Originally Posted by ChrisK7
I'm also interested in how you accomplished this mod. I install security systems for a living, so I have experience with low voltage wiring, but I'm hoping you can give me a shove in the right direction so I could try this for myself?
Hello Chris, nice to hear from you.
This mod includes wiring of a mains plug in the radio, make sure that you know what you doing!
So later after I posted this I have changed the transformer to slightly bigger and to paradox charger board. They are sold together as a kit.
The radio originally has a battery dock that I have cut out with hack saw blade. (keep in mind two battery contact wires are the main power input for the radio)
The 7Ah battery is a tight fit and luckily, the back "firewall" can just stay there! That was the luckiest bit, the whole reason I did this.
The safer way would be to keep the transformer on the main body part, but there is a battery backup bay (2xAA) right on the bottom of the "firewall". You can see how high the battery has to hold there for that reason, I used some rack-mount bracket of some old equipment and some beefy cable ties to keep it in place. The bracket should be bolted down using nylock nuts and the biggest washers available.
The front 'charger' inlet harness was removed and the rubber cap was glued down. Perhaps can be fitted with second AUX IN that is at the battery bay!
I have drilled through the front panel close to volume knob to fit a battery switch. (please use decent switch ideally with an LED)
The mains power socket is from old computer power supply and has to be wired correctly. I haven't use a mains switch because I wanted the radio to simply charge when it's plugged in. If your socket does not have fuse inside, use insulated panel fuse holder.
The charger board has AC input from the transformer, 12V battery input and 12VDC output with backup.
There is also a LED that is coupled to the current draw to the battery, when the battery is being charged the LED is ON. I have unsoldered the LED and replaced it with bright blue LED that lives next to the mains connector.
The charger board itself is attached to the bottom floor in between the speakers. I use 3M 6382 foam tape if I want something to stay there
I have connected the radio to 12VDC output, battery runs through a switch on front panel. The LED on that switch has 470ohm resistor on one of it's legs, all connected to the battery terminal on the board.
If you connect the radio to the battery input on the board, you get it to run longer but the cut-out will be down to 9V which is not healthy for the battery.
If you do use the same board, remove the jumper for higher charging current. It should be also possible to tweak the charging voltage threshold up to 14 volts or so (better for cyclic use) but I have never even tried.
Also, let's say all wiring should be cable tied to something solid, LED wiring harness should be glued down. That and good cable ties (with through-holes drilled with a strategy) to hold the battery and your mod should survive daily use.