EV BATTERY DISCUSSION AND SUGGESTIONS

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Randall679
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EV BATTERY DISCUSSION AND SUGGESTIONS

Post by Randall679 » Fri, 22 Mar 2019, 06:58

Can I start an EV battery discussion?

I have two EVs I want to bring back from the dead. The batteries they had were Thundersky L-Ion ... what's out there now that I should consider?

Those Lithium-Titanate batteries someone here is selling?

https://en.wikipedia.org/wiki/Lithium-titanate_battery

All suggestions would be welcome.

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Re: EV BATTERY DISCUSSION AND SUGGESTIONS

Post by francisco.shi » Fri, 22 Mar 2019, 07:08

How many kwh do you need?
I am trying to get some people to do a group buy to get the price down for the freight.
The cells I want to buy are 3.6v 63Ah. The price per cell from the supplier is US$45.
I also have developed a cooling system and all the mounting hardware which I can sell to you as well. The total energy density of the pack including the mounting hardware and cooling system is 207wh/kg.
Would you be interested in getting some?

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Re: EV BATTERY DISCUSSION AND SUGGESTIONS

Post by Randall679 » Fri, 22 Mar 2019, 07:47

francisco.shi wrote:
Fri, 22 Mar 2019, 07:08
How many kwh do you need?I am trying to get some people to do a group buy to get the price down for the freight.
The cells I want to buy are 3.6v 63Ah. The price per cell from the supplier is US$45.
I also have developed a cooling system and all the mounting hardware which I can sell to you as well. The total energy density of the pack including the mounting hardware and cooling system is 207wh/kg.Would you be interested in getting some?
I saw your post and pictures ... very interested!

I'll put it to my Brains Trust ... a bunch of rusty old EV engineers ...
Last edited by Randall679 on Fri, 22 Mar 2019, 07:54, edited 1 time in total.

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Re: EV BATTERY DISCUSSION AND SUGGESTIONS

Post by Randall679 » Fri, 22 Mar 2019, 07:49

Another suggestion are cells from wrecked EVs ... I know in the US a lot of Tesla wrecks are supplying batteries for conversions and upgrades ... the entire floor plan is a big battery!

or simply replacement cells for those models ... the two mentioned are Nissan Leafs and Holden Volts ...

Discuss?

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Re: EV BATTERY DISCUSSION AND SUGGESTIONS

Post by francisco.shi » Fri, 22 Mar 2019, 08:33

If I use the 63Ah cells I get higher energy density than using the Tesla modules because the battery box is very light as it does not have to provide mechanical support for the battery pack. Also I can make the pack suit the space available. The 63Ah cells are new and the cooling system is far superior to the Tesla cooling system. Also the 63Ah cells are always available.

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Re: EV BATTERY DISCUSSION AND SUGGESTIONS

Post by Rusdy » Fri, 22 Mar 2019, 08:57

francisco.shi wrote:
Fri, 22 Mar 2019, 07:08

... The total energy density of the pack including the mounting hardware and cooling system is 207wh/kg...
I've just found Model-3 pack density is merely 159.5Wh/kg. How on earth yours get that high, even with LTO? I thought LTO is much lower energy density?? I'm super impressed!! :o

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Re: EV BATTERY DISCUSSION AND SUGGESTIONS

Post by Randall679 » Fri, 22 Mar 2019, 10:37

Francisco ... What are the overall dimensions of the big cases in your photos ...

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Re: EV BATTERY DISCUSSION AND SUGGESTIONS

Post by jonescg » Fri, 22 Mar 2019, 10:51

Rusdy wrote:
Fri, 22 Mar 2019, 08:57
I've just found Model-3 pack density is merely 159.5Wh/kg. How on earth yours get that high, even with LTO? I thought LTO is much lower energy density?? I'm super impressed!! :o
That mass includes the charger, DC/DC converter, HV switch gear, cooling system and related control electronics. If you take that mass out of the system you have something closer to 200 Wh/kg.

The 63 Ah cells from LG are Li-NMC, not titanate.
AEVA National Secretary, WA branch chair.

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Re: EV BATTERY DISCUSSION AND SUGGESTIONS

Post by Rusdy » Fri, 22 Mar 2019, 11:03

jonescg wrote:
Fri, 22 Mar 2019, 10:51

That mass includes the charger, DC/DC converter, HV switch gear, cooling system and related control electronics. If you take that mass out of the system you have something closer to 200 Wh/kg.

The 63 Ah cells from LG are Li-NMC, not titanate.
Tesla's 2170 cell is indeed impressive. The cell itself is very close to 250Wh/kg which matched by the new semi-solid-state battery.

Ah, I missed Fransisco's battery pack spec. I can't wait until that car is finished with the full spec. Impressive build indeed! Just need to put a ray gun on the back, that'll be the most impressive car ever built! 8-) (beating my previous fav car, a hilux with a machine gun on the back :lol: ).

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Re: EV BATTERY DISCUSSION AND SUGGESTIONS

Post by francisco.shi » Fri, 22 Mar 2019, 11:24

The cooling system is part of the structure that holds the battery together so that saves weight by not needing the battery case to provide the support. It is also very light and strong because of the shape. Because the cells have the tabs on opposite ends I do not need to put a heavy copper bus bars between the terminals so this saves the weight of the bus bars and reduces the resistance of the interconnect. If you get an even number of rows in the battery pack you effectively have no interconnect bus bars between the cells and you end up with both +ve and -ve terminals on the same side of the battery.
So I have just done a very good job with the packing. The pouches are 3.6v 63Ah and weigh 0.96kg. The pouch energy density is 236wh/kg.

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Re: EV BATTERY DISCUSSION AND SUGGESTIONS

Post by francisco.shi » Fri, 22 Mar 2019, 11:27

The battery box is 1900x1025x(210/160)mm. Total capacity is about 70kwh.

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