OT Laptop Power I Pods

Hey, its tractor related, I use my Laptop allllllll the time while on the road in my RV to answer tractor questions here.....

ISSUE NUMBER ONE

As we do a fair amount of Dry Camping (aka Boondocking) in my RV Im always loking for ways to conserve coach battery energy. Sooooo they sell these "thingys" you plug into a 12 VDC Cigarette Lighter output with built in USB receptacles, supposedly to power up USB compatible (receptacle equipped) devices such as my laptop?????

Anywho I cant find a USB to USB cable as most are USB to Mini USB for printers buttttttt I have a Belkin Easy Transfer Cable USB to USB device so I plug one end into the USB thingy (it converts 12 VDC down to 5 VDC computer power I believe) and the other end into my laptop USB and it sees and recognizes the Belkin cable device (I tried it both ways) BUTTTTTTTTTTTTTTTT it DOES NOT CHARGE THE LAPTOP OR KEEP IT POWERED UP GRRRRRRRRRRRRR

QUESTION: Is the problem I need a straight USB to USB Cable (maybe the Belkin easy Transfer cable device does NOT allow the 5 VDC to pass through device to device, perhaps a diode or something so 5VDC dont mix n match puter to other puter) OR my idea just doesnt work???????? My best guess is still a regular USB to USB will allow the 5VDC to power up my puter although its a backfeed but MAYBE THERE ARE STILL DIODES TO ALLOW POWER OUT BUT NOT IN???

Sure, I have a 12VDC to 120VAC inverter I use butttttttt why waste heat energy to convert 12 VDC to 120 VAC (my inverter) and plug in the computer which converts 120 VAC to 5 VDC????

ISSUE NUMBER TWO

My RV radio has a 1/8 input jack so my I Pod output can be plugged into it for good audio out my RV/Truck speakers, works great sounds fine. I also have one of those Griffin Road Trip thingys that takes my I Pod audio output and transmits it to my FM radio so I can hear the I Pod via wireless, works great......

BUTTTTTTTTTTTTTT if I use the 12VDC to power up and charge the I Pods battery (without using the Griffin transmitter system) and then try to use its audio output out my radio speakers (i.e. NOT do the transmitter thing) SHE SQUEALS AND SORT OF BACKFEEDS grrrrrrrrrrrrrr Sure, the Griffin thing charges the I Pod and transmits to my radio buttttttttttttttt the quality isnt as good as if the I Pod output goes directly to the radio BUTTTTTTTTT if I use any other sort of device/cables to charge the I Pod and at the same time use its audio output (1/8 cable to radio) then the radio squeals

Its a tough life, all these modern devices, my Amish friends dont have all these problems ya know lol

John T

you cannot charge a laptop through the USB port.

Ipod issue does sound like feed back through the 12 volt to 5 volt converter. Otherwise I have no idea.

The USB cable is supplied with 5 volts to power small items, it cones from an internal circuit that limits the output watts, and also prevents any and all back feed from the device to the computer.
There is no way The Specification will allow inflow.
I use a 3D scanner on a laptop that draws 1.5 amps. That unit is powered by an external Power supply to avoid taxing the internal wiring.
On the squeal issue. The power lead to the charger might (probably is not) be unshielded. My first try would be to splice on shielded power wire to the Ipod from its 12v charger.
If that failed, I would probably get a motorcycle battery and use it to drive the Ipod with clean DC. Jim