Using H340 without battery

[wada]

Hi
I have H340 with almost completely dead battery (it goes for one minute or so).
all the batteries I saw are quite expensive (at least in Israel).

I would like to fit my player in my car so I figured that I don't need a battery.

Is it possible to just work with no battery or maybe connecting the battery connector to 5V power supply?

thanks a lot
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edit:
Well, I've opened it up and disconnected the battery. It works without a problem.

I wonder if there is a way to config rockbox to load when connecting to AC power, instead of loading iriver "charging screen".

and also shutting down right after disconnecting from AC, now I can only choose 1min idle time shutdown, I'd like it to be few seconds, so there will be still enough juice in the battery  to properly shutdown Rockbox.