Battery wiring

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Tellico Bob

Tellico Bob

Senior Member
Joined
Nov 14, 2014
Messages
104
Location
USA
Vessel Name
Twilight Time
Vessel Make
1986 48' Californian MY
I have a 1986 48 MY and from day one I have been concerned how the three battery banks were wired. The boat came with a 1989 Carver owners manual and the wiring diagrams made no sense. The leads from the three batteries did not go to the starters but rather to two battery switches. What I found was they were wired to what you would call the output terminals rather than the input terminals and the normal input terminals were connected. I found one wire coming off the input terminal going to the Port Engine starter. From the port engine starter there was a wire to the Gen Set starter and another to the Starboard Starter. From the S/B starter is a wirer to the main house breaker. If the left battery switch is on number 1 and the right switch is off battery number one is the only 12 volt source on the boat. If on number 2 then battery number 2 is the only power source. When I bought the boat both switches were in the Both position. In this position all three batteries were tied together. If you have a 1986 thru 89 MY you should check to see how your boat is wired. I have not been able to find anyone who sees this as the correct way to wire a boat. Will be rewiring everything this winter. FYI
 
Never tested our like that. However I will also be re-wiring this winter so as too have an isolated house battery bank. On our 1988 CPMY the battery wiring is just way to long in length. I plan to shorten the routes in some cases by half. I do agree it is a mess.
 
You are so right. The cable length is way to long for 12 volts. With three banks I thought I had one battery for each engine and one for the Gen Set and I could never figure out where my house power was coming from. My new batteries will be three 8D's and a new bank of three series 31 deep cycle batteries. One of the 8D's will be for the gen set but not connected to the charger. Do you have a wiring diagram for your boat? The one I have I believe is 1989 and if it applies to my 48 MY it should apply to yours.
 
An 8D gen start battery? A Group 27 would likely be large enough.

Tellico Bob said:
You are so right. The cable length is way to long for 12 volts. With three banks I thought I had one battery for each engine and one for the Gen Set and I could never figure out where my house power was coming from. My new batteries will be three 8D's and a new bank of three series 31 deep cycle batteries. One of the 8D's will be for the gen set but not connected to the charger. Do you have a wiring diagram for your boat? The one I have I believe is 1989 and if it applies to my 48 MY it should apply to yours.
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Only information I have is what you graciously copied and sent me. I'll just have to dig into it and then draw out a new diagram.
 
sean9c said:
An 8D gen start battery? A Group 27 would likely be large enough.
Click to expand...

Yep...I thought the same thing. I had a Group 31 Gen start battery and added it to my house bank and put a group 27 for my generator. I felt the 31 was even overkill.
 
Jon, you should have the two wiring diagrams that I have. Take a look you may in for a big surprise. Do you have two battery switches in the salon on the port side and do all your positive leads go there? I was on a Carver built 1991 55MYCP and the wiring is different. A 55 is a 48 with a 7 ft cp add on. If the light is just right you can see the seam. Carver took 2'4" out of the salon which means they took 2"4" out of the engine room when they changed the forward cabin and did away with the bunks.

As for the GenSet starting battery I haven't pulled the trigger yet and a 27 or 31 may work.

Now Capt Tellico Bob
 
Capt. Jon said:
Never tested our like that. However I will also be re-wiring this winter so as too have an isolated house battery bank. On our 1988 CPMY the battery wiring is just way to long in length. I plan to shorten the routes in some cases by half. I do agree it is a mess.
Click to expand...

My new (to me) Marine Trader has three batteries, one for each engine (Twin Volvos and a Westerbeke Gen set). Coming from a sail boat I would have thought there would be a separate set of "House" batteries, but no. I want to set up at least a 400Ahr house bank but I'm not sure how to isolate it from the engine batteries. Also, would I need a separate battery charger (connected to the shore/gen set source) for those batteries? Do you have a simple diagram of how you did it?
 
Boatowner-s-Mechanical-and-Electrical-Manual-How-to-Maintain-Repair-and-Calder-Nigel-EB9780071784061.jpg
 
Hey RTF thanks for the link. I will look into it. Don, to answer your question I like to apply the KISS principal to on board systems where ever possible. You should not need an additional battery charger if you have a three bank charger now. one bank each for your mains and one for the house bank.. If the gen set battery has nothing other than the generator on it and you run it often you should be OK. The four bank system that was used on the 88 and 89 Californians did not have a charger on the gen battery. Do you know where the house is getting power from? If you do just relocate that lead to your new house bank. If you have an as built wiring diagram spend time learning as much as you can about your boat. I have a good friend with a Marine Trader and it is my understanding that no two Traders are the same. Good luck with your project and stay in touch.
 
As a follow up and additional information that I have discovered about this project I offer the following. Capt. Jon, have you started rewiring yet? I did some research on the wire used in my boat. All the battery feeds to the battery switch and then to the starters is 262.6 gauge. This is a wire about twice the size a 4/0 wire and is listed as diesel locomotive wire. Cost about $6.75/ft. The big problem is I have not found anyone who can crimp lug that big. Deka is only good for 4/0. I was told when I bought our Californian that it was over built and now I believe it. Capt. Jon if you have 262.6 wire you may not have to rewire. Long runs will be ok with this wire when you consider the amperage of your starters.
 
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I'm not sure what you mean by 262.6 wire but I just rewired my batteries using 2/0 wire which is 5/8" diameter w/ jacket aprox. 1/2" w/o (about twice the size of 4/0}. I made my own crimper from a pair of bolt cutters from Harbor Freight $11. grinding a notch in each "blade". It makes a nice crimp and where I put the notches leaves room to cut the cable too.
 
Bob, we too have the larger wiring. Must be close to 7/8" overall diameter. I plan on re-using that portion of the system. What I plan to change is the house battery system setup. Currently we have four 8D batteries which are all used for a combination of starting and house battires. My plan is to separate them and use some of the space for a house setup of golf cart batteries. This way I can have both a good starting setup and a large reserve of house battires.

I've already changed the alternators to 90amp units from the old 51 amp Motorola units. Just need time to finish all the rest.
 
Brooksie said:
I'm not sure what you mean by 262.6 wire but I just rewired my batteries using 2/0 wire which is 5/8" diameter w/ jacket aprox. 1/2" w/o (about twice the size of 4/0}. I made my own crimper from a pair of bolt cutters from Harbor Freight $11. grinding a notch in each "blade". It makes a nice crimp and where I put the notches leaves room to cut the cable too.
Click to expand...

Brooksie, did you mean "half the size of 4/0"?

To the OP: have you consulted a marine electrician? I'm not one but I believe you can double up on cables to get the same current carrying and voltage drop capacity that a much larger single cable might have.
 
Carol 5310.01262 | 262.6 kcmil Diesel Locomotive Cable from Allied Wire and Cable, General Cable Distributor

Nope that 262.2 is heavy stuff with a 2,000V rating. It is slightly larger than 250MCM which is itself a size larger than 4/0. So 262.2 is several jumps up from 2/0.

I note the stranding is coarser than the TEW that most "boat cable" is made of [so would be stiffer] and the insulation is a lower temp rating of 90oC vs 105oC. However it would be good stuff and if you already have it and it is in good condition I expect it should serve well.

No I have never seen or used it. Just spec. looking.
 
Many of the older Taiwan boats have wiring that is coarse stranded.....mine had/has several cables of it up in the 1 ga to 2/0 ga (it metric) without any issues of strands breaking after 30 years of pretty steady cruising.

I think once you get over 2 ga size wire, and it is properly supported, using the finely stranded wire sure seems less important other than it is less flexible. Heck, sometimes just the brand and the insulation affects flexibility nearly as much.
 
Tellico Bob said:
With three banks I thought I had one battery for each engine and one for the Gen Set and I could never figure out where my house power was coming from. My new batteries will be three 8D's and a new bank of three series 31 deep cycle batteries. One of the 8D's will be for the gen set but not connected to the charger.
Click to expand...


I think it's been fairly common that production boats often come with "shared" batteries, i.e., for both engine and house functions. All three of our boats have been that way. Last two (including our current boat), twin engines, came with three banks. One each for engine start/half-house, one for genset.

On our current ride, the starboard bank starts that engine, runs half the house, and also runs the electronics load on the bridge. The port bank almost ditto, but the third load is bridge electrics (nav lights and so forth). So far, that kind of system has been reasonably reliable.

Our two large banks could have been single 8Ds, but the builder delivered with 3x G27s (or maybe G29s) each. I've since morphed those to 3x G31s each side... since schlepping the individual weights is slightly easier, and I end up with more Ah per bank (~300 each) than a single 8D would provide anyway.

I've since figured out I can replaced the 3x G31s on our starboard bank with 4x golf cart batteries, to increase that bank to about 440 Ah. (Follow-up to our recent inverter/charger installation, on that bank)

Our genset battery is now a G34, not on a charger... no problem so far... but I'm intending to start carrying a short set of jumper cables. :)

-Chris
 
psneeld said:
I think once you get over 2 ga size wire, and it is properly supported, using the finely stranded wire sure seems less important other than it is less flexible. Heck, sometimes just the brand and the insulation affects flexibility nearly as much.
Click to expand...

That reminds me... and not sure whether relevant or not... but when we were doing our inverter/charger installation, the system called for a big fat (green) grounding cable. Near as we could find, battery cable only comes in yellow or black. (Maybe red? didn't check that...) Not green, though.

Anyway, I found some green welding cable, and sizes could have worked... but research suggested that stuff isn't as well insulated against a saltwater environment, and strands could become brittle over time... something like that... so it wasn't recommended for boat use.

We went with black, with green tape at each end.

-Chris
 
ranger42c said:
That reminds me... and not sure whether relevant or not... but when we were doing our inverter/charger installation, the system called for a big fat (green) grounding cable. Near as we could find, battery cable only comes in yellow or black. (Maybe red? didn't check that...) Not green, though.

Anyway, I found some green welding cable, and sizes could have worked... but research suggested that stuff isn't as well insulated against a saltwater environment, and strands could become brittle over time... something like that... so it wasn't recommended for boat use.8

We went with black, with green tape at each end.

-Chris
Click to expand...

I have heard both sides of the welding cable story.

Based on my personal experience around welders and using personally using welding cable, I believe that welding cable lives in 10 times a harsh environment that my battery cables live in.

While true that for many of us, the difference in price for premium marine wire versus anything else, especially for short runs of battery cable, isn't enough to get ecited zbout.

But for someone who wants to use some wire that is not commonly available as boat wire, for a single project and is carefully with installation, I doubt it is a huge mistake as long as it meets the minimum safety requirements.
 
It appears that boat manufactures lack common sense. I have three battery banks but they are tied together. I can select battery #1 but it than becomes the only battery for starting both engines and the g/s and the house. Or I can select battery #2 or #3 and you have the same situation as if I select #1. Or I can select #1 and #2 or #1, #2 and #3 but nothing changes. Everything goes through the Port Engine. I believe one of the batteries is also wired to the house breaker and there is no way to turn the power off to the breaker. All power feeds to the port eng and then to the g/s and to the starboard eng through the port eng. A typical run from the battery to the starter is about 30 ft. When I get done rewiring battery to starter will be between 5 and 8ft. Since 250AWG is about the same as 262.6 DLC should connectors that are available for 250 work on 262.6?
 
Just a few quick bullet points here:
-There is no need for wire that is twice as thick as 4/0 wire on a boat your size. If there is, someone please tell me what load you are running that needs this size cable, because I can't think of one.
-While welding wire can be used and is sturdy for the environment, the difference in the two is the fire rating of the insulation. You can use it (and lots of 80's builders did), but it isn't ideal.
-Unless you are using very high-priced floor buffing or forklift batteries, there is no such thing as 8D deep cycle batteries. So while you think you have a big house bank, fact is, it's just a big starter bank. Be careful charging and discharging it because you will shorten the capacity and lifespan quickly. You can read up on it on MaineSail's site: What Is A "Deep Cycle" Battery? Photo Gallery by Compass Marine How To at pbase.com

That is all :flowers:
 
I have to work with what I have and that is all 262.6 DLC wire. Because it is so big I don't have to worry about amp load or voltage drop but I do need to isolate a battery were eng. I will be using 8D's for my mains, S31 cranking for my gen/set and 3 s31 DP for the house. Right now I have three banks and when done I will have four.
 
Tellico Bob said:
I have to work with what I have and that is all 262.6 DLC wire. Because it is so big I don't have to worry about amp load or voltage drop but I do need to isolate a battery were eng. I will be using 8D's for my mains, S31 cranking for my gen/set and 3 s31 DP for the house. Right now I have three banks and when done I will have four.
Click to expand...

Well, it seems you have a plan then.

When you say you have to work with what you have, do you have this wire lying around and feel like you have to use it? Was it free? Are you not wanting to pay for new? It just seems like you are using unnecessarily large wire for this. If you can find lugs, will you even be able to stack two on the battery terminal and have a lock nut still thread on?

What I have learned in all the research I did when completely overhauling the DC systems of both of our boats was that simpler is better. Why not go from three banks to two? (I did) Far fewer switches, wires, and crimping cable ends. Fewer charging hassles. Fewer points-of-failure. Easier design and understanding for, not just you, but future owners. One bank is a house made of actual deep-cycle batteries (that don't weigh 130# :)), the other starts engines and is made up of dual purpose batteries that acts as a house backup.

I am not trying to be argumentative here. I just want you to expose you to a little bit different thinking here.
 
I am looking to hear a down side to using this in place, existing 262.6 wire. Please go back to my first post. The existing 262.6 wire has terminal lugs attached but when I finish the rewiring each run will be very short and I will be cutting the existing cables and installing new lugs. Each engine and the gen/set will be on their own battery and the house will be a separate battery bank. My three bank charger will be connected to the engines and house banks. The genset will not have a charger.
 
Ok the job is done. I was able to move some of the wires around and reconfigure the two rotary switches. Deka gave me a great price on all the batteries and provided the jumpers to connect the three G31 house batteries. I pulled the old electrical tape off all the wire lugs, cleaned and then rapped them with silicone tape. Everything seems to work better. I didn't need to add any new battery lugs so crimping was not a problem. The 262.6 cable is made up of 648 fine strands made into 24 bundles. After thirty years it is still very flexible. I now have two 8D's one for each engine but through the battery switches I can combine them if needed. I plan on adding a battery isolation relay that will allow me to charge the house bank via the engine alternators when cruising and the generator is not running or needed but will not allow the house bank to drain the engine cranking batteries. Thanks to everyone who added to the conversation it has been a fun winter project.
 
Tellico Bob said:
Ok the job is done. I was able to move some of the wires around and reconfigure the two rotary switches. Deka gave me a great price on all the batteries and provided the jumpers to connect the three G31 house batteries. I pulled the old electrical tape off all the wire lugs, cleaned and then rapped them with silicone tape. Everything seems to work better. I didn't need to add any new battery lugs so crimping was not a problem. The 262.6 cable is made up of 648 fine strands made into 24 bundles. After thirty years it is still very flexible. I now have two 8D's one for each engine but through the battery switches I can combine them if needed. I plan on adding a battery isolation relay that will allow me to charge the house bank via the engine alternators when cruising and the generator is not running or needed but will not allow the house bank to drain the engine cranking batteries. Thanks to everyone who added to the conversation it has been a fun winter project.
Click to expand...

Cool... You might, however, want to consider routing the alternators to the house and use the ACR to charge (top off) the starter batteries. Staring engines doesn't take that much from starter batts, but a day or two on the hook will. It is more accepted to use the alts to replenish the house batteries when you are underway, saaaayyy, between anchorages. :) At least from all that I have learned about the subject.
 
Tom.B said:
Cool... You might, however, want to consider routing the alternators to the house and use the ACR to charge (top off) the starter batteries. Staring engines doesn't take that much from starter batts, but a day or two on the hook will. It is more accepted to use the alts to replenish the house batteries when you are underway, saaaayyy, between anchorages. :) At least from all that I have learned about the subject.
Click to expand...

I have organized my ME charging this way and can attest that it works very well.
 
Tom.B said:
Cool... You might, however, want to consider routing the alternators to the house and use the ACR to charge (top off) the starter batteries. Staring engines doesn't take that much from starter batts, but a day or two on the hook will. It is more accepted to use the alts to replenish the house batteries when you are underway, saaaayyy, between anchorages. :) At least from all that I have learned about the subject.
Click to expand...



Yeah, I would also second this. Direct all charging sources to the house bank and use an ACR, Duo-chargers, or Echo chargers to charge the engine start batteries.
 
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