BFL13 wrote:
BTW, Some folks want a voltage sensing wire to get the battery voltage showing at the charger.
But that voltage drop gets smaller as current tapers, so by the time the battery is nearly full, there is hardly any voltage drop. So who cares about this magic sensing wire? It doesn't help you with anything I can figure out.
The idea is to have whatever voltage the charger is set for actually show up on the battery(ies) terminals - regardless of wire size - from the beginning right on through until the charger (automatically), or the operator (manually), changes the output voltage setting of the charger.
This extra sensing wire makes up part of a feedback loop that enables the charger's circuitry to at all times compensate for voltage losses in the cabling between the charger and the battery(ies). (Basic EE feedback loop principles.)
What you get is battery terminal voltage during charging stages exactly what you want it to be - and maybe exactly what voltages the battery manufacturer specifies to be held on the terminals during the Boost, Bulk, and Float stages.
A charger that - can force exact voltages onto battery terminals, adjust this voltage in accordance with the air temperature around the battery, and power factor correct for the incoming AC power to the charger would be "ideal", IMHO. Whether any of us could afford a charger like that might be an issue. :)
Mex seems to be getting closer and closer to this ideal with his excellent component searching. What may be taking so long is he probably is trying to arrive at this ideal in a way that we mortals can afford.
P.S. In my previous life we used $300K-$400K automatic testers that could present whatever voltage onto the leads, at whatever current flow that could be accepted into the leads - of integrated circuits we were testing. But the $$$$ four-quadrant power supplies in those testers did indeed border on "magic".
