Which portable AA->USB charger?

[GeoffR]

Can anyone recommend a gadget that will allow me to power my Kobo Glo from AA NiMH batteries?

I want to take my Glo hiking, and if (when) the weather turns bad I expect to hole up in a hut and read. All my other devices (torch, radio, camera) use AA batteries, so it would be ideal if I could use them to power my e-reader too.

[piratepanda]

Not exatly what you're looking for but maybe also interesting:
http://www.kickstarter.com/projects/...r-power-statio

[Moody12b]

Originally Posted by GeoffR

Can anyone recommend a gadget that will allow me to power my Kobo Glo from AA NiMH batteries?

I want to take my Glo hiking, and if (when) the weather turns bad I expect to hole up in a hut and read. All my other devices (torch, radio, camera) use AA batteries, so it would be ideal if I could use them to power my e-reader too.

I have an external battery - http://www.amazon.com/5600mAh-Extern...ternal+battery

which has enough power to recharge the Kobo many times.

[Cdesja5]

Originally Posted by Moody12b

I have an external battery - http://www.amazon.com/5600mAh-Extern...ternal+battery

which has enough power to recharge the Kobo many times.

I have this one :
http://www.amazon.com/10000mAh-Multi...f=pd_sim_cps_5

It has enough power of keep everything going (ereader, phone, ipod etc) for several recharges each instead of bringing batteries... Great charger!

[tshering]

If you like doing things yourself you might be interested in this clip. I guess the first (most simple and cheapest) version, discussed from 10:55 to 15:00, might work. However, please be aware that I have no qualifications to be sure about it.

[46jimbo]

Here's a solar charger that might meet your needs:

http://ca.cellphoneshop.net/blackmini.html

[GeoffR]

Thanks for the suggestions: I have thought about a solar charger but I don't know how well it will work on a dark rainy day, which is mainly when I will need it. The battery packs with a lithium rechargable battery would work, but I think one that uses replacable AA batteries would be more useful. Building one myself is a nice idea, 4x NiMH batteries would make 4.8V which might be close enough to 5V, although I'm a little nervous about damaging my reader if I get it wrong :-(

These look almost ideal:
http://www.japantrendshop.com/eneloo...bs-p-1171.html
http://www.japantrendshop.com/sanyo-...er-p-1234.html

The second one can use a USB source to charge the AA batteries as well as use the AA batteries to charge a USB device, which sounds neat. I just wonder if anyone has actually used one of these or something similar with the Kobo readers? Some devices seem fussier about the power source than others.

[TechniSol]

This one is hard to beat based on pricing/capacity:

http://www.merimobiles.com/cager-b03...p/meri7080.htm

They also have even less expensive models with solar cells and lower capacity lithium batteries. If you have enough sun and they're high output solar cells, a lower capacity battery may be more than enough if you can continue to recharge the battery... OTOH, that 10 Amp unit looks like a pretty good deal, if you don't need solar recharging.

[GeoffR]

Originally Posted by TechniSol

This one is hard to beat based on pricing/capacity:

http://www.merimobiles.com/cager-b03...p/meri7080.htm

Hey that is a good price, and free international shipping too. Thanks!

[GeoffR]

This sort of solar charger might work for me: the solar panels charge 2x AA NiMH batteries which are used to power the usb device. If there is no sun then I could just insert precharged AA batteries to keep the reader going.

http://www.powerfilmsolar.com/produc...-remote/usb-aa

[TechniSol]

Well, if you're not overly concerned with efficiency you can make a simple one by hanging an LM7805 5Vdc regulator off a battery pack of sufficient current and voltage overhead(probably 6 x 1.2Vdc rechargeable) and it'll give you a decent 5 volt regulated supply, probably better if you add a couple capacitors, maybe an LED and a switch. There are regulators with lower voltage overhead needs. Trickiest part is making sure you get the polarity right on the micro-usb connector/cable. Charging could be done with whatever charger you already have by swapping the batteries out.

I've been considering building one of these to recharge my cell phone, tablet, etc. during the occasional power outage. I'll probably go with a lead acid/gel cell 12 volt system for flexibility(tablet needs 12Vdc). It'd also be easy to recharge by hooking it directly to my car battery during an outage while driving around. But the thought of throwing away 7 volts+ through a resistor/regulator combo makes me want to design a DC-DC converter for the 5Vdc output.

There are at least a couple of kits out there(Google it) that step two AA batteries up to 5Vdc, but the cheapest ones still cost more than I'd prefer to spend. Of course, 2 AAs @ 2500maH gives you 3V x 2.5A or 7.5W @ even 75-80% efficiency you get over 1000ma @ 5Vdc. I'd like to try a 4 cell pack (4.8 nominal, but nearer 5.6Vdc fully charged), but so far I've chickened out. Back in the day you could count on +/- 0.25 under over being safe, but I'd just about bet most devices could handle the initial extra overhead, and the 5.6 is measured with no load. Loaded, it would drop off to 5.25, or less, quickly.

I may wise up and buy the one I linked to, and just drag the tablet along and charge it in the car or the office if I need.

[DNSB]

that I built a few years back is still working for me -- actually, built two versions as I updated to the v2 version and then added the resistors around the data pins to keep some devices happy to move to v3. Check MintyBoost in a Google search for more information on this DIY project. I think the kits have been out of stock for the last while but the instructions are still there including the last mods to the kit ( http://www.ladyada.net/make/mintyboost/parts.html ). The parts list has the updated schematics for some odd reason.

The last one I build used three D cells in series (staying below the 5V maximum) and worked quite well on a long camping trip for keeping the our devices charged other than the daughter's tablet which needed about 1.4A through a micro-USB connector to charge.

While a fairly simple project, it's more for those who enjoying tinkering with electronics or want to start doing so.


Regards,
David

[DNSB]

Why did this post twice?

[theinfamousj]

Originally Posted by GeoffR

Can anyone recommend a gadget that will allow me to power my Kobo Glo from AA NiMH batteries?

I want to take my Glo hiking, and if (when) the weather turns bad I expect to hole up in a hut and read. All my other devices (torch, radio, camera) use AA batteries, so it would be ideal if I could use them to power my e-reader too.

As a fellow hiker, I completely understand what you mean. I have a Goal Zero Guide 10 battery pack and, while heavier than I'd like, it does exactly what you want, plus it can charge those batteries too.

It outputs to USB from four AA or AAA NiMH rechargable batteries (it comes with AAs).

[jackastor]

Originally Posted by GeoffR

Thanks for the suggestions: I have thought about a solar charger but I don't know how well it will work on a dark rainy day, which is mainly when I will need it. The battery packs with a lithium rechargable battery would work, but I think one that uses replacable AA batteries would be more useful. Building one myself is a nice idea, 4x NiMH batteries would make 4.8V which might be close enough to 5V, although I'm a little nervous about damaging my reader if I get it wrong :-(

These look almost ideal:
http://www.japantrendshop.com/eneloo...bs-p-1171.html
http://www.japantrendshop.com/sanyo-...er-p-1234.html

The second one can use a USB source to charge the AA batteries as well as use the AA batteries to charge a USB device, which sounds neat. I just wonder if anyone has actually used one of these or something similar with the Kobo readers? Some devices seem fussier about the power source than others.

There is a back back accessory that has flexible solar panels that is designed for hiking. I cant recall the manufacture but it does allow for a sizable solar panel and many connectors for many things. I think it utilizes a lithium battery as well. Found the link here it is

http://www.voltaicsystems.com/fuse4w...FYYWMgodHGYAag

The cost is 129$

This might work best for you. Btw Most solar panels today work preety good in most light conditions. However it is obvious that brighter lighting such as full daylight would work best and provide the most amount of renewable energy.

Regards

Jack