Inverter Keeps Resetting Due to Voltage Drop

[CLi87]

Hi all,

I'm currently restoring a 1986 Bayliner Contessa 2850 and I'm currently trying to hookup a new mini fridge to replace the old one. I chose not to buy an expensive marine fridge with both AC/DC and instead just got a cheap $80 AC fridge. So I figure hookup the DC lines to a 700 watt inverter and then plug my mini fridge into the inverter. I can turn the inverter on no problem, but when I plug in the fridge, the surge will cause the voltage to drop from 13v to 7v up and down. I know the inverter is good because i've tested the setup with a standalone battery. The DC pos/neg wires go to a fuse panel behind the dash, and then from the fuse panel the pos wire goes to a main relay on the engine and the neg grounds on the engine block. I cleaned all the grounds on the engine when I first got it. I've checked for resistance and it's reading .7-.8 ohms, I'm using quite the long wire to test for continuity from inside the boat to the engine bay though. At least point it's beyond my electrical diagnostic abilities and I'm hoping someone here with more experience may be able to help me out

 

[alldodge]

Guess I'm missing something, and I'm old so it happens often
An inverter takes 12VDC and changes it to 120VAC. So why connect a AC/DC fridge to an inverter on the DC side?

 

[CLi87]

Guess I'm missing something, and I'm old so it happens often
An inverter takes 12VDC and changes it to 120VAC. So why connect a AC/DC fridge to an inverter on the DC side?

I didn't get an AC/DC marine fridge, lol, I got a cheapo $80 AC mini fridge from walmart and put it in, that's why I need to connect the original DC wires to an inverter then connect the AC mini fridge to the inverter.

 

[GA_Boater]

How much draw by the fridge on startup? What dorm fridge?

 

[roscoe]

Are you doing this with the engine running? or off?

Maybe try it with the engine running.

Maybe will need a multiple battery setup?

Maybe need an electrical expert like "silvertip".

 

[dingbat]

Running a fridge is asking a lot of a 700W inverter, particularly if the compressor is capacitor start which I suspect it is.

 

[Scott Danforth]

a few things

you need a bigger inverter, my guess a 1500 watt minimum, probably a 2000 watt. those small fridges will draw 13 amps when the motor first starts
and
you need to run dedicated wiring to a dedicated circuit breaker going straight to the battery. I doubt there is a run to the helm heavy enough for the load you plan on running.

the former multi-voltage refrigerator would have had much less current draw than a cheapy $80 fridge because it was designed for RV/Boat use. Dorm fridges are intended to be connected to the grid, hence the cheap price

 

[CLi87]

Thanks for the replies guys, I'm going to run a straight pos/neg wire from the inverter directly to the battery, seems like this is the best solution as it seems I'm getting power loss from the inverter to the battery.

I know the inverter is powerful enough to power the small Galanz 0.8 amp mini-fridge as I had it working when I connected the inverter to a standalone small 20Ah motorcycle battery.

 

[The Force power]

Thanks for the replies guys, I'm going to run a straight pos/neg wire from the inverter directly to the battery,

Make sure to use #1 gauge battery-cables if the length is more then 5' that you need to run

Also, like a few pointed out already the Inverter maybe /is too small most inverters post max out-put & not constant out-put
even if it works the under powered inverter won't last

 

[Scott Danforth]

that in-rush when the motor starts is more than 700 watts. the 0.8 amps is not starting current.

 

[CLi87]

Hey guys, I was thinking to make things easier, I could mount a 2000w inverter I have in the engine bay next to the batteries, then run an extension cord underneath the boat to the shore power connector, my inverter only has 15 amp plugs so I would use a 15 amp - 30 amp adapter. Would this work? and any potential fire or overheating hazards I should be wary of?

 

[sam am I]

I know the inverter is powerful enough to power the small Galanz 0.8 amp mini-fridge

Mini's can vary in "run current" from around 80 watts to around 200/300 watts HOWEVER, as mentioned above a few times, it's the "startup current" that is most likely tripping your inverter (unless you don't have heavy enough wires, see below, under voltage). As a general rule of thumb "startup current" is 6X the "run current".

Inverters can trip off with BOTH over current and under voltage. Under voltage can be caused by too small (or too small of battery for a given load) of wire gauge between the battery and the inverter. You could be experiencing more of one and/or a bit of both situations depending of the fridge, your wiring and the invetrter spec's.

I could mount a 2000w inverter I have in the engine bay next to the batteries

NO! Not sure i'd recommend anyone put a inverter (or anything of the like) in a engine bay (especially not next to battery's) unless it was specifically designed and approved to be intrinsically safe.

 

[CLi87]

Where would be a good place to mount the inverter? I wanted to keep it as close as possible to the batteries so the cable length would be short

 

[sam am I]

Sometimes ya just have to bite the bullet...........I ran about 15' (30' there and back) of heavy wires and installed my inverter in a nook just aft of the cuddy under the helm area.....Lots free of air etc.