I will have to check with the distributor (AER) and see if they would up trade me.

Post edited 11:53 am – September 15, 2009 by Steve Pooler

Speakrdude said:

From the inverter, with the batteries fully charged. 13.19VDC, 1:40PM, Cabin temp 77 degrees, air temp (at the discharge vent) 66 degrees.

1:50, 11.94Vdc, all temps same.

2:02, 11.74 Vdc, all temps same.

2:12, 11.52 Vdc, all temps same.

2:24, 11.11 Vdc, all temps same.

2:36, 10.58Vdc, System shut down……..

Inverter outside temp, extremely warm.

---

Looking at your chart here this morning…Sorry was kinda busy Sunday eve…

Given the limited info I can only go by voltages (no amp reading) and the published amp draw spec.

You are showing a 9.48% voltage drop (1.25 volts) Immediately from standby fully charged, to the unit running…This is way to much drop and is the first indication of too small of wire….Not carrying the load effectively.

Next reading difference 12 min later is 1.68%

Next 10 min is……………………………….1.87%

Next 10 min………………………………….3.56%

Next 12 min………………………………….4.77%

This all points to a wire or connection problem…But also points to high amperage draw over what the specs indicate…I would guess that at startup the voltage at the batteries is much higher than the 11.94 volts you are seeing at the inverter…..And that it would not be 11.94 at the inverter if you had larger wire…It would be much closer to what the batteries reading is at that time….

Do the wires get hot ?

If you do end up staying with this setup…My thought is to increase wire size to #2 cable (both neg & pos) and up battery capacity from 140 to 450 AH. 

#2 wire will have Half the resistance as the #4 being used…Thus supply the inverter a much higher start voltage under the same load…

It's going to take that 3500 btu unit a long time to cool that cabin to a temp that satisfies the t-stat and cycles the unit off…And in a 100 degree day as you mention…The heat leaking into that cabin for sure may be more than the 3500 btu the unit is capable taking out…Thus no cabin temp drop….Maybe even an increase in temp when the cabin is closed up.

It may be well into the night before it cycles, or even begins to cool off…

Not having seen the cabin or boat…I can only guess at all this as well, but my experience and what you are saying is telling me it's all so…

Let me know how things go with the distributor…If you need advise on a unit, I'd love to help, but will need more info…Maybe some pictures of space/s ?

Steve~