Question Is a modified USB-B cable safe to use as a Portable Nintendo DSI Charger?

[Gamefreaknet]

Hi. I've had the Nintendo DSI for a while however on the go the charge doesn't last very long. To get past this issue I slightly altered the shape of the end of a USB-B cable which allowed it to fit into the DSI's charging port and the DSI seemed fine as it charged through the cable just as it did with the official charger however is it dangerous to do this or will it be fine regardless of which cable I use?
(The official charger and DSI battery are rated at 4.6v)

 

[Eximo]

Well, most charging circuits will take a fairly wide range of voltage as input. Using 5V to charge a 3.7 volt lithium battery cell is pretty typical. Not sure why they opted for 4.6 volt other than to make their charger look proprietary.

As to the physical modification, I would have to see pictures. As long as nothing is shorting out, it is probably okay. Maybe a little extra load on the circuit to take it from 5V down to the 4.2 or so used to charge the battery, but hopefully they already have thermal protections. The chips available on the market for this certainly do, I see no reason Nintendo would ask for a custom one.