Hi all,
After having controllers explained a while back, and now agreeing that
they are the cats meow, the idea of pulsing dc instead of lower volt dc
to save battery drain is genius, so, it is time for attempting to
understand more things.
I have another major thing that I just cannot get my head around, and it
is the amps used when charging.
I understand amps when running something, and that a starter motor from
a car, for instance, has thicker wire in the windings, and will
therefore draw more amps than a heater blower motor or similar.
This seems to mean that the greater the load, the more amps get drawn,
and the shorter the battery charge will last. Simple.
Now, what about when charging?
I know that some car battery chargers have a select switch, for, say, a
2 amp trickle charge, or a ten amp regular charge.
Yet the battery is the same, so the same rules as for running something
FROM a battery, do not apply to when a battery is being charged. The
load is the same battery, so how the heck can the amps change? I can
understand that when the battery gets almost fully charged, then the
amps will decrease, as there is less load drawing the amps. And I can
understand that if a battery is extremely low in charge, it might tend
to suck more amps, so the charger meter will show a greater amount of
amps, then slowly get less amps drawing as the battery condition
improves. But my basic question is, how do the charging amps change at
the flick of a switch?
My reason for wanting to understand this is that I am collecting parts
to build a wind generator that will work in conjunction with the
electric motor and battery etc (that I am currently also gathering parts
for) in a boat. I know that if I rewind the generator armature with
thinner wire to get more turns onto it, that the power created is
proportional to the number of turns, assuming the rpm is the same. That
is, double the turns, double the volts. (But less amps are possible due
to the thinner wire).
The thing is, how thin can I go with the windings before the charging
load (that I cannot understand) is too great for the generator, and it
overheats? My understanding is that I need around 15 volts as a minimum
figure, then this would feed a charge controller, which then feeds about
13.7 volts to the 12v battery.
Or am I overthinking here, (like I have been known to before!) and the
charge controller will prevent anything frying?
Simple explanations appreciated.
Thanks,
John
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