Lipo Saftey Sack

Having surfed Overlander I noticed their excellant idea fo the Lipo safety sack for storage/charging. £16.25 each

Mark Barnes said "Invaluable for charging and storing Lipos, we have all seen and heard the horror stories, this give me peace of mind".

Wow Mark, can we get a club discount, I'm sure there are enough lipo/electric members in the club now for a baulk order now?

Why waste £16.25, look after your batteries, keep them seperate, never charge them unless your present for the full charge.

I personally don't like them as you put all your eggs in one basket, if one battery becomes faulty then you have the potential to loose all the batteries in the lipo bag.

I'm with Rich on this one. I haven't seen the need for a safety sack for my batteries in about 4-5 years of using those pesky Lipo cells (including some pretty hefty sized ones!). Store them in a cool place (I use those cheap "bits" boxes you can get from B&Q for about £3-4) and only charge them when I am sat next to them, or they are in the middle of a field

They seem like a good idea if you use one for every pack, but when you have a lot of packs (at the last count I have about 30 or so), that is going to get preeetty expensive, discount or no discount.

Cheers
Andy

Truth be known i only use the sack to charge my bigger lipo`s 4s/5s/6s as i dont like the idea of them going bang, I was using them to store my smaller ones but as the guys said I had one back go and potentualy could have lost 10 other packs.

I think its a good idea for charging and if a club order is required i will sort one

M

PS glad you didnt have a good look round the site as there are some quite doggy quotes on there

you dont have to put all of them in there just the one thats charging. that said ive never had a problem with charging my lipos, i have left them unattended occasionally but if i do there always surrounded by non flamable items, ie not charged in the back of the car or next to a pile of oily models.

[quote="Rich"]Why waste £16.25, look after your batteries, keep them seperate, never charge them unless your present for the full charge.

It did occur to me:-

How important is lipo cell cooling during charging ?

lipos work best when they are warm, they take a charge better when there warm and discharge better when there warm. tis afterall an exothermic chemical reaction which takes place. these happen faster with a bit of heat.

be careful with big words like that you may set Andy off

Just sounded like a good idea for charging, but there you go. I suppose everyone stores their packs many feet away from each other? I only have a couple and I keep them in two ammunition box (on their own ) for storage but I've noticed a prolific use in the club. Those that have posted are experienced but what about the new commers? Maybe someone would like to do an article on Lipo Saftey for the newsletter?

I thought Tim had done an article already, good thing these forums brings out some interesting points relating to all types of aero modelling

From what I've read and heard about lipos all the issues revolve around charging them. They don't spontaneously combust there's usually finger or equipment trouble around the charge process. As Richie says Tim has done articles on lipos and the attendant safety issues

Rich wrote:be careful with big words like that you may set Andy off

Ha ha!

Lipos on charge should not really warm up at all. You should only be putting in around 1C when charging a pack (e.g. 2.1A for a 2100mAh capacity pack) , and this shouldn't stress any of the Lipos made in the last ten years enough to heat up noticably. If it does, you may want to keep an eye on the pack, as it is a sign of impending doom!

The packs do heat up a bit when you start to pull proper current out of them though, and this tends to be the limiting factor when it comes to how many "C" you can use them for. If you can keep the cell from heating up past the danger point (anything more than about 50°C is starting to get very iffy!) then you can keep pulling more and more current from them.

Cheers
Andy

PS. It's the internal resistance of the cells that causes the heating of the pack when you discharge it (or charge it too quickly)....

I have around 50 various packs I guess at the moment, and never use a LiPo sack or anything similar. What I do use however is a careful and regimented routine, and treat the job of charging (where most if not all Lipo fires occur ) very seriously...as some may have noticed, I am a particularly ignorant sod when connecting packs up to the cooker - just try having a chat and you will see what I mean
Andy is right about the cell heating too - should not be getting warm during a normal charge.
I did indeed do an article some time back for the club magazine, but If anyone is interested I also had a 2 part article in RCME a few weeks back. This has now been published on the RCME forum too, so if you want to be bored to death about batteries, heres a link.battery care