Wire Gauge Required Question

smkettner wrote:
I do not think you will see amps drop from 16 to 8 in one swoop at Vabs.
Controller will hold voltage at Vabs while the battery tapers the current.
Morningstar also reverts to PWM at some point.

I somehow see another test coming ;)

Thanks all, for the great help with this! Tip on speaker wire noted!

Smk, you might be right. I found a note from last April where I took readings with the four 6s and 20a of solar on PWM-all panels tilted South but not on swivels. Starting at noon (1315)

time, amps, battery volts, est SOC from Trimetric

1315- 20.5 , 12.6 , 86.4
1330- 19.8 , 13.4 , 87.5
1500- 16.7 , 13.6 , 92.6
1615- 13.4 , 13.8 , 96.3
1715- 7.6 , 13.9 , 98.6
1730- 6.3 , 13.9 , 99.0

(Normal battery charging is about 3 amps per battery at 14.6v for 97% so that would be 12a. The SOC estimates above may be a bit high, but it fits well enough for being in the ball park for this purpose.)

That controller starts controlling at 13.9v even though its Vabs is 14.6v, so that plus a lower sun and worse angle to panel by then accounts for the drop in amps between 1615 and 1715.

So we'll just have to see what that Eco-W MPPT does, but it looks like it won't matter much if it does drop to 8 amps at Vabs.

It also shows that in real life, you can't easily tell if you are "losing" any amps (from voltage drop say) at any point other than when you should be getting your max amps. That is only during part of the day. (a longer part if you swivel the panels)