USB Charger incorporation into a PT feasibility inquiry

[Mark Linehan]

I am going to make a small USB passthru and I was thinking that it would be cool if I could make one of my little TUFF flashlight mods into a combo Passthru-Charger-PV mod.

It will use a 10440 battery when I am walking around. Then I can come home, plug in the USB cable and let it charge and be used as a passthru.

I have a number of old USB chargers from my tornado/ego batteries. I am sure I can crunch the numbers and throw in a small circuit to back down the mA enough to not blow up the 10440 battery if that is my only issue. I do not know a ton about battery charging circuits though. The batteries are protected and the circuit has built in protections as well. I am not positive on how the 10440 will appreciate the circuit for the ego usb charger though.

Has anyone ever wired up something like this? Any suggestions or advice for this? I would have to replace the male USB connector on the charger with a small remale usb port so I can plug into it and I would not be able to fit a larger style usb connector into the .... end of one of these tiny flashlights either. Now that I think about, I will have to get the charger circuit into the end beside the battery and I will have to see if there will be room for that. I may have to switch to using a slightly larger battery for this to work.

Mark

 

[Java_Az]

Some folks have done it , it works. The bad thing about it is the ecig USB chargers have a constant drain on the battery of about 10mA . With a small battery it will have a large impact on the vape time. Here is a thread about it and Minus posted a link to a USB charger that has some awesome reverse protection rated @ .7 uA. For something as small as you have might be the best bet To go with that type of charger. But you will have to get the data sheet and drop the charge rate down on it by changing out a resistor. It charges @ 500mA by default. You dont want to charge at more then the rated Mah of the battery Really for the longest life of the battery charging at 1/2 the rated mah of the is ideal. http://www.e-cigarette-forum.com/forum/modders-forum/164527-usb-charging-box-mod.html

 

[jufreese]

I have seen a few questions on here as to how to do this.

Here is how I did it with a USB charger from an old BLU e cig kit.

First of all, the USB charger only outputs @ 100mA so this is not nearly enough to directly power the ecig as it takes over 1A or 1000mA.

So while charging, the battery needs to be disconnected from the load (in this case our atty).

There is an easy way to do this with just 1 part. A relay!

The relay you must use though is a 5v dc relay with a Normally Open side and a Normally Closed Side.

When the relay gets 5v across it's coil, the Normally open side closes, and the normally closed side opens.

So....re-read that if you didn't understand. The relay has a coil and two switches inside of it. One switch normally closed, one normally open.

So if you put your battery on the normally closed side and the 5v dc on the normally open side, and then use the 5v dc on the coil.....when 5v dc is present, the coil is energized which disconnects the battery and connects the 5v dc to your load.

Now you will put the battery charger directly from your 5v dc to the battery in parallel with the relay.

So now when 5v dc is present (needs to be 5v dc @ at least 1.5 amps) the charger turns on and charges the battery and turns the relay on with disconnects the battery from load.

The load is going to be your switch and atty.

 

[Mark Linehan]

Unfortunately I do not think this flashlight would allow for me to install a relay into an already tight space along with the chager board used in a breakout fashion. Relays tend to be more larger than smaller. I mean, even if it is a small relay it will probably still be at least 2mmx2mmx3mm or so, right? ..or are they making them even smaller than that these days???

 

[jufreese]

The relay is probably more around 10w x 11h x 20L mm. I fit one into a box the other day. AA batteries have about a 10.5 mm radius.
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