more electronics than electrics - battery and charging question

I’m assuming you are taking a purist approach and want to keep the radio in pristine unadulterated condition rather than butchering it to make it work.


How are you actually determining those voltages without a functioning battery, have you connected the radio to the mains adapter are measured what voltage is presented at the pins?


I still have my original DAB radio in my garage connected to a mains adapter, I bought it and ran it off removable rechargeable batteries, but it absolutely hammered them and running off batteries was not worthwhile, I never did really work out why the same batteries could run an AM/FM radio all day.


 Andy

Digging a bit it seems that these radios were sold without batteries mostly even when new, so  the odds are really slim now.

A possibility may be to track down a service manual -  a schematic of the charger circuit would reveal more All cells rise  in voltage as they charge, and when the plates are fully coated any excess goes into splitting the water .  NiMH cells are ok for a slow constant current charge once 'full' , as the nickel catalyses any Oxygen and Hydrogen produced back to water, at least it can do this at a rates less than the 10 hour rate of charge (so <= 50mA for a 500mAh cell for many hours is OK)  Li Ion have no gas dispersal mechanism short of explosion, so need to have the rising voltage monitored and cut off hard at 4V or so, and the electronics will reflect this, also it is usual to bring a centre contact out to make sure one cell is not over voltage.

However, it is also common in all types of battery pack to include a thermistor to act as a warning of impending doom and throttle back the charge current.


However, if we cannot be sure, I'd say it is far safer to ignore the built in charger, and see if any of These standard battery holders for AA or AAA cells  can be fitted in the battery bay, such that 7V or so ends up across  pins 1 and 4 in the same polarity you are measuring with the mains supply, I;d probably tack solder  some thin red and black ( call me old fashioned) to the back of the connector, and try with the mains power removed, supplying battery power in at those points.


If that work, then you could do worse than  buy tagged cells AA tagged    or   tagged AAA        and with a bit of fast soldering and some tape you can roll your own battery packs to whatever funny shape you need.

@sparking -  nope, not interested in keeping pristine - its a bit battered. It was a freebie aquisition.

@mapj - you have confirmed my thoughts on this and along with other comments, it would seem a bit of a challenge (as sparking observed, i already knew)


Fine then, I am convinced. I'll leave it.  My interest was to see if there was some way to deduce how it was wired and get the company who offered to construct the battery pack (subject to knowing the charging arrangements etc), but given my limited electronics abilities/experience it would seem better to leave it.


Thanks for the interest, but consider it closed (or dormant as who knows what might pop up).

I'd keep it and use it off a mains adaptor. It is a highly respected, trendy, stylish radio with good sound quality and real wooden parts.


Z.

At that age it will be obsolete with no DAB+ facility, so not really worth spending money on.

Radios with real wooden parts.

Those were the days.

Often had decent speakers too.

Whoops I`m showing mee age again.

A Seven Valve Phillips, back in the day ?