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4 - 6 Volt Preposed Setup

May 2, 2012
233
Catalina 310 Toronto
I'm getting close to setting up my 4 - 6 Volt Trojan 105 - 225's. I have used a diagram I picked up form this forum (JK Boston) and modified it to what I think it should look like for my boat. I'm very open to input. Please drop a line in this topic.

Cheers & Thanks
2 Old Pirates
1-jk-wiring-diagram_6v-house.jpg

I've just added a starter battery. Trojan 12 Volt TMX Deep Cycle (85 ah)
 
Last edited:
Nov 16, 2012
998
Catalina 310, 2000, #31 31 Santa Cruz
One: I would run the ground from the charger to the batteries, rather than the engine block, unless that's one of the wires you're asking about size, in which case it should be the same as your hot, #4. Maybe think about going with a 50 A charger, and #2 wire. Even at 40 A your voltage drop for 20 feet of #4 will be about 0.4 V.

Two: Your design has just a single (large) bank. Are you going to add a starter/reserve bank? If so you'll need to work out how to charge it.

Three: your negative from the engine block to the battery bank should be at least 1/0, the same as the supply.

Four: the temp sensor wire is telephone type wire, I think. Minimal current, so size doesn't matter there. I did have to add an extension to mine.
 
Jan 22, 2008
8,050
Beneteau 323 Annapolis MD
I do not agree with post 2, but I'll leave that up to someone else. Are you sure you can input #4 wire into your charger? #6 should do it. No need to change charger. 40 works my 3 x 31 batteries.
 
Nov 16, 2012
998
Catalina 310, 2000, #31 31 Santa Cruz
I do not agree with post 2, but I'll leave that up to someone else. Are you sure you can input #4 wire into your charger? #6 should do it. No need to change charger. 40 works my 3 x 31 batteries.
I think 2 Old Pirates will have 450 Ah with the new bank. Normally you want your charger to be at least 10% of the bank (plus whatever DC loads you run at the same time), so 45 A minimum.

20 feet of #6 @ 40 A and 12 V will drop 0.65 V. Your boat, your choice, but #6 seems quite undersized to me. I’ll bet the PROMariner manual recommends something larger.
 
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Oct 29, 2016
1,743
Hunter 41 DS Port Huron
Will you have a separate starter bank? if not you don't need the 1/2/Both Switch, this could be just like the service switch on/off, the system ground should be the same ampacity as the positive, whats the green #8? ground? if so what is the black from the charge to the negative battery
 
Nov 16, 2012
998
Catalina 310, 2000, #31 31 Santa Cruz
Will you have a separate starter bank? if not you don't need the 1/2/Both Switch, this could be just like the service switch on/off, the system ground should be the same ampacity as the positive, whats the green #8? ground? if so what is the black from the charge to the negative battery
I think both PROMariner and Sterling call for a green wire as a case ground, 1 size smaller than the “hot” wire.
 
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Ward H

.
Nov 7, 2011
3,076
Catalina 30 Mk II Barnegat, NJ
The temp sensor wire should have come with the charger so no need to choose a wire size.
Agree the negative should be 1/0, same as positive. I used the same 1/0 from positive bus bar to alt disconnect, then use #2 to take some of the weight off the alt.
Really need to know the distance of wire run for the charger to properly size the wire. If its 20' as Rob said, I get 2% voltage drop with #2. I wouldn't go smaller.
You fuse for the wire size, not the device. Also, the larger the fuse the lower the voltage drop. I'd use 150A fuses for the alt and charger if you go with the #2 wire.
 
Jan 22, 2008
8,050
Beneteau 323 Annapolis MD
I think both PROMariner and Sterling call for a green wire as a case ground, 1 size smaller than the “hot” wire.
+1to above, and the + wire should be 8 or 6 or 4, dependng on the distance round trip.
 
Nov 16, 2012
998
Catalina 310, 2000, #31 31 Santa Cruz
+1to above, and the + wire should be 8 or 6 or 4, dependng on the distance round trip.
It’s almost 20 feet one way, so 35-40 feet total, unless you move the charger from the factory location. Both manufacturers manuals say #4 wire for the 40 A charger at 30 feet. For the 50 A charger they say #2.
 

Ward H

.
Nov 7, 2011
3,076
Catalina 30 Mk II Barnegat, NJ
It’s almost 20 feet one way, so 35-40 feet total, unless you move the charger from the factory location. Both manufacturers manuals say #4 wire for the 40 A charger at 30 feet. For the 50 A charger they say #2.
I saw that in the manual. Using the voltage drop calculator at genuinedealz.com, 40' round trip of 4 awg will have a .4 volt / 3.4% voltage drop. Wiring for a 3.4% voltage drop seems to defeat the purpose of having a nice programmable charger like the Sterling/ProNautic.
 

Tom J

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Sep 30, 2008
1,956
Catalina 310 Quincy, MA
I'm confused about the operation of the 1/2/both switch. If your intention is to switch between house and starter functions, shouldn't the house load go to #1, and starter to #2, or vice versa, and the battery 1/0 gauge wire to common?
 
May 2, 2012
233
Catalina 310 Toronto
Wow great feed back. There will not be a starter battery. The ProNauticP - 40 is new. It will be put roughly 10ft away from the batteries. With your feed back I'll re-look what has to be done. Back in few hours .... off to the Docs.
Cheers
2 Old Pirates
 
Feb 6, 1998
11,436
Canadian Sailcraft 36T Casco Bay, ME
There will not be a starter battery.
While I see a lot of folks doing this, and carrying a "jump pack", we need to remember that in a well designed cruising system the second bank is not just a "starter" it can be designed to be used as a reserve and a starter battery. A jump pack won't power your vessel for long should a problem with the house bank occur and they can, and do..

Keep this customer in mind when designing a marine battery system:




In other words his "start / reserve" battery, a 125Ah deep cycle G-31, did not save the expensive steaks in the fridge but it allowed them to have navigation DC power all the way to Marsh Harbour Bahamas in some pretty snotty weather.
 
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