LFP battery mounting orientation

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BigMouse
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LFP battery mounting orientation

Post by BigMouse » Sun, 13 Oct 2013, 20:24

Hey everyone. I've been curious about this as I'm currently planning on mounting the batteries in the 300zx on their sides. Everything I've seen and read about these batteries is that it shouldn't matter which orientation they're mounted in as they're simply pouch cells inside the plastic enclosures anyway.

I did find this page about battery orientation for Thundersky cells.

They claim that the batteries should not be installed in the "flat" position and this is the image they used to explain why:

Image

I assume that these cells (Thundersky/Winston/CALB/Sky/HiPower) all have the same internal construction. As I understand it there is no free electrolyte in the cells and the pouches don't care which orientation they're mounted in. These pouches are the same basic construction as batteries used in mobile phones and the like anyway.

My current plan is to mount the majority of my batteries on their narrow edge (like the middle image), but they'd be on a slope. Half the cells would be mounted with the terminals on the downward side of the slope, so rotated a bit towards being upside down, but still mostly horizontal.

Does anybody see any problem with mounting them this way? I have the CALB CA60FI grey cells.

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LFP battery mounting orientation

Post by acmotor » Mon, 14 Oct 2013, 01:05

Perhaps layers rather than plates would be a better term for lithium cells ?
The logic seems reasonable though there is an assumption being made (may well be true) about the orientation of the layers. Is there info on that ?
The LiFePO4 TS LFP cells are not the same as LiPo or A123 or 18650 or headway in chemistry detail/voltage/construction. The latter contain no free electrolyte. TS LFP definitely does so the reasoning seems fine if you can confirm the layer orientation.

edit: speyln
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LFP battery mounting orientation

Post by BigMouse » Mon, 14 Oct 2013, 01:47

What about the CALB CA series grey cells?

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LFP battery mounting orientation

Post by jonescg » Mon, 14 Oct 2013, 02:30

I'd say in terms of electrolyte starvation, the CALB grey cells would be treated much the same as Winstons. Laying flat is generally not recommended for most cells, but the large format cells with electrolyte vents would do well to be kept off their faces.
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LFP battery mounting orientation

Post by evric » Mon, 14 Oct 2013, 04:45

We need to get someone to cut one (CALB CA) open!

The yellow Thunderskys did have free electrolyte in them, when cut open about 3 to 4 tablespoons full could be poured out. Jack Rickard (EVTV)did this and found that they weren't pouch cells but simply layer upon layer of open ended cathode/separator/anode/separator... Not actually sealed into pouches.
I personally know of 2 cases where Thunderskys, laid flat have failed. (Paul Hunter's Lotus Elise (now sold after placing all the cells upright- yes, the flat cells revived from being down around 0.8Volts.)
The other one was Mic Chapman's Honda Post-E bike conversion. He now has also changed them to all vertical.
I have not heard about the new CALB CA series. Time will tell.
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LFP battery mounting orientation

Post by acmotor » Mon, 14 Oct 2013, 16:37

So are you saying vertical (terminals at top) is the only option ? i.e. on edge is not ok ? (for TS/WIN at least)
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Post by evric » Mon, 14 Oct 2013, 18:07

If you have to, on the edge should be OK. Vertical is best.
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LFP battery mounting orientation

Post by Richo » Mon, 14 Oct 2013, 20:34

There was some pics on the AEVA forum of an open TS cell.

Here's another:
http://liionbms.com/php/prismatic_cells.php
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Post by acmotor » Mon, 14 Oct 2013, 22:32

Mmmmm, looking at that construction I am back to the original vertical only with dimensional restraint for LFP operation unless someone has 3000 cycles and 10 years proof otherwise. But then isn't that the manufacturer's advice ? It is hard to spend $10k on cells and not give them the best chance.

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LFP battery mounting orientation

Post by BigMouse » Tue, 15 Oct 2013, 01:02

Good info. If the CA cells are the same, then I can definitely see that I wouldn't want to mount them even a little bit upside down.

Time to redesign the battery mounting... again.

This is sort of the idea I was planning on:
Image

I had also planned to make a "flat" pack (cells mounted on their sides, resting on the narrow edge, bottom to bottom) to mount under the car where the fuel tank used to be. Sounds like I'll have to reconsider that too. Perhaps I should have went for the CA63CFI cells. They're a "low profile" cell basically the same shape as a CA60 cell on its side with the terminals and vent relocated to the long edge. I'll keep that in mind when I order my next set of batteries when this car is done.

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LFP battery mounting orientation

Post by acmotor » Wed, 16 Oct 2013, 01:42

While you are at it.... I know this has all been said before and you probably have it part of your design criteria....

Make the tops/terminals/BMS system easily accessable and individual cells changeable without too much trouble. Death, taxes and cell failures are part of life. The cell (tops at least) need to be kept dry. IP67 if you can.
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LFP battery mounting orientation

Post by BigMouse » Fri, 18 Oct 2013, 03:29

acmotor wrote: While you are at it.... I know this has all been said before and you probably have it part of your design criteria....

Make the tops/terminals/BMS system easily accessable and individual cells changeable without too much trouble. Death, taxes and cell failures are part of life. The cell (tops at least) need to be kept dry. IP67 if you can.


Yeah, that's an important part of my arrangement. I've worked as a mechanic for years and always vowed that if I was ever an engineer, I'd make tings easy to get to ;-)

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LFP battery mounting orientation

Post by Johny » Fri, 18 Oct 2013, 14:03

BigMouse wrote:Yeah, that's an important part of my arrangement. I've worked as a mechanic for years and always vowed that if I was ever an engineer, I'd make tings easy to get to ;-)
Unfortunately, if not building a vehicle from the grond up, there will be comprimises. I was intent on making access to all components easy but you still have these big heavy objects that have to be layered to fit.

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LFP battery mounting orientation

Post by acmotor » Fri, 18 Oct 2013, 15:57

Passengers ? Image
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