If the battery is duff then the charger is working overtime and will also get damaged, this in turn could cause the trip.
Sounds like it requires a good service.
Don't get me wrong, I mean on monitored systems, in most cases the door and PIR should confirm anyway without the risk of any external influence that could be introduced by a shock.
Can't get reported to the trading standards if they don't have your number
Invoices with a fake VAT number and a PAYG mobile number you change every couple of months...
I like it...