One for the leccies.

[sunquest]

Reading all the recent threads on inverters, I decided to install an additional 12v socket in the saloon to power the TV and digibox. As I already had a 12v socket powering an Igloo coolbox, I wired the additional socket in parallel off of it.
Problem. When the coolbox is on the inverter sounds an alarm. when it is off, no problem. Any thoughts other than the obvious to wire seperately?
Thanks Geoff.

 

[mikefleetwood]

Assuming battery capacity, fusing, etc. is adequate - I would suggest voltage drop in the cable is your problem. I don't know the current drawn by the "coolbox", but if the wire is too small/long the voltage at the inverter may drop below the alarm level. Borrow a voltmeter and have a look.

As for a cure/solution, I think you have 2 choices. You can re-wire your entire "domestic" circuit using heaver-gauge wire (I suggest it needs at least 2.5 sq.mm), or you can wire the feed for the coolbox back to the fuse with it's own cables (that way it won't affect the inverter supply).

Good luck!

 

[andyball]

you've got too much voltage-drop, most likely. Many inverters have a low-volts alarm buzzer.


either increase the wiring size to those sockets ( and fit a bigger fuse, or that'll get blmmin hot ), or yep, the obvious, but still take care to fuse correctly & ensure the wires are man-enough.

 

[ccscott49]

You've either screwed up with your wiring. It could be the low inout voltage alarm, check battery voltage.
Parallel is the correct way to wire the sockets. As long as you got the wiring correct, IE. pos to pos and neg to neg for both sockets and the bcable is large enough, sounds to me that it isnt.
.

 

[sunquest]

Thanks everyone It does appear to be voltage drop. I used 2.5mm tinned cable for the additional socket, but the existing cable is smaller probably 1.5mm. I will have to rewire back to the consumer panel, something I hoped to avoid. Geoff

 

[Chris_d]

Its voltage drop alright, best thing is to mount the inverter next to the battery with as short a cable as possible, then extend the 240V side to your load.

 

[mikefleetwood]

I would agree with this, but for one issue. If 240V is only required at one point, it is not a good idea to have "mains" wiring spread about the boat. At the moment, everything is 12V, so wires can be assumed to be "safe". Haveing high voltage wiring as well complicates things from a safety point of view!

 

[st599]

What type of cable de-rating did you use from BS7671?

PS use the correct fuse - don't put a bigger one in to prevent it blowing. The fuse is there to protect the wiring from catching fire. Ensure that there's something in circuit to auto-kill the power within a couple of milliseconds too.