Increasing the house bank, adding 2 additional group 31 AGM to bring the total to 4 house with a combined 420 amp hours my question; cable size wiring in parallel, with the longest run's of 12" to 18" max, can i use the ready made 4.0 cables or should i go with the heavier 2.0 cables ??
Thanks much,
Capt. Ron
S/V Wind Dreamer
40.5 Legend
What size is the rest of your high amperage wire? How is the boat wired? At a bare minimum it should match what is already there but what is there may already undersized.. Unfortunately Hunter and many other US builders undersized this wire for years with some boats using high amperage starter wiring as small as 4GA. Today those same builders are using 1/0 and 2/0 wire and often times with shorter circuit lengths.....
I don't know what 2.0 wire or 4.0 wire is but 4/0 (0000) wire is much larger than 2/0 (00) wire. 2GA (not 2/0) is larger than 4GA (not 4/0) but 4GA is really pretty undersized for a 40 footer, especially if the vessel has a windlass.
Here are some minimum manufacturer suggestions for battery/starter cable from Westerbeke & Universal.
Universal / Westerbeke BATTERY CABLE REQUIREMENTS (wire length round trip)
2GA = 8'
1GA = 10'
1/0 = 14'
2/0 = 18'
3/0 = 22'
4/0 = 28'
They no longer even suggest 4GA.. It does not take much to have 14' of wire circuit length even with batteries just a few feet from the engine. Remember, these numbers are wire lengths
along the conductor not an
as the crow flies distance.
The last Hunter 40 I was on, was from the early 90's, and used 4GA wire in a circuit approaching 25'. Owner was on his third starter motor in 6 years and peak low voltage at the stater was sagging to 4.2V during cranking. I would suggest using the Westerbeke guidance as a bare minimum and this means the entire round trip
circuit length...