Wednesday, March 16, 2011

Charging the Albrecht

Several people seem to have found what I have written about the Albrecht AE2900AFS a.k.a. Dragon SS-301 and various other names useful. Now here's a chance for owners of those radios to help me.

The radio came without a charger. I haven't even seen one advertised for sale. No problem - I can make one. But I have no idea what the charging voltage should be. The manual is no help whatever. If you apply 12V or even 13.8V DC no current is taken - hardly surprising as that is not a high enough voltage to charge nine NiMH cells which probably have some reverse polarity protection in series with them.

Is the charger a regulated or unregulated wall-wart and what is the voltage and current rating?

2 comments:

Fenris said...

According to the spec shown on one of the ebay pages, the DC supply range is 9-13.2V, so that suggests it should charge if you assume fully charged is about 1.4V for a NiMH cell which makes 12.6V total for 9 cells.

Possibly there is no internal charging circuit, or it needs to be enabled like the FT-817's "fast" charging timer.

Is there any indication in the manual?

Julian said...

The schematic shows a polarity diode and a fairly low value current limiting resistor. That's connected to the charger socket. There are charging terminals on the bottom of the battery pack. They aren't shown on the schematic at all and I'm not sure what they are connected to.

The current at 13.2V (or even 13.8V) is only a few mA when the cells are charged which would mean it would take a very long time to fully charge the batteries.