battery-to-battery charger

[Joe Ibershoff]

Hey folks,

I'm going to be backpacking in another country for a while, and my wife gave me the task of making sure our camera doesn't run out of juice.  I have a 220V->110V stepdown transformer, but it's heavy and (obviously) can't be used unless I have access to a power outlet.

The camera battery is a LI40B, 3.6V with 660mAh capacity.  I have a couple 5000mAh USB battery packs with 700mA max output, and was considering whether it is safe (for the battery and for myself) to just connect the 5V and neutral wires from a butchered USB cable to the contacts on the 3.6V battery as a cheap, portable, and lightweight method of charging.  I would bring 2, so 1 can be charging while the other is in use, and thus charge time is not an issue.

I found a statement (http://www.afrotechmods.com/reallycheap/lithiumbatterycharge/lithiumbatterycharging.htm) that says "Modern camera and phone batteries also contain overcharge and overcurrent protection circuitry in them", which could be important as I know lithium batteries are not happy with overcharging.

Any thoughts/warnings about this?

Thanks,

 -- Yeti

[Sean McPherson]

Li Batts seem crazy sensitive to charge voltage. Heck, Adafruit even has a big red warning on their charging/battery pack page about it (very bottom). I think you're going to want to step it down to charge them w/o damage.

 

http://learn.adafruit.com/li-ion-and-lipoly-batteries/voltages

 

Got time to build one of these?

 

http://www.instructables.com/id/USB-Li-ion-battery-charger/

 

 

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[Sean McPherson]

If not, they sell little ones premade such as http://www.batteryspace.com/usb-3.7v-li-ion/polymer-charging-module.aspx but this one calls out >1000 mAh capacity and yours is 660 mAh. Maybe charge 2 in parallel :)

 

You can find oodles of these on eBay and such (there're more than it's worth trying to sort so here's a random one)

 

http://www.ebay.com/itm/3-7v-1-5A-single-cell-lithium-battery-charging-module-5v-4-2v-usb-port-/281106959082?_trksid=p3284.m263&_trkparms=algo%3DSIC%26its%3DI%26itu%3DUCI%252BIA%252BUA%252BFICS%252BUFI%26otn%3D21%26pmod%3D121017503840%26ps%3D54

[DE 'Tad' Heckaman III]

Most chargers/powersupplies don't need a stepdown transformer, only a simple adapter to allow you to plug it into the outlet.... it should say on the charger what the input range is.

Also:

AC/Car charger (also compatible with both 110/220 voltages): http://www.amazon.com/Premium-Digital-Battery-Charger-Adapter/dp/B00208FBRC

and a portable 12V battery that could (in-theory) allow you to charge the camera batteries on-the-go via the above adapter:

http://www.ianker.com/anker-astro-external-battery-backup-charger/product/79UN5V2-B16P100A

On Fri, May 17, 2013 at 8:38 AM, Joe Ibershoff <j...@ibershoff.com> wrote:

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[Joe Ibershoff]

Ah, good call, my existing charger does seem to accept up to 240V input.  An adapter plus a couple spare batteries will probably do it for me.

Also Sean, thanks for the Adafruit link, it appears the highest voltage I could safely apply to my nominally 3.6V battery is 4.1V.  Seems like 5V is a bad idea then.

Thanks folks!

 -- Yeti

[Greg Miller]

What type of camera is it? Most SLRs have battery grips that allow
you to use standard AA which you can buy along the way as needed.

[Joe Ibershoff]

No SLR for me (yet), it's just a digital point-and-shoot.

[Lockadoc]

Why not bring a small inverter that plugs into the car lighter socket 12Volt DC, use a 400 watt inverter (small) that should be able to power your standard charger 

Bill S

Sent from my iPhone

[#]

for most all my gadgets ive converted them over to use 18650 lipo batteries then i can solder those into packs ,,   like 2 cell, 4 cell         then you can also solder in a balance lead into the packs and use a Universal charger like one of these   "b6 clone"

  it can charge  auto ballance, discharge lead acid , nickel , lithium batteries  and runs off 12 VDC  which you can get from convertor , car ,  solar ,etc,,        i dunno just how ive done all my junk so i dont need ten kinds of batteries an chargers .       

Spec.
Input Voltage: 11~17v
Circuit power: Max Charge: 50W / Max Discharge: 5W
Charge Current Range: .1~6.0A
Ni-MH/NiCd cells: 1~15
Li-ion/Poly cells: 1~6
Pb battery voltage: 2~20v
Weight: 355g

18650's are in alot of laptop cells an if you crack open a bad one bet most are still good !
   dell's are good ones to look for .    get some nice panasonic 18650's out of em , lol

[Joshua Wilcox]

Just throwing this in there. You could make a solar panel over at the hack which would charge while your out snapping pictures.