UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Was there something odd about Japanese primary cells?

TonyDuell · 11th Feb 2020, 11:35 am

I was always told it was a bad idea to attempt to charge primary cells, in this case probably of the zinc-carbon type.

But a number of Japanese units from the 1960s/1970s float a battery of such cells across the output of the mains PSU. In other words there is no battery/mains changeover switch. Just a transformer/rectifier with the battery directly across the output, feeding the rest of the unit.

OK, the rectifier will prevent the cells discharging via the mains transformer, but surely the cells are being 'charged' when the unit runs on the mains.

The thing that has prompted this post is a Juliette 606 tape recorder which does this. So do the Sanyo 'briefcase' music centres. I've not seen instructions to remove the battery before connecting the mains lead on any such unit. So were they just hoping for the best (that the cells wouldn't leak or even explode) or was there something special about the (presumably) Japanese cells it was designed with?

11th Feb 2020, 11:35 am	#1
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,208	Was there something odd about Japanese primary cells? I was always told it was a bad idea to attempt to charge primary cells, in this case probably of the zinc-carbon type. But a number of Japanese units from the 1960s/1970s float a battery of such cells across the output of the mains PSU. In other words there is no battery/mains changeover switch. Just a transformer/rectifier with the battery directly across the output, feeding the rest of the unit. OK, the rectifier will prevent the cells discharging via the mains transformer, but surely the cells are being 'charged' when the unit runs on the mains. The thing that has prompted this post is a Juliette 606 tape recorder which does this. So do the Sanyo 'briefcase' music centres. I've not seen instructions to remove the battery before connecting the mains lead on any such unit. So were they just hoping for the best (that the cells wouldn't leak or even explode) or was there something special about the (presumably) Japanese cells it was designed with?