Fuse blowing

[Taw]

I have a Honeywell ade gen4 alarm system installed which is working fine. But every time I try to connect ,12v 2.1ah back up battery it blows the 1.6al 250v quick blow battery fuse. anyone no why?

 

[Harry Bloomfield]

Is the battery very flat and drawing much more than 1.6amps to charge it?

Have you tested the voltage across the battery?

Have you double checked you are connecting it with the correct polarity?

 

[Taw]

Its a new battery but I will check the readings

 

[Taw]

Battery reads 12.7 v

 

[sparkymarka]

Post picture of battery leads connected to pcb and battery

 

[Harry Bloomfield]

Battery reads 12.7 v

That seems OK, almost or fully charged.

 

[Taw]

https://photos.app.goo.gl/8CHzHnhZbn9JQ2U29

 

[Harry Bloomfield]

Your connect of the battery is correct in the photo...

Best guess is that it is drawing current from the battery and blowing the fuse, rather than charging the battery.

The fuse is a glass one, can you look at a blown one and tell me whether it is completely blasted inside the glass, or has the wire has simply burnt out?

 

[Taw]

With the battery leads connected I tried connecting the wires to the screw terminal.when the + lead touched the + terminal there was a flash.the wire in the fuse is completely melted.

 

[Taw]

I've tried with the mains off and on still blows the fuse

 

[mattylad]

Have you got larger fuses? momentarily trying a larger fuse may enable you to see if it is the inrush current.
If it does not blow with say a 2 or 3 amp fuse then its the current its trying to take at first.

Is this a new install i.e. never had a battery on before - or a battery replacement?
If new install does the PCB have +/- markings for the battery leads and do they match the leads?
If a battery replacement, what happens if you try the old battery?

 

[Harry Bloomfield]

I've tried with the mains off and on still blows the fuse

So it is the battery discharge which is taking out the fuse - there is a fault on the PCB. Unless you are very good at repairing electronics, there i not much you can do.....

One thing you could try, is disconnecting everything external which is connected to the alarm PCB - then reconnecting the battery with a new fuse. If it then doesn't blow, you know it is something external to the unit.

 

[bernardgreen]

With the mains on and the battery disconnected what voltage is there on the terminals on the PCB. ? If it is less than 12 volts then the charging circuit has probably failed. The fact that the fuse blows when with mains off the battery is connected suggest the charging circuit has failed and has put a short circuit across the terminals the battery connects to.

A competent electronics engineer should be able to fault find and repair the charging cui

 

[Taw]

It is a new install and is the first time a battery has been fitted. thanks for the info I will now dig deeper with your ideas.

 

[sparkymarka]

Two options .... try a different battery if that’s ok it’s the battery , if not panel is faulty .....
Make sure the red battery lead is in the + in the pcb and black is in - as it may have been reversed....