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6v wired in series/parallel

Bob S

.
Sep 27, 2007
1,479
Beneteau 393 New Bedford, MA
what color wire when wiring pos to neg when wiring in series? Does it make a difference?
Also, the runs are short. What size wire between batteries for 6 6v bank. Coming off the ends I’m using 1 aw
 
Oct 29, 2016
1,489
Hunter 41 DS Port Huron
Color is your preference, red positive, black negative, yellow series connection. Size is dependent on the amperes the batteries are capable of and type of cable you are using at a given length and temperature rating. The cabling I did on our Sapphire when converted to 3 pairs of T105's was all done in BC5W-2 Marine Cable - 2/0. Best pricing I could find on cabling was at
www.genuinedealz.com
 
Last edited:
Jan 11, 2014
4,776
Sabre 362 113 Fair Haven, NY
I also used 2/0 cable between the batteries. For the series I black wire with different colored heat shrink, red for the positive side, black for the negative.

Genuinedealz.com is a competitive source. Also check out MarineHowTo.com. MS is selling battery cable now.
 

Bob S

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Sep 27, 2007
1,479
Beneteau 393 New Bedford, MA
Thanks Dave I did buy my 2/0 from RC. I like your suggestion of different color heat shrink along with Daydreamer's yellow. Anyway to make it visually easy to identify. I was also thinking of wrapping a candy cane stripe with white or yellow electrical tape.
 
May 10, 2008
381
Catalina 355 Boston
DD99F2DC-B16C-4A51-900B-BFFE78103110.jpeg
Bob,
I did the same. Used 2/0 between batteries and heat shrink to differentiate.
 
May 10, 2008
381
Catalina 355 Boston
Thanks....Rolls Wet Cells. We are fortunate to have the distributor close by and I’ve always been very happy with the quality.
 
Nov 16, 2012
873
Catalina 310, 2000, #31 Santa Cruz
what color wire when wiring pos to neg when wiring in series? Does it make a difference?
Also, the runs are short. What size wire between batteries for 6 6v bank. Coming off the ends I’m using 1 aw
Any reason to use larger wire between the batteries than leaving them?
 
Nov 16, 2012
873
Catalina 310, 2000, #31 Santa Cruz
Those exposed lugs are protected, they are naked for photo purposes :waycool:
I think they only need to be protected if there’s anything else in the compartment that might cause a short, but probably a good idea regardless.
 

Bob S

.
Sep 27, 2007
1,479
Beneteau 393 New Bedford, MA
Jon
I like those hold downs looks custom made. Great idea! I bought battery boxes that attach at the base but there is still space enough for the batteries to move around inside the box. The boxes have threaded inserts to bolt the cover on.
 
Jan 11, 2014
4,776
Sabre 362 113 Fair Haven, NY
Any reason to use larger wire between the batteries than leaving them?
The larger the wires, the lower the resistance, the lower the voltage loss. Even on the short distances.

The wires should be able to easily handle the maximum load on the battery bank.

What size are the wires leading away from the bank?
 
Nov 16, 2012
873
Catalina 310, 2000, #31 Santa Cruz
The larger the wires, the lower the resistance, the lower the voltage loss. Even on the short distances.

The wires should be able to easily handle the maximum load on the battery bank.

What size are the wires leading away from the bank?
I get that, just wondering if bigger wire for such a short run actually makes any difference.
I’ve got 1/0 leading away from the bank, and just used the same for the jumpers (and all the connections to bus bars, ACR, etc.).
 
May 17, 2004
2,206
Beneteau Oceanis 37 LE Havre de Grace
1/0 has a resitance of .098 ohms per 1000 feet. 2/0 is .078 ohms per 1000 feet. If the jumper is 1 foot long and you're drawing 100 amps the difference in voltage loss is about 2mv. Pretty academic. Having said that, it's a short straight run so there's not really much extra trouble in using the thicker cable.
 

jviss

.
Feb 5, 2004
3,934
Tartan 3800 Westport, MA
so there's not really much extra trouble in using the thicker cable.
I kinda think it is a lot more trouble. You need to buy the thicker cable, and the bigger lugs, and crimp them, and fit them in. The difference from 2/0 to 4 is 17mV at 100 A. Why not just use AWG 4 everywhere, assuming it's not the run to the windlass?
 
May 17, 2004
2,206
Beneteau Oceanis 37 LE Havre de Grace
I kinda think it is a lot more trouble. You need to buy the thicker cable, and the bigger lugs, and crimp them, and fit them in
I was thinking from the standpoint of not needing to run the cable around sharp bends through hidden locations. Good point that it does make the terminals a little harder.
The difference from 2/0 to 4 is 17mV at 100 A
The calculators I find say 2/0 has a drop of 16mV per foot at 100A, but AWG 4 is 50mV per foot. 50mV per foot will add up quickly if running from a high output alternator, starter, or even autopilot motor (admittedly less than 100A, but still not insignificant).
 

jviss

.
Feb 5, 2004
3,934
Tartan 3800 Westport, MA
The calculators I find say 2/0 has a drop of 16mV per foot at 100A, but AWG 4 is 50mV per foot. 50mV per foot will add up quickly if running from a high output alternator, starter, or even autopilot motor (admittedly less than 100A, but still not insignificant).
Maybe I made a mistake. I made a spreadsheet and used published values of Ω/1k'. Let me check.
 

jviss

.
Feb 5, 2004
3,934
Tartan 3800 Westport, MA
Yes, O.K., using good-old George Ohm's Law, I calculated that there's a difference in voltage drop of 17 mV going from 2/0 to 4AWG over one foot at 100 Amps. That's one way. Your calculator must be giving you the round-trip loss for 1', as 2/0 drops 7.8mV over 1' at 100A. (100A * 78E-6Ω = 7.8E-3V).

For 4AWG, you you drop 25mV one way at 100A. So, yes, maybe that is something to be concerned about. If you are charging at high current for any length of time, you should use remote sense of the regulator, and the second batt in a two batt bank would be charged 25mV lower. I don't think it would be a big deal for a momentary 100A load, like a windlass.
 
May 17, 2004
2,206
Beneteau Oceanis 37 LE Havre de Grace
Yes, O.K., using good-old George Ohm's Law, I calculated that there's a difference in voltage drop of 17 mV going from 2/0 to 4AWG over one foot at 100 Amps. That's one way. Your calculator must be giving you the round-trip loss for 1', as 2/0 drops 7.8mV over 1' at 100A. (100A * 78E-6Ω = 7.8E-3V).

For 4AWG, you you drop 25mV one way at 100A. So, yes, maybe that is something to be concerned about. If you are charging at high current for any length of time, you should use remote sense of the regulator, and the second batt in a two batt bank would be charged 25mV lower. I don't think it would be a big deal for a momentary 100A load, like a windlass.
Makes sense. Fair enough.