New AA LiFePO4 cell measures 0.3V

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Gordy7

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#195275 13-Apr-2016 09:42

Just bought a new rechargeable LiFePO4 cell (Powertech 600mAh).

These are nominally 3.2v with very low self disharge.

Out of the box, the voltage measured just 0.3v open circuit.

I thought that the cell voltage should not be allowed to drop below about 2.7v (maybe as low as 2v) otherwise the cell would be damaged.

If I recharge the cell will the long life expectation be obtained?

I am thinking of returning it to the shop.

Gordy

My first ever AM radio network connection was with a 1MHz AM crystal(OA91) radio receiver.

Gordy7

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#1532398 13-Apr-2016 10:30

Just received 4x 1700mAh LiFePO4 cells from Aliexpress.

They measure 3.45, 3.53, 3.4 and 3.26v all pretty much as expected :-)

Gordy

My first ever AM radio network connection was with a 1MHz AM crystal(OA91) radio receiver.

ubergeeknz

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#1532402 13-Apr-2016 10:33

I'd say that's stuffed. These shouldn't be allowed to get below 2.8v

Gordy7

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#1532405 13-Apr-2016 10:40

ubergeeknz:

I'd say that's stuffed. These shouldn't be allowed to get below 2.8v

Pretty much what I thought.

Have not been able to find out what happens if they are low voltage on arrival and if there is any chance of effective recovery if I recharge a low cell.

Gordy

My first ever AM radio network connection was with a 1MHz AM crystal(OA91) radio receiver.

ubergeeknz

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#1532864 14-Apr-2016 10:29

Gordy7:

ubergeeknz:

I'd say that's stuffed. These shouldn't be allowed to get below 2.8v

Pretty much what I thought.

Have not been able to find out what happens if they are low voltage on arrival and if there is any chance of effective recovery if I recharge a low cell.

Is it protected? In which case it may be only slightly below 2.8v and it's the protection circuit kicking in, and it will charge. Life is probably reduced, at minimum. IMO see what happens just keep an eye on things and keep an extinguisher handy...

muppet

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#1532869 14-Apr-2016 10:40

ubergeeknz:

Is it protected? In which case it may be only slightly below 2.8v and it's the protection circuit kicking in, and it will charge. Life is probably reduced, at minimum. IMO see what happens just keep an eye on things and keep an extinguisher handy...

This is the answer. If it's not protected, it's stuffed. If it is protected, a few short jolts should bring it to life.

Audiophiles are such twits! They buy such pointless stuff: Gold plated cables, $2000 power cords. Idiots.

OOOHHHH HYPERFIBRE!

Gordy7

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#1532903 14-Apr-2016 10:55

I hadn't thought about built in protection shutting down the cell output.

No mention of cell protection on Jaycar's web site

The only info I have:

On the box: SB2305

On the cell:

SB2305 PowerTech, 14500 LiFePO4, 3.2V 600mAh, Made in China 141217.

Gordy

My first ever AM radio network connection was with a 1MHz AM crystal(OA91) radio receiver.

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ubergeeknz

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#1532916 14-Apr-2016 11:14

A close look you can tell, basically there will be a very thin circuit board wedged in atop the cell, and a strip of metal running down inside the outer wrapper

Gordy7

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#1533402 15-Apr-2016 09:01

Just heard that the LiFePO4 that I bought is from faulty stock and is to be replaced.

Gordy

My first ever AM radio network connection was with a 1MHz AM crystal(OA91) radio receiver.