You need more amperage. The 1,600 ma is only 1.6 amp and your stereo probably pulls more than that at half crank. There are schools of thought for and against smart chargers.

A conventional charger of good quality with high and low charge rate switch that will deliver something from 7 up to 10 amps should do the job for you. However you will need to keep an eye on things to avoid cooking the batteries.

Another thing you could do to avoid working your batteries all the time is isolate the batteries from the house load and connect a regulated 12 volt power supply into your house load circuit. You plug it into 240 volts one side and get a regulated 12 volt DC power supply out the other side.

I have a 4 amp regulated power supply unit you can have for the cost of postage. Get more opinions on how to solve your problem and on what I said above, then let me know if you want me to send you the power supply.

So what you say Charriot appears to confirm my advice????

Your battery may also be shot. To test it get a $9.99 Digital Multimeter from an electronics shop.

Disconnect everything from it for a few minutes then measure it. If you get a reading better than 12V battery is probably OK. If 11V or so battery is badly flat, possibly damaged. If reads in the 10V range or less its bad, get a new one.

After that, as mentioned above, If the battery is in good shape the power into boat via your shore power must be more than what you use and 1.6A is small for say a 100AH car battery and what you have connected.

I found fridges are bad for flattening boat batteries because they are a 24/7 load. And lots of electronic equipment (stereos TVs etc) dont actually turn off when you switch them off, the lights just go off but the circuitry inside is still on. They dont draw much but over 24 hours they do.

Live aboard Yay! I did it for a year and a half once, it was one of the best times of my life :-)

No problem. It weighs about 1.5 kg. Will find out cost of postage or might be able to send it C.O.D.

My PL20 controller and the 240vlt power supply along side. The 13.5 vlt d/c , 17 amp regulated output from the 240 vlt power supply is wired through the PL20 solar regulator. Most of the 12vlt wiring goes through the PL20 load terminal so current draw can be measured as well as amp/hr in and out. A simple bypass switch disconnects everything from the load terminal and switches directly to the battery in case of PL20 overload or failure.The PL20 can be configured to accept charge from the auxiliary 240 vlt /12vlt power supply when the solar input drops to a low level.