Скачать или смотреть Blackstar ID:CORE Stereo 10 - battery conversion after power supply failure

After falling victim to the popular power supply failure, I decided to try to convert it to battery power for less than $8, since I already had a large capacity 12V battery on hand. When I asked the manufacturer if it was safe to use 12V into the amp, they stated all of the warranty disclaimer stuff and that it "would power it"... but I was nervous about "overpowering it" and ruining the amp. So since the original power supply output was rated at 10V although the amp input is rated for 6.5V... I figured the 9V output converter was safe. So far, so good - so I just wanted to share this experiment in case others were curious and interested in trying it.

The 12V-to-9V step-down 3A converter I'm using:
https://amzn.to/2uVdy99

The battery I'm using:
https://amzn.to/2GJ7zqC

The amp (even though it hisses like a snake, I'd still buy it again because the stereo effects are so good):
https://amzn.to/36TuGcC

Does is make a noticeable reduction in the inherent 'hiss' of the amp? No. Is it now totally portable? Yes, although, of course, much heavier. Not a problem for a stationary household (and now backyard) compact combo practice amp. I've got no idea on battery life yet, but buskers may be interested, since this stereo amp actually sounds surprisingly good when playing backing tracks through it.

What I'd like to do now is to add a voltage (?) meter (so I know when I need to recharge). Secondly, also be able to wire the existing cut-off power cable to a 12V charger, so I can easily connect to the existing power receptacle to recharge without having to remove the top amp plate to access the internal battery. I don't know much about electronics and would be grateful if someone could help by letting me know which parts I may need along with a simple schematic or description of how I need to configure the parts. Much appreciated in advance!

jr