Casing for Aluminum Cells

[Qismat]

Hi - New here, and looking into LiFePo4.

I think i've read everything there is to read, and I still have questions!

I'm looking at buying some aluminum cased cells - Unlike the plastic ones (winston, etc) that have the yellow or white casing, from what I've read, these blue aluminum cells don't need a compression case. Am I wrong?

How would one put the "battery" together?

Thanks!

[nebster]

Right, you are not supposed to compress these cells. They encourage you to put space between each one. I have read that there is a possibility of current leakage through the aluminum, which may be why they all seem to come wrapped in that thin blue plastic.

A lot of the manufacturers also have one or more styles of some kind of injection-molded plastic spacer. You either get them for free or buy them when you order. The designs vary, but one way or another they fit onto the batteries and force them to have a small gap in each direction.

[mikedefieslife]

Never heard of this. My blue aluminium cells are in compression

[Reefmagnet]

You should check out this guy's youtube channel (no affiliation).

https://www.youtube.com/watch?v=buNx...Q&index=2&t=0s

[markcouz]

Note that the alu casing is common with the negative terminal of the cell. If in compression it should have some form of insulating material over the flimsy blue plastic coating to ensure that a direct short between 2 series cells does not occur.

[markcouz]

...also the insulator/separator used should not be able to absorb moisture (eg. wood will be a poor choice).

[Steve_C]

This is quite interesting, I really like the Fortune cells shown in the video above. They also seem very reasonable in cost compared to the plastic cased alternatives from Winston or Calb.

So many choices for DIY. Hard to know what is best!

[newhaul]

Originally Posted by mikedefieslife

Never heard of this. My blue aluminium cells are in compression

Mine are in compression as well .
Planning to use 1/4 inch aluminum plate on the ends when finished .

[markcouz]

Oh brother!

If the aluminium plates chafe through the flimsy plastic coating then you will have effectively connected the 1st neg terminal with the last neg terminal using 2 steel rods - the result is going to be pretty spectacular with no way of controlling it until the cells are depleted.

[newhaul]

Originally Posted by markcouz

Oh brother!

If the aluminium plates chafe through the flimsy plastic coating then you will have effectively connected the 1st neg terminal with the last neg terminal using 2 steel rods - the result is going to be pretty spectacular with no way of controlling it until the cells are depleted.

There is one little flaw in your theory.
There is no continuity between the negative poles of the cells and the cases.
My other bank is comprised of aluminum cased cells that are not wrapped in blue or any other color for that matter.
No issues .

[newhaul]

Originally Posted by markcouz

Note that the alu casing is common with the negative terminal of the cell. If in compression it should have some form of insulating material over the flimsy blue plastic coating to ensure that a direct short between 2 series cells does not occur.

There is no continuity between the negative terminal and the case in any of my aluminum cased cells ( and i have multiple banks of them) please provide the technical data i would really like to know if this a possibility

[markcouz]

I wish I had your cells, I have a 12v 400Ah and 48v 100Ah bank both with aluminium/blue plastic casing. If I measure between + and alu case I get full cell voltage.

As I result I have gone to great lengths to seperate the cells and waterproof the housing. I have nightmares about the boat taking on water and these cells sitting in a highly conductive electrolyte.

If I had known this characteristic prior to purchase I would have gone with the more expensive calb cells (or yours if I had known of their existence).

[mikedefieslife]

Originally Posted by newhaul

Mine are in compression as well .
Planning to use 1/4 inch aluminum plate on the ends when finished .

I don't think we have to worry. markcouz seems to keep reiterating it but has not shown any manufacturer data, or any evidence. No-one else ever seems to have heard of such an issue either. Perhaps he's had a bad experience with a specific brand of cells in the past.

I'm more than happy to be shown to be wrong, but I do have to be shown.

[markcouz]

The cells that I used where stripped from new Narada 48v battery, I can't show you evidence because I live 1500km from the boat.

I have no reason to make this up, but I have been an electrician for 30 years so please be assured that I am comfortable with the function of a voltmeter.

I have no experience of other aluminium cased cells, only my own. I assumed that what I found would apply in general- glad to hear that is not the case.

However I do think that others should be aware of this possibility and take precautions if necessary.

[newhaul]

Originally Posted by markcouz

I wish I had your cells, I have a 12v 400Ah and 48v 100Ah bank both with aluminium/blue plastic casing. If I measure between + and alu case I get full cell voltage.

As I result I have gone to great lengths to seperate the cells and waterproof the housing. I have nightmares about the boat taking on water and these cells sitting in a highly conductive electrolyte.

If I had known this characteristic prior to purchase I would have gone with the more expensive calb cells (or yours if I had known of their existence).

the 100ah bank of bare aluminum are 25ah camel brand cells .
And the 240ah bank ( the blue ones are xld branded new cells )
I posted specs for both on my refit page for my defender.

Are you sure your cells are not refurbished ones?