tapping into 12v

[michael02]

I will be renting a boat for an offshore research project (Angler Boat) and the boat we are renting does not have a 12v cigarette lighter. Well that is a problem for me as I have invested some cash in a underwater p.a. (speaker system so topside and can talk to divers underwater). the system runs off 12v and has a cigarette lighter.

could you please recommend the safest way to tap into boat power to use this system. should i be concerned with grounding?

there will be a single speaker in the water at a depth of 15 feet. amplifier on the surface along with mic for boat captain and research team

thanks in advance!!!

[mydauphin]

Does boat have 12volts? Some boats only have 24 or 32 volts systems. IF so you can put a tap into one battery only. IF it does have 12 volt system, then you can put a tap directly on battery and run a extension cable to your device. Becareful with cable length because 12 volt has more of a problem with resistance than 110 volt ac. Buy a thicker marine cable than you think, and make your own extension. I wouldnt think your amplifier device would use a lot of voltage.

Grounding... If you device is made for marine use, then it should already be taking this into account. I would think it would be ground at whatever part it has immerse in water. Also by attaching to boat battery, if it is gounded then your whole circuit is grounded anyway. But with 12 volts DC you dont have to worry about electrocuting your divers anyway.

Very importantly make sure you hook this up to a house battery and not your starting engine batteries. This device could drain your batteries and then you cant start your engines.

Send more info on device and layout of boat electrical and I would be hapy to give you further info.

[michael02]

to answer your questions:
- boat is a 22 foot angler (center console)
- 2004 model
- 12 volt

I wish i could get a wiring diagram but the rental place laughed when I asked. i called the boat manufacturer but they indicated that electrical is added at the deal so they have no clue

i know this is as simple as hooking up 2 leads to the battery but because of the water factor, I want to make sure I have the safest way to tap into the 12volt and extend the cable

the power leads for my amplifier (12v) will be bare wire.

can you please advise me on how to 1. extend and also how to 2 tap in to the battery the safest way

also how will I know which battery to hook up to and which one is the start enginer battery

the device is a custom made amplifer and underwater speaker system with mic built into the amp. the speaker is outputting roughly 100w. that is
thanks a ton!!

[Ike]

Run a wire to the common ground. Look at the battery The negative (black wire) should come off the battery and go directly to a common ground, if not hook up directly to the negative terminal.

The positive wire (red) should go from the battery to a battery switch ,or if no battery switch, to a main buss power strip. If there is a free lug hook your positive wire to this lug. If not find a lug that has only on wire comimg off of it and use that.

[Poida]

After you have paid all that money, I assume, for an amplifier why not buy yourself a spare car battery. Fully charge it and see if it lasts long enough by doing a test with the radio mike etc.

If it lasts long enough then fully charge it and use that as your power supply.

Attach your radio using heavy duty insulated cables, as used in jumper leads, the red terminal goes to positive and the black to negative. Install a fuse in the positive lead as per radio manufacturers specifications.

This system means you are not draining a battery you may need to start the boat with and not interfering with the boats electrics which may cost you should anything get damaged from your alterations.

Almost forgot the cig lighter bit, the female sockets are available from most electronics parts outlet and boat stores.

Poida