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Fire proofing a robot


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Tim



Joined: 30 Oct 2013
Posts: 247
Location: QLD


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Fire proofing a robot

At some point in time we have all seen the dreaded magic white smoke, I saw some at the Nats this year ( not from a battery as far as I am aware ). After reading about battery fires I have been wondering has /does any one segregate their battery from the rest of the electronics?

I understand this may not be possible, however, if so is it common. Also on the same matter batteries get hot I felt a pack of a123's ( I think they were a123's that came out of Wanda after a full on round very warm ) Has any one wrapped their batteries in fire blanket or lined a Battery area /compartment in their bot for this purpose. ( I am aware space is a major issue )

This may sound counter intuitive as it would trap heat which would otherwise need to disperse, however if the battery could survive 3 minutes ( wrapped conservatively obviously ) in the event of a battery explosion / fire the risk of damage to other components amongst other things would be minimized one would expect.

What has been the common or not so common experience of the above idea?

Post Mon Dec 02, 2013 8:25 pm 
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marto
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Joined: 08 Jul 2004
Posts: 5459
Location: Brisbane, QLD


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If your battery is getting that hot it really means your battery is not big enough. Generally the main source of battery fires is either poor mounting which leads to puncturing or a short across the battery.

Making sure its padded is a good first step. Or stick with A123s.

Steve
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Post Mon Dec 02, 2013 10:57 pm 
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Tim



Joined: 30 Oct 2013
Posts: 247
Location: QLD


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Definitely have padding and mounting covered I would like to think atleast, the batteries I intend to use are [url] http://www.hobbyking.com/hobbyking/store/__35473__Turnigy_nano_tech_2650mah_4S_35_70C_Lipo_Pack_AUS_Warehouse_.html?strSearch=Turnigy%20nano-tech%202650mah%204S%202 I have / will have a spare as to not be constantly recharging between rounds so as to keep them cool.

They will run 2 x 12v or ( possibly up to 2 x 18v drill motors ) with the tz85a'a

As for padding it was my intention to use sound deadening material ( the kind you would find in a speaker ) a thick (10mm) / fairly firm foam, it has a good memory as long as it is not completely crushed flat for extended periods. My only concern with that is in regard to heat retention.

As for mounting nothing in the bot will be sitting on the base ( other than the motor/gearbox mounts ) so as to save components from the direct force translation from an impact /weapon and will be "mid-mounted" on a cross brace fashion fixture, which will be covered by padding the hard surface ( brace ) and using zip ties to hold the components on to it.

I have even considered mounting motors / battery / tz85a's, rx & safety switch in three separate "cells" inside the bot but that may be overkill!

Post Tue Dec 03, 2013 12:12 am 
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miles&Jules
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Joined: 19 May 2010
Posts: 3973
Location: ipswich QLD


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Hi Tim
I reckon just shove some foam around the battery ….you'll be right….Im surprised theres not more battery explosions at comps with all the big hits

…..we seem to always have battery fires with our ants ….but its always during charging and because we have shorted the battery ….cause its so damn tiny. he he Sad
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Post Tue Dec 03, 2013 10:23 pm 
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Valen
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Joined: 07 Jul 2004
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Location: Sydney


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most people use 5mm or less foam
the issue isn't so much preventing shock as preventing crushing of the pack itself, so steel or Al, then a few mm of something soft mostly to act to disperse any sharp points, like some welding slag or whatever.
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Post Wed Dec 04, 2013 4:26 pm 
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