Should Radio and Depth Finder be wired through Accessories switch?

[arminius]

Bought a used 19' deckboat last year, and noticed I don't need to turn the Access switch on to use the radio or depth finder. Always concerning as if I leave on, could drain the battery. Also, I was early morning fishing today and noticed there is a constant light on my radio also light around the "power" button. Obviously this pulls on the battery (even though a tiny amount).

What is best practice when running power to radio and depth finder?

Another issue related, is I put a new battery in a few days ago, and when I have the depth finder on and then turn the engine on, it turns off the depth finder sometimes. Any help with these electrical issues would be very helpful!

 

[Silvertip]

Every modern electronic device such as your locator have high and low voltage cut-off specifications. When you start the engine with the electronics on, the very high current draw of the starter causes the voltage to drop below the cut-off so the device shuts off. You may have a battery that has too low a capacity for the engine but the best practice is to start the engine, then turn on the electronics.

​If you tend to be forgetful, wire the electronics through a master switch. But be reminded that the radio will lose it's station memory each time to kill power. That is unless you wire the memory wire directly to a +12 volt source that's on all the time. It is just too simple to just "remember" to turn stuff off. Each time you add another switch you add another couple of potential points of failure. But that's just me. I just never forget!!!!!!!!!!! Except where I put the car keys, what day it is, my dentist appointment, you know -- minor stuff.

 

[arminius]

Every modern electronic device such as your locator have high and low voltage cut-off specifications. When you start the engine with the electronics on, the very high current draw of the starter causes the voltage to drop below the cut-off so the device shuts off. You may have a battery that has too low a capacity for the engine but the best practice is to start the engine, then turn on the electronics.

​If you tend to be forgetful, wire the electronics through a master switch. But be reminded that the radio will lose it's station memory each time to kill power. That is unless you wire the memory wire directly to a +12 volt source that's on all the time. It is just too simple to just "remember" to turn stuff off. Each time you add another switch you add another couple of potential points of failure. But that's just me. I just never forget!!!!!!!!!!! Except where I put the car keys, what day it is, my dentist appointment, you know -- minor stuff.

So it sounds like I shouldn't change anything except now just make sure my depth finder is off when I turn on the engine.

 

[Silvertip]

Even that's not necessary. You are just inconvenienced a little if you were fishing, engine OFF, locator ON and then started the engine. If the locator clicks off just turn it back on. We know you have a 19 foot deck boat which means nothing when it comes to electrical. What matters is the make and size of the engine and the size (capacity in Amp/Hours) of the battery. If the boat is an inboard and has tiny battery you can be assured the voltage drop on starting is the reason for the shut-off of electronics. Bigger capacity batteries are never a problem. Just those that are to small. It is a common misconception that a large capacity (high amp hour) battery can burn out electronics. Batteries do not FORCE current into a device. The device "SUCKS" or draws as much current as it needs to operate. A starter can draw several hundred amps with an even higher momentary in-rush so a rather capable battery is always needed to start the engine. Bigger engines need bigger batteries.

 

[edit-Insert]

Is the radio for music or ship to shore? If it is a communication radio, I would call it a life safety device and I would put it on its own fused circuit. Remember with DC you want to fuse the negative and put switches on the negatives. Although cars usually switch and adjust voltage on the positive lead. All of my boat wiring is switched and fused negative.