What Multiple Port USB Car Chargers Are Highest Power?

That one doesn't look too bad. I went through the info on their website; I didn't find a clear answer to my major question, but one of the pics they showed gave me a hint.

Executive summary: Car electronics are hard, as car electrical systems are not friendly. Expect to pay more than $10 for a high-power car charger if you want it to last, want the things you connect to it to last, and don't want it melting itself in place.

Look for, or ask about device efficiency.

Technical rant:

Car electrical systems deliver from 10 to 14 Volts most of the time, but this can go over 40 Volts for brief periods, and can spike far above that. Nasty.

Cig lighter accessory outlets stink. Yes, they're designed to deliver 10 to 20 Amps, but only for a short period -- a cig lighter, remember? It's hard to make plug-ins that retain an electrically secure connection, especially in light of bumpy roads, spirited driving, etc. Hard wired is always better (but more expensive).

Voltage regulators: the car delivers 10 to 40 volts (most of the time it's 10 - 14 Volts). You want 5.2 Volts to charge your USB electronics (why 5.2 discussed later). That's the job of the voltage regulator, to take in whatever and deliver a steady 5.2 Volts.

Question: where does the difference between the input voltage, 10 to 14 volts, and the output voltage, 5.2 Volts go?

That's where we get into the two kinds of regulators. The first, cheap and ubiquitous, is the linear voltage regulator.

A 5 Volt regulator integrated circuit like the 7805 can deliver an amp and a half at 5 Volts and costs around 20 cents in volume. That's what you'll find in the $10 plug-in chargers. They take very little skill to design into something that will more or less work most of the time.

Here's the point: linear regulators turn the difference between the input and output voltages into HEAT. So for 13.2 Volts input, 5.2 Volts output at 1 Amp, that's a difference of 8 volts times 1 amp is 8 Watts from that poor little voltage regulator. That is going to get HOT! Hell, if you're charging something that wants 2 Amps, a linear regulator is dissipating 16 Watts or so and is going to get damn HOT!

In terms of efficiency, you're drawing 13.2 Volts at one Amp from the car -- 13.2 Watts. Delivering 5.1 Volts at 1 Amp to the device, 5.2 Watts. Overall efficiency sucks at 5.2/13.2 = 40%, with 60% of the energy going into HEAT.

Second type of voltage regulator: the switching regulator. These are complicated and expensive beasties, requiring six to ten components (including specialized integrated circuits, inductor, capacitor, and other parts) to do the job. Takes some skill to design, but reference designs are readily available.

The beauty of a switching regulator: efficiency. The switching regulators I use in a car environment have an efficiency on the order of 90%, producing a lot less heat.

One of the images of the device in question shows an integrated circuit and some components I'd associate with a switching regulator. If it really can deliver 8 Amps at 5 Volts, it's a bargain.

Side rant: Why did I say 5.2 Volts?

Isn't USB 5 Volts? Yes it is, but with a margin -- 5%, so that "5 Volts" can range from 4.75 to 5.25 Volts and still be in spec.

The problem is that most USB cables suck. They use small wires which result in a voltage drop. I tested a bunch of USB cables (using a 500 mA load, half an Amp), and found some that introduced more than a 0.5 Volt drop!

This means that if you use a wall wart or other cheezy charger that delivers at the low end of the USB spec, say 4.8 Volts, and use a cheap cable, your device might be getting only 4.2 Volts or so, which might not be high enough to charge it.

That's why any number of good USB chargers actually deliver 5.2 Volts -- it's within the USB spec, and it compensates for cheezy sucky cables.

End of rant. Let me know if you want more.

Always check a switching regulator for its regulatory label. In the US it's an FCC label, Canada has a CSA label. These help insure the regulators don't cause other interference problems like noise in the radios or cell phones to even stopping Bluetooth.

That would explain the wide range in prices I've seen. I always enjoy learning about the how of things. Thanks for the brief tutorial.

http://www.amazon.com/gp/product/B006SU0SX0/ref=oh_aui_detai...

1 port for Android (2A) and 1 port for Apple (which Android considers USB and charges at 0.5A standard).

It needs a higher charge level. Anyone?

I have the same charger (in white) and it works well. However, if you read the discription in the link, the 2A port is for Apple (IPad) and the 1A port is for "other devices".

Interestingly, I have a nuvi 3597LMTHD and Garmin recently released a firmware update that makes the unit very picky about the charger being used. After applying the update, the nuvi still operates fine using the 1A port on the PowerGen, but gives an error when plugged into the 2A port. This was discussed recently in this thread: http://www.poi-factory.com/node/43416.

I use this charger. It's very well made and meets all specs.

http://www.amazon.com/gp/product/B00FME4NAW

EDIT: Sorry, this one only has two USB ports...carry on.

http://www.amazon.com/gp/product/B006SU0SX0/ref=oh_aui_detai...

Anker makes good products. I use their 2 amp products and they work well.

on Anker stuff...though I don't have the car charger from them...they are good people and they have an 18 month warranty

I didn't realize switching regulators were available for automotive applications - what brands do you use/recommend, or are you building yours from scratch?

Dual 12 watt ports

http://www.amazon.com/SCOSCHE-USBC242M-Charger-iPhone-Lightn...

The anker stuff looks good, and the warranty says they stand behind it.

For my home-grown stuff, I use modules from Pololu (www.pololu.com) -- they're a U.S. company, and they do good stuff.

I think switchers will become more prevalent in the auto market with the wider use of iPads and the larger smartphones that require 1 or 2 A for charging -- up to now, most devices were in the 500mA range where a cheepie linear regulator would suffice. The low cost of the linear solution prices the better switchers out of the market. But now they're needed as the linears can't really deliver at the 2A level.

I tend to do direct connect -- my Mini Cooper has 20A circuits for the heated seats I don't have, giving me a pair of 20A circuits to use!

I never understood the logic behind heated seats...if you sit in them for 5 minutes, aren't they already heated up by your own body in that 5 minutes? But then again, I'm in SoCal and am probably spoiled when it comes to the weather.

That's a cool website, thanks!

If you live somewhere where it's gets freezing cold in the winter time, you would certainly appreciate the heated seats when getting inside your vehicle at 04.00 am at 25 below zero, trust me

I do ... Iowa USA, and have been thru that "starting out from freezing cold" scenario many times. We just went thru our "Polar vortex" winter last year. And my ford truck sits outside and has vinyl seats. But in spite of that, still agree with DorkusNimrod. Heated seats are a luxury I don't need and I wouldn't pay extra for in a car.

OTOH ... as they say, to each his own.

I too live in a relatively cold area but I haven't owned a vehicle with vinyl seats in over 30 years. We always specified cloth as we knew it would warm to our buns quickly and still wick the moisture away on those hot days. Our current vehicle does have 'bun warmers' and they are a nice feature. Definitely needed with leather along with being vented for the AC as well.

Wait...there are vented seats with the A/C blowing through them?

I haven't bought a car since my 1994 Mustang GT...it's still going strong and have no desire to even look at cars.