Mis-wired 12VDC jack (let the smoke out)

[john61ct]

Originally Posted by Lake-Effect

Depends on the panel, of course...

Depends on each consuming device in the holes. Usually easily swapped.

And actual consumption easily measured, any DIYer should learn to do so if they don't know how yet.

[Boatyarddog]

Originally Posted by Spot

This is a cautionary tale of what I did wrong and what I could have done differently. There was no loss of life or limb or machinery, only a burnt fuse and a blown 12VDC USB power adapter. OK, maybe a little of my pride went up in smoke too, but I am glad it was a driveway incident and not on the water.

I redid the electrical in the trailer sailor to remove some doorbell wire and failing switches and what not from previous owners. I was quite pleased with my work, even though it was going to be temporary until I got tinned wire and proper crimp connectors. Anyhow, I did that last fall and thought all was OK, battery being trickle charged by solar and looking good after the winter. Pride comes before the fall...


I went to plug my tablet to the 12v jack and there was nothing indicating a charge. I smelled a little something 'chemical' but thought it was just probably 'old boat' early season.
I unplug and eventually I go to investigate. No tools on board, so down and up the ladder for a screwdriver and multi-meter. Pulled out the 12v USB power plug and it smelled burnt. I took the USB plug apart to see that the the chip and coil of the circuit were destroyed, or in professional terms, I had 'let the smoke out'...


Started to suspect...probed the jack, turns out I wired the one and only 12VDC jack backwards so that the tip was negative and the shell was positive. I probably tested it previously with an incandescent bulb that will not indicate reversed voltage. Messed around some more, checked the fuse, it was also blown. No spares on the boat so down and up the ladder for fuses, colored tape, knife, and a pre-wired 12V plug to use as a jack tester.


I took the electrical panel apart, turned off master power (yes, in that order, part of the confessional), rewired the jack, and marked the white and grey leads of the jack with red and green tape to match other wiring in the temporary box. Checked it 2 or 3 times, reassembled panel, checked again, etc...

Lessons learned:
1. turn off master 12VDC power first or disconnect battery
2. double-check as-wired polarity of jacks before using them
3. mark wires if colors and polarities are not self-indicating
4. keeps spare fuses onboard
5. keep basic tools on board, even when in driveway

Happy weekend to all, Spot

Especially working with LED.
Lots of these aftermarket product don't come with color coding for polarity.
They typically use the black wire to positive (counterintuitive) and white to Negative.
Call and check if you don't have the instructions handy.
Cheers
SV Cloud Duster

[john61ct]

Call? How funny, almost quaint.

[hellosailor]

spot-
The parasitic draw of a panel will totally vary with what's on it. If there are LED indicators, you can figure maybe 20mA per standard small LED. If the voltmeter has big LED numbers...four seven-segment digits at more, maybe 30mA per segment, average half of them lit at any time would be 840mA ? So an LCD meter that draws maybe 50mA would save a lot of power.
How long is a piece of string? You'd have to ask the maker, or spec out your own.
The price of some panels is rather striking. You can find a number of shops on the internet that will fabricate (cut, finish, lettering, etc.) 'panels' of all kinds. Some places like emachineshop.com will even supply free CAD software, so you can design away, upload a file, and get back a panel--or something way more complex.
And there's a company called Bass, if they are still around their modular panels are what Pearson used, very easy to assemble stacks of what you need.
No matter what you buy, or build, make sure there are spares on the panel. Plenty of spares, so you don't want up bodging it with more stuff later. And if you plan to add a power meter to show total power used/generated, etc? Make sure to leave room for that. Somehow, a panel is always just one row smaller than it needs to be a year later.(G)
If you have the time and skills to just cut a simple panel for your needs, any bowling trophy shop can also do the engraving on it, to your specs, usually quite reasonably.

[AKA-None]

Blue sea makes extensible panels with mix and match sub panels

[Spot]

Those Blue Sea panels look really nice. I saw a video at PKYS of a tech putting one together.
I had a chance today to visit the local surplus store, whose employees are inclined to add both facts and humor to product descriptions. I thought this one went well with this thread:

[john61ct]

Originally Posted by Spot

I thought this one went well with this thread:

Funny 'cause it's true. . .

Gonna hafta steal that!

[Spot]

I decided to go DIY with the panel. The guts of the original fuse box will be cleaned up and wired to the toggle switches with tinned primary wire and crimped connectors. There will be a 25 amp auto-reset breaker between the battery and panel. There is now a box for the battery. So far I am about 35$ deep in parts including the battery box, breaker, switches, tinned wire, and panel box. Connectors and black FR4 for the face plate were already here.I will have 6 circuits with the potential to add 5 more, which would require either a new fuse or added fuse panel. The switch plate took a little while to design but only 15 minutes to cut out and another 5 minutes to add the switches. I did not engrave the face plate. I think I will use a labeling machine so I can change the layout without having to machine a new piece just to fix the labels.
Thanks again for all the ideas and encouragement.

[Lake-Effect]

Originally Posted by Spot

I decided to go DIY with the panel. The guts of the original fuse box will be cleaned up and wired to the toggle switches with tinned primary wire and crimped connectors. There will be a 25 amp auto-reset breaker between the battery and panel. There is now a box for the battery. So far I am about 35$ deep in parts including the battery box, breaker, switches, tinned wire, and panel box. Connectors and black FR4 for the face plate were already here.I will have 6 circuits with the potential to add 5 more, which would require either a new fuse or added fuse panel. The switch plate took a little while to design but only 15 minutes to cut out and another 5 minutes to add the switches. I did not engrave the face plate. I think I will use a labeling machine so I can change the layout without having to machine a new piece just to fix the labels.
Thanks again for all the ideas and encouragement.

Looks pretty good!


For breaker and switch labels I simply used a laser-printer, cut paper labels into strips, then stuck them inside some clear plastic folder tabs that were trimmed down to fit above each switch/breaker. The plastic tabs were stuck to the panel with double-sided tape. I did this so it would be easy to change labels... but in several years I've never made a change.



Those Brother P-Touch labelers would do a pretty good job as well.