Old battery cable.

[Ed Schenck]

Really do appreciate the comments and help. But Stu, you can't be agreeing with me!
To clarify maybe, I do have a microwave and have run it with my inverter for twelve years. I do have a windlass but it is manual and I am only 70 so no plans to upgrade.

 

[Stu Jackson]

But Stu, you can't be agreeing with me!

Oh, yes, I did and may do so again! And again...and again. I don't even have a manual windlass. Maybe that's what makes those #4 wires so attractive.

 

[Maine Sail]

do you suppose was the reason for Universal disallowing #4 at, say, 6 inches? I mean, I believe you when you say you witnessed the slow starting, but how come?

Probably because the average starting loads exceed the wires ABYC max "ampacity rating".. Even if the voltage drop might be okay all wires carry and ampacity rating for inside and outside engine spaces and add corrections for the temp rating of the jacket.

Inside engine spaces

105C wire, 4GA, the max ampacity is 135A
90C wire, 4GA, the max ampacity is 110A

105C wire. 2GA, the max ampacity is 175A
90C wire, 2GA, the max ampacity is 145A

105C wire, 1/0, the max ampacity is 240A
90C wire, 1/0, the max ampacity is 200A


Many builders used to use less than 90C wire...


This is 2/0:

You can buy 1/0 105C tinned marine wire for $4.39 foot and #4 for $1.59 ft. If you needed 30' the price difference is well under $85.00 and you can properly fuse it. You can't technically fuse 4GA to current safety standards if you might start your engine off that bank. Re-terminating old battery cable is generally not a good idea as it is often oxidized and as a result makes horrible electrical connection. This oxidation is very hard to clean off all the stranding on large GA wire so you maintain your stated wire GA carrying capacity.

I have not kept track of it but I know I replace or have re-built many more starters that are fed from small GA wire than ones fed from larger GA wire. I have one off a Universal diesel at the shop right now being re-built. The cable was #4 75C non-tinned, with incorrect stranding, and the starter was seeing a low of less than 7 volts from a healthy bank. The cables are corroded, were poorly crimped from the factory, un-tinned lugs and undersized. This will be the second time, that I and the current owner know of, this starter has been re-built or replaced. Even after all connections were clean, including engine ground points I was still getting under 8V at the starter lug. Starters really don't like that. The battery wire on this boat will be replaced on Tuesday with 1/0 wire. Along with the re-built starter the banks will then get over current protection.... With this bank, I've installed similar banks/cables, I fully expect to see a low of about 10.5 - 11.5 volts at the starter as a low..

 

[Ed Schenck]

Looking at my plan(below) then is there any piece of it that could be lighter wire? I am leaning toward all 1/0 cable. I have had the battery switch apart but can't remember, how hard to get 1/0 in there? I think I'll go to the boat this week and bring it home.

 

[John Nantz]

Ummm..... what are you using for a tow vehicle?

Not to change the subject, but:

I think I'll go to the boat this week and bring it home.

What will you be using for a tow vehicle for that 37-footer?

Got a somewhat "spam" email a couple days ago from a friend about news paper headlines that were really comical and after reading this post things fell into place and I just couldn't resist.

 

[Maine Sail]

Looking at my plan(below) then is there any piece of it that could be lighter wire? I am leaning toward all 1/0 cable. I have had the battery switch apart but can't remember, how hard to get 1/0 in there? I think I'll go to the boat this week and bring it home.

Ed,

If you go 1/0, or what ever you choose, these are the wires that are critical to size the same...


Parallel Jumpers
Series Jumpers
Bank #1 to switch position #1
Bank #2 to switch position #2
"C" post of switch to starter stud
OR
"C" post of switch to positive buss bar (items off buss would be sized accordingly, starter can be fed off a DC pos buss bar as long as it is "switched"..)



Your DC panel would be sized to what it needs keeping in mind that nav lights electronics and other essential equipment should be sized for a max 3% voltage drop. An inverter wire would be sized for what it needs and pulled off the POS buss bar. A windlass the same.

 

[Stu Jackson]

Not to be contrary, but the West Marine combiner literature and install instructions suggest the use of much smaller wire between the house bank and the reserve bank. I have the 130A combiner, which, it appears, so do you, Ed. If one designs for loads, as Maine Sail suggests, quite correctly, if the reserve bank rarely needs a "heavy" charge when combined, could the combiner manual suggestion of "3 foot minimum #6 wire to connect the contactor on the battery combiner to the positive connection of the battery system." So, does #2 or 1/0 need to be applied in Ed's sketch?

 

[Maine Sail]

Not to be contrary, but the West Marine combiner literature and install instructions suggest the use of much smaller wire between the house bank and the reserve bank. I have the 130A combiner, which, it appears, so do you, Ed. If one designs for loads, as Maine Sail suggests, quite correctly, if the reserve bank rarely needs a "heavy" charge when combined, could the combiner manual suggestion of "3 foot minimum #6 wire to connect the contactor on the battery combiner to the positive connection of the battery system." So, does #2 or 1/0 need to be applied in Ed's sketch?

With the Yandina/West combiners you should adhere to the wire lengths and GA. This is because it helps limit the potential current flowing through the relay. I suspect the Blue Sea relays are more robust so no hard and fast wire GA limits.

There was a Yandina Combiner 150 on our boat for roughly 2700 engine hours and a 5 year 24/7 world cruise. The boat has solar so it was subjected to 365 days per year of combining and un-combining. It still works fine. I do install Blue Sea ACR's these days instead because I prefer the way they wire and mount. The studs on the Blue Sea are more robust 3/8" studs which gives a lot more options when wiring them..

 

[John Nantz]

Inverter cable and battery cable sizes

Ed - recently you mentioned there is an inverter. Some of these can come with fairly large cables (furnished or specified) as well as limitations on length. Thinking about the whole system, battery terminal to the inverter, one should do a calculation of the round-trip wire/cable size requirements.

It's amazing how a few inches here and a few inches there really add up. I'm talking about batter terminal to fuse, fuse to switch, switch 1 to switch 2, switch 2 to, say, inverter, inverter to ground buss, ground buss back to battery terminal.

Inverters appreciate good power and wasn't there a microwave too? So do they. If the microwave kinda "groans" a bit or sounds less enthusiastic than when it's hooked up to shorepower, those are pretty good signs that the cable size and length might like a visit.

What was said about the boats of our vintage coming from the builder with #4 cables is really true. That's what ours came stock with, along with a couple small group 24 "house" batteries. Back then the builders were just coming on strong with electrical systems and the panels were going from glass fuses to circuit breakers. The other thing of interest is the battery selector switch because many of them were Perco and didn't have the ampacity of what is available today from the likes of Blue Sea.

Once one starts upgrading one thing, say the battery banks, it kinda causes a ripple effect where one thing leads to another. What about checking what the battery selector switch(s) is rated for against the proposed system? That would be interesting.

By the way, I'm glad to help as long as it isn't costing me any of my money!

 

[Ed Schenck]

Thanks for all the help guys. Good point about the switch John. I am going to bring it home this week. And the Heart Inverter/Charger does have much heavier cable. You can see the ground cable here going to the shunt. Positive is the same size naturally. My combiner/fuse/bus panel will mount just to the right of that shunt. The Charger is within a foot of that. The starter battery will be right under the shunt. The back of the battery switch is 12" forward of the panel.

 

[Maine Sail]

Thanks for all the help guys. Good point about the switch John. I am going to bring it home this week. And the Heart Inverter/Charger does have much heavier cable. You can see the ground cable here going to the shunt. Positive is the same size naturally. My combiner/fuse/bus panel will mount just to the right of that shunt. The Charger is within a foot of that. The starter battery will be right under the shunt. The back of the battery switch is 12" forward of the panel.

Ed,

There's your answer. Everything should at least be sized to deliver the design current and min voltage drop to that inverter. It will greatly help your starter too. As it is now you're feeding what looks like 1GA - 2/0 wire with 4GA..

 

[John Nantz]

Hey! Wait a minute!

Thanks for all the help guys.

I'm not through! We haven't killed this project yet!

In my previous job I had kinda fun reviewing Government proposed projects and often wound up "killing" them because the cost/benefit ratio skyrocketed. Kept finding "little things" that the Project Managers either didn't consider or tried not to include because it would drive the cost of their project up and it wouldn't get funded. I really don't mean to do that here, but .... just one more little thing.....

What about ..... ahem, let me rephrase that, let's see.... how can I word this? Dang, there's no easy way.

What is the situation with the batteries and the battery boxes, or battery space? That is, is the inverter/charger in the same space? Or some other electrical item that can cause sparks, like maybe the battery selector switch? If so, that could be a problem.

Our little Freedom 10 puts out 50 amps when charging and that's enough to gas the electrolyte in the batteries. I located the inverter in the lazarette which is separated from the battery compartment because of the gassing when the batteries are being charged. Also, the alternator is capable of putting out in excess of 100 amps when it first starts and is cold. It was actually bench tested at over 130 amps when cold and when new. Doesn't do that much anymore because of it's age, though. It's a 70 amp Balmar.

So, just something else to think about....

I'm into these little details because I've seen a deep cycle battery that had it's top blown off due to a spark. Seems that a battery cable was disconnected while it was being charged with a battery charger and it (the battery) sure didn't look very pretty although the plates actually looked pretty good. Don't know if there was a fire or not but it didn't look burned or melted.

Anyhow.....

... Let's see, Christmas is right around the corner and is it snowing there yet? I've got this for you (to the tune of Partridge in a Pear Tree):

10 feet of black cable,
9 feet of yellow cable,
8 battery lug covers,
7 (geeze, can't think of anything - help!)
6
5
4
3
2 battery selector switches, and a
brand new e-lec-tri-cal $ystem.

(always willing to help - with someone else's time and money, of course)
Oh, and thank you for thanking us for, ahem, "helping."

 

[Ed Schenck]

Appreciate the deep thinking. For twelve years that locker had four maintenance free batteries right in there with the Heart Freedom 20. Now the only battery will be an AGM start battery. The two new golf cart batteries will be fifteen feet forward in the bilge.