I recently began checking the car battery over in an attempt to find why it’s often in need of charging, and ended up removing the powersounder.
I’d discovered that the PS appeared to be drawing no current – a combination of current measurements at the car battery both with PS connected and then disconnected led me to this conclusion – and I’d seen the reports on here of PS fires and wanted to investigate mine, and avoid a surprise fire whilst away on holiday – and in fact at any other time.
Whilst testing I armed the car alarm, and after a minute or so I removed the battery negative lead, and nothing happened. No sound, no siren, not a squawk – except from me.
I removed it and started investigating. Some photos at the googledrive link below.
https://drive.google.com/folderview?id=0B2DhCMiAZdPRNkVibHd5eWlBTnc&usp=sharingAfter removal I tested at the PS terminals with a voltmeter and only obtained a reading of 0.2 volts dc (between terminals 2+4). I considered that the unit might be dioded to prevent discharge when the car battery goes flat, and that this may explain the almost no output voltage – also keeping in mind the reports of PS’s being discharged by flat car batterys – trying to keep an open mind.
So I opened it up, splitting the casing. I found the PS to be filled with a rubber compound, and clawed away at it with a screwdriver and managed to expose the surface of the PCB. I tested the ‘batteries’ soldered to the PCB and discovered 6.4 volts dc across both batteries and 3.2 volts across each battery, and at the time thought that this was reasonable.
I then read that 7.2 volts is expected across these batteries, and I do believe that to be correct. When I’m testing emergency lights I always find batteries made up of cells, each measuring 1.2 volts – and my PS has 2 batteries with 3 cells visible in each.
Strange that the reduced voltage didn’t just cause a reduced siren output.
Stranger that reports of combusting PowerSounders include descriptions of some filled with a rubber compound- like mine.!
I decided to put this to the test by throwing a piece of the removed compound onto the barbeque. The edges of the piece glowed red at the very tips, but did not burn. At all.
Maybe this compound is intended to be a fire resistant measure?
So what to do next. I cant get enough of the compound out to remove the PCB intact. The compound appears to be all the way under the PCB, where the siren is.
I’d like to remove the 2 cells and replace them,
I’d like to inspect the electronics to see if it’s charging circuit is faulty. And I’d like to get it back in working order and fitted to the car – right now its outside in case it combusts, and wrapped in plastic bags to keep the rain off. (the sounder I mean, not the car).
Any feedback / comments / suggestions are most welcome.