Duracell Deep Cycle Group 31 Lead-Acid - 105 AH

[Zil]

My Duracell EGC2 batteries have more liquid above the plates than all but the cheapest 12 volt batteries I have examined. Cheap ones use less lead, so have more room for liquid.

[ramblinrod]

Originally Posted by S/V Illusion

If electrolyte is "much higher", that's operator error, not some design parameter distinct to 12 v batteries.

Assuming battery fluid level is as designed, the geometry speaks for itself. As does the free surface flooding potential to dry larger battery plates. The science isn't a matter of opinion.

In general, the depth of the electrolyte reservoir above the plates is much deeper in a 12 Vdc battery than in a 6 Vdc battery when both are filled in accordance with manufacturers instructions.

[RobMinton]

Originally Posted by Zil

Charging requirements aren't by battery capacity, but by use. Use 100 amp hours from a small bank, or use the same from a large bank. It is still 100 amp hours. The interconnections are the most important in building a bank. Use 2/0 for battery to battery. Then size wiring by the length and amps for the panel feed. Use a voltage drop table.

Thanks for the input. I'll use 2/0 for my battery interconnects and per Blue Sea's chart I'll run 2 AWG (for full panel capacity) as my feed.
My next question: Can I run that 2 AWG from the batteries to the isolator switch and then 2 AWG to the panel? Currently there is 2/0 from the battery to the switch and then an undersized 8 AWG to the panel.
And - should I run that same sized (2 AWG) from battery negative back to the engine block/common ground? Or do I need a hefty 2/0 for that return?

[RobMinton]

Originally Posted by mitiempo

Keep in mind that the 4 GC batteries are also an emergency start bank. I would not use wire any smaller than the start battery has for inter-connects and run to the switch. When I wire such a system that is either 1/0 or most often 2/0 cabling. All battery cables should be the same gauge.

From the switch to the panel for house loads I would use a chart such as Blue Seas has on their site for a voltage drop of less than 3%, figuring the panel is at max. This depends on the loads but for say 50 amps I would use 4 awg minimum.

So If I use 1/0 or 2/0 cable for inter-connects on my house bank, should I use the same gauge to the isolation switch? And then also from the negative of the bank returning to the engine block/common ground?

From the isolation switch I'll run 2 AWG as a feeder to the panel and then 2 AWG from the DC neg bus back to engine block/common ground. Does this sound accurate?

[ranger58sb]

Originally Posted by Adelie

The OP discussed buying 4 Grp-31s, which is not the same as having space for 4 GC2s. GC2s are a different form than Grp-31s and 4 of them may or may not fit in the space available.

FWIW, 4x GC2s will fit in the same horizontal dimension that 4x G31s use. GC2s are slightly taller, so may not fit within the same vertical dimension.

Not sure germane, here...

-Chris

[mitiempo]

Originally Posted by RobMinton

So If I use 1/0 or 2/0 cable for inter-connects on my house bank, should I use the same gauge to the isolation switch? And then also from the negative of the bank returning to the engine block/common ground?

From the isolation switch I'll run 2 AWG as a feeder to the panel and then 2 AWG from the DC neg bus back to engine block/common ground. Does this sound accurate?

If you are using 1/0 or 2/0 for battery inter-connects keep the wiring the same size to the switch, from the switch to the starter, and for the negative to the engine. The feed to the panel - both positive and negative - can be 2 gauge or whatever gauge you decide on.

Just today I wired a simple 2 battery system for a 16 hp diesel with 1/0. It was a small simple boat and for the main panel, which only powers a stereo and lights I used 8 awg, but the run from switch to panel was only 10".