Was going away from the weekend, and I needed a way of topping up my phone. Didn't think far enough ahead to buy one of the 18650 boxes from DX, and I don't even really have enough 18650's as it is, so I decided to put this battery pack to another use!
Disclaimer: This "mod" relies on the fact that the battery provides an output voltage on it's jack, which is used by the charger to detect when it's full. I have not investigated what circuitry is behind this jack, so be careful how much juice you try pull from it. Also be very cautious of short circuiting it. If there is no actual circuitry between the jack and the battery pack, shorting it out can be seriously dangerous.
Basically, all it is is a 7805 voltage regulator, a capacitor, a USB jack and a DC jack.
A linear regulator is not the best way to do this, those battery charging boxes use switchmode topology for a reason, the linear regulator gets fairly hot at this voltage input, especially with large loads, such as mobile phones. As it only has the USB connectors as it's heatsinking, I wouldn't recommend using this for high power devices.
The DC jack connector isn't very solid how I have it now, so you need to be careful you can't accidentally bend the jack and short something out.
Also note that the USB connector has small pressure pads on each side. When I soldered the 7805 regulator on, it pushes these little tabs down, making it slightly difficult to insert the USB cable. However, there is no way the connector could fall out like this, and it also aids in thermal transfer from the connector to the plug a bit more. If you want to build it like this, I'd recommend trimming the tabs, or insert the USB cable before plugging it into the battery.
Aaannndd, another note. Because I have not opened the battery up and looked at the circuitry, I am not sure whether this jack has low voltage cutoff protection or not. Be wary of that, I'm not responsible if you blow yourself up or burn your house down!
Anyway, pictures!
The regulator looks a bit old and beaten up, because, well, it is
It is just soldered to the USB connector, as the 7805 tab is ground.
It gets warm/hot pretty quickly charging my phone, but hopefully it should last enough to give me some decent usage.
Picoprojector too!
Although it gets hot rather quickly running this, so like I said, good for small devices.
Dan
Disclaimer: This "mod" relies on the fact that the battery provides an output voltage on it's jack, which is used by the charger to detect when it's full. I have not investigated what circuitry is behind this jack, so be careful how much juice you try pull from it. Also be very cautious of short circuiting it. If there is no actual circuitry between the jack and the battery pack, shorting it out can be seriously dangerous.
Basically, all it is is a 7805 voltage regulator, a capacitor, a USB jack and a DC jack.
A linear regulator is not the best way to do this, those battery charging boxes use switchmode topology for a reason, the linear regulator gets fairly hot at this voltage input, especially with large loads, such as mobile phones. As it only has the USB connectors as it's heatsinking, I wouldn't recommend using this for high power devices.
The DC jack connector isn't very solid how I have it now, so you need to be careful you can't accidentally bend the jack and short something out.
Also note that the USB connector has small pressure pads on each side. When I soldered the 7805 regulator on, it pushes these little tabs down, making it slightly difficult to insert the USB cable. However, there is no way the connector could fall out like this, and it also aids in thermal transfer from the connector to the plug a bit more. If you want to build it like this, I'd recommend trimming the tabs, or insert the USB cable before plugging it into the battery.
Aaannndd, another note. Because I have not opened the battery up and looked at the circuitry, I am not sure whether this jack has low voltage cutoff protection or not. Be wary of that, I'm not responsible if you blow yourself up or burn your house down!
Anyway, pictures!
The regulator looks a bit old and beaten up, because, well, it is
It is just soldered to the USB connector, as the 7805 tab is ground.
It gets warm/hot pretty quickly charging my phone, but hopefully it should last enough to give me some decent usage.
Picoprojector too!
Although it gets hot rather quickly running this, so like I said, good for small devices.
Dan
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