Mosaic
Well-Known Member
Well Mike, I guess you never met a self limiting wall wart charger.....transformer, rectifier, maybe a cap and little else, no fuse, no bimetal strip or PTC. The charger is 'sized' to charge to 13.8V or so as current load drops to a trickle. Higher currents cause increased voltage drop loss due to DCR winding loss plus rectifier and wiring losses and is thereby self limiting. Such chargers are not suitable for every size battery, they have a window of compatibility and are as cheap as they come. No dedicated current limiting electronics at all. That approach sidesteps hysteresis as well and would probably serve elecv better than Colin's circuit (which I found on other sites as well, so it may not be Colin's at all)
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BTW I converted an AC3U Nokia clone cellular charger ($3.00 ea) to deliver 13.5V (changed a zener) and used a 5 ohm, 5 watt resistor as a series current limiter , effectively making my own Wall Wart 'extra efficient' charger and there have been no 'fires'.
Edit:
BTW I converted an AC3U Nokia clone cellular charger ($3.00 ea) to deliver 13.5V (changed a zener) and used a 5 ohm, 5 watt resistor as a series current limiter , effectively making my own Wall Wart 'extra efficient' charger and there have been no 'fires'.
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