Charging a tablet from a 12 volt socket.

Petronella

Petronella

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Scarborough Marina, Australia
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For the last six years I have run the excellent SailFreeGPS app on an old Huawei tablet charging continuously from a 12 volt cigarette lighter socket with the usual USB car adapter plugged into it. It runs all the time on passage. It just charges quicker than it drains it's battery. That is, it works great.

After many thousands of miles and lots of sun it has deteriorated and I needed to replace it. I bought a second hand 8" Samsung tab A with the same micro USB connection as the Huawei but unfortunately this device drains faster than it charges so is no use.

So I'm looking for a small (8") tablet that you know will run continuously from a 12 volt socket. Basically it must charge faster than it drains so it is always fully charged. Any ideas?
 
Petronella said:
For the last six years I have run the excellent SailFreeGPS app on an old Huawei tablet charging continuously from a 12 volt cigarette lighter socket with the usual USB car adapter plugged into it. It runs all the time on passage. It just charges quicker than it drains it's battery. That is, it works great.

After many thousands of miles and lots of sun it has deteriorated and I needed to replace it. I bought a second hand 8" Samsung tab A with the same micro USB connection as the Huawei but unfortunately this device drains faster than it charges so is no use.

So I'm looking for a small (8") tablet that you know will run continuously from a 12 volt socket. Basically it must charge faster than it drains so it is always fully charged. Any ideas?
Click to expand...
Post #5 is the answer.
 
Get an Amazon basics 2 x 2.4 A 12 volt plug in usb charge adapter for £6.64.
Note the 2.4 Amps against the typical 2.1A .
I have run either of my 10" Samsung tablets continuously for navigation ( Marine Navigator/Open CPN/Navionics) plugged into this over several years - typically beyond 10 hours.
I can start with say 60 % charge and always finish at 100%.
In other words there is a continuous small gain,not a drain.
Amazon.co.uk
 
bluerm166 said:
Get an Amazon basics 2 x 2.4 A 12 volt plug in usb charge adapter for £6.64.
Note the 2.4 Amps against the typical 2.1A .
I have run either of my 10" Samsung tablets continuously for navigation ( Marine Navigator/Open CPN/Navionics) plugged into this over several years - typically beyond 10 hours.
I can start with say 60 % charge and always finish at 100%.
In other words there is a continuous small gain,not a drain.
Amazon.co.uk
Click to expand...
And don't forget to get a cable that will allow a higher charge rate.
 
I fitted the Scanstrut Rokk+ charger which is a fast charger and waterproof. Fitted under cockpit canopy and waterproof cover over the USB sockets. Works well for me especially as I should really replace the battery in my 10" Samsung tablet but decided fitting the Rokk+ charger was better.
 
bluerm166 said:
Get an Amazon basics 2 x 2.4 A 12 volt plug in usb charge adapter for £6.64.
Note the 2.4 Amps against the typical 2.1A .
I have run either of my 10" Samsung tablets continuously for navigation ( Marine Navigator/Open CPN/Navionics) plugged into this over several years - typically beyond 10 hours.
I can start with say 60 % charge and always finish at 100%.
In other words there is a continuous small gain,not a drain.
Amazon.co.uk
Click to expand...
Bought similar dropper from Ebay .
Drops boat 12v to usb socket and whatever volts my tablet needs to charge.
Now using a Generic 10" tablet with 1000ma battery, it lasts all day, junked a fragile Ipad with a hopeless battery life.
Dropper installed on the flybridge and has been powered up for over 2 years.
Really must get round to fitting a toggle switch someday.
 
PaulRainbow said:
Don't see how any of this helps. The charging socket isn't supplying enough current, it just needs changing.
Click to expand...
It helps because over time (it is second hand) tablets battery capacity fails. I have a Samsung tab that can't keep its charge even when it's plugged In at home.
 
The standard maximum charging current for a Micro-USB connector is 1.5 Amps.
You need to check the maximum charging current the Tab A will take.
Then get a socket/adapter/cable that will supply that current.
 
As my post #8 above :
I use the twin 2.4 A adapter to charge continuously on both my old tablet a Tab A from 2016 ( I installed new the battery once) which uses an old micro usb connector and on a newer Tab A 9+ which uses a C connector.Not at the same time but no doubt could.
I hadn't realised that even the old £25 type 'value' panels with push in fuses were were limited to anything like 3A amps on the 12v socket ,although they were certainly crude.I upgraded mine to the simplest Blue Sea panels.
 
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My phone charger...bit more than 1.5A I think...in my car it's a 2.5A. I am often getting msg saying cable is incorrect...coz I use wrong small one.
1000030783.jpg
 
Fitting a higher current output charger is a good idea but will not make a difference if the tablet is only drawing, say, 1amp from a 3amp charger. One of these is really useful to measure the actual current draw of the tablet. Will also highlight the difference in your charging cables, some are more efficient than others:
Pardon our interruption...
(USB-micro and USB-C versions are available)
 
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It appears that micro usb 2.0 takes 2.5w or 2.1 A at 12v. My Tab A 10.1 uses this and is happy to increase battery charge in use.I doubt that the 8" tab A in question uses the ancient micro USB 1.0 standard.
Maybe Petronella is using an older 1.0 A c/l adapter which was ok for the Huawai tablet but not for the more demanding Samsung.Or has a suspect cable ,as noted by others above,which restricts its real charge rate.
 
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