Lithium Battery Safety

[Guest]

I picked up this safety warning on www.jcrc.com (an American club site) issued by the AMA. Hope BMFA and SAA issue something similar here using the same graphic style. Have a look and tremble !

[Guest]

Yeah, I've heard stories of people blowing them up by overcharging. Yet I wonder, my son's mobile phone has a Li-Po battery and the charger looks pretty standard to me. But hey, what do I know? I'm all ears to hear all about them cos when the price drops a bit I'll be using them as RX packs (with a regulator, of course!)

Reminds me of the NiMH batteries when they first appeared. There were all sorts of stories of them just "dying" in flight and so on. Me, I've been using them for, oooh, at least two years, with no problems at all (he said, touching wood!). In fact I was worrying about lost capacity because I'm always overcharging them. I was talking to a friend of mine, who is an electronics wizard, about it. Anyhow, next time I saw him he'd built me a wonderful little discharger. It discharges your RX pack at exactly 200ma, when it gets to one volt per cell a buzzer sounds (buzzer doesn't do it justice, I can hear it in the garage with the discharger in the front upstairs of the house!). So, if the pack was 600mah and it takes three hours to discharge, then it's still at rated capacity, and every one of mine was! Within a couple of percent. Very reassuring I can tell you! :thumbs:

[Guest]

if i remember it`s the same as some of the horror stories that you heard with ni-cads. as long as they are treated with respect , there shouldn`t be any probs with them ?

or is this wrong on lithypoly`s ?

[Guest]

i like your avatoart

[Guest]

avator

*avtar sorry

[Guest]

oo i sdint know that

[Guest]

LiIon and LiPoly batteries need much more respect than NiMhs or NiCds, the balance between constant current charging and then switch to constant voltage is vital, as is contantly managed an balanced discharging. This is what thyere is a safety circuit in the pack or the device it is powering.

Get it wrong and you do more than burst the cell, the Li can burn a building down. See the UN Transportation testing regulations. LiIon batteries are designated hazardous, in the same category as explosives.

Mobile chargers are designed to operate with the cells/ packs in the phones with constant feed back from the phone to the safety circutry in order to manage the process safely.

Motto is ALWAYS follow the manufacturer's guidelines and never split LiIon pack like you might with older technologies.

ex LiIon battery salesman for AEA Technology Battery Systems, Thurso

[wonwinglo]

A word of warning to purchasers of Li-poly batteries after a expensive experience,two 7.4 v/1020 cell batteries were purchased for £53.00 each in January 2004,they had 20 charges with the special charger and never allowed to go flat,after this they would not charge up,I returned the batteries to Messrs Perkins who returned them with a note which said-On test batteries would not hold to full capacity,this could be due to high current discharge rates or voltage control cut off not covered by warranty,returned to customer.

I am far from impressed with these Li-poly cells especially as I went to the expense of buying one of the best chargers on the market the Chamelon 6300D and following the instructions to the book,even so they failed at a mere 20 charges.

I will not be replacing them with similar cells but prefer to wait until hopefully electric cells will improve especially in the area of reliability and user friendly.

I think that I was short changed by Perkins especially as I adhered to the instructions with the batteries and observed all of the safety procedures.

Anyone else had similar experiences with such products ?

[Guest]

There are a couple of known cases of lithium battery fires in mobile phones in the UK. There was an urgent recall on the chargers and there have been no more reported incidents. I believe it was Sony Erricson.

[Guest]

Sorry to dig up an old thread!

I was reading this on my Laptop whist using it to charge up three 10.8v 4.0Ahr batteries...

...those horror stories makes you think but they do keep your legs nice and warm!

[wonwinglo]

The high discharge rate on model batteries is the important factor,with laptops and mobile phones there should be no problems.

Remember the golden rule,never leave a Lipoly battery in the discharged state otherwise they die.

[Guest]

i have about 5 x little 4.8 volts li-po packs for my electric plane, the packs sit for about 6 weeks sometimes between charges, is there a guidline as to how long one can leave a li po pack discharged without it dying ?

[wonwinglo]

Guy,those automatic domestic plugs are good,set them for say half hour a day when the batteries are laid up as a trickle charge,but never allow the batteries to stand discharged,best to buy fresh stock from people who manufacture them,beware of old model shop stock that has been on the shelf for goodness knows how long ?

Fully charged good cells should be ok for between sessions of 5-6 weeks.

i have about 5 x little 4.8 volts li-po packs for my electric plane' date=' the packs sit for about 6 weeks sometimes between charges, is there a guidline as to how long one can leave a li po pack discharged without it dying ?[/quote']

[Guest]

Ok Thanks For That Barry, I Do 'warm Them Up Abit' ( Sorry I Do Give Them A Trickle Charge) Every 6 Weeks Or So To Try And Keep Some Life In Them,

They Are Ok At Present, And Dont Seem To Be Dying, But They Are Cheap Cells I Think, The Standard Items That Come With The Almost Ready To Fly Kit....

But Will Keep Giving Them A Little Trickle At Regular Intervals