UltegraSTI

iTrader: (20)

Anyone else put off by many tracks policy on lipo sacks/box (which they'll be happy to sell u at 30-40bux, and their required for each battery u use), when folks can sit there and blast their nickels with 12amps or more (540 classes)?

are we missing something? i know less and less folks are using them, but will we all wait til somethin like what happened in finland (IIRC) before action is taken. perhaps actions that nobody will like. almost want to deal with a small fire than an acid-laiden explosion. case in pt, the track i went to last wk, what kinda battery was an all burnt up mess sittin outside the backdoor. the hint is 12 amps, 6 individual cells, and accidently shorting on a graphite chassis.

thoughts folks? is it an increasingly dead issue with nimh so but sure demise...or with classes out there still utilizing nimh (T/A, mini, spec, 540, gt3, and larger races lets be honest. i omit 1/12 stock b/c they still gotta make 8min) is it still a problem left unaddressed on a grand scale?

R

(personally, unless i forget it, i do charge my new lipos in an ammo box).

geeunit1014

iTrader: (14)

It all comes down to the line thats on every battery bought, "do not charge unnatended". You can charge Nimh's at very high amps (10+) and do it safley, you just have to pay attn to the temps on them, and turn the d-peak down(helps keep temps & overcharging down). As long as theyre in the normal temp range, they are fine. My personal record is 18, and ive seen 24 before. Im not saying do this everytime (The only reason these happend was because of being in a rush), but it can be done, if your willing to watch the pack with an eagle eye.

Lipos are the same way. You can prevent explosions/fires if your paying attn to the pack, they puff/swell before they go, and if you can catch them before the get to the size of a watermellon, generally they wont go. Nimh's are the same, they get real hot before they vent, and if you can catch it it reduces the chance they go boom.

We are creating systems to continue to let the idiots be idiots, when we should be trying to educate them to follow the instructions that come with the product they are trying to use.

RTFM FTW!

C_O_jones

iTrader: (11)

ROAR doesn't seem to think that lipo-sacks are all that important.
2008 ROAR Off-road Elect Nats got a waiver for lipo-sacks before quals even started. They were required in the published entry form, most bought lipo-sacks, me included, only to have them sit in the pit box, 5 months latter it's still in the bottom of my pit box, hasn't been required at any indoor event I have been too.

skypilot

iTrader: (14)

can't blame roar, gotta blame all the whiny little Rc racers that complained and asked for the waiver, it was a must at paved nats, no ifs, and, or buts. none of our local tracks are roar tracks so they pick and chose which rules to follow. oh wait, even our local roar tracks do that

joe of loath

iTrader: (1)

gotta agree with you here! NI-MH can be pretty dangerous, almost as much as lipo, but more likely to explode.

Oh, and I know of someone charging GP3300's at 30 amps...

jiml

iTrader: (3)

Nicads and Nimh has been used in RC for what 30 years now, and it's only in the last couple that there has been a problem. Also the biggest problem came from one manufacturer and one cell. That cell is no longer made, and there have been few incidents since.

When a NiMh cell lets go, it's an explosion. It lasts for an instant, and collateral damage is usually zero, as long as you don't count soiled underwear.

When a lipo lets go, it's a chemical fire that can last minutes, with everything close to it getting burned. The danger from lipos is far greater than from nickel batteries. We have been very fortunate that there have been no incidents yet. However already we are seeing racers blindly pushing these batteries further with higher charge currents and heating batteries.

The idea of a protective device (like a Lipo Sack, but it doesn't have to be a Lipo Sack) came from the manufacturers. It is a very good idea to use one.

Tubaboy

iTrader: (9)

Having seen the photos from oval champs 2 years ago of what happens when an idiot charges a nimh at 10amps with peak lock out turned on, then said battery embeds itself in a 2x4, I think its a bit stupid.

Had that battery flown the opposite way, it would have killed whoever it hit.

2 years ago, one person at a track I race at was hit in the ass by an exploding nimh. Funny to think about, and definitely a good thing he had his back turned!

Paul

Wild Cherry

Suspension of the sacks



Sometimes Roar accidentally does the right thing...

joe of loath

iTrader: (1)

I had 8 AA's go off in my garage (dont ask...). They melted themselves to everything, and damaged the workbench pretty bad. These cells went off like shotgun shells.

a_main_attendee

iTrader: (2)

Usually zero collateral damage my @$$!!

A few years ago an oval guy at the local carpet track left a batt unatended, i don't neccesarily know what happened but i'm pretty sure a pack overcharged. Needless to say it shot a soldered-on cell clean through a wooden door about 10 feet away from his pit space. I also had a friend with a m18 and GP 1100's that where charged at way too high of an amperage, which resulted in a cell (a small one at that) bursting and not only breaking the main carbon fiber chassis plate but bending the metal driveshaft into a near 45 degree angle.

Now image what would have happened if his fingures where there...

Lemme say this, i dunno about you guys but i've only seen nimhs go "boom" not any lipos...

joe of loath

iTrader: (1)

+1, and lipo's outnumber nimh's at my track too.

Sabin

iTrader: (1)

I bring a surplus ammo box with me to the track. If anything goes poof or bang inside, all you would hear is a thump and some gas would vent.

drperry

iTrader: (3)

I've got a little slot cut in mine so I can fit the deans plug into it...

Ammo boxes make you feel safe when attempting to bring nimh battery packs back from the dead

The sacks are always a good idea, just incase something happened to the pack itself somewhere along the line...

Nimh's should be stuffed in some sort of uber tough box...

Anyone want to sacrifice a nimh pack and an ammo box to see what happens?

No matter what we say or do... There will always be stupid people... They'll hurt themselves. They'll sue the manufacturer or whoever is handy. They will win.

jiml

iTrader: (3)

I have, and they don't go boom. They ignite more like flares.

Look, the simple matter is safety is the primary concern, no matter what batteries you're using. Don't be stupid, and just because you haven't seen it doesn't mean it can't happen.

I'm curious, how many of you have used a Dremel tool without safety glasses?

joe of loath

iTrader: (1)

umm, never actually