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[Steamboat Willie]

 {:-{I am upgrading my fast electric boat to lipo batteries, I have bought a proper charger (Turnigy) and proper 11.1 volt batteries (Turnigy) the ESC and motor can operate with these in series up to 24 volts (the spec says), up to now I have been using 8.4 volt Metal Hydrides.
Everyone keeps warning me these are dangerous during charging but seem unable to say what exactly the danger is, so can you enlighten me.
I realise that the ESC needs to be reprogrammed to accept these cells.

[AlisterL]

Willie,

the danger, if any, is due to the LiPo cells overheating during charging and catching fire. Of course the risk is then what else catches fire as well. There are numerous stories around about cellphones catching fire when charging - this is the same problem. I believe that the best ways to reduce the risk are to charge at a low current or place the batteries in a LiPo charging bag - I'm not 100% sure of the name of these things. One of the first signs of danger is swelling of the cells. If that happens, immediately stop using or charging dispose of it safely.

I don't use LiPo's myself (anymore - I had one in a cheapish RC Heli that I sold earlier this year) as I haven't yet needed to in a boat. A matter of time before I do I suspect.

[red181]

I use lipos all the time, boats and helis, they are fine, provided they are charged and discharged correctly. If the cells puff or swell, the pack is finished, do not over discharge past 3.0v per cell, they will not recover.Buy packs with balance leads, and balance charge, then all cells will be monitored, and when discharged your balance charger will tell you how the cells are performing. Your charger should also cut out when fully charged.

They have no memory effect like nicads, so can be partially discharged without ant detrimental effect, you can buy big mah cells, and are generally lighter than comparable nimhs.

Big downside, most are bought from fleabay far east sellers, quite cheap, warranty is as long as it takes to open the package from a lot of these sellers (personal experience!) and the cheaper packs are usually overstated on the mah and "c" rating, higher "c" rating gives better performance, chinese specs are usually "exagerated"!!

I have tested many times, nims against lipo, lipo wins every time in "giving up" the mah, but I have to monitior with a cheaply bought low voltage alarm, which plugs into the balance lead,  run time is a lot less than nims as you cant run till flat. Turnigy are ok, they are one of the best of the budget range, I run my Huntsman on 2 x 3cell turnigy 11.1v 5000mah 30c packs, flat out is 15 mins run time, with my 4600mah nims, the speed is a third that of the lipos, and they get too hot as they cant deliver the mah quick enough, hope that helps

[hazmat]

Megger dangerous when over charged i.e. BIG BANG WITH FIRE and if you let the voltage drop too low it normally kills the battery.
Physical damage to the battery can produce internal shorts which can explosively destroy the battery. (Done that with a helicopter crash)

See http://www.rcgroups.com/forums/showthread.php?t=209187 for an in depth guide or
http://www.flyingsites.co.uk/features/lipo.htm

Personally I'm Sticking to Ni-mh . It's safer.

Paul

[HS93 (RIP)]

Yep nicads are safe, till they do this. then they go bag if overcharged, so don't be complacent. 


Peter

[jabba]

nothing wrong with lipo's ,been using them over 3 years and hav'nt lost one yet,but i had
a nimh pack explode,
just make sure you purchase the correct C rating on the lipo and
buy a quality charger,
check to see if your esc is compatable with lipo's,if not you can buy a lipo moniter.
 never leave a lipo charging by itself,and me personally i never carry a lipo home in the boot of the car,
lipo's explode into flames  so get a steel toolbox to carry them.
    jabba.

 http://www.youtube.com/watch?v=SQ0SNESIkWk

[Circlip]

Wow, where's me tin hat, incendiary batteries, exploding pots of resin, ability to easily glue yourself to the bench with super glues. No wonder the HSE have such a birthday nowadays and the kidiwinks bask in the "Safety" of killing aliens on a screen.

  Spose ultimately RTFM is the watch word and don't forget, look both ways when crossing the road.

  Regards  Ian.

[Dekan]

I use one of those nomex style lipo charging sack  http://robotbirds.com/catalog/product_info.php?cPath=9_270&products_id=3879  and a metal box

[John Mk2]

All the above You look after them & they will serve you well  Get the best you can afford Paks & chargers /balancer ect  go cheap & you pay in the long term.

[essex2visuvesi]

I use one of those nomex style lipo charging sack  http://robotbirds.com/catalog/product_info.php?cPath=9_270&products_id=3879  and a metal box

same here.  I also first charge new packs outside in the garden for the first few times, but then my house is made of wood and the nearest Fire Engine is 30mins away

[John Mk2]

Also Check the E.S.C Program every now & again As sometimes they can go to the default setting (Mines 7s) for no reason  Better safe than sorry 

[rockets]

Avoid cheapo chinese ones, someone burnt the armoury down at my camp with a cheap ebay rc helicopter!

Rockets.

[justboatonic]

Avoid cheapo chinese ones, someone burnt the armoury down at my camp with a cheap ebay rc helicopter!

Rockets.

Blimey!

[snowwolflair]

I use a Kevlar charging bag to charge them indoors.