Car Chargers

[Ryan P.]

Finding a car charger that will charge and Android Tablet is proving
to be highly annoying. The vast majority of chargers out there are
built for Apple devices, which have different logic for determining how
much power to draw from the charger.

I have ZTE Optik (actually, we'd like to use these in our fleet)
tablet. ZTE does not offer a vehicle charger, and none of the 2.1a
chargers we've tried will send more than .5a to the tablet... which
means it consistently loses battery throughout the day.

Has anyone run into this problem with this, or any other USB car
charger? Can you recommend one that you've used to charge your device?

Thanks,

Ryan

[Paul Miner]

On Fri, 04 May 2012 13:23:25 -0500, "Ryan P."

Post by Ryan P.
Finding a car charger that will charge and Android Tablet is proving
to be highly annoying. The vast majority of chargers out there are
built for Apple devices, which have different logic for determining how
much power to draw from the charger.
I have ZTE Optik (actually, we'd like to use these in our fleet)
tablet. ZTE does not offer a vehicle charger, and none of the 2.1a
chargers we've tried will send more than .5a to the tablet... which
means it consistently loses battery throughout the day.
Has anyone run into this problem with this, or any other USB car
charger? Can you recommend one that you've used to charge your device?

Does it have to be USB? Google shows multiple hits for ZTE Optik car
chargers, but they seem to plug into a lighter socket rather than USB.

On a related note, I don't know of any generic USB ports that can
handle a sustained 2.1 amp load. They're usually limited to about .5
amps, as you've seen.

[Ryan P.]

Post by Paul Miner
On Fri, 04 May 2012 13:23:25 -0500, "Ryan P."

Post by Ryan P.
Finding a car charger that will charge and Android Tablet is proving
to be highly annoying. The vast majority of chargers out there are
built for Apple devices, which have different logic for determining how
much power to draw from the charger.
I have ZTE Optik (actually, we'd like to use these in our fleet)
tablet. ZTE does not offer a vehicle charger, and none of the 2.1a
chargers we've tried will send more than .5a to the tablet... which
means it consistently loses battery throughout the day.
Has anyone run into this problem with this, or any other USB car
charger? Can you recommend one that you've used to charge your device?

Does it have to be USB? Google shows multiple hits for ZTE Optik car
chargers, but they seem to plug into a lighter socket rather than USB.
On a related note, I don't know of any generic USB ports that can
handle a sustained 2.1 amp load. They're usually limited to about .5
amps, as you've seen.

Sorry, I could have been a little clearer. :) There are no (that
I've found) dedicated ZTE Optik (tablet version) car chargers. The only
official option is to use an inverter and plug the AC adapter into that
(which is what our Sprint said ZTE suggested). This is impractical for
a fleet to use, because it is bulky and creates two potential points of
failure.

Most of the ZTE Optik results in Google point to chargers for the
phone version, not the tablet version. The tablet has a 40-pin
connector at the other end of the USB cable.

Since I know iPads and can be charged using certain 12v USB car
chargers, I know its possible for a tablet with a 2.1a power requirement
to be charged in a car... Its just a matter of either finding a way to
fool the logic in the Android tablet, or finding a car charger made for
the Optik tablet.

I've read that shorting the two data terminals on the USB port will
fool Android devices in drawing more than .5a... I'm tempted to try that.

[SMS]

Post by Ryan P.

Post by Paul Miner
On Fri, 04 May 2012 13:23:25 -0500, "Ryan P."

Post by Ryan P.
Finding a car charger that will charge and Android Tablet is proving
to be highly annoying. The vast majority of chargers out there are
built for Apple devices, which have different logic for determining how
much power to draw from the charger.
I have ZTE Optik (actually, we'd like to use these in our fleet)
tablet. ZTE does not offer a vehicle charger, and none of the 2.1a
chargers we've tried will send more than .5a to the tablet... which
means it consistently loses battery throughout the day.
Has anyone run into this problem with this, or any other USB car
charger? Can you recommend one that you've used to charge your device?

Does it have to be USB? Google shows multiple hits for ZTE Optik car
chargers, but they seem to plug into a lighter socket rather than USB.
On a related note, I don't know of any generic USB ports that can
handle a sustained 2.1 amp load. They're usually limited to about .5
amps, as you've seen.

Sorry, I could have been a little clearer.

You can still be clearer.

Does the AC charger use a USB socket and a cord with the 40 pin
connector, or is the cord wired directly into the AC charger?

If it's the former, there might be some hope in diddling with data+ and
data-. If it's the latter, forget it.

[Ryan P.]

Post by SMS

Post by Ryan P.
Sorry, I could have been a little clearer.

You can still be clearer.
Does the AC charger use a USB socket and a cord with the 40 pin
connector, or is the cord wired directly into the AC charger?
If it's the former, there might be some hope in diddling with data+ and
data-. If it's the latter, forget it.

Its USB on one end, 40 pin on the other.

I indeed shorted the two data pins, and that allowed the tablet to
draw the 2.1a that it required.

I was hoping I wouldn't have to modify 50 car chargers, but it looks
like that's what I'm going to have to do.

[Bobby]

Try Here Hope You Find What Your Looking For
http://www.tmiwireless.com/accessories/?aid=6808

[SMS]

Finding a car charger that will charge and Android Tablet is proving to
be highly annoying. The vast majority of chargers out there are built
for Apple devices, which have different logic for determining how much
power to draw from the charger.
I have ZTE Optik (actually, we'd like to use these in our fleet) tablet.
ZTE does not offer a vehicle charger, and none of the 2.1a chargers
we've tried will send more than .5a to the tablet... which means it
consistently loses battery throughout the day.
Has anyone run into this problem with this, or any other USB car
charger? Can you recommend one that you've used to charge your device?

I assume that the travel adapter charging via the Micro-USB port, not
the 40 pin port? If so, forget it, other people with ZTE tablets have
reported the same issue.

Using one of the 2.1A USB port/car chargers is not going to help you.
ZTE will not draw more than 0.5A on the Micro-USB port no matter what
you do. Many others have run into this problem.

The logic for determining the available power is not in the high-power
USB port, it's in the cable that came with the tablet, or in the tablet
itself. Motorola has done this sort of thing for years, and hence a
plain USB to Mini-USB cable not designed for Motorola will give an
"Unauthorized Charger" message (except when it's plugged into a USB port
on a computer with Motorola Phone tools installed).

ZTE has recently released a slew of tablets with that 40 pin connector,
so there should be an after-market solution soon.

[Mike S.]

Post by SMS

Finding a car charger that will charge and Android Tablet is proving to
be highly annoying. The vast majority of chargers out there are built
for Apple devices, which have different logic for determining how much
power to draw from the charger.
I have ZTE Optik (actually, we'd like to use these in our fleet) tablet.
ZTE does not offer a vehicle charger, and none of the 2.1a chargers
we've tried will send more than .5a to the tablet... which means it
consistently loses battery throughout the day.
Has anyone run into this problem with this, or any other USB car
charger? Can you recommend one that you've used to charge your device?

I assume that the travel adapter charging via the Micro-USB port, not
the 40 pin port? If so, forget it, other people with ZTE tablets have
reported the same issue.
Using one of the 2.1A USB port/car chargers is not going to help you.
ZTE will not draw more than 0.5A on the Micro-USB port no matter what
you do. Many others have run into this problem.
The logic for determining the available power is not in the high-power
USB port, it's in the cable that came with the tablet, or in the tablet
itself. Motorola has done this sort of thing for years, and hence a
plain USB to Mini-USB cable not designed for Motorola will give an
"Unauthorized Charger" message (except when it's plugged into a USB port
on a computer with Motorola Phone tools installed).
ZTE has recently released a slew of tablets with that 40 pin connector,
so there should be an after-market solution soon.

eBay is full of dongles that perform the proper jumpering to charge
Samsung tablets using generic high-current USB adaptors. Ditto for iPad.
Perhaps one of these will work; or maybe there already is such a dongle
for the OP's brand.

[SMS]

Post by Mike S.
eBay is full of dongles that perform the proper jumpering to charge
Samsung tablets using generic high-current USB adaptors. Ditto for iPad.
Perhaps one of these will work; or maybe there already is such a dongle
for the OP's brand.

Perhaps. Too little information was given. The ZTE tablets with that 40
pin connector are just hitting the market so we'll soon see.

I assume that ZTE provides a USB to 40 pin cable that is used for two
things:

1) To connect the tablet to a computer, where you don't want to draw
much more than 500mA (most computers won't trip the USB over-current
protection until 800-1000mA even though they don't have to supply more
than 500mA).

2) To connect the tablet to the AC charger.

So for the tablet to draw more than 500mA from the AC charger, there
must be something on the USB data pins that the tablet looks at. Since
they're unlikely to have put a micro-controller in the AC charger that
generates any data (even Apple doesn't do this), I would suspect that
it's a voltage on one or both of the data pins created by a voltage
divider for each pin, or both data pins shorted together and one voltage
divider network for both pins.

Looking at the pins with a VOM could determine what's going on.

What Other Tablet Makers Do
---------------------------
Samsung shorts the data pins together and uses a voltage divider to put
1V on the both data pins.

Apple has multiple charge rates based on the voltage on each data pin.
Data+ and Data- can be either +2.0 or +2.8, giving four possible charge
rates.

500mA (probably iPod)
D- 2.0V
D+ 2.0V

1000mA (probably iPhone, iPod Touch)
D- 2.8V
D+ 2.0V

2000mA (iPad)
D- 2.0V
D+ 2.8V

Not Used
D- 2.8V
D+ 2.8V

[Ryan P.]

Post by Mike S.

Post by SMS

Finding a car charger that will charge and Android Tablet is proving to
be highly annoying. The vast majority of chargers out there are built
for Apple devices, which have different logic for determining how much
power to draw from the charger.
I have ZTE Optik (actually, we'd like to use these in our fleet) tablet.
ZTE does not offer a vehicle charger, and none of the 2.1a chargers
we've tried will send more than .5a to the tablet... which means it
consistently loses battery throughout the day.
Has anyone run into this problem with this, or any other USB car
charger? Can you recommend one that you've used to charge your device?

I assume that the travel adapter charging via the Micro-USB port, not
the 40 pin port? If so, forget it, other people with ZTE tablets have
reported the same issue.
Using one of the 2.1A USB port/car chargers is not going to help you.
ZTE will not draw more than 0.5A on the Micro-USB port no matter what
you do. Many others have run into this problem.
The logic for determining the available power is not in the high-power
USB port, it's in the cable that came with the tablet, or in the tablet
itself. Motorola has done this sort of thing for years, and hence a
plain USB to Mini-USB cable not designed for Motorola will give an
"Unauthorized Charger" message (except when it's plugged into a USB port
on a computer with Motorola Phone tools installed).
ZTE has recently released a slew of tablets with that 40 pin connector,
so there should be an after-market solution soon.

eBay is full of dongles that perform the proper jumpering to charge
Samsung tablets using generic high-current USB adaptors. Ditto for iPad.
Perhaps one of these will work; or maybe there already is such a dongle
for the OP's brand.

I did see some chargers listed as being compatible with the
Transformer, but all the details I saw on them implied that provide TOO
much power, and I'm not sure how much I trust such a cheap tablet to be
be able to regulate an over-abundance of power.

Other 40 pin "charger cables" I've found online didn't provide enough
information in the description for me to know if it was a modified cable
or just a spare "normal" cable.

So far, it looks like I will have to manually short the data pins on
the chargers. I tried this over the weekend, and haven't seen any nasty
side effects on either the tablet or the vehicle I left it charging in.

According to our Sprint rep, ZTE does not offer a DC charger. In
fact, ZTE's response to their inquiry was to tell me to use an inverter,
which over a fleet of 50 vehicles is a bit impractical.

Thank you all for the information on chargers, though. I knew that
there were differences in how the devices decided how much power to
draw, but I received a good education here.

Ryan

[SMS]

So far, it looks like I will have to manually short the data pins on the
chargers. I tried this over the weekend, and haven't seen any nasty side
effects on either the tablet or the vehicle I left it charging in.

I think what I would do would to be to buy 50 of these:
<http://www.monoprice.com/products/product.asp?seq=1&p_id=6504>, cut
them in half, short the data pins, solder them back together and use
heat shrink tubing over the cable. Depending on where you are, you could
probably find someone to do the work for you for a few dollars per cable.

By doing the cable, you can use any high-current 12V to USB adapter.

Also, chargers tend to be something that break a lot, and you'd probably
void the Sprint/ZTE warranty buy opening it and shorting the data pins.

Oh, and maybe make up some extras to sell on eBay!

[Paul Miner]

Post by SMS

So far, it looks like I will have to manually short the data pins on the
chargers. I tried this over the weekend, and haven't seen any nasty side
effects on either the tablet or the vehicle I left it charging in.

<http://www.monoprice.com/products/product.asp?seq=1&p_id=6504>, cut
them in half, short the data pins, solder them back together and use
heat shrink tubing over the cable. Depending on where you are, you could
probably find someone to do the work for you for a few dollars per cable.
By doing the cable, you can use any high-current 12V to USB adapter.
Also, chargers tend to be something that break a lot, and you'd probably
void the Sprint/ZTE warranty buy opening it and shorting the data pins.
Oh, and maybe make up some extras to sell on eBay!

I had the same idea and think it's the best way to go. No damage to
the chargers and it's all plug and play.