Optima XM intruder alarm power supply.

[Dibbler]

Thanks for that.

Doesn't seem that I'm missing much, apart from having a faded keypad. As long as it continues to do what it is supposed to do then it will be fine.

 

[alanvickers]

Thanks spsrkymarka. This helps me to decide which replacement alarm panel to have installed, should this become necessary.

Alan

 

[alanvickers]

The manager of the company called today to take a measurement of the charging voltage. He recorded a charging voltage of 10.55 volts and a battery voltage of 13.28 volta. He said that he had come across this problem before with Optima panels and that usually it was caused by a diode going 'open circuit' in the rectifier circuit. This proved to be the case in my alarm panel.

I wonder if this is the type of problem referred to by Sparkymarka in the second posting to this thread.

In this condition the rectifiers are working in 'half-wave' rather than 'full-wave' mode as only two of the diodes are conducting. The meter is recording an average of the voltage during the active and the inactive half cycles. It seems that the peak voltage that is present during the active half cycle is sufficient to provide some charge to the battery. The voltage recrded at the + and - terminals is the same as the charging voltage.

All is working OK as the PIR's will work with a voltage down to about 8.5 volts and the battery in the bell box is 6 volts so that it will charge up OK.

The short-term option for me is to monitor what is happening and see if there are any changes. In the longer term I can have a reeplacement Optima panel installed or have a completely new alarm panel, probably a Texecom and I will probably opt for that in due course.

Alan.

 

[bernardgreen]

If one of the four diodes in the bridge has failed it means the two left working will be working harder. If the diodes were already border line design ( as the failure of one suggests ) then failure of one of the working diodes may happen sooner than later.

 

[sparkymarka]

i would also think that a half wave supply to the battery is not going to do it any good in the long term and shorten its lifespan also.

 

[alanvickers]

The alarm panel has been in use for 19 years so I do not really believe that the components were necesarily 'borderline' in their duty. Compare this service with failures in the power supplies of some entertainment type set-top boxes where capacitors often break down after not much longer that 12 months. If another diode does go open circuit then the alarm panel is off completely and I am aware of that.

As regards charging with 'half-wave' curren, only time will tell what effect this has on the battery and this is why I intend to try and monitor what is happening over the next few weeks or months.

Alan.

 

[sparkymarka]

lets just hope your bell box is up to date with a cut off timer for that time when it finally fails.... lol

 

[Europlex]

How can a charging voltage of 10.55v be any good for a (hint) 12v battery?

As the battery is not being charged correctly I would suggest when it gets to be below the threshold the panel is looking for, you are going to have problems.

Usually at silly o'clock in the morning, still, it's your choice, we know nothing.

 

[alanvickers]

The bell box is 1 year old and I believe that the timer is set for 20 minutes.

The peak value of the rectified half cycle is greater thatn the mean value of 10.5 volts that is being measured by the meter and is also greater than 12 volts and it is this peak, which is only present for part of the cycle, that is providing a very limited charging current.

I am not sure for how many weeks or months the panel has been in this condition, however it is on 'borrowed time' and will be replaced before too many weeks as there are too many uncertainties.