I have the above system installed for about 5 years. Last year the batteries run out for the siren and i got 2 x 20k mah batteries from the supplier below...
http://www.ebay.co.uk/itm/Visonic-Powermax-Siren-Alarm-Battery-MCS-730-MCS-710-MCS-720-0-9912-K-/161911999072?var=&hash=item25b2b50a60
I...
