Daisy chain cable size?

[swimmer_spe]

I will be boondocking for a week. I have several deep cell batteries that I plan to daisy chain them. I know how to do it, but I do not know with what to do it with - specifically the gauge of wire. I can get either 4 gauge or 1 gauge. Can I go with the 4, or is the 1 needed?
Only thing I'll be running is the furnace and lights.

[swimmer_spe]

wolfe10 wrote:
When the OP said "daisy chaining batteries", I ASSUMED they were in the same location and were referring to a couple of feet of wire.

I am the OP. The batteries would all be almost touching. Your assumption is correct.

[valhalla360]

wolfe10 wrote:
When the OP said "daisy chaining batteries", I ASSUMED they were in the same location and were referring to a couple of feet of wire.

If true, it's even less critical. A big part of voltage drop has to do with the length of the cabling.

[wolfe10]

When the OP said "daisy chaining batteries", I ASSUMED they were in the same location and were referring to a couple of feet of wire.

[valhalla360]

wolfe10 wrote:

Can't believe there is enough difference in cost that you would go with smaller gauge wire.

Did a quick check:
- $1.70/ft vs $4.00/ft.

Assuming 15ft X 2, it's an extra $70.

Assuming 5amps, it's a 0.05v drop.

With 1 gauge, it's a 0.025v drop.

Really not worth the cost.

[CA_Traveler]

The 2 inside batteries would be the same and the 2 outside ones the same if the 2 inside batteries are connected in a balanced manor.

However I apply the term balanced to mean all batteries having the same amp draw or charge.

[Horsedoc]

TRaveler - Not trying to beat a dead horse. With that rationale, would the end battery in the sketch be more 'unbalanced' than the other end?

[CA_Traveler]

Wiring calculator: 4ga wire, 12.7V, 15A and 10' one way results in 12.6V at the load. Small voltage drop. Smaller wire could certainly be used.

[CA_Traveler]

Horsedoc wrote:
Why was I under the impression that with the 4 batteries sketched the wire going to the device being powered should be fd from between the two sets of 2? Same with the grounding wire.

IF your referring to the smartgauge link and I understand what you are asking then the 2 inside batteries would supply/draw more amps than the 2 outside batteries, hence not balanced.

[Horsedoc]

Why was I under the impression that with the 4 batteries sketched the wire going to the device being powered should be fed from between the two sets of 2? Same with the grounding wire.

[swimmer_spe]

wolfe10 wrote:
If in doubt, larger gauge is better.

Can't believe there is enough difference in cost that you would go with smaller gauge wire.

About double.

[naturist]

small detail: do not daisy chain a bunch of batteries. Doing so will cause them to carry uneven loads, ware out unevenly and make headaches down the line. If you have a "bunch" of them, connect them all to a single common connection point using carefully measured cables of matched lengths. To be sure, this will have the closest batteries with excessively long cables (or so it will appear), but the resistance will match, they will carry the load equally, and work much better in the long run.

[wolfe10]

If in doubt, larger gauge is better.

Can't believe there is enough difference in cost that you would go with smaller gauge wire.

[Grit_dog]

Use a voltage drop calculator rather than speculation. Easy google solution.
You’ll likely find that you only really need 6 or 8 ga depending on actual lengths if you can keep it relatively short.
If building a permanent system I’d likely upsize a bit more but frankly, you could just as easily round up a few sets of jumper cables even cheapo ones and achieve the same or better results for free.

[valhalla360]

While bigger is better in principal unless you are pulling huge amperage, the improvement is likely to be negligible.

If it's just lights, water pump and maybe a furnace fan, the smaller cables are just fine.