I need help with an electric issue.

[Dom]

This post extends off of this thread: https://www.reef2reef.com/threads/a...iple-issues-in-my-tank.1091454/#post-13208215

The equipment rack for my tank has two circuits.

The first circuit (a mounted power strip) plugs directly into the utility (wall) and is where I plug in all non-mission critical equipment in the event of a power failure. On this strip, you will find display lights, utility lights, and dosing pumps.

The second circuit has battery backup for mission critical equipment: main return pump, power heads and skimmer.

​

This circuit begins with a new GFI outlet. From there, it goes to a 15 amp auto transfer switch. On one side of the switch is utility power, and on the other side, a deep cycle lead-acid battery with a 500watt inverter connected.​

​

Here's the issue; when I pull the plug from the GFI to test the backup, it switches over as it should. But then within a few minutes, the breaker on the battery trips. When I plug back in to utility, everything comes back on as it should. Then I can reset the breaker on the battery.​

​

I thought the issue may be the ATS, but still tripped the battery breaker when I plugged the circuit directly into the inverter.​

​

The inverter is rated at 500 watts, and KILL-O-WATT reports that the circuit is drawing 172 watts.​

​

I have the same inverter which is rated at 1000watts. Does it make sense to try a different inverter? At this point, I feel it is the inverter or something with the battery bank.

Feeling a bit lost with this one and am calling on members with electrical background/experience to help set me in the right direction.

Thank you,
Dom

​

​

​

​

​

​

​

 

[Reefering1]

Try the bigger inverter...

 

[Dom]

Try the bigger inverter...

I will. But if it works, what does that tell us? I'm only drawing 172 watts from a 500 watt inverter, so it isn't that the inverter is under powered. I would conclude that there is something wrong with the inverter.

 

[Reefering1]

Draw/ send a schematic of how you have it wired...

 

[Dom]

Draw/ send a schematic of how you have it wired...

Working on it.

 

[Dom]

I know... amateur. But I think it gives a clear idea.

 

[Reefering1]

So the inverter is on and ready at all times? Or turns on one power fails?

 

[ThisIsTheWay]

What size (Amp rating) is the battery breaker?

Watts = Amps * Volts
Watts/Volts = Amps

172W at 120V is ~1.43A (172/120 = 1.43)
172W at 12V is 14.33A (172/12 = 14.33)

It sounds like the 172W of power you're pulling from the battery through the inverter is juuusst enough to blow a 15A circuit breaker if there are fluctuations or a little power loss from going through the transformer.

I could be totally off but based on what I know that's my first suspect.

EDIT:
If this is the issue, then a larger inverter won't solve your problem. The issue it sounds like is when you go from 120V down to 12V your amperage goes up a lot for the same watt output (ohms law). In this case you'd be close to 15A of current between the battery and inverter.

 

[Dom]

So the inverter is on and ready at all times? Or turns on one power fails?

Inverter is on at all times.