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power setup for small accessories

Posted: Thu Apr 29, 2010 3:29 pm
by crewedattempt
Hi all - searched the forum and did not find the info sought, so if my search missed something there, please direct me to it.

I have a 1971 F31 with no inverter or 12V accessory ports. I want to be able to charge small accessories (handheld radio, ipod, etc.) and/or run/charge a laptop computer.

First, in re the 12V accessory ports: any recommendations as to how to add these to an accessory circuit so that they can be switched off?

Second, the boat has no battery master switch - is this a bug or a feature? Are Trojans generally wired to run accessories off of one battery so that the other (starter) battery does not get run down?

Third, in re an inverter,
1. do you install it before the circuit breakers and switch 120V, or after?
2. any thoughts on a recommended model? Have you had bad luck with any?
3. any thoughts on a recommended location?
4. how do you switch between shorepower and inverter?

Any and all help is greatly appreciated!

Thank you,
Mike

Posted: Thu Apr 29, 2010 4:13 pm
by ready123
Since you only want to charge those low powered items I will ignore talking about the Inverter route which supplies 110V from 12 v batteries and is kind of overkill and inefficient.... 12V up to 110V then back down to 6/9V of the equipment.

Use the 12V source to charge those items.....
You can get adaptors from local electronic shop (Radioshack) that will take the 12V supply and output varied lower DC Volts say 9V, 6V or whatever.
Then you set it to the Volt required by equipment, laptop, ipod etc. and connect it.
Where do you get the 12V from for that adaptor.... go to the DC fuse panel and find an empty slot that you can take the power from.

Posted: Thu Apr 29, 2010 8:20 pm
by randyp
Not sure where to start, but I agree that you don't need an inverter to charge your laptop. If you have a 12V automotive adapter or can buy one then you can charge your laptop and other small dc accessories using the battery (house bank).

Suggest that you check out several posts from previous years about adding a battery switch and perhaps an auto charging relay (acr) which will make the chance of draining both house and starting banks by accident a thing of the past.

At the very least you can add a 1-2-all-0ff battery switch and follow the directions on how the wire up your 2 batteries and the main power cable coming off the engines.

On my F26 I installed 2 12V house batteries in parallel (pos to pos, neg to neg) and then ran the positive cable to the post on the battery switch. Same thing for the single engine battery (since I only have one engine). I wired all accessories to the fuse panel vs directly off the batteries and have fused all positive leads off the batteries. I installed a 600W small inverter to power an AC fan and my laptop when I use either or both of them underway for extended periods of time. Again, fused to protect the circuits.

There a plenty of posts on all of this on the forum, and you can get some really good advice from Beacon Marine, as well as any number of websites that sell marine electronics and electrical gear. Try Blue Seas as a recommendation from me, but call Beacon also.

Posted: Fri Apr 30, 2010 7:42 am
by g36
some laptops require more than 12volts to charge/operate. mine has 18v batteries so you will need to check your unit. if you need more than 12volts you could always purchase a small dc invertor that plugs into a cigarette lighter. (walmart,autozone just about anywhere)you could also use it in your car etc. and use the ac adaptor/plug that came with the equipment . it will also charge your other accesories you mentioned with their ac adaptor. their around $20. running what you suggested would not drain that much power. if you think you will operate other items for longer periods then a installed invertor with a larger house bank might be in order. i have 6 volt batteries and a large invertor but i run alot and dont want to have to start my genertor like all my buddies have to just to heat something in the microwave or watch some tv.