12volt iPad charger

Submitted: Monday, Sep 07, 2015 at 12:45
ThreadID: 130210 Views:2024 Replies:12 FollowUps:26
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Hi All,

I am after a 12volt hard wired charger for a iPad, not one to plug into a cig lighter. The issue with iPad is that it requires reference voltage on D+ and D- of the USB socket (D+ = 2.8 V and D- = 2.0 V) to tell the iPad that it can charge at the high current. I have tried Jaycar and Baintech, both rated at 2.1A but they only charge iPad at 1amp.

Thanks, Kevin
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Reply By: Member -Pinko (NSW) - Monday, Sep 07, 2015 at 13:09

Monday, Sep 07, 2015 at 13:09
kevin look here
http://www.ebay.com.au/sch/i.html?ul_noapp=true&_fromfsb=0&_nkw=usb+socket&_trksid=m270.l1313
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Follow Up By: 116hynes - Monday, Sep 07, 2015 at 13:21

Monday, Sep 07, 2015 at 13:21
Hi,

Should this link have taken me to a specific listing?

Kevin
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Follow Up By: vk1dx - Tuesday, Sep 08, 2015 at 15:22

Tuesday, Sep 08, 2015 at 15:22
I installed two of these in the rear of the center console fed directly from a dedicated 4WD accessory fusebox under the bonnet next to the second battery bank. Output is 3.1 Amp.

Phil

USB charger 3.1Amp socket

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Follow Up By: 116hynes - Tuesday, Sep 08, 2015 at 16:05

Tuesday, Sep 08, 2015 at 16:05
I have just tried a similar looking unit, only 1amp to iPad
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Follow Up By: vk1dx - Tuesday, Sep 08, 2015 at 22:57

Tuesday, Sep 08, 2015 at 22:57
The specifications for this one say 3.1 amp.
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Follow Up By: 116hynes - Wednesday, Sep 09, 2015 at 09:08

Wednesday, Sep 09, 2015 at 09:08
Mate, have a read of the last post by Alan B.
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Follow Up By: vk1dx - Wednesday, Sep 09, 2015 at 10:03

Wednesday, Sep 09, 2015 at 10:03
Mate!

I know exactly what you were after. That's why I posted these. Our grand kids have heaps of these "toys" and they all charge quite nicely on long and trips with us.

Phil
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Follow Up By: Allan B (Member, SunCoast) - Wednesday, Sep 09, 2015 at 11:52

Wednesday, Sep 09, 2015 at 11:52
Oh dear! The output is 3.1 Amps IN TOTAL from two USB outlets, not 3.1 from any one.
See my replies further down.
Cheers
Allan

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Follow Up By: vk1dx - Wednesday, Sep 09, 2015 at 12:21

Wednesday, Sep 09, 2015 at 12:21
What a shame.
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Reply By: Member -Pinko (NSW) - Monday, Sep 07, 2015 at 13:33

Monday, Sep 07, 2015 at 13:33
kevin
There are many flush mounted devices with dual amperages listed there.
Some fit into a vacant dash switch with 1amp and a 2.5amp. usb.
I have a remote fitting with 4 cig. sockets and two separate usb sockets with different amps. fastened low down on the console and I charge and run my ipad from that.
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Follow Up By: 116hynes - Monday, Sep 07, 2015 at 13:46

Monday, Sep 07, 2015 at 13:46
Thanks,

I have already trawled thru Ebay. Unless a socket is specifically wired for a iPad (D+ and D- reference volt on USB socket) the iPad will never charge at the high current of 2.1a no matter what the socket is capable of delivering.

Both the Jaycar and Baintech I have tried where rated at 2.1A but would only charge a iPad at 1A

I was hoping someone had been down this path.

Kevin
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Reply By: Slow one - Monday, Sep 07, 2015 at 14:31

Monday, Sep 07, 2015 at 14:31
This may suit as it is 2 amp output.

Ticky Dickies
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Follow Up By: 116hynes - Monday, Sep 07, 2015 at 14:52

Monday, Sep 07, 2015 at 14:52
Thanks, I'm after a hard wired unit.
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Reply By: Member -Pinko (NSW) - Monday, Sep 07, 2015 at 15:20

Monday, Sep 07, 2015 at 15:20
Kevin
The ipad 240v. wall charger has a 5v.- 2.1 amp output.
I have just connected my ipad to the 2.1amp usb output in the car and charge has gone from 79% to 85% since I last replied.
Jaycar has a hardwired under dash panel mount 5v. / 2.1amp output device.
I cannot see why this will not work for you.
There are no higher output usb's.
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Follow Up By: 116hynes - Monday, Sep 07, 2015 at 15:26

Monday, Sep 07, 2015 at 15:26
Sorry mate, the Jaycar unit will only supply 1Amp to a iPad. It will never go into high charge(2.1amp) Below is the link to unit I am talking about.

http://www.jaycar.com.au/PRODUCTS/Power-Products-Electrical/Power-Conversion-%26-Transformation/12VDC-Power-Supplies/Dual-Port-3-1A-USB-Charger%2C-Panel-Surface-Mount-12VDC-Input/p/MP3616
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Follow Up By: 116hynes - Monday, Sep 07, 2015 at 15:28

Monday, Sep 07, 2015 at 15:28
The Apple 240V wall charger for iPad has the D+,D- reference voltages on the USB socket that the iPad sees and then goes into high charge mode.

Kevin
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Follow Up By: Member -Pinko (NSW) - Monday, Sep 07, 2015 at 15:36

Monday, Sep 07, 2015 at 15:36
Well it looks like you need a pure sine wave inverter ?
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Follow Up By: 116hynes - Monday, Sep 07, 2015 at 15:51

Monday, Sep 07, 2015 at 15:51
No, I already have cig lighter plugins that work, I am trying to tidy things up. Also after some for the van.

Kevin
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Reply By: Iza B - Monday, Sep 07, 2015 at 16:21

Monday, Sep 07, 2015 at 16:21
I will have to check, BUT, for what it may be worth, my DMax has a flying lead USB female in the glove box. I plug the iPad into that and close the glovebox. As said, I have not checked but that outlet seems to provide fast charge, as you require. IF, the DMax arrangement is really a fast charge outlet, that may be a lead to a supply source.

Iza
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Follow Up By: 116hynes - Monday, Sep 07, 2015 at 16:29

Monday, Sep 07, 2015 at 16:29
Is this factory supplied or did you fit it?

Kevin
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Reply By: Bruce B11 - Monday, Sep 07, 2015 at 20:31

Monday, Sep 07, 2015 at 20:31
This article may help explain your problem
http://www.epanorama.net/newepa/2010/08/18/apple-charger-secrets/
The July 2015 edition of Silicon Chip magazine has a project building a 12v to 5v USB charger. Jaycar may have this a kit by now.
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Follow Up By: 116hynes - Monday, Sep 07, 2015 at 21:18

Monday, Sep 07, 2015 at 21:18
Yes, that's what I was saying in my opening query. I thought someone may have made a hardwired unit by now. Looks like I will have to make an adapter cable to supply B+,B-
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Follow Up By: 116hynes - Monday, Sep 07, 2015 at 21:31

Monday, Sep 07, 2015 at 21:31
This is also a good explanation.


http://www.voltaicsystems.com/blog/choosing-usb-pin-voltages-for-iphones-and-ipads/
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Reply By: CSeaJay - Tuesday, Sep 08, 2015 at 12:06

Tuesday, Sep 08, 2015 at 12:06
Kevin
Double check your statement about JCar.
I bought their standard USB plug that goes into the cig lighter. It has two USB outputs, one normal and the other at 2.1 A for the ipad. I use it all the time for the ipad, works every time
CJ
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Follow Up By: 116hynes - Tuesday, Sep 08, 2015 at 12:09

Tuesday, Sep 08, 2015 at 12:09
It will "work", but does not charge IPad at 2amp, only 1amp.
Kevin
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Follow Up By: 116hynes - Tuesday, Sep 08, 2015 at 12:11

Tuesday, Sep 08, 2015 at 12:11
Whoops, sorry didn't read your post properly. I was referring to hardwired unit.
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Reply By: Member - tojofixa - Tuesday, Sep 08, 2015 at 14:14

Tuesday, Sep 08, 2015 at 14:14
Have a look on the Narva website at product code 81134BL. It's a heavy duty dual USB socket with a 5volt 2.5 amp output. I have one of these and it works very well, charges my iPad & my phone at the same time. Narva.com.au
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Follow Up By: 116hynes - Tuesday, Sep 08, 2015 at 15:52

Tuesday, Sep 08, 2015 at 15:52
Hi,

Unfortunately that unit will only charge a iPad at 1amp. I received email confirmation from Narva yesterday. The unit referred to in the email is the same as 81134BL only in a surface mount. Have also received email confirmation from ABR Sidewinder that their unit will also only charge a iPad at 1amp. I am only referring to hardwired units. Must stress again that it doesn't matter it the charging unit is capable of delivering 2.5A, if it doesn't have the correct voltages on the D+,D- on the USB socket the iPad will only charge at 1amp.

"Hi Kevin, seems your concerns are warranted. After some investigation the general standard reference voltage (2.5v) is adopted by most manufacturers but the Apple reference voltage of 2.8V apparently limits the output. (something I only just learned)
At this stage we don’t have intentions of releasing a version that will suit Apple devices.
Sorry our 81154BL will not suit your application."
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Reply By: Allan B (Member, SunCoast) - Tuesday, Sep 08, 2015 at 17:40

Tuesday, Sep 08, 2015 at 17:40
The point that the OP, Kevin, has made repeatedly that is not being grasped by some responders is that the manufacturer's current rating of some USB chargers may not be accepted by some devices unless the correct data voltage is imposed on the D+ and D- pins. Apple products are the most notable (naturally) but Samsung tablets and others also require this data to accept full charge. Without it they will charge at a reduced rate.
As an example, the Samsung tablet that this is being written on is also used as my navigation map and without the correct Data voltages the charge rate will not keep up to the constant operation demand.

12 volt-to-USB chargers designed and sold specifically for these products should conform to this need but 'general purpose' 5V USB chargers will not. The required Data Voltages on pins 2 & 3 are achieved by a pair of resistors for each pin arranged as voltage dividers but unless you have some electronic skills it can be difficult to DIY the necessary modification to the USB output socket.

In short, the current rating marked on the USB charger is not the whole story.
Cheers
Allan

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Follow Up By: Bob Y. - Qld - Wednesday, Sep 09, 2015 at 08:13

Wednesday, Sep 09, 2015 at 08:13
Thanks for that, Allan.

Explains why the iPad runs out of puff after 6-8 hours of logging a trip. :-(. And creates a little tension in the cab as well. "Didn't you charge it last night?" "Of course I bloody charged it......there's something bloody wrong somewhere!"

And now we know what's wrong.

Bob

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Can't remember most of it.

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Follow Up By: 116hynes - Wednesday, Sep 09, 2015 at 09:23

Wednesday, Sep 09, 2015 at 09:23
I haven't been able to source a hardwired unit for iPad so I am going to make up a patch cable with the correct D+,D- voltages. Will post back when it's done.

Kevin
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Follow Up By: Allan B (Member, SunCoast) - Wednesday, Sep 09, 2015 at 10:57

Wednesday, Sep 09, 2015 at 10:57
Hi Bob,
Yep, that would be your problem.

I modified a 2.1 amp adaptor to suit the Samsung Galaxy map machine but even then it barely keeps up. Putting the screen to sleep when not watching it helps.

For the iPad and phones I find it simpler to charge them from the inverter using the original supplied chargers.

If you cannot obtain a 12v USB adaptor suitable for the iPad let me know by Member Message and I'll knock one up for you, gratis.
Cheers
Allan

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Reply By: Allan B (Member, SunCoast) - Wednesday, Sep 09, 2015 at 11:44

Wednesday, Sep 09, 2015 at 11:44
Further to all that has been said above, USB charging problems have abounded in threads on this forum in the past. Just search "USB" and you will find them.

I raised the compatabilty issue in Thread 105046 in Nov 2013 and you will find in that thread an extract from Silicon Chip magazine providing details of the required Data Voltages for various machines together with the resistor values used to create those voltages. The subject was revisited in Thread 111013 in Feb 2015 with further information.
The Silicon Chip article is very useful for anyone wishing to modify or construct their own custom charger. The full constructional article can be obtainedfrom Silicon Chip archives.

I see in those Threads promotion of some USB adaptors, notably by ABR, promoting such as "5 Amp" devices. This (and similar devices) have several USB outlets of say 1.2 Amps each which amount to 5 Amps IN TOTAL ONLY, not 5 Amps from any one outlet. There is much mis-information offered on this subject
Cheers
Allan

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Reply By: Member Boroma 604 - Wednesday, Sep 09, 2015 at 12:23

Wednesday, Sep 09, 2015 at 12:23
Gooday,
Have you explored one of those storage devices, you could have it connected to charge and run your piece of gear out of the other end at the same time,
I have one I bought in the US late last year and it is great, used it on the plane on the way back from Hong Kong a few months ago as the on-bpoard aeroplane USB socket would not fire up the I pad.
Used my portable supply unit to finish what I was doing. Maybe worth a try?. You will need a mini USB to std USB lead to connect for charge. Have not tried it but the little Storage unit is a PNY brand cost me $20-00, has a digital charge read out, 2 different output ratings and holds 100% for months when sleeping.
Cheers,
Boroma 604.
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Reply By: 116hynes - Thursday, Sep 10, 2015 at 13:58

Thursday, Sep 10, 2015 at 13:58


OK, patch cable made. Mark 1 version. These were done with a Jaycar MP3616. One shows the iPad plugged into the 2.1A outlet, the charge is 0.86A. The other shows the iPad connected to the 2.1A outlet via the patch cable which is supplying the required D+,D- for high charge. Even with the voltage drop of the 5v down to 4.8 from the cable loss it is still charging at 1.62A.

AnswerID: 590213

Follow Up By: Bob Y. - Qld - Thursday, Sep 10, 2015 at 18:21

Thursday, Sep 10, 2015 at 18:21
Where'd you pick up the smig little volt/amp thingy?

Bob

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Can't remember most of it.

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Follow Up By: vk1dx - Thursday, Sep 10, 2015 at 18:52

Thursday, Sep 10, 2015 at 18:52
Heaps on ebay Bob.

Phil
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Follow Up By: Allan B (Member, SunCoast) - Tuesday, Sep 15, 2015 at 17:58

Tuesday, Sep 15, 2015 at 17:58
Geez Kevin, you are going to tidy up the resistor divider network, aren't you? lol
Cheers
Allan

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