Quote:
Originally Posted by rlw
Could we have more discussion on the pros and cons of using a full wave bridge in a charger vs. the designed half wave?
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The stock output circuit is a full wave rectifier. (IE: Output ripple frequency is 120Hz with a 60Hz input)
It consisting of two discreet diodes that are fed by either a center tapped secondary of a ferroresonant transformer, or two secondaries that are tied together to effectively form a center tap.
All a bridge rectifier does is eliminate the need for a center tapped transformer.
Quote:
Originally Posted by brock
Jonnie B is correct, a diode is a diode, the peak inverse or reverse voltage ( prv) won't make much difference on a half wave rectifier charger, 35 amps should be ok as the load is shared but bigger is always better on diodes, if it will physically fit, they make 1/4" studs all the way up to 45 amps, for the same money, I generally take that assembly out of the circuit all together and use a full wave bridge recitifer of 50 + amps, bolted to that aluminium sink, they charge cleaner and ramp up in voltage with current demand, -vs- a hard charge that will boil a battary and warp the plates, those old chargers are, hard on the dead or old batts, but hard charge, means fast charge, and thats what everyone wants.
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Depending on how you wire the transformer's secondary(ies) to the bridge rectifier assembly, you'll either have the same open circuit output voltage as the original design, or twice the open circuit voltage.
Since the ferroresonant transformer and capacitor pair operate in the core saturation mode, the current will be limited to about 20A with either, and after the battery reaches 2.35V/cell (about 42.3V for a 36V pack) and the voltage developed across the battery pack begins to limit the current, I'm not sure if having the capability of producing twice the voltage will alter the charge profile significantly.
Basically, the ferroresonant transformer and capacitor pair limit the charger's output current and the charger's output voltage is limited by the cells, so what and how the AC from the secondary is rectified to DC has little, if any, bearing on the charging process.
Of course, if I every blow the diodes in my Powerwise II, which I seldom use these days since I have a DPI 36V charger that goes into a float charge mode, I'll probably replace the nearly non-repairable Diode assembly it uses with a bridge rectifier and just use two of the diodes, duplicating the original design.
That will give me a spare pair, if I blow them again.
