Mobile/Portable Power?

Mackieman · EVDO Junkie Joined: 31 Oct 2005 Posts: 472

USB doesn't provide anywhere near enough power to operate KR1. USB spec provides 500mA of power; KR1 uses 5W at 1A.

tz1 · Posted: Thu Jun 14, 2007 1:05 pm Post subject:

USB can provide up to 2.5A (consider chained hubs or the power supply going into a hub), although the spec has 500mA as a limit somewhere.

Pulling too much current (it works on my laptop) is probably not a good idea as it will stress the power supplies. However you can find high powered 5v supplies that have a USB jack, but only provide power.

Kermee · EVDO Newbie Joined: 11 Jun 2007 Posts: 10

If the KR1 truly does only use 5W @ 5V * 1A, then you can probably power it off two USB ports with a modified cable such as this:

addonics.com/products/power_adapter/usb_power_cable.asp

Some 2.5" notebook HDD's use to have a power requirements of 5V * 1A with some of the newer more efficient models only requiring 5V @ 500mA. Older 2.5" external notebook HDD's use to have a single USB port with a cable that splits to two USB connectors. One connector for the actual data connection plus the 5V @ 500mA and another connector purely for the other 5V @ 500mA to give the drive a total 5V @ 1A.

I'm willing to buy a cheap USB PCI card (to fry) for my desktop and jury-rig the cable to see if it has enough juice to power the KR1.

orbitalcomp · EVDO User Joined: 28 Apr 2007 Posts: 41 Location: Texas

How about using the Y-cable from the U720? Maybe someone who has a KR1, a U720 and the Kyocera USB cable can try this out, at your own risk of course...

tz1 · Posted: Tue Jul 03, 2007 10:32 am Post subject:

Solar power - the specs seem to be sufficient to power the KR1 and there is a 35% off coupon:

http://www.bargainist.com/deals/2007/07/batteriescom-35-off-everything/

http://www.batteries.com/productprofile.asp?appid=386433

I'm tempted - it's in my shopping card but I've not hit checkout yet (I also need some other batteries and I'm looking for other items)

tz1 · Posted: Wed Jul 04, 2007 9:38 am Post subject:

One new things I've had time to do with the holiday (and my Bike waiting for repair) is a variant of the circuit here:

http://www.astron.nl/~smirnov/poweroff.html

Charges a backup battery and provides a 10 minute (approximate) power-off delay (like when you refuel or make another quick stop - long enough to pull off the latest GPS coordinates). There is an instant-off switch.

I've added a switch similar to the resistor-ground immediate off with a resistor-ground to battery 12v so I can get in and turn on the unit before I start the ignition and reset the timeout. I'm using a 10A relay which is more than enough for the KR1 and such.

Notes: There is no connection between the battery positive and the gate, the crossing without dot. The relay's coil is not automatically connected to the contacts, I just connect one end of the coil to either the common or normally open contact (the latter on my prototyping circuit board).

All with parts all from Radio Shack.

275-248 Relay
276-2072 IRF510 Power MOSFET

Some I don't have part numbers, but are in the parts bins:
100 microfarad electrolytic Cap
1 megohm resistor (or a 1 megohm taper potentiometer)
(this combo gives about 12 minutes, but it may vary)
1k or so resistors for each switch.

A small perfboard.
275-1571 submini SPST momentary switches, one red, one black.
276-1661 or similar "big" diode for power in and charging.
276-1101 or similar "small" diode to sense external power.

Some 12v lead-acid battery. I use a 2.3aH I got from Digikey - similar are at batteries plus, or Radio Shack.

The FET will be on while the gate voltage is even a little positive, so with vehicle (or other) power through the small diode it will be turned on and charge the capacitor which will hold the positive charge. The discharge through the 1M resistor takes about 10 minutes, but I use the black switch to quickly discharge it, and the red switch to recharge the cap it from the battery turning it on even without the vehicle power.

The relay uses little current (enough for a Power MOSFET without heatsink) but will handle 10A. The big diode prevents the battery from sending power back to the vehicle ignition or whatever.

tz1 · Posted: Wed Jul 04, 2007 5:33 pm Post subject:

One small thing the above circuit doesn't do - if you are running off a battery as "accessory", it will leave things on for a very long time as the battery discharges (both - the backup and main).

Capt.Dan · Posted: Thu Aug 16, 2007 6:41 pm Post subject:

Hi, I'm not sure why but my KR1 came with the ac transformer and a 12 volt power cord! When I go down the road in my rv, I can plug it in to 12 volt and I can leave it as my converter can put out 80 amps and that is about the same as my alt. on the engine. Did I get luck or ???

jackrodgers · EVDO Addict Joined: 23 Mar 2006 Posts: 1131

Check your local super store for rechargeable battery packs and pads. APC makes several capable of power a laptop from 4-8 hours and they aren't to big.

deparson · EVDO Junkie Joined: 30 Aug 2006 Posts: 248

Go with a 12v auto jump start style setup with a lighter socket, IMO. The KR1 has a 12v cable included so you can skip the costly inverter and save the power that would be wasted going from 12v-120v-12v.

I would think you could get 15+ hours for well under $75.

Added bonus is that most can be plugged in (if 120v power happens to be available at for a time) without powering down your KR1.

jackrodgers · EVDO Addict Joined: 23 Mar 2006 Posts: 1131

Just saw a largish auto battery size unit by Black & Decker at Walmart.

It will inflate your tires, jump your car battery, has several ac outlets and a few dc outlets and so on and it is less than $100. It is,however, considerably heavier than the portable battery devices mentioned above.