12V charger blows USB car plugin

Chief RA · Apr 8, 2015

Boat fuse for cigarette lighter outlet. Chief

Dannotti · Apr 8, 2015

besides checking the 12v breaker for the helm outlet< I don't have any ideas? Our helm outlet on our hunter33 has its own breaker on 12v panel. Does anything else 12v work when plugged into helm outlet?

Maine Sail · Apr 8, 2015

carlager said:
I have installed a 12V car charger in the cockpit in order to charge our iPad mini when using it as a plotter.

The iPad mini loaded fast to 100% battery using a USB lightning cable on a USB car plugin (12-24 volt on 2,4 A) and a - both approved by Apple.

When I unplugged the USB car plugin and plugged it back again it had stopped working (no light and no charging)

Any Ideas what is wrong ?

* If it charged correctly once, in this same socket, then it should not be a polarity issue.

* Positive is the center pin and negative is the shell of the socket. You will often blow a USB charger plugging it into reverse polarity, especially cheap Chinese ones...

* Many of these USB 12V outlet chargers are pure unadulterated junk. I have seen too many of these that fried to shake a stick at. I used to have a box full of dead ones. The best & most reliable USB charger I have found is the Scosche reVolt USBC242M 12W + 12W.

* Also be careful with non Apple cables. Some that claim to be "certified" may only really be certified for a cell phone not an iPad.

* Obviously check the fuse for the 12V outlet and wiring...

* A USB charger in a cockpit is not going to be long lived, especially if you are in salt water.. I would suggest charging the iPad below then using it on battery power in the cockpit, unless an absolute emergency....

* Test the 12V outlet with a DVM to confirm 12V. If you have 12V then you likely have a bad cable or USB 12V charger. Would not be the first time for either...

Maine Sail · Apr 9, 2015

carlager said:
Some further information

1. The outlet gives 13,5V (excludes a blown fuse and a brokeb outlet)

With the correct polarity?

carlager said:
2. The outlet is wired from another 12V cigarette outlet.

How was this "paralleled" wiring wise?

carlager said:
When checking this outlet this morning this outlet turns out to have died, wheas there is still 13,5V on the newly installed outlet.

What "outlet"..?

carlager said:
Could the wirering be the problem ?

Absolutely... Could also be polarity or a dead USB charger / 12V insert or a blown fuse... We really need a diagram or pictures...

Ron20324 · Apr 9, 2015

There COULD be a fuse in the outlet itself.

Benny17441 · Apr 9, 2015

Check if you have power to the 12V socket. If you don't check the fuse or breaker. If you do check the 12V charger as they usually have a small fuse inside the plug. 12V sockets usually come in two types, one for lighters and the other for accessory plugs. The ones for lighters accommodate for the pop out release function and heat dissipation; I have found that accessory plugs sometimes don't work well when plugged to a lighter type socket. A solid connection at the terminal points for the plug are necessary to avoid heat build up. Make sure your polarity is correct with (+) to center connector and (-) to internal sleeve.

caguy · Apr 9, 2015

There is a fuse in the charger plug as well. On most if you twist the tip it will unscrew to get to the fuse. There are other variations of the same theme.
As far as the 13+ volts at the plug: Could it be from a solar panel or generator on you motor? I would check my IPad manual to see if that is within acceptable range. When it came up on my Surface Pro 2 it was not a problem.

Ron20324 · Apr 9, 2015

carlager said:
This is the wiring

I think I see the problem. Your NEG is supposed to be black, the POS is supposed to be the red! Sorry, I couldn't resist. I had a three-martini lunch.

Actually, when you plugged into a "hot" outlet, there might have been an arc of electricity that might have zapped something in the charger cord/supply. Like static electricity, so to speak.