Charging a Phoenix sound system

What’s the best way to charge the battery for a Phoenix sound system? The system worked great and then I didn’t run the trains for about 6 months and now the sound works for short time and then quits.

Swomotion

In my LGB loco, I can just shut off the engine with the internal switch and place the engine on the track to recharge te battery… The sound unit is attached to track power on the engine.

Was a charging jack installed when the sound was added?

Or just run the engine for 2 hours. with the track voltage at 8 volts or more. per the 2K2 instruction manual posted at the Phoenix download site.

There was no charging jack installed…I have turned off everything and sat the engine on the track and powered up for more than 2 hours. Maybe I need a new battery.

I had one sit for a long time. It took a while to get it back to normal. The best is to place it on the track and turn the power up. I like to put the sound in tenders with power pickups, and then I take the loco off and charge the tender. Works well if a non LGB (with power switch) loco.

It took about 8 hours of continuous power to get it back up to normal.

Since the battery gets its charge from pin 1&2, you should be able to add a charging jack across pins 1 & 2 to mimic normal power when running. Book says that the battery starts charging at 8V and the pin 1&2 limit is 24V so that suggests you can put between 8 - 24V on it and it should reach full charge in 2 hours. Book also says you should get enough charge for normal operation in 30 min.
I think there must be some trickle drain on the battery even when everything is powered off because mine loses most of its charge if I let it sit idle for a week or two.
Paul D