Affordable Inverters Provide Power at the Range
These days, it’s not uncommon for shooters to bring electrical gadgets to the shooting range, particularly when testing loads. You’ll see guys running chronos with laptop computers, or loading with electronic powder dispensers (such as the RCBS ChargeMaster). If your favorite range doesn’t have AC outlets, how do you keep all that stuff powered up? You can get one of those portable 120v power supplies (basically a big battery with inverter and carry handle), but they are heavy and fairly expensive.
Another option, for those needing 120v AC to drive powder dispensers, laptops etc., is to use your car battery. Compact, affordable, and reliable inverters are now available that let you draw current from your car/truck’s cigarette lighter or accessory jack. Yes, it would be possible to run-down your battery, but if you start with a healthy vehicle battery, you’re not going to drain it by throwing a couple dozen charges with a ChargeMaster.
Black & Decker makes a rugged 100-Watt Inverter that converts your vehicle’s 12-volt DC power into 115-volt AC power. The unit has a single AC outlet, with an accessory plug that adjusts 45 degrees for convenience. An automatic low battery shutdown prevents draining the vehicle battery, and an LED indicator shows charging status. Black & Decker backs its inverter with a 2-year warranty. The Black & Decker 100-Watt Inverter costs $22.96 at Amazon.com.
Duracell has a similar Pocket Power Inverter fitted with a cord on the 12V end. (The cord is much longer than shown in picture). The cord can be helpful if your power take-off or cigarette lighter jack is hard to access. The Duracell unit has been popular, but, unlike the Black & Decker, the Duracell only delivers 100 Watts for for 5 minutes, after that it delivers 80 watts. That’s still enough to drive most of the gadgets you’ll use for load testing at the range. Duracells Pocket Power Inverter sells for $19.99 on Amazon.com. A more powerful 175 watt version sells for $48.75.
This is about the stupidest thing I have ever seen. I have never seen a laptop computer that ran off AC power. Yes you do plug it into the wall to get AC, but the transformer converts it to DC. The nice big block thing in the middle of the power cable is a transformer that takes an AC power source and converts in to DC power to run the computer. That’s why they also have a battery that is also a DC power source. So if I get this right I will take a DC power source from the charging system in the car convert that to AC so the transformer to just convert it back to DC power. WOW
If you look on your laptop power cable and fine the block that has a power cord running in one side and out the other side. Take a look at the writing on the back of it. You will see INPUT POWER 100v –240v AC / OUTPUT 20v DC.
You will have better luck just getting a car charger for you computer
Chris,
The main purpose of the inverter, in this situation, is not to charge the laptop — though that is one possible function. A Chargemaster requires 110-120 volt AC power, likewise many other devices, though they may run on DC internally, are set up to draw AC current through their power ports/cords. Yes you could have a step-down DC transformer that would give you 5v or 6v DC for your computer, but most laptops are NOT set up to handle DC power sources in (unless you were to get a custom charging cord or you were to remove the battery and try to jury rig something).
What the inverter does is let your car replace an AC outlet if the range doesn’t have one. That lets you run any device which normally “plugs into the wall socket”.
Ok first of all, this type of thing is what I do for a living. You are wrong most laptops run of DC current, not AC. The AC from the wall is converted to DC by the transformer that is in the power cord; it’s the square thing that gets warm. It then sends DC current to the battery pack that is in the computer. That battery pack is what powers the computer that’s why a laptop still works when it’s unplugged. A battery stores DC power not AC. If you take a multimeter and test the output from a laptop power cord at the point it plugs into the computer it will show DC current. No “rigging” of anything.
Most items that like a laptop, digital scale, or a ChargeMaster work from DC power. Just like I described above. Both the Chargemaster and its scale work on DC power. Yes the have a power cord that plugs into a wall, which has a transformer that plugs into the wall. It is the black square thing that plugs in the wall that gets warm, and has a cord running out of it. Same concept as a AC cell phone charger. If you have ever taken a cell phone car charger a part you will see resisters inside. All this does is drop the voltage from the cigarette lighter from 12 volts DC to whatever voltage that required to charge your cell phone most likely around 3v DC. The Chargemasters input it 110 to 120 input with an output of 9v DC. A better source of power would be to get an cigarette lighter adapter the steps down the 12v DC to 9vDC to power the Chargemaster. Doing the you would not be able to use the power cord that comes with the Chargemaster
Chris,
We KNOW that most devices run on DC. Read my last comment. The problem is simply that the power cord that comes with the machine is set up to use 110-120 Volt AC at the plug end. Yes if you were to cut off the cord, remove the internal transformer circuit and set up a step-down DC-DC circuit to deliver what the machine runs internally, you could do it. But you might have to create a different step down to give the right DC voltage for each machine you have — some 3V, some 5V, some 6V, some 9V. With the inverter you can run any machine that comes with an AC power cord.
Is it intelligent to go from DC (in car) to AC (from inverter) back to DC (device internals)? NO, but unless you create your own custom cord for each device, plugging in to an inverter is simple.
I understand what you’re saying though. I’ve got someone working right now on trying to run a PVM chronograph from the DC USB ports on my laptop, rather than using AC power. Problem is that the USB ports deliver 5V and the chrono needs 12v, so I still need a transformer.
Adapters are made with adjustable DC out puts as well as many different conectors. This would ensure you get a male end to plug in that’s the same as what was on the factory cord.
DC curent to DC
Similar to this one
http://www.powerstream.com/dc-3318.htm
Chris,
If you want to build or buy a 12v DC to [some other DC voltage] converter for every machine you might use at the range that is great. But you’re missing the point. The DC to DC converter is an extra cord you have to build or buy. The multi-voltage, multi end-plug DC converter to which you linked is “is OBSOLETE and no longer available.” The same company makes DC to DC converters for particular laptops and those converters (with one end plug design) START at $48.00 and some are over $100.00. See: http://www.powerstream.com/dc-3318.htm
The inverter gives you one universal fitting for about $22 that can be used with any device that has an AC cord. The other factor to consider is, with inverter-supplied AC output from the vehicle, you can use an ordinary outdoor extension cord to run power 20′ or more to the bench.
We really DO understand that, from an engineering standpoint, a DC to DC converter makes more sense than converting from 12v car battery to AC then back to DC. But the inverter lets you use the charging/power cord that comes with the machine.
If you want to go out and purchase or fabricate a DC to DC converter for each machine you may want to operate from the car battery, that’s fine.