Paddy_SP Posted September 24, 2009 Share Posted September 24, 2009 Yesterday morning, whilst driving through the security gates of a large defence company, the alarm siren on my 300Tdi Disco went up in smoke... Luckily, I was able to rip the connector out before the fire spread. It came away with half the internals in one big blob of molten black stuff... I then cut the wires away and then taped them over to prevent further shorting-out. I was extremely thankful that the engine fired up without problems as I had a long journey home ahead of me... So - my question is this - what caused the problem, what can I do to prevent it happening again, and is there anything else I should be looking out for? Quote Link to comment Share on other sites More sharing options...
teabag Posted September 24, 2009 Share Posted September 24, 2009 I suspect it was the battery overheating and melting and the terminals coming together resulting in the fire. I never never heard of such a thing before with a disco alarm sounder. Although I have seen the result of this thing happening once in a control panel housing sealed batteries. Quote Link to comment Share on other sites More sharing options...
Paddy_SP Posted September 24, 2009 Author Share Posted September 24, 2009 I've just unbolted the siren from the vehicle - it looks like this: http://i73.photobucket.com/albums/i207/Paddy_SP/AlarmSiren_1123.jpg Quote Link to comment Share on other sites More sharing options...
teabag Posted September 24, 2009 Share Posted September 24, 2009 The alarm sounder didn't go up in smoke then, just a small fire at the connection terminals caused by loose electrical plug arcing, i'm suprised that a fuse didn't blow them perhaps the sounder isn't fused on a disco. To prevent fires make sure any electrical plug and wiring carrying voltage are sound. I would say that as i'm in the fire detection industry. Quote Link to comment Share on other sites More sharing options...
pw8757 Posted September 24, 2009 Share Posted September 24, 2009 I suspect it was the battery overheating and melting and the terminals coming together resulting in the fire. I never never heard of such a thing before with a disco alarm sounder. Although I have seen the result of this thing happening once in a control panel housing sealed batteries. Scuse me for jumping in............ Battery overheating? What would cause that? I know you specialise in fire detection, but given I'm pretty sure I could work out that my car's on fire, can you help with some tips on fire prevention re this? Quote Link to comment Share on other sites More sharing options...
teabag Posted September 24, 2009 Share Posted September 24, 2009 We are not talking 70Ah vehicle batteries, but ie. jell 7Ah sealed batteries used in alarm systems, and in the disco's sounder perhaps a 0.5Ah or 1.0Ah which will normally be made up of six button cells. As we know batteries don't last for ever and there is a rare possiblity with jell cells/batteries the internal structure/plates collapse and short out resulting in over heating, melting and damaging surrounding material/kit if not protected by a fuse. All modern control panels now are multi fused (inputs/outputs)and therefore a battery going faulty will 'pop'the fuse, also with todays battery technology some larger Ah batteries are internally fused so batteries overheating is rare they just fail or blow the fuse signaling "Battery Fail". It did not happen in this disco's case as it was the plug & socket fault that caused a fire. Quote Link to comment Share on other sites More sharing options...
Paddy_SP Posted September 24, 2009 Author Share Posted September 24, 2009 Many thanks - having inspected the damaged unit, I agree that it was probably a short in the connector. My main concern was whether disconnecting the siren might cause the alarm to lock the vehicle down. As it's still going, this clearly hasn't happened, but it was a worry, especially as I was so far from home! Quote Link to comment Share on other sites More sharing options...
teabag Posted September 24, 2009 Share Posted September 24, 2009 So your alarm system is still working then, that's good but no sound now just the indecators flashing. Quote Link to comment Share on other sites More sharing options...
pw8757 Posted September 25, 2009 Share Posted September 25, 2009 Teabag - thanks for the response to the technical bit. Quote Link to comment Share on other sites More sharing options...
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