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post #1 of Old 06-02-2013 Thread Starter
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Question Series / Parallel Battery Jumper Sizing

First time boat owner here. 1982 Irwin Citation 40 MKII with 2 previous owners worth of headaches.

To start, I want to go through and ensure all cables are sized correctly and properly fused. I have a basic understanding of how to use voltage drop and ampacity tables, read and re-read Nigel Calder, but cant for the life of me grasp how to size the parallel and series jumpers. I have 4 6-volt 225 (20hr) Crown Deep Cycles. Currently sized with #2. I would like to replace, label, have install new properly sized lugs, adhesive heat shrink, etc. So if I should go bigger now is the time, if I should use #2 then I have some crimping tools to purchase.

How do I calculate the maximum amount of amps that will go through the jumpers? If the total bank is going to be 450Ah @12v should these jumpers be 0/4 and sized as high as I can get to 450Amps? Or does this have to do with the maximum load that will be place on the bank, i.e. the starter? Which I understand the recommendation is for a 200Amp fuse. While I understand bigger is better, being cost efficient prudent for this mariner.

I'll attach a photo of the fun I am about to have.

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