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[2nddaniel]

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=sharing

After 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.

[05omegav6]

Either leave it off, or replace with a new one if not having one bothers you

Relatively inexpensive from VX iirc...

[zirk]

As Al says, best left off, destroy it and discard it, even when there working there a pain in the rear.

The working ones do give a reduced sound output with a low battery voltage, right down to a few chirps or clicks until it dies completely.

The stuff inside is a potting compound, probably some form of epoxy resin, its there for water / moisture protection, no idea whether its actually flame retarded or not, thats not to say it wont burn if it gets hot enough.

Ive set fire to Data and RF Communication Cables that are LSF rated (low smoke and fume, zero halogen) in controlled tests, and they actually burn a treat once they get hot enough.

[flyer 0712]

Sorry to jump in on this.....my alarm has just on a few occasions began to chirp when exiting the car...is this ok or is it the start of trouble and throw it in the bin job..thanks 

[biggriffin]

Sorry to jump in on this.....my alarm has just on a few occasions began to chirp when exiting the car...is this ok or is it the start of trouble and throw it in the bin job..thanks 

Remove it asap, don't want a fire. Plenty of threads and pictures on here,and a how to.

[zirk]

Sorry to jump in on this.....my alarm has just on a few occasions began to chirp when exiting the car...is this ok or is it the start of trouble and throw it in the bin job..thanks 

Its a sign of the internal battery failing or leaking, which the general view on here is 'the writing is on the wall'.

I would get it out and bin it mate. 

 

[flyer 0712]

Cheers biggriffin....spanner and screwdriver in hand and now going to remove it...thats the joy of being an old git ..i have all day to do things...thanks again.

[flyer 0712]

Removed power sounder today.because it has on a couple of occasions .made the dreaded chirp..chirp noise....noticed the date of production on the casing was 26/7/2007 so had been changed after that date,,anyway I carefully cut open the casing and at first could not see anything wrong....On closer inspection i saw that one of the batteries was just showing signs of leakage on the terminals  where it is soldered to the p.c.b...the p.c.b. has a very minor /very small area that is stained..about 1/16 round area of an inch and the rest is ok..so if batteries can be obtained ( for insurance ) would it be ok to replace the two batteries on the p.c.b......

[Diamond Black Geezer]

Insurance is the weird issue. You're supposed to tell your insurance company that you've removed the alarm power sounder - whereupon your premium should go up, as you've removed part of the alarm system, thereby making the car more twockable... because as we know, whenever we hear a car alarm go off we all go sprinting out of our front doors at 3am, to check for car thieves, don't we? 

Or... in order to keep our cars 'factory' we should leave the power sounder where it is, the insurance company is happy, then let it spontaneously combust, and then end up claiming for the loss of our vehicle. 

Or... buy a brand new one from Vx (which, though not inexpensive, it's still a cost which we could all prefer to not have)

None of the above scenarios cover you taking apart a flammable thing, fiddling with it, then reassembling, and refitting.


In no way am I suggesting there's anything wrong with you doing that, personally, I say go for it.  If you can get the power sounder working, and without the dreaded battery leakage at a reasonable price, do it. Personally I'd be very interested. All I'm saying is, don't do it worrying about 'Mr Insurance', because as I say, even though your intentions are honourable, they'd see your attempt at repairing part of the security system of the car as an excuse for not paying up, should that ever be the case.

I say do it for your Omega, and do it for your peace of mind, but not for 'Mr Insurance'. The only option that He will be happy with is a brand new power sounder, fitted by a qualified mechanic, with a receipt, if you follow? 

[ronnyd]

To answer the OP, the sounder has it,s own battery supply so it won,t draw any power from main battery. There stands the PS problem, these batteries start to degrade and cause the fire risk mentioned. If i,ve got this wrong someone, hopefully, will put me right.

[05omegav6]

The issue is that when the internal batteries degrade and leak all over the circuitry,  it shorts out the trigger connections to the main battery...

This then puts the full power of the car battery through two relatively thin wires causing alot of heat, which inturn causes the powersounder and it's surroundings to spontaneously combust. Which is what destroys the car...

And to preempt your next question, you can't, so either remove or renew the complete unit

[ronnyd]

Thanks Al.

[Kevin Wood]

The issue is that when the internal batteries degrade and leak all over the circuitry,  it shorts out the trigger connections to the main battery...

What he said^

For some daft reason, the permanent feed to the power sounder is made with thin cable yet it's not fused other than at one of the 80A fusible links. The power sounder doesn't have to ignite itself, it's enough that the feed from the main battery shorts out because that will then ignite the wiring loom. Often the fire actually starts under the dashboard where the power sounder wiring meets the main feed from the fusible link.