battery question

[ezmac]

I have a 17ft Century center console that I fish lakes and inshore salt water, It has three batteries. One group 24 deep cycle that is the house as well as the battery used to run the 90hp Yamaha. The other two batteries are group 27 deep cycle wired in series to power the 80lb thrust trolling motor. All the batteries are under the center console. What I would like to do is transfer the power requirements for the bait well, horn, bilge pump, running lights, radio, 12 volt accessory plug, depth finder and anything else I can come up with to the trolling motor batteries. I'll leave the console gauges on the starting motor battery. I need to drop 24 volts to 12. I am not worrying about charging them as I have a three bank charger for that. I'm only out 6 or 8 hours at a time. I will mount a new buss plate to transfer my connections. My question is about how many amps I'll need to power all that stuff. I'lI use a converter I guess so would 20 amps output be enough or should I have 30? I am completely lost when it comes to electric requirements. Grateful for any help.

 

[joeanna]

don't guess, add up all the max amp ratings of each item that will be on that circuit, then add up the max amount of add-ons current draw for that accessory plug that you may use and add that to your previous sum, that could/would will be your currant draw on that circuit. then add a little more for a safety margine That is the only way to be sure of what your currant rating will be.

 

[Silvertip]

You have a 24 volt system consisting of two 12 volt batteries. Tap your 12 volt accessories into the battery that has the 24 volt ground connection on it. Presto - 12 volts and no converter needed. Now you say that will discharge that single 12 volt battery more than the other. Yes it will. But using a 24-12 volt converter will still suck the same amount of juice out of the system thus cutting down your troller run time as well.

 

[ezmac]

Will a converter discharge both batteries equally? How much is a little more? Not knowing what I will be adding on or what the running lights draw or any of that other stuff, can I just mount a 30 amp and be done with it? I don't think my trips are long enough to drain those two big batteries. I just want to take the load off my house battery and tap into the reserves of my trolling batteries.

 

[ezmac]

joeanna, silvertip thanks. I owe you both a beer.