Mark1959 Posted June 28, 2004 Report Share Posted June 28, 2004 Needing some help for an idea on a rechargeable battery pack and circuit that will maintain the Clock and memory on an in dash type AM/FM radio.I Quote Link to comment Share on other sites More sharing options...
ante Posted June 28, 2004 Report Share Posted June 28, 2004 Hi Mark,Welcome to this community.Is it standard to have 12 Volts in a truck where you live? In Europe most trucks have 24 Volts at least if they are bigger than 3.5 tons.I have a couple of questions about your radio system: How much current is needed to supply the Quote Link to comment Share on other sites More sharing options...
Mark1959 Posted June 30, 2004 Author Report Share Posted June 30, 2004 Hi Ante,Thanks for the welcome and the return to my inquiry. Here in the states the starter that turns the motor over uses 24VDC but everything else runs on 12VDC for the large trucks anyway. To answer your questions: Quote Link to comment Share on other sites More sharing options...
ante Posted July 1, 2004 Report Share Posted July 1, 2004 Mark,Here is a suggestion; the backup battery should be a 9-cell pack. I suppose the 12 V line in your truck rises to something like 13.8 Quote Link to comment Share on other sites More sharing options...
Mark1959 Posted July 2, 2004 Author Report Share Posted July 2, 2004 Hey Ante,This circuit of yours looks great, guess I was over engineering the thing with my idea of the step transformer. Ante; please forgive my ignorance for my knowledge of this hobby is limited and it Quote Link to comment Share on other sites More sharing options...
ante Posted July 3, 2004 Report Share Posted July 3, 2004 Mark,The diodes are 1N5821 or similar and the resistor depends on the mA rate of the NiCad pack and the voltage at the input. The input voltage can vary from 12.7V (12V battery in rest) to 14.4V (alternator full charge). Sometimes the cells are marked trickle charge 50mA or some rate that is about one tenth of the capacity (mAh) value. It Quote Link to comment Share on other sites More sharing options...
Mark1959 Posted July 3, 2004 Author Report Share Posted July 3, 2004 Thanks Ante,Will get started on this circuit right away. I will let you know how it works out. Thanks again for all your help. Have a great weekend.Regards,Mark D. Quote Link to comment Share on other sites More sharing options...
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