Talk about voltage drop (12v)

Should mention the circuit is roughly 15 feet long and i believe 14 gauge wire feeds it. I tapped in and added another couple feet of 14 gauge wire up to the USB panel.

Its been a couple years but im pretty sure im on a dedicated circuit. I might have tapped into the electric awning. Point being i dont think there is any other load besides the 3amps.

Sounds about right!

What brand is that panel meter ?

Some inexpensive meters are known to be off by 10%.

#14 and 300 watts... is that the fuse? Or is that by design so the inverter will drop out before the fire ensues?

Hmm good point. It's that little red cube. Maybe a 150W.

The meter and LEDs add to the load. There is losses within the unit that draws power.

#10 wire would be much better. I would expect 7.5% voltage drop with 15 feet of #14 and the loads.

300 watts is about 30 amps at the battery 14GA is good for half that at 120 volt and even less at 12 volt due to voltage drop.

Plus there is a voltage drop INTERNAL to the batteries (I do not know how much)

The key to battery/inverter is three fold
One, Keep the leads as short as you can but do not mount the inverter inside the same space as the batteries

Two HEAVY cable for a 300 watt Starter cable works very well and is low cost up to around 750 watts it works well. long about 1000 it might be a bit...er.. anemic

3: for as much of the run tape or wire loom the cables like this ============
Side by side. This is more important on larger inverters.

AND MORE battery never hurts..

DEEP CYCLE batteries work best for House use.
(As opposed to MARINE/deep cycle) note how I use case on those)

I'm seeing voltage drop along the wire correct? Not battery sag? The test is during the day with solar hooked up. Only drawing 3amps.

Why dont I see similar voltage drop while on shore power? Pretend the Led display read 14v. When I apply the same 3a load why doesnt the display show 12-13 volts?

I understand that higher voltage sags less. But we are only talking the difference of 12v boondocking to 14v on shore power.

wopachop wrote:
I'm seeing voltage drop along the wire correct? Not battery sag? The test is during the day with solar hooked up. Only drawing 3amps. Measure the battery voltage at the posts under load to determine wire vs battery voltage drop.

Why dont I see similar voltage drop while on shore power? Pretend the Led display read 14v. When I apply the same 3a load why doesnt the display show 12-13 volts? Your charger can supply many more amps for house loads and battery charging including the inverter amps.

I understand that higher voltage sags less. But we are only talking the difference of 12v boondocking to 14v on shore power.

You stated old batteries - Have them load tested, then consider deep cycle batteries - Marine batteries are a modified starting battery, not so much deep.

Clarification: Your charging sources supply power to all house load FIRST and that includes appliances that can't be turned off like smoke dedectors etc. What's left is used to charge the battery.

150W solar is light. It might be 5A+ in bright direct sun and less otherwise.