T&T: 24 volt charger replacement

[Ken Bloomfield]

> Jeff has no intention of putting in a relay to break apart the 24 volt 
> bank when charging.
And rightly so.  What everyone seems to forget is that a 12 volt battery 
or 24 volt battery, is really only 2 volt cells (ok, for the incipient 
nitpicker, not precisely 2 volt) arranged and sold in various 
groupings.  As such,  i.e. The same logic that would demand the midpoint 
tap in the two six volt batteries would demand that a six volt battery 
be charged with three 2-volt chargers with taps.  Not going to happen.

I do, however understand the point that I believe some are driving at, 
and that is that in the old days with simple transformer/diode/regulator 
systems that the secondary circuits were all intrinsically isolated, and 
thus you could merrily series them with little trepidation.  However, in 
the modern day -- the use of transformers is getting rare, and the 
alternative is the switching power supply is used -- thus supplying lots 
of current with little weight.  Just compare an old Raritan 10/10 amp 
dual charger with a modern charger with similar capabilities and you 
will see an enormous weight reduction thanks to no transformer.  
However, the downside to the switching supply system is that it is not 
so easily floated.  Depending on the design, this could either be a 
piece of cake, or a recipe for toasted charger.  It would be prudent to 
ask the manufacturer if it is OK to float the negative rail of the 
charger at +12 VDC.

Never ceases to amaze and amuse me how our list seems to make a meal out 
of fundamentally simple issues.  Please keep it up, the entertainment 
value is worth the entrance fee.  {;-)

Ken Bloomfield
M/V Tellico Lady
50' Marine Trader, Walkaround
Maryville, TN