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HelicopterAerial Photography and Video › My fire resistant lipo charging setup
12-09-2004 08:16 AM  13 years agoPost 1
GMcNair

rrKey Veteran

Birmingham AL

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Rule # 1 with battery charging is do not leave them unattended. Rule #2 is do not set batteries on concrete. The cold will suck the life out of the cell. So for those of you who charge your lipos by setting them on the concrete floor, you could be extending your charge time because you're fighting the cold floor effect. Don't belive me? Take the battery out of your car tonight and set it on the floor of your garage. Put it back in the car in the morning and see if you can even power the interior light!

People have suggested using a fireproof box like the $19 ones from Wal Mart and elsewhere, but consider how fire works...it requires oxygen to stay alive. What is the point behind a fireproof box if you have to cut holes in it so your wires don't get pinched when you close it? If you seal this with a rubber grommet, don't count on that to seal it for long. And if by some luck you're able to choke out most of the oxygen, it then becomes a pressure cooker, aka a bomb. The extremely hot gasses released from a burning battery will quickly expand, and when they reach their pressure point, they will explode. The tighter the pressure, the larger the explosion.

My design is based on one that I read about in RCGroups. It's not very portable, but in theory it should be very effective. It isn't "high tech sleek" like a briefcase sized fireproof box, but it won't contain gasses and become a bomb either. And given a strong enough workbench, it can be placed indoors on it. I take no responsibility if it doesn't work for you, but it should provide a bit of peace of mind. The primary suppression agent is sand and/or baking soda, but understand that companies like Ansul have created Lithium fire specific agents. Ansul's product is called Lith-X and it is essentially powdered graphite. At $130 for a 5 gallon pail of the stuff, it isn't cheap. But if enough people want to go in on a purchase of it for use in a similar design to mine, to replace the sand and baking soda, let me know and we'll make it happen. Here's the design:
Fire resistant container

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12-09-2004 11:16 AM  13 years agoPost 2
Crusty

rrApprentice

N51 degrees 29.823 minutes W3 degrees 16.133 minut

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You could of course just place the pack in a metal pale outside yer garage door, lets not turn this into rocket science.
as for the problems you point out with a fire safe
believe me a small hole of a couple of mm is not going to replenish oxygen as fast as it would be used if the pack caught fire, you have a point about explosian risk if contained in a sealed container.
the car battery analogy is totally bogus, it would start yer car fine...unless you live in Norway
Crusty

I am dsylexia of borg..resistance is fruity...your arse will be laminated

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12-09-2004 04:14 PM  13 years agoPost 3
Smithprod

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Oklahoma

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The concrete theory is common knowledge, but the draining your car battery overnight part is what is bogus. That's being a little dramatic.

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12-09-2004 04:26 PM  13 years agoPost 4
pilotError

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Long Island, NY

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Battery Bunker
Theres a little crockpot style container that someone sells called the battery bunker.

He's tested it on some smaller lipo's and seems to work fine. You might get the smoke still, but it contains the flame.

FWIW...

Battery Bunker

Good Judgement comes from Experience. Great Judgement comes from Bad Experience.

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12-09-2004 04:32 PM  13 years agoPost 5
MPA

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Australia

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Common knowledge to automobile mechanics.
Not to my knowledge it isnt and Im qualified 24yrs.

If you leave a battery on a cold concrete floor for some month or more in sub zero conditions it will "promote" greater oxidisation of the plates than is already the case, that may cause shorting of cells to some degree.
The battery wont just be discharged it will be rooted, but that takes a months or more and no charging of the battery.
Charge the battery periodically and the concrete floor theory leaps out the window.

So it is true in part in a small way, but not for the reasons stated and only applicable to storage of batteries you dont intend to charge for lengthy periods to avoid promoting corrosion.

As far has putting it on a floor and it loosing charge over night, if that the case it has nothing to do with the floor or the temperature of it, your battery is on the sag and life as is knows it is heading south.

In general avoid storing batteries on cold concrete floor if they are stored for lengthy peirods not periodically sharged, like wehn you go on holidays.
But then, that has nothing to do with RC Helis because this applies only to wet lead acid batteries.
Which Lipoly batts are not, nor NiCads or NiMh.

Rgds
Dave

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12-09-2004 08:05 PM  13 years agoPost 6
GMcNair

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Birmingham AL

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Good Lord, I spent some time drawing up a fancy diagram to show something that would offer some help to folks. As of this writing, 157 folks viewed this topic, and all I see is a fight over a "dramatic" comment I made about a car battery and pointing folks to another device. Typical RR fashion, someone makes a post and has to deal with the negativity of a half dozen 1 gallon experts. To hell with it. Last time I try to post anything helpful.

If anyone wishes to see the photo, feel free to PM me and I'll send you the link.

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12-09-2004 09:58 PM  13 years agoPost 7
MPA

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Australia

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No need to be defensive about it.

The fire container is great idea which is the point.

It just the analogy you used to car batteries was a little flawed, and you know, everyones a mechanic when it comes to car talk..
Mentoin something about cars and it usually gets a side debate in any forum.
But it wasnt criticising your fire contaiment design.

Rgds
Dave

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12-10-2004 07:32 AM  13 years agoPost 8
Crusty

rrApprentice

N51 degrees 29.823 minutes W3 degrees 16.133 minut

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Apologies, After re reading my post it does sound completely negative, please dont take it to heart, I'll try to be little more diplomatic in future.

I am dsylexia of borg..resistance is fruity...your arse will be laminated

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12-11-2004 12:52 AM  13 years agoPost 9
HeliCool

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Florida

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A crucible would work
A foundry crucible would work. Of course you would have to heat cure it fist, but if it can handle molten iron I think a small lithium pack would not be much of a challange. They come in many sizes and arent that expensive. I would say a #2 would work fine.

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12-11-2004 02:06 AM  13 years agoPost 10
CKY

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Sunshine Coast, BC, Canada

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MPA,
you said
your battery is on the sag and life as is knows it is heading south.
In Oz wouldn't it be more appropriate to say heading North??

Chris

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12-11-2004 05:29 AM  13 years agoPost 11
MPA

rrElite Veteran

Australia

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South in the USA is the same direction as south in Australia matey.

I worked in the RACV for a few years, we did a lot of batteries.
We used to get battery points for each one we ordered to be replaced by the battery vans, one year I got a cordless drill and espresso machine from battery points.

I assure you the workshop term we use here is "the battery is phucked."
To customers and RA members, "the battery is toast"
Its not heading anywhere.

But as the universal saying goes
When in Rome do as the Romans do
So in this forum and accounting for the battery residing in the US,
The battery is "heading south" I beleive.

So there you go.
And just remember
Wherever you go
There you are.

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12-11-2004 12:46 PM  13 years agoPost 12
Ace Dude

rrProfessor

USA

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Hi Greg, it appears the link at the bottom of your original post isn't working. Can you fix the link? I'd like to see the picture of your idea. Thanks.

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12-14-2004 01:59 AM  13 years agoPost 13
Dr. Fibinotchi

rrKey Veteran

Sioux Falls SD

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forward thinking..back on track.
What if we aproach this from a diffrent angle and instead of using a better devices that catches a fire what about using a device that prevents one. I am trying to forward think this.

Is there a temp. in charging that a lipo would / could be condsidered unsafe aka about to burn temp? I wonder if the chargin systems like the shulze and other manufacters have put a temp or safety system to prevent charging too much or in a wrong way on its auto charge sequence?

Another onboard the heli in high temp conditions the battery agreablly would reach moderatly warm temp. If the temp is lets say 75 degrees warmer for a fire temp you could use things like thermasters/ or other circuit designs (audable) to prevent damage (fire) in the lipo. heli and possiblly the womens new bmw in the garage.

I do agree lipos can be dangerous, but I think that if you prevent it from ever happening like a thermisitor kill switch Normally closed circuit mounted on the battery for example might deter 'some' of the issues from ever happening.

A fire retardent wrap maybe could be used on around the battery to prevent(minimize) a battery fire as well. I know there are diffrent types of materials that work, but I understand the temps get very hot I dont know how well this would work in reality.

do lipos only swell when getting to many amps in charging or discharging?


Just trying to look from outside the box and be proactive instead of reactive.

-Cody

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