Wireless Charging

barbed wire Bob · Jul 27, 2013

Dernells Casket n Flagon said:
So my new Nexus 7 (two actually, since my girlfriend also receive one) just arrived in the mail today and one of the features is wireless charging. This is my first device with Wireless charging (though I guess i could buy a kit to convert my S3). Anyone have much experience good or bad with wireless charging? What do I need to think about? Will my phone charge any faster or slower?

Good wireless charging pads? Nothing appears to be better than 4 stars on Amazons even when you're spending up to $80 on a pad. I'm potentially okay spending that money on a pad because I think potentially almost all of my future devices will have wireless charging, but are any worth the money? I'd love to have spend closer to $40-50 and then purchase two or three to have at home and work, but it seems there's not much good in that price range either. Would the Orb from the Nexus 4 be a good charger for the Nexus 7?

What's been your experience so far?

It's an inefficient way to charge a battery so your charge times will be longer.

barbed wire Bob · Jul 28, 2013

Based on theory.

begranter · Jul 28, 2013

Completely unrelated, but I've been saying this for years now. Whoever 'perfects' pure wireless charging (no contact needed) will revolutionize the world as we know it. And probably make a bundle along the way.

SumnerH · Jul 28, 2013

grantb said:
Completely unrelated, but I've been saying this for years now. Whoever 'perfects' pure wireless charging (no contact needed) will revolutionize the world as we know it. And probably make a bundle along the way.

What does this mean? Wireless charging's been widely and stably deployed in commercial consumer goods for decades, it's already a solved problem. Oral B toothbrushes were advertising it back in the late 80s or early 90s, the GM EV2 electric car and the electric RAV4 both used inductive chargers.

It's less efficient (that's for hard scientific reasons, not something that engineering will overcome), but it's not that much less efficient--the EV2's inductive chargers got something like 85-90% efficiency. That is enough that it might be problematic for a car charge where there's a lot of energy being transferred, but may not matter much for charging cell phones, game controllers, etc (and it might get pushed closer to 95%, especially at very short distances).

begranter · Jul 28, 2013

SumnerH said:
What does this mean? Wireless charging's been widely and stably deployed in commercial consumer goods for decades, it's already a solved problem. Oral B toothbrushes were advertising it back in the late 80s or early 90s, the GM EV2 electric car and the electric RAV4 both used inductive chargers.

It's less efficient (that's for hard scientific reasons, not something that engineering will overcome), but it's not that much less efficient--the EV2's inductive chargers got something like 85-90% efficiency. That is enough that it might be problematic for a car charge where there's a lot of energy being transferred, but may not matter much for charging cell phones, game controllers, etc (and it might get pushed closer to 95%, especially at very short distances).

I mean more like Wi-Fi for power, like uBeam is trying to do. I think it could eventually make batteries unnecessary. Having to keep it on a pad or close by defeats the point. If you could charge your phone while it's in your pocket, not plugged into anything for instance.

barbed wire Bob · Jul 28, 2013

SumnerH said:
What does this mean? Wireless charging's been widely and stably deployed in commercial consumer goods for decades, it's already a solved problem. Oral B toothbrushes were advertising it back in the late 80s or early 90s, the GM EV2 electric car and the electric RAV4 both used inductive chargers.
It's less efficient (that's for hard scientific reasons, not something that engineering will overcome), but it's not that much less efficient--the EV2's inductive chargers got something like 85-90% efficiency. That is enough that it might be problematic for a car charge where there's a lot of energy being transferred, but may not matter much for charging cell phones, game controllers, etc (and it might get pushed closer to 95%, especially at very short distances).

Minor nit but I think you are referring to the EV1 gen. 2 . GM never came out with the EV2. http://en.wikipedia.org/wiki/General_Motors_EV1

The car did use an induction charger-called a Magne Charge system- but it is an obsolete system since CARB adopted a wired charging interface for electric vehicles. http://en.wikipedia.org/wiki/Magne_Charge

10-20% power loss doesn't sound like much when you are talking about a single cell phone but,when you are talking about millions of cell phones, it adds up to a lot of power being wasted. This blog talks about how wireless charging may not be good for the environment. http://www.eetimes.com/author.asp?section_id=36&doc_id=1287060

begranter · Jul 28, 2013

barbed wire Bob said:
10-20% power loss doesn't sound like much when you are talking about a single cell phone but,when you are talking about millions of cell phones, it adds up to a lot of power being wasted. This blog talks about how wireless charging may not be good for the environment. http://www.eetimes.com/author.asp?section_id=36&doc_id=1287060

That's like saying since batteries typically use 30-80% more energy to charge them than they put out, to be economical we should only use hard-lined electronics... Plus if you no longer used a battery as your main power source (backup only for instance) that's a net win as far as energy consumption goes.

mt8thsw9th · Jul 28, 2013

I think it's saying that there's no point in adding more inefficiency to the whole process.

I'm just imagining people getting electrocuted by faulty wireless charging systems because a bar owner decided to nickel and dime and by a cheap Chinese knock-off. Sort of like a Cocoanut Grove 2023.

barbed wire Bob · Jul 28, 2013

mt8thsw9th said:
I think it's saying that there's no point in adding more inefficiency to the whole process.

Bingo. We are talking about wireless battery charging systems vs. wired charging systems. We are not talking about wireless power systems which would do away with the battery.

Fwiw, ever since Tesla's experiments in the late 19th century, people have been investigating wireless power system. Today, it is used in certain applications but it doesn't seem very practical for general use. The efficiency really drops off over relatively modest distances and the RF fields generated by such devices could be hazardous to people health. This is an old article but it does a pretty good summarizing the pros and cons of wireless power.

http://spectrum.ieee.org/green-tech/mass-transit/a-critical-look-at-wireless-power

jayhoz · Jul 28, 2013

I would wait for the Google charger built for the Nexus. I believe this tablet uses the Qi standard for inductive chargers. The deficiencies of Qi, and all the inductive chargers, are:

1) the charging coil size needs to match the size of the coil in the device.
2) both coils need to be aligned.
3) the coils need to be virtually in contact with each other.

If you buy a third party charger you run the risk of having the wrong size coil in a position that is hard to get right under the coil in the Nexus.

Also, this is one of the first tablets with wireless charging. Most of the pads on the market are built to charge phones that require half the power of tablets (1amp V 2amps).

I tried an older Powermat inductive charger on a pre-release sample of the new Nexus 7. It didn't work.

jayhoz · Jul 28, 2013

I wouldn't be so sure that any pad you buy today will work with any device you buy over the next couple of years. There is a standards war going on between Qi, PMA, A4WP, and others. Qi is the clear leader w/ device manufacturers, and PMA has some big clout with placements in Starbucks locations. No one knows who is going to win in the end.

The sleeping giant is resonance based charging. This technology can throw charging across distances and through many materials. You can attach a pad under you desk and just drop your phone on top of the desk and it charges. This is the technology that most device manufacturers would like to use, I believe. Costs are close, but not quite low enough yet. If you are interested in resonance, check out Witricity in Cambridge.

jayhoz · Jul 28, 2013

When everything is perfectly aligned the efficiency is pretty good. Unfortunately, perfect alignment isn't something you get by just dropping the device on the pad. Many first time users think they are charging only to find at the end of the day that they were a few centimeters off and their battery is dead.

Max Power · Jul 28, 2013

I have a Nokia phone with wireless charging. I don't really notice any difference in charging time between the charging plate and hard wire. It may be slower, but not nearly enough to notice a difference. The convenience is great when I'm at work. I can just drop the phone on the charging plate when I'm at my desk and it always stays topped off. Alignment isn't an issue at all since the phone and charging device are just about the same size. I could see having trouble lining up a tablet that dwarfs the charger.

PortlandSoxFan · Jul 28, 2013

I have 2 different wireless chargers for my Nexus 4. One I originally had 2 of; one of them never worked and the other works most of the time. the one I have at home, made by LG, works like a charm.

good:
http://www.amazon.com/gp/product/B00C6VP03I/ref=wms_ohs_product?ie=UTF8&psc=1

risky (my mother has this one, too, and I guess it works OK for her)
http://www.amazon.com/gp/product/B00B7LPA42/ref=wms_ohs_product?ie=UTF8&psc=1

Fratboy · Jul 29, 2013

*A little off topic*

Does anybody have any recommendations for a good (and inexpensive <$20) super powerful wired charger ( > 2.0 Amp) that can charge multiple devices, say like 4 simultaneously?

mt8thsw9th · Jul 29, 2013

Fratboy said:
*A little off topic*

Does anybody have any recommendations for a good (and inexpensive <$20) super powerful wired charger ( > 2.0 Amp) that can charge multiple devices, say like 4 simultaneously?

Is something like this what you're looking for?

jayhoz · Jul 29, 2013

Frat - Are you charging tablets, phones, or both? What is important is the per port amperage. Some vendors will try to sell you a "2 amp, 2 port" charger and not tell you that each port only gets 1 amp and that tablets will take forever to charge on them.

Fratboy · Jul 29, 2013

Something like what mt8thsw9th posted is similar to what I'm looking for, yeah, and Jayhoz, it'd be like a phone and a tablet simultaneously. And that's a great point - I know if you're charging 4 devices simultaneously it'll take forever. That's not an issue overnight per se, but yeah, not something I'd do during the day.

(I lost my Nexus 7 charger, and that's a pretty kickass charger, and using my old Nook charger instead, which fits the bill too, but I'd like to replace them with something more useful. I'm considering switching out a power plate or three in my house as well.)

jayhoz · Jul 29, 2013

Dernells Casket n Flagon said:
Thanks, Jayhoz. Those posts are both super helpful. I did some searching on my favorite tech blogs and was surprised to not find much. As far as charging time is it generally the same with wireless as wired?

I wasn't aware that there was still a standards war going on with wireless charging, I thought that Qi had basically won out and to be honest was the only standard I could have named.

http://allthingsd.com/20130729/starbucks-latest-move-ups-the-stakes-in-battle-over-wireless-charging/?mod=tweet

Reverend · Aug 1, 2013

SumnerH said:
What does this mean? Wireless charging's been widely and stably deployed in commercial consumer goods for decades, it's already a solved problem. Oral B toothbrushes were advertising it back in the late 80s or early 90s, the GM EV2 electric car and the electric RAV4 both used inductive chargers.

It's less efficient (that's for hard scientific reasons, not something that engineering will overcome), but it's not that much less efficient--the EV2's inductive chargers got something like 85-90% efficiency. That is enough that it might be problematic for a car charge where there's a lot of energy being transferred, but may not matter much for charging cell phones, game controllers, etc (and it might get pushed closer to 95%, especially at very short distances).

He doesn't understand what lightning is and why we're not going to employ it in consumer electronics.

cgori · Aug 3, 2013

Fratboy said:
Something like what mt8thsw9th posted is similar to what I'm looking for, yeah, and Jayhoz, it'd be like a phone and a tablet simultaneously. And that's a great point - I know if you're charging 4 devices simultaneously it'll take forever. That's not an issue overnight per se, but yeah, not something I'd do during the day.

(I lost my Nexus 7 charger, and that's a pretty kickass charger, and using my old Nook charger instead, which fits the bill too, but I'd like to replace them with something more useful. I'm considering switching out a power plate or three in my house as well.)

Two of these still ends up cheaper (I have one of these and it's great for travel, compact and sturdy): link - Amazon is offering me an additional $3 off when I buy two, YMMV.

jayhoz · Aug 4, 2013

Two of these still ends up cheaper (I have one of these and it's great for travel, compact and sturdy): link - Amazon is offering me an additional $3 off when I buy two, YMMV.

That charger has 10 watts total output. It would charge two phones or one tablet at full speed. Trying to charge multiple tablets or a tablet and phone at once would be slow.

PortlandSoxFan · Aug 7, 2013

PortlandSoxFan said:
I have 2 different wireless chargers for my Nexus 4. One I originally had 2 of; one of them never worked and the other works most of the time. the one I have at home, made by LG, works like a charm.

good:
http://www.amazon.com/gp/product/B00C6VP03I/ref=wms_ohs_product?ie=UTF8&psc=1

risky (my mother has this one, too, and I guess it works OK for her)
http://www.amazon.com/gp/product/B00B7LPA42/ref=wms_ohs_product?ie=UTF8&psc=1

Update: Avoid the risky one. My mother's crapped out, so of 3 purchased, only 1 is still working.

jayhoz · Aug 14, 2013

Short of starting a new thread ill piggy back here for a quick question. I bought a car and wall charger on amazon, both double USB. Each has one labeled NA and one labeled A. Would the charge times be different and if so which is faster?? Thanks.

I found a review on Amazon that referenced the A an NA ports. According to the review they stand for Apple and non-Apple. I take that to mean that the A port has the correct circuit to perform the proper handshake with the i device. If this handshake does not occur, the i device can charge at a slower rate and/or say not charging on screen. If that is true then my guess is that both ports are receiving the same watts.

mt8thsw9th · Sep 9, 2013

http://www.engadget.com/2013/09/09/cota-by-ossia-wireless-power/#continued

NortheasternPJ · Nov 25, 2013

Love Google put on it "Designed by Google in California"

Wireless Charging

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