mounting lifepo4 laying down, bulging cells

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iamalavalamp
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mounting lifepo4 laying down, bulging cells

We have purchased 16 off 3.3 V x 20 Amp hour Lithium Iron Batteries
and wish to know if they can be mounted laying down?

Shining a bright torch light through the casing it is possible to see
that the plates occupy about 80% of the total height of the casing.
Then there appears to be an air gap at the top of the cell equal to
about 15 to 20% of the case volume to allow for internal connection to
the battery posts etc.

If they were to be laid on their side, would the electrolyte or
whatever is in the cell construction as paste etc slump out into the
20% void and decrease the effectiveness of each battery?

These batteries are 3.3 V x 20 Amp hour. On the bottom of the casing
in raised letters it says 20Ah. They are made in China and have
Chinese letters on the bottom of the casing. They are of a rectangular
shape approximately 102mm long x 32.mm wide x 154 mm high to the top
of the white plastic case. On the top side of the casing there are the
terminal posts each with an Aluminium ¼’’ screw in the centre of each
Al post. On the top in between the two posts there appears to be a
filling cap (now sealed).

I have also noticed s some slight bulging of the sides of some of the
battery casings, is this acceptable or should they be clamped/held
together to restrain them from casing distortion?

I have not found any detail on whether such batteries can be placed on
their side; hence I would appreciate your views,

Thankyou

reikiman
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Re: mounting lifepo4 laying down, bulging cells

You didn't say what brand. And was there any recommendation made by the manufacturer?

I assume these are packaged as plastic boxes?

At least one manufacturer of the plastic box shaped batteries IIRC does recommend mounting them upright for the reason you say. On the Thundersky yahoo group someone recently cut open a thundersky cell and found only a little bit of liquid, and didn't think mounting them sideways would be a problem. And certainly I've seen plenty of vehicles with the cells mounted any which way.

As for bulging, I understand from thundersky people that thundersky says bulging is normal. Thundersky recommends so far as I know to strap the cells with metal gizmos.

PJD
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Re: mounting lifepo4 laying down, bulging cells

My thundersky cells are built with headspace at the top where free liquid electrolyte is present when they are new, but seems to get absorbed due to volume changes in the porous active material (either the graphite or the phosphate) with the first deep charge/discharge cycle. If the cell is laid on it's side, some of the active material won't be submerged in the liquid electrolyte.

My opinion is that they should be mounted right side up if at all possible. If they must be mounted on their side, subject them to initial conditioning cycles (for Thundersky, it is charge them at 1/3C, to at least 3.7 volts, then discharge them at 1/3 C to just above 2.5 volts), in a right-side up position until no free liquid electrolyte is audible or visible. Then they can be mounted on their sides.

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