Yale wireless alarm. Problem with power supply

[Graham1947]

I recently purchased and installed a Yale wireless alarm system which worked OK for a few weeks. Then when we came home one day, it showed an error (fault) display that the power supply to the control panel was faulty. I have checked the plug socket, OK, but failed to correct the fault display, now the control panel is completely dead, presumably the backup battery is exhausted. I assume the 12v transformer has failed, so a) how do I replace this without setting off the tamper alarm, and b) will the entire system need reprogramming. Any advice would be appreciated

 

[Europlex]

Don't you have all this on the paperwork that came with your purchase?
It's a Yale problem. Your first sentence.

Yale

Give us a call on 01902 364606

Helpline open Mon-Thu 8.30am-4.30pm / Fri 9.30am-2.30pm
Our address

Yale UK
School Street
Willenhall
West Midlands
WV13 3PW

 

[JohnD]

the backup battery is a rechargable one, so you don't need to replace it. Either the power supply, or the panel, sounds like it is faulty and no doubt you will get a new one under the guarantee.

I presume you have verified the socket, fuse and connector are in place and undamaged, and your pupply hasn't chewed the cable.

 

[mdf290]

Sounds like a dud transformer.

Yale keep swapping transformer suppliers which isn't good to be fair.

Have you tried testing the output from the transformer?

I tested one after a similar scenario and it was only delivering 6v.

Hence over a period of time the internal battery exhausts itself.

Good news is you should get a replacement and you wont have to reprogram the system again when you plug in the new transformer.

 

[Graham1947]

Took it back to suppliers who gave me new transformer and control box. Need to program the new box, but am assured this is no problem. Thanks for all the advice, especially Steve

 

[Europlex]

the backup battery is a rechargable one, so you don't need to replace it.

Taking this bit a stage further, are you suggesting that rechargeable batteries do not fail and go on for ever?

 

[JohnD]

no, I am suggesting that he has had it for a few weks, and the wallwart transformer has (apparently) failed so the standby battery went flat after 12 hours or so. That does not mean it needs replacing.

 

[bernardgreen]

Some types of re-chargeable batteries can be damaged by a deep discharge ( ie gone flat ) and their storage capacity is then reduced to the extent that they are best replaced.

If the system is designed so it justs fades away without shutting down before the battery enters deep discharge then the battery may need replacing or monitoring to see if it still has its rated storage capacity.

 

[JohnD]

It is a NiMH

 

[bernardgreen]

Makes no difference

For convenience from Wikipedia ( save me writing it )

A complete discharge of a cell until it goes into polarity reversal can cause permanent damage to the cell. This situation can occur in the common arrangement of four AA cells in series in a digital camera, where one will be completely discharged before the others due to small differences in capacity among the cells. When this happens, the good cells will start to drive the discharged cell in reverse, which can cause permanent damage to that cell. Some cameras, GPS receivers and PDAs detect the safe end-of-discharge voltage of the series cells and auto-shutdown, but devices like flashlights and some toys do not. A single cell driving a load can't suffer from polarity reversal, because there are no other cells to reverse-charge it when it becomes discharged.

Irreversible damage from polarity reversal is a particular danger in systems, even when a low voltage threshold cutout is employed, where cells in the battery are of different temperatures. This is because the capacity of NiMH cells significantly declines as the cells are cooled. This results in a lower voltage under load of the colder cells.[19]

 

[JohnD]

you think polarity reversal is relevant here?

 

[chaindaisy]

John,

Bernard has a wealth of knowledge in electronics, and it is worth taking his comments on board in many issues. In this particular case we could delve into the deep and mysterious for hours, making things even more complex. Bernard may be perfectly correct as far as electronic theory is concerned. However, the engineers on the ground, such as yourself, tend to think on their feet. You are perfectly correct, a battery which is virtually brand new and has been shown to retain it's charge, although presumed dead, is well worth recharging. If it recharges correctly and maintains that charge then all is well and (sorry Bernard) who gives a hoot about polarity reversal in cells. It's probably worth mentioning for Bernard's sake that it is not unknown for you and I to find a 'duff' battery straight off the trade counter shelf, and we act accordingly.

Yale, this is not the best of adverts for your products. Engineers don't like to 'take things back to the shop'..... time is money.

 

[bernardgreen]

If a battery has been discharged to below its minimum voltage then any current taken from it will be reverse "charging" one or more cells. This reverse charging can result in a cell that is damaged and no longer converts all the intentional charging current into chemically stored energy. Instead the current creates heat energy in the cell which, in fast charging, can be enough heat to result in an explosion in the cell.

So it is sensible to test charge such suspect batteries on a test bench with a low charging current and monitoring of the temperature of the battery and then a test of capacity and internal resistance.

A battery with a damaged cell can appear OK with a simple voltage check until the very reduced capacity of the damaged cell has been used up and it voltage drops to zero reducing the battery's voltage by one cell voltage.

Better that than a damaged / destroyed alarm panel ( or lap top as has happened in the past )

PS there have been many many times that I have had to think on my feet.....

 

[chaindaisy]

Hi,

"....PS there have been many many times that I have had to think on my feet....."

You obviously do Bernard, and no one can take that away from you. We, in the trade, would either carry out an indepth battery test away from the control panel, and attempt recharge on a seperate power supply thus ensuring no damage to the control panel would ensue.