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cliveg  
#1 Posted : 21 January 2013 17:27:57(UTC)
Rank: Forum user
cliveg

Does anyone out there know of any definitive guide or info sources about Lithium Polymer batteries and their safe handling?

It seems that these things are prone to bursting into flames in a spectacular way if they have been been subject of impact, charged in the wrong way, or even allowed to become completely discharged.

It seems they don't like being fitted to some aeroplanes either....

Thanks for any help you can give
achrn  
#2 Posted : 22 January 2013 09:01:34(UTC)
Rank: Super forum user
achrn

I think the Dreamliner was a lithium-ion battery (though it's hard to tell, because most journalists don't know what they are writing about). Lithium-polymer are more rugged (though only slightly - not so rugged as, say, NiCd) and less prone to bursting into flames, but do have a lower energy density.

Don't over charge, don't short-circuit, don't physically damage seem to be the safety issues.

Don't over-discharge is just because you wreck the battery - it doesn't explode or burst into flames in that case.
Safety Smurf  
#3 Posted : 22 January 2013 09:38:10(UTC)
Rank: Super forum user
Safety Smurf

I'm in the early stages of looking into using Li-Po batteries myself (hobby application, not work). They are common in radio control aircraft because of their relative weight and size.

I found my local R/C shop to be extremely knowledgeable and helpful.
cliveg  
#4 Posted : 22 January 2013 16:45:20(UTC)
Rank: Forum user
cliveg

Thanks both

I have found a couple of useful pdf files, one is a user guide by Ultralife batteries, - google ultralife lithium polymer precautions.

The other is by 4-max.co.uk called dos-and-donts-lipos.pdf which is mainly aimed at the model user, so might be up your street Smurf.

Alarmingly there is already a company that produces fireproof bags for use when charging them! Called Liposacks, cost a £5 a piece.
SimonL  
#5 Posted : 22 January 2013 17:00:41(UTC)
Rank: Forum user
SimonL

Hi
the key points to consider are the charge and discharge rates, the max and min voltage levels and also the cell temperatures. However, I cannot stress strongly enough that every manufacturer, every cell and every cell technology (and there are lots of seemingly similar technologies) will be different and only the manufacturer of that specific cell will be a reliable source of data.
Please do not rely on anything you find here or on Google.
Regards
Simon
cliveg  
#6 Posted : 22 January 2013 20:05:01(UTC)
Rank: Forum user
cliveg

Thanks for that Simon, you make a good point. I have already advised the people who are buying a set of these batteries to make sure they have the data sheets - and the chargers - that go with that particular battery. They don't seem to be interchangeable.
achrn  
#7 Posted : 23 January 2013 08:30:38(UTC)
Rank: Super forum user
achrn

Technically, the chargers are electrically interchangeable, as long as you don't exceed cell ratings limits. In principle, you can safely charge a lipo or li-ion cell with a voltage-limited current-limited power supply - you simply hold the cell at a constant current until it hits the target voltage, then hold it at that voltage until the current drops to a negligible value.

The problems are one of physical connection, mostly - you can't just charge a battery, you need to balance the individual cells, and that means interfacing with whatever connections there are on the battery.

RC model types do it all the time - use a generic charger to charge lipos from different manufacturers. I use a http://www.revolectrix.com/m4_description_tab.htm because I only charge smallish cells and not more than four to a battery. For a lipo you set the limiting current, limiting voltage and some belt-and-braces safety cutoff values like max total time, max charge input, then connect up every cell and off it goes.

However, I do have the battery in a fireproof enclosure (actually a golden-syrup tin sitting on a small paving slab) and I keep half an eye on it while it charges. So actually, it's not an approach I'd use in a work environment - it's one of those things we (at least, I) do at home that I wouldn't permit at work.
Safety Smurf  
#8 Posted : 23 January 2013 11:14:41(UTC)
Rank: Super forum user
Safety Smurf

Think I might chicken out and try NiCads instead. Weight isn't as much of an issue for me as size. I'm limited to the size of the original alkaline battery compartment but I need to up the voltage.
johnmurray  
#9 Posted : 23 January 2013 18:26:45(UTC)
Rank: Super forum user
johnmurray

They rarely burn unless punctured.
If the cell voltage drops below a certain level they will never recharge.
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