USB Charger Stand (Making My Own) ?

[MEXICOWANDERER]

Cellulars, Kindle, Nook, Yadda. Too many gizmos to count, it seems like. And the ebooks much prefer gentle charge rates (current limiters). Then there is Mexican electricity. In a fit of optimism, I purchased a Meanwell 12-amp power supply ($8.00). 5.0 volts + - 10% adjustment.

Yet another project.

If and only if I can get my hands on the necessary goodies to complete the project.

I want six outlets, but the USB outlets will have permanent 16" long USB cords and they will be designed to be changeable when their tips wear out. Where to buy shorter really great quality charge cords is a question, here. I like braided cords but they are usually 5' in length.

Four of the charging cords will be direct connect while two will have current limiting to 500ma for the ereaders. NOOK is especially mad-dog about insisting on gentle charging currents. It's OK - I have all night to recharge the devices.

Now some more questions...

Obviously 3.7 volt lithium batteries cannot tolerate 5.0 volts. So a device must have an onboard circuit to manage the disparity. A charge controller. What I do not know is if it is "best" to limit current with stuff other than the ereaders. If the answer is "yes" then all 6 outlets will get current limiters.

Do the batteries "suffer" with continuous charging? A laptop's circuit stops charging altogether. Laptop charging circuits cost more than the entire cost of a USB charged gizmo. They can stay plugged in. Putting individual charge time limiters on the new charger will be child's play. And look, it's ridiculous to think precise charging limits are mandatory. I can install 6-hour limiters. Some of the USB gizmos may stay connected for days and days and -that- is what I am concerned about.

Ho ho ho, you say?

Have a friend connect a Scope Meter to the output of YOUR USB charger. Check the RIPPLE developed by your USB charger. Then read up on lithium batteries and their vulnerability to being exposed to a charging current that has ripple. Surprise! It's pure cyanide for the battery. OF course the degree of ripple has everything to do with how good or bad the charging current is for the lithium battery.

With the Meanwell I can build an AC power inlet filter to make its life easier, then add capacitors to keep output ripple to under one millivolt. If you feel like arguing the ripple/battery life issue please do it with the battery manufacturer not me.

Why is this necessary?

It is necessary when one lives so far from the United States that buying (for example) a replacement NOOK means incurring a hundred fifty dollar DHL shipping charge once transfer from the seller's shipper to DHL is made (a hassle and a half). Then, arranging a 300-mile round trip to get to the DHL office. Wanna wait two weeks for a three hundred eighty dollar NOOK? I don't. And NO the battery is not field replaceable, period. I wish they were.

If I can manage to learn what I do not know about small device lithium battery onboard chargers, and secure great quality charging cords, I will build a bedroom shelf device charger that will last. And yes, the Meanwell is built to go the distance 24/7 for many years.

Thanks in advance for tips, and help. And yes, I am close to the border at present and yes the Nook and Kindle are sparkling brand new. After surgeries, I move 2,550 miles further south.

[MrWizard]

The best way to know what your usb devices draw is to measure them with a USB amp meter
I see them all the time on Amazon and eBay for about $10, maybe less



USB power meter ...Amazon

use with any usb port/supply to measure device charging/draw

[MrWizard]

It seems to me a small line conditioner, for the utility power, would be a better idea, then you would not be blowing the wall wort power supplies

I have a 600w model from Tripplite, boost and trim functions totally automatic
Just an on off switch , 120v 5.3a input, 120v 600w output
6 ft love cord, and 6 outlets for other cords, need a power strip to use wall worts

https://www.tripplite.com/600w-120v-power-conditioner-automatic-voltage-regulation-avr-ac-surge-prot...

I know you love building stuff, but what ever you build still needs to be protected from Mexican utility power, either built in, or put something in front of it, between the PowerMex and your USB charger/s

[MEXICOWANDERER]

I'll let you know how things turn out. Blew yey another USB charger today. No output right at secondary outlet. Block itself quit. The ????? $30.00 charger dies out after 10 min.

[MEXICOWANDERER]

Qtla9111

Try Lago Atitlan Guat or Gracias Honduras.

[GordonThree]

OOps forgot about this thread.

So, charging something by it's USB port is a tad more complex than just providing nice clean 5.0v (or 5.1 if you want to push a bit more juice)

My recommendation is; get a 12v to multi USB charger, and use its guts in your own design. Here's why:

Most everything has both a smart charger wall adapter (or car adapter) and a smart charge control IC inside the device. The two talk to each other and determine the best charge rate and period for the health of the battery.

Providing 5v without any communication (data lines open) will likely result in the slowest charge the device is capable of, likely 100-500mA. This is because the charge control IC doesn't know what the host capabilities are, so it limits itself to something safe.

In the olden days, setting the data lines to specific static voltages using resistors was enough to communicate with the charge control IC and report on charge current available. The Nook being newer, probably uses a serial handshake (data lines change state one or more times after connection.)

A decent commodity USB multi charger will contain chips designed to talk to lots of different devices, and provide charging based on what those devices request.

Regarding leaving something on the charger all the time, well, that's going to vary widely from one device to another. Small device lithium packs from my research tolerate a "float charge" at 80% capacity. This gives a lot of headroom for temperature fluctuations that could change the 100% voltage level (4090 mV, 4150 mV, etc). Your idea to use timers is probably the best simple solution.

[Tom_M1]

MEXICOWANDERER wrote:
"If it was me, I would shut the NOOK down and recharge the battery at no more than 300 milliamps.

All my USB charge modules are between 2.0 and 2.4 amps and that is what I use to charge my Nook GlowLight. It is the first generation GlowLight so I have had it a few years. I have had no problems.

[qtla9111]

Nooks are available on both Amazon Mexico and Mercolibre with free shipping very similar U.S. prices.

Not sure where you're headed but let's say you're in San Diego then 2550 would put you in Guatemala, Guatemala or Merida, Yucatan.

[hawkeye-08]

I've had real good results with Anker cords and devices. I had one cable go bad and they replaced it over night.

[MEXICOWANDERER]

Polar opposite my view on generator battery charging I have all the time in the world to recharge the batteries.

Do not gizmo manufacturers have to be sensitive about how long their chargers take to recharge the gizmo battery? A 12-hour recharge would really raise consumer's eyebrows. I have a hunch this is an extremely valid point.

By playing around with voltage on my lab power supply I can root out optimum charge voltage limit assuming there is not a wide variance in gizmo battery chemistry.

As an example a 12-hour charge time overnight at 300ma would supply a significant kWh value to a gizmo battery.

[MrWizard]

I think all devices can charge on the original usb spec 500ma limit

i don't remember ever seeing a wall wort phone charger or other device that was less than 500 ma, they may exist but i don't remember seeing them, maybe one of my first flip phones

take a look at the OEM device charger, get out the magnifier and look at the fine print for the power output

a lot of my stuff is charged with 750 ma or 1 amp 5v usb chargers

the smallest usb charger i have is 5v 300ma, and it charges my
"IQ Massager", and that thing is small as a ipod micro

[MEXICOWANDERER]

Thanks folks. These are exactly the type of questions I would like to get a handle on. About four years ago I telephoned NOOK and managed to talk to a technician who knew what he was doing rebuilding the devices. "If it was me, I would shut the NOOK down and recharge the battery at no more than 300 milliamps. That, and not leaving the battery flat or on the charger for extended periods will increase battery life tremendously you wouldn't believe it".

THAT got my attention.

Thanks for the Amazon braided cord tip.

I am going to have to think about my S4 rate of charge, but I do not have to think about whether it needs a fresh battery. Is there a truly superior brand of battery for the S4?

[pianotuna]

Hi Mex,

There are lots of posts about batteries swelling up from continuous charging for MIFI (hot spot) devices.

I try to not leave my devices permanently plugged in. I try to disconnect them when they are at between 95 and 98% state of charge. I plug them in when they are at 30%.

My S4 will gradually discharge if I am actively using google maps with it plugged into a 12 volt outlet. It does stay charged if I use a small MSW invter and plug the OEM charger into that.

[nickdarr]

Don't know which cord ends you want, but Amazon has braided one foot cords in six packs with USB to micro USB or USB to USB. I bought an assorted six pack with two each of 1, 3, and 6 foot. The cords have held up well in the truck for a little over a year.

[pnichols]

Your project brought some questions to mind:

1. Are the lithium batteries in most of today's small, personal, mobile devices 3.7 volts?

2. If so, why does the multi-output USB charger I recently bought have it's outlets labeled at different values of current output?

3. In other words, why do some 3.7 volt lithium batteries need to be charged at lower current USB charging ports than other 3.7 volt lithium batteries ... and how does one know which current output capability USB port to use on a multi-output charger?

:h

[dalenoel]

I got a Multi Port USB Charger and put it under the rear TV where there was a small shelf. All the items to be charged are then plugged in with their own cords. The cords are replaceable and any new items can be added.

For some we have two cords alike as we might need to plug both phones in during the night.