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Old 05-08-2015, 23:24   #31
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Re: Laptop charging

Ah, I've had the melted 12V car charger issue too. Very scarry and a fire danger from the melted burning plastic. I replaced the outlet with a duplex outlet... same issue. replaced the 12V male plug two times... same issue. I'll be hard wiring the 12V brick to the 12V wiring,with fuse and a switch for on off. It's on my todo list.

The issue is the dc/dc converter is pulling ~9 amps at 12.5V to make 5.5 amps at 19V (in my case). It's at the very top of what the typical 12V outlet can do.
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Old 06-08-2015, 00:12   #32
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Re: Laptop charging

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The hard wired sine wave inverter that I mentioned before, that works fine charging a MacBook is over 300 w maybe 350 w but it's not in front of me.

The one with the cigarette lighter plug that wouldn't work with the MacBook was around 270 w from memory. I had wired the lighter type socket in the boat myself with the heaviest cable that I could attach to the socket with a 2 wire run of less than 1 metre. Neither would that inverter work with a MacBook when tried in a couple of cars.

I don't think lighter type plugs are very satisfactory because of the restricted size of cable that is possible fit into the confined space inside the plugs. I'm well aware of this because just yesterday I wired a couple of them for another project. That and the connection inside the socket where the spring loaded plug positive pin is trying to push it out of the socket.

The inverters with lighter plugs are only made that way to make it convenient for car owners.
P=ExI. Power = current x voltage.

Voltage = 12 more or less
Power = 270
Current = 270 /12 = 22.5 AMPS!

NO CIG LIGHTER IN THE WORLD CAN HANDLE THAT.

Hardwire through a fuse to the 12v mains with BIG short wire
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Old 06-08-2015, 10:13   #33
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Re: Laptop charging

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Originally Posted by sailorchic34 View Post
Ah, I've had the melted 12V car charger issue too. Very scarry and a fire danger from the melted burning plastic. I replaced the outlet with a duplex outlet... same issue. replaced the 12V male plug two times... same issue. I'll be hard wiring the 12V brick to the 12V wiring,with fuse and a switch for on off. It's on my todo list.

The issue is the dc/dc converter is pulling ~9 amps at 12.5V to make 5.5 amps at 19V (in my case). It's at the very top of what the typical 12V outlet can do.
So go with a Marinco 3-prong twist-lock trolling motor plug, as someone suggested very early on in this thread.

I installed one on the 12V cable for our Engel cooler, which we use as a freezer. The supplied cigarette adapter would sometimes slip slightly out of the two-outlet WM 12V outlet at the nav station, so the twist-lock trolling motor adapter prevents that...
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Old 08-08-2015, 23:37   #34
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Re: Laptop charging

When shopping yesterday to upgrade the cig lighter charger.

I found a marine grade male cig lighter plug that was rated to 20A and a female connector from the same company rated at 16A. I also bought some 4mm cable and a fuse box.

Hopefully that will solve my heat/melting issues and I won't need the inverter.
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Old 09-08-2015, 00:36   #35
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Re: Laptop charging

It is a common problem. I have melted a couple myself.

I use Sutars brand cig lighter connectors. These are marine rated and are supposed to cope with 20A, but I think that is a bit optimistic.

Usually it is the male end that melts. I think the problem is the computer power supplies are designed on the assumption that they will be used in a car. Here the voltage is kept at a constant 13.8v by the alternator. On a boat system the voltage can be significantly less which increases the current and heat.

Using the best quality female boat sockets with thick wiring is a big help, but I would still be a bit cautious, especially in hot weather.

The maximium current and hence heat will be when the boat battery voltage is low (ie not charging via solar etc), the computer is on with full screen brightness and the computer battery is at a low state of charge.

The best solution is to cut off the cig lighter plug and use something else. Anderson plugs/sockets are great. They will handle a genuine 50A are polarised and have silver plated contacts which keeps the resistance low in a salt water environment. They will accept large diameter cable. Anderson plugs are not very attractive so they need to fitted out of the way under tables, but they will safely provide a high powered socket that will run not just computer power supplies, but spotlights, a wandering emergancy bilge pump etc

I have a couple of these for high powered devices. You need to cut off the male cig lighter plug and replace it with Anderson plug. Be careful there may be a fuse in cig lighter plug which will be lost. Make sure you have a suitable fuse to the socket if this is the case.

I also made an Anderson to cig lighter adapter (see photo which also shows when an Anderson socket looks like) so a can use the sockets as a conventional cig lighter socket. I currently have 12 cig lighter sockets on board which you would think should be sufficient, but the number of devices that use these seems to be ever growing.

Usually the 12v DC to DC use about 20% less power than a small inverter and AC to DC converter. So it is worth getting a 12v system that works and is safe.
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Old 09-08-2015, 01:03   #36
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Re: Laptop charging

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I use Sutars brand cig lighter connectors. These are marine rated and are supposed to cope with 20A, but I think that is a bit optimistic.
The new plugs I bought are Sutars

Maybe I will hut around for another connector as well as a backup plan

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Usually it is the male end that melts.
Sutars are made in Sweden and your observation is a very accurate description of what I've seen during my 15 years living in Sweden

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I
I currently have 12 cig lighter sockets on board which you would think should be sufficient, but the number of devices that use these seems to be ever growing.
I would guess that quite a number of them are used by USB powered devices? I fitted 5 double USB outlets. They directly replace the cig lighter plugs.

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Old 09-08-2015, 01:46   #37
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Re: Laptop charging

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I would guess that quite a number of them are used by USB powered devices? I fitted 5 double USB outlets. They directly replace the cig lighter plugs.

Yes good idea.i added some extra sockets a few years ago and I think doing it again I would use some of those.

My only slight concen is they keep upping the current requirment. The maximum now is 2.1A @5v so that is generally the maximium current the sockets will deliver.

I think in a few years devices like tablets will be demanding higher currents. There is also a code (it is a voltage difference between some of the pins) that tells the device what current the socket will deliver. Some devices will not work without the correct code and they are likely to change this.

Those sockets look like they would be easy to replace if they become obsolete so it is not a big deal. With a pure cig lighter socket you have the drawback of another connection, which is not ideal, but a least you can can plug in any adapter and of course use other devices that don't run on 5v.

A mixture is probably the best solution, but make sure the USB sockets use a standard cut out to allow for replacment in the future.
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Old 09-08-2015, 02:11   #38
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Re: Laptop charging

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A mixture is probably the best solution, but make sure the USB sockets use a standard cut out to allow for replacment in the future.
I started with 3 cig lighter plugs at the Nav table and replaced 2 with these. Simple replacement and if they are not future proof, then I'm sure they will be swappable in the future.

My Nav "wall" is at an angle to the table opening and added the plugs at the narrow end. So when I first started using charges and USB adapters that stuck out a few cm, it fowled the table opening DOH. Flush fitting USB adapter plugs and then these saved the day




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Old 09-08-2015, 02:33   #39
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Re: Laptop charging

What brand are they? Any failures?
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Old 09-08-2015, 03:04   #40
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Re: Laptop charging

No idea on the brand, bought them from Swedish chandlery's.

The first 2 installed have been working 3 or 4 seasons without problems.

Last winter I Installed a double in each cabin plus a cig lighter in my cabin. I will have to upgrade the cig lighter and the wire as it is for charging my MacBook if I need to in bed.

Been looking online for MBP car chargers in Sweden and can only find the one I have (old MagSafe needing an adapter) which has a separate voltage converter or all in one units (voltage done in the plug) which may only be for the AIR. I might buy another of the unit I have now as a backup or possibly to fit a different style of plug.


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Old 09-08-2015, 04:15   #41
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Re: Laptop charging

I have indecision from my MacBook Pro touch pad all the time on mains or inverter. A wireless mouse is better though not so convenient.

I did have problems with my MacBook battery on a square wave inverter which is why I changed to sine wave.

As far as the computer is concerned a charger working from a sine wave inverter must be the same as mains. I can't see a connection between an inverter used for charging the battery and a touchpad.
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Old 09-08-2015, 14:46   #42
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Re: Laptop charging

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When shopping yesterday to upgrade the cig lighter charger.

I found a marine grade male cig lighter plug that was rated to 20A and a female connector from the same company rated at 16A. I also bought some 4mm cable and a fuse box.

Hopefully that will solve my heat/melting issues and I won't need the inverter.
Good luck with that. I hope you can wire that plug with suitable heavy wiring to the inverter. The marine grade plugs I've just wired (only for solar to car) are still very confined inside to use suitable cable for an inverter. No doubt they might pass 20a for a short time with a big fuse inside the plug but there will be voltage drop with a load.

Better to change from lighter plugs to something more substantial and use heavy cable with the fuse / breaker back on the switch board. But then the existing supplied DC cable into the inverter will still be too small. At your own risk you could open the inverter and install heavier DC cable??

I will be interested though to hear how it works for you.
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Old 09-08-2015, 15:15   #43
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Re: Laptop charging

Hopefully the main idea in this thread that most people will remember is that cigarette lighter plugs/sockets are just not reasonable idea in this day and age.

Back when they were the only source of 12V in most any vehicle, and everyone smoked so the lighter was a great feature, they did make a great amount of sense but it just is not that way any more.

They are a very poor and often unreliable way of accessing power, and as people have noticed the physical construction of the plug lends itself vulnerable to overheating and melting.

Nowadays there are plenty of different options for accessing 12V power so everyone can decide what works best for them but just try for it not to be cigarette plugs.

Getting back to laptop chargers, I have never disassembled one to see how they are constructed but if they have a transformer first that feeds low voltage DC into a charging circuit a person might be able to get by with removing the transformer feeding it with 24V DC. However, the charging circuit might be controlled by AC and I've been too lazy at this point to research it much but it might be a worthwhile project for a person looking for a robust permanent mount DC charger.
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Old 09-08-2015, 15:16   #44
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Re: Laptop charging

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I have indecision from my MacBook Pro touch pad all the time on mains or inverter. A wireless mouse is better though not so convenient.

I did have problems with my MacBook battery on a square wave inverter which is why I changed to sine wave.

As far as the computer is concerned a charger working from a sine wave inverter must be the same as mains. I can't see a connection between an inverter used for charging the battery and a touchpad.
I had that with the previous Mac OS.... lots of debate on the net about it suggesting amongst other things that the battery was pressing against base of track pad etc etc etc ... when I started using Yosemite the problem went away on the instant....
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Old 09-08-2015, 15:58   #45
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Re: Laptop charging

How do ciggy plug chargers designed for a steady 13.8 V in a car handle the varying voltages present on a yacht?
I know mine ( mentioned above) can take anything from 6 to 32 in while still putting out the desired voltage on the far side.
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