he said : For the Roadster, we use an almost unmodified laptop cell, but for the Model S, it is actually a highly modified cell. It's an 18650 cell, so the external form factor is the same, so we can take advantage of the economies of scale of 18650 production, but the internals are quite different. More than that, I cannot say...
 
"In March of 2012, Panasonic begins the production run of a brazillion of their new NNP 3.4Ah cell. This is there New Nickel Platform. It's actually a Lithium Nickel Cobalt Aluminum Oxide cathode material with a carbon anode. And the thing carries 12.24 wH of energy in a 46 gram package. This is something like 266 wH per kilogram. By contrast, the CALB or Winston type cells are more like 109 wH/kg in their optimum size.

Ergo the 300 mile Tesla Model S.

Cycle life to the industry "traditional" 80% of original capacity is somewhere in the 500-800 cycle range. Not good. But if you look to 70% as the mark, it gets much better as the deterioration curve flattens out in a very unusual fashion. You're looking at well over 2000 cycles to that level.

These are not here yet. But I do not classify them as unobtanium per se. They have good prospects for being available subsequent to March 2012. Tesla has contracted for enough of these cells to do 80,000 cars over four years. That's 640 million cells. As it will also be the highest energy density of any 18650 form factor cell, it will undoubtedly be popular in a number of other applications - flashlights if no where else. And so we have a truly MASS market battery cell here. That brings in economies of scale.
..Panasonic has already announced plans for 2013 to bump this very 3.4Ah cell to 4.0Ah by using a silicon alloy anode in place of the carbon anode in this cell, for example. But if a fire ensued in the battery market, there are plenty of players and plenty of advances to come. I think Moore's law is alive an dwell in Batteryville. And a car with a 1000 mile range is not inherently a preposterous notion."
EVTV.ME
 
We're trying to gauge interest in aftermarket replacement roadster sheets.
I'm thinking to use Model 3 cells with a custom designed assembly, wire bonded to custom busbars - basically a fully drop in factory replacement.
There are two schools of thought. Fill up the modules and get a pack capacity of about 90-100kWh, and eliminate water cooling. The Model 3 cells have very low internal resistance compared to the factory cells (and the LG cells), so I don't feel active cooling will be necessary. Eliminating water cooling allows for even more cells to be packed in which further decreases the pack impedance.
OTOH, go with a much smaller pack of about 40kWh, and cooling will be needed.
The cells are 5mm taller, but this doesn't appear to be a blocker; we can go to a single sided busbar design ala Model 3, and there's some room between the modules anyway.

The cost difference for 11 modules is about $5500, 100kwh vs 40kwh, taking into account the need for cooling on the smaller pack.
Please share your thoughts!
 
Firstly who’s going to reprogram the PEM for such battery’s, for the r80 there are changes to be made to charging profiles. The charger/inverter is all housed in the PEM unlike the rest of the tesla’s where the components are separate. Will the software throw codes with no water cooling/waterpump running, or are you going to close loop the water pump and monitor temperatures. I’m all for a re-engineered battery but I don’t know cylindrical cells are the way to go. I know you know your way around these cells and are set up to strip modules and reweld new ones. But I’m not convinced we can simply swap the pack out for a different one. I feel the BMS and BMB’s will sense the capacity and feel it’s overcharging, not receiving coolant flow and the software will be the major problem, not the hardware.
 
That said I’d go for a proper temperature regulated pack regardless of size, there’s a reason the battery’s are lasting 8-10 years. I would also like while you are programming, the car to die before it bricks itself.
If you build the smaller packs, what would be the replacement cell cost once we own one. Is the cost coming from cells, manufacturing or other hardware/consumables.
 
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The BMS can be handled. We have already designed drop in BMB replacements. The BMS/SoC computer can be fooled.
The model 3 cells charging profile is the same as the LG cells.
I believe we can still accomplish the life goal of 10 or more years without active cooling. The roadster only pulls 700A IIRC, and a 95kwh pack of Model 3 cells won't even blink at that. Active cooling would only be needed for supercharging/roadtrips, IMHO.
If in the rare circumstance the cells get above 50°C, power would be pulled to keep the cells from heating further.
Yes we would have to fool the water-cooling systems.
Heating is the only issue for a large pack. The cells will still need to be heated if the car needs to be charged if the cells are below 0°C. However; it's a lot easier to integrate a HV resistive heater then water cooling.
 
That said I’d go for a proper temperature regulated pack regardless of size, there’s a reason the battery’s are lasting 8-10 years. I would also like while you are programming, the car to die before it bricks itself.
If you build the smaller packs, what would be the replacement cell cost once we own one. Is the cost coming from cells, manufacturing or other hardware/consumables.

The cost drivers are
1. the cells
2. the tooling to be able to manufacture the sheets (CNC wire bonding machine, maybe a molded part or two)
3. the engineering work to design/manufacture them

Perhaps we could have a deal where replacement sheets should a sheet fail for an existing customer be much cheaper since we could exclude the tooling/engineering costs.
 
I’m glad you are at least thinking about the active heating for charging below 0C.
That's the most important part. Charging too fast at low temp leads to lithium plating and dendrites, which may puncture the separator resulting in a fire. The BMS must limit charge current based on SoC and temperature, active heating allows for the pack to be charged sooner.
I'm thinking with the size of the pack, and the niche nature of the roadster, maybe active heating would not be needed if the owner is educated to know to not leave the car outside on a cold night at low SoC and expect to be able to charge it in the morning. :-D
 
I’m glad you are at least thinking about the active heating for charging below 0C.
That's the most important part. Charging too fast at low temp leads to lithium plating and dendrites, which may puncture the separator resulting in a fire. The BMS must limit charge current based on SoC and temperature, active heating allows for the pack to be charged sooner.
I'm thinking with the size of the pack, and the niche nature of the roadster, maybe active heating would not be needed if the owner is educated to know to not leave the car outside on a cold night at low SoC and expect to be able to charge it in the morning. :-D
 
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I think for 95% of owners the large capacity pack could work, I don’t think the allowing for longer trips works, you use 95Kw you replace 95Kw. Anyone going on a long trip is already conserving energy, therefore heat. I mean a thousand miles, not pushing the 170 mile range limit by missing out an charging one night. I like the idea, I would want an assurance you can fool the software. That’s going to be the big question. Obviously if it’s reversible it opens up the choice of rebuilt packs if they. Become available. There are probably a dozen bricked roadsters with owners trying to breath life into their dead cells. They would be your first target group maybe take an old pack in exchange and rebuild a stock pack for people that want the original battery with PEM cooling and heating, maybe model S cells if you can reprogram the PEM anyhow. I would not look into one solution. The dead packs need something, anything. The ones that are fine now will not be changing anytime soon. Even 1.5-2.5 packs. A quick search would pull 5-6 owners instantly that would give you a better indication as they are the ones needing to part with money. If I had a new 80 pack I may feel everyone needs more capacity but I don’t feel that’s as important as something that works like the original. I bet 80 owners wouldn’t remove the cooling and heating if their pack to show it made little difference. I don’t have an opinion either way and as my battery is healthy I don’t feel I should. The people who are going to pay should make the decision for you.
 
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