A new battery pack for the '06 Prius

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T1 Terry
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A new battery pack for the '06 Prius

Post by T1 Terry »

Finally getting a start on the battery upgrade on my silver Prius I purchased from Jason (85turbo) back in 2018. viewtopic.php?p=69376#p69376

After managing to set the NiMh traction battery on fire, the volunteer fire brigade boys emptying a 9 kg dry powder extinguisher into the rear of the car and then the insurance company declaring the vehicle a write off, I purchased the wreck back from the insurance company with the intention of building an LTO traction battery pack to replace the extended range pack of 74 x 40Ah cells and the incinerated NiMh traction battery.

I bought 180 x 55Ah Yinlong LTO cells from OSN Power after many helpful replies from Dinah at OSN Power who handled the whole thing for me ... many thanks Dinah. As part of the purchase I also bought the plastic click together retainers to build a stable battery pack out of cylindrical cells.

Down to the back of the envelope calculations :roll:

The load current for a Gen 2 Prius is roughly 150 amps (reference https://www.batterydesign.net/toyota-pr ... 2-battery/

The Yinlong 55Ah LTO cell is sold as a 66260, but in reality, after the studs are welded on each end they measure 66mm diameter x 320mm long. The studs themselves are roughly 25mm long on each end but could be shortened a bit depending on the nut and busbar used.

84 of these cells would give me the required substitute for the 28 module NiMh traction battery. 6 cells roughly equals the voltage of 2 modules and the Prius BMS reads the voltage per 2 modules, 14 groups adds up to the 84 LTO cells .....and gives me a capacity of 11kwh nom. compared to the original 1.3kwh and usable 520wh according to the battery design link I posted earlier.

The capacity is tested at 2CA or 110 amps for these cells, they have a max charge rate of 4CA (220 amps) and max discharge rate of 10CA (550 amps) so both peak regen and peak discharge is well inside the load window for these cells .... but they are seriously big. :shock:

Laying on their side, they equal 3 modules wide, the length of a module (plus the studs) and stacked 2 high is roughly the same height as the NiMh traction with its 2 rods on top and 2 rods on the bottom for compressing the modules.
Roughly 20 cells will fit where the original traction pack was mounted.
The box that held the 74 x 40Ah LFP cells that were part of the extended range kit, with a bit of modification will hold 63 cells ..... still gotta find where to put the remaining cell :rolleyes:

Another alternative:
With a bit of modification I could fit 35 cells where the original traction pack was and 16 cells in the spare wheel well and 1 layer of 15 across the top of that backed up against the traction pack and another layer 18 wide between that and the rear of the inside panel and that would give me the required 84 cells ...... some oxy work and panel beating coming up I think :lol:
The bonus is I could then modify the plastic insert that was originally in the space between the traction battery and rear hatch so I could put the jack and spare tyre in there ..... Sounds like a plan .....

I'll add some photos as I go transition from the back of the envelope to actual construction in the vehicle

T1 Terry
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poprock
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Re: A new battery pack for the '06 Prius

Post by poprock »

Hi, prius pack pn FB tonite.
T1 Terry
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Re: A new battery pack for the '06 Prius

Post by T1 Terry »

Sorry Brian but I'm not on Farce Book, I'm assuming that is what FB means.

T1 Terry
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T1 Terry
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Re: A new battery pack for the '06 Prius

Post by T1 Terry »

Today I assembled the jigsaw puzzle that makes up the cell cradles for the 84 x 55Ah Yinlong cylindrical LTO cells and I was surprised just how little modification will be required and I'll be able to carry the jack and spare tyre in the under floor storage area again. That wasn't possible with the 74 GBS 40Ah extended range pack fitted.
The over all weight will be roughly the same, 168kg, and the total nom. capacity of 11 kwh is a tad more than the combined capacity of the GBS cells and the NiMh traction pack, just a lot more of the nom. capacity should be available.

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T1 Terry
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Re: A new battery pack for the '06 Prius

Post by T1 Terry »

Revisited the configuration and by standing the cells upright I can fit 48 in the area where the original traction pack was and this would be directly over the rear axle. Then by cutting out the wheel well and welding in a square edged box, I can fit 40 cells in that spot.
This gives me back the area the original plastic box fitted so the spare wheel, jack and all the other stuff needed to operate the vehicle will fit under the original floor panel.

I've made the commitment, attacked the wheel well with the angle grinder and removed that section ....
When you watch these car mod shows on 9 Rush, they never seem to find things in the way after you make the first cuts :oops: Seems the muffler will have to be moved or a replacement fitted that takes up less room ...... I wonder what a Prius on full noise would sound like with a "Hot Dog" on it .... my teeth go on edge when I hear a poxy 4 cyl ICE with a noisy muffler being wound out up past our workshop .... so maybe not :lol:

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T1 Terry
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Re: A new battery pack for the '06 Prius

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Today's assault should have started with me reading this instead of trying to re design the whole thing :roll: For some reason I'd forgotten about the idea of standing the cells upright and couldn't figure out how I'd planned to get 48 cells in there, only a few hrs wasted thankfully :oops:

I've assembled the plastic frames that hold the cells together and realise I'll have to sacrifice an equal number to make the spacers required to hold the cell terminals clear of the bottom of the box.
It looks like the box will be a bit like one of those origami folding things to get around the rear strut braces and other assorted bits that are attached here and there.
I'll have to look in my other Prius to see if some of the bits can be relocated and used as battery box supports.
I'll attempt to add some photos either this afternoon or tomorrow.

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OzSpider
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Re: A new battery pack for the '06 Prius

Post by OzSpider »

Hi Terry,

Sounds like you were happy with OSN. Did they sort delivery for you to your door? All go ok?

I see they sell LTO prismatic cells, did you consider them in lieu of cylindrical for better space efficiency?

The decision to go with LTO is really interesting. Was it the high C rating or the long cycle life that made it for you?
T1 Terry
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Re: A new battery pack for the '06 Prius

Post by T1 Terry »

At the time I don't think they sold the prismatic LTO chemistry cells .... either that or I didn't read the website properly :roll: Dinah was very helpful with organising the shipment to Adelaide wharf and we picked the cells up from the shipping agents warehouse.
I bought 180 cells in one shipment, the cost of getting it from the ship, onto the dock, then through customs and everyone else who wanted a piece of the action cost close to the same as the cells, the shipping itself only cost US$70, but from memory the total was over AU$11,500. So roughly AU$84 each, some what more than the factory door US$ price, but still within the cost of LFP cells bought here in Australia, so ......

The decision to LTO was based on the high C rating for both discharging and charging, the Prius regen braking is serious current and both the load and regen current is well beyond the capabilities of LFP cells if a decent cycle life is expected. The LFP chemistry can do it, but it shortens the cycle life and the terminal voltage sags under the high load and goes way over voltage when trying to recharge much over 1C, but the 200 amps plus the Prius can generate is 4C for a 50Ah cell, not big numbers for the LTO chemistry but well out of operating range for LFP cells.

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T1 Terry
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Re: A new battery pack for the '06 Prius

Post by T1 Terry »

I'll try again, hopefully this time the photos come up ok .....
Empty boot with a lot of the extingusher powder removed small.jpg
Empty boot with a lot of the extingusher powder removed small.jpg (124.42 KiB) Viewed 188 times
Cells mounted laying down.jpg
Cells mounted laying down.jpg (153.37 KiB) Viewed 188 times
The down side of this layout was most of the weight was still behind the rear axle, only part of the spare wheel well is used and still quite a bit of the boot space taken up ..... the battery box would have been "interesting" to construct as well :lol:

The idea I'm going with
48 cells standing up where the original traction battery mounted.jpg
48 cells standing up where the original traction battery mounted.jpg (113.22 KiB) Viewed 188 times
As can be seen, there is a big hole where the spare wheel well was, 40 cells will fit in that spot laying on their side, 2 layers 2S10P.

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T1 Terry
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Re: A new battery pack for the '06 Prius

Post by T1 Terry »

Realised the added height of the cells standing up meant the pack had to move further to the rear so the seat backs could be opened up. That still gives me 44 cells where the orifinal traction battery was and 40 cells under the floor for the required 84 cells

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T1 Terry
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Re: A new battery pack for the '06 Prius

Post by T1 Terry »

Today's progress
Front battery box base folded.jpg
Front battery box base folded.jpg (129.7 KiB) Viewed 159 times
T1 Terry
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T1 Terry
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Re: A new battery pack for the '06 Prius

Post by T1 Terry »

Started welding the tread plate 1.6mm aluminium plate box up for the top battery pack ..... hopefully, by the time I've finished my welding will have improved :oops: I'll go with "lack of practice" as my excuse :lol:

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