DC-DC converters to avoid running inverter

[highdesertranger]

^Anderson Power Poles are far superior to ciggy outlets. highdesertranger

 

[Ralph Furley]

^Anderson Power Poles are far superior to ciggy outlets.   highdesertranger

Thanks, I'll check that out and do my homework.

 

[Weight]

All this is good if your device uses less than 12 volts to charge. My laptop uses 19 volts. Any DC to DC converter that steps voltage up, must make the 12 volts alternate in order to raise the voltage for the output. Sort of a inverter with power inefficiency. A small, quality, Sine Wave inverter is not very expensive. And it can be used for other purposes as well as the lap top. For phones, tablets, and things that use USB chargers, direct 12 volt to 5 volt is the only way.
Inverter; Changes 12 DC volts to 120 AC volts. There are two types, modified and pure sine wave.
Converter; Like a battery charger, changes 120 AC volts to 12 DC volts.
Transformer: Changes 120 volts AC to a lower voltage.
Brick; The devise to charge your lap top. A transformer that plugs into 120 volts AC, then changes a lower voltage to DC to charge the battery in the lap top.
In this explanation 12 volts, 120 volts could be other numbers. Lower could be higher. I used these numbers because that is the most common among this crowd. Speak to the audience.

 

[highdesertranger]

Powerwerx is a great source for Anderson Power Poles,

https://vanlivingforum.com/Thread-DC-DC-converters-to-avoid-running-inverter?pid=346253#pid346253

highdesertranger

 

[John61CT]

Any DC to DC converter that steps voltage up, must make the 12 volts alternate in order to raise the voltage for the output. Sort of a inverter with power inefficiency.

No, converters do not "alternate" anything. And are much more energy efficient than any inverter. And if buying decent quality, much less expensive.

IMO inverters are to be avoided, until the become truly necessary.

Converter; Like a battery charger, changes 120 AC volts to 12 DC volts.

That term is used (confusingly) only by the US RV industry. These days it just means battery charger, identical functionality to others intended for charging deep cycle batts while concurrently running loads.

The old dumb ones did not charge batts well.

In this explanation 12 volts, 120 volts could be other numbers. Lower could be higher.

In other words

12V nominal actually means operating in a range between 11 and 22V. Other common DC voltages like 24, 48 etc are also nominal and have their own ranges.

120AC or US mains may actually be 110 or 115V, most of the rest of the world uses 220-240.

 

[Weight]

Ok, John. i haven't got around to testing any 12 volt to 19 volt DC converters, as I haven't bought one. How do they step-up the DC voltage? They must use a transformer. A transformer only works on interrupted current. Interrupted current through a transformer results in a alternating current that needs be rectified into DC. Other wise they just pass through the 12 volts and only partially charge the lap top battery. That would cause many problems with my equipment. I do use my tablet often, with 5 volt charger, but need the big stuff for my challenges.

 

[tx2sturgis]

Ok, John. i haven't got around to testing any 12 volt to 19 volt DC converters, as I haven't bought one.  How do they step-up the DC voltage? They must use a transformer. A transformer only works on interrupted current.

I'm not John and he will have an answer I'm sure.

But the jist of it is, the 'guts' of a step-up DC to DC boost converter work a bit of electronic 'magic'.

If you understand transformers, you know they work by varying, collapsing, or alternating magnetic fields. Leave out the iron core, to remove most of the hysteresis, and wind the coils around each other in a helical form.

Capacitors can be added and they will change the phase of the way the circuit works, spiking and holding voltages up when they would normally be collapsing, and vice versa. If you use rapidly switching transistors and switch the current thru the capacitors and inductors in or out of phase FAST enough, and provide positive feedback, you can get some impressive voltage gains.

The output is filtered, and voila, higher DC voltage out than what came in.

The downside with these is they are VERY noisy in the RF spectrum, so filtering has to added to reduce or eliminate it.

 

[Mastertheo]

I need to charge a laptop, and I plan on buying Car Jump Starter and a laptop to ciggie port cord to charge it.

Could I just skip the buying the cord altogether? Can I just charge the laptop off of the jump starter while it's charging off the ciggie port? Would I lose a lot of juice this way? The cord is kinda pricey. 30 bucks.

 

[John61CT]

It is just called a converter, up is "boost", down is "buck"


Google, Amazon, and eBay have dozens, just search on your laptop model and 12V or car, adapter etc

Or contact the mfg support



For "universal", lots of different tip sizes, add that string to

12v to 19v car charger

The variables are

Volts

Watts enough (65-90 is normal, some big gaming rigs 120+

Tip style

Polarity, center pos or neg, some are only one or the other, others you can swap

I'd be surprised if BestBuy and Fry's didn't have them on the shelf, maybe even Walmart

Obviously Monoprice and Newegg

We're talking under $20

 

[John61CT]

My OEMtools 18000mAH has a 19V output with standard 5521 style jack, I think standard for Dell and/or IBM

there are universal tip only sets, and a 5521 pigtail, so likely can power any in the 18-21V range

And yes plug into 12V charge source, output to laptop, no need to buy a separate converter

 

[Weight]

tx2Sturgis. Yes. and all that is very efficient with no losses. Plus it does all the other jobs my inverter can handle.

 

[tx2sturgis]

There are SOME losses, since those little laptop charging bricks can get warm, but its not as lossy as an inverter since the DC to DC units tend to be properly sized for the expected load, with little overhead capacity, and also, they operate in the 'digital' range of the switching transistors, ie: they just switch on or off, without the heat buildup of transistors operating in 'analog' mode.

This is exactly why they are also called 'switching' power supplies.

Most larger inverters have a heatsink and a fan to cool things off, and this tells you right up front that there is some waste heat to get rid of.