Model Forum / Radio Controlled / Air Models / July 2006

Anyone?

I don't know alot about what you have asked but I can point you to someone
who does.
http://www.rcbatteryclinic.com/

Read away! :)
mk

The charger is open-loop, that is both charge and discharge are done
with no feedback from the battery to indicate its charge state and
control the process.  Suggest you buy a cheap digital voltmeter
(Harbor Freight has them under 5 bucks) and stop discharging them at
0.9 V per cell;  for your 6-cell battery, that is 5.4 V.

Again, it's a guess with an old charger designed for 80's vintage
C-cell NiCd batteries.  Your 1900's will probably take two full 15 min
charge cycles to be fully charged from the nominal (0.9V/cell)
discharge state.  If you don't know the state of charge when you
begin, best to frequently monitor by touch for a significant rise in
temperature, and stop then.

Yes.  While still on charge and near end of cycle, expect to see 9+ V.

Not likely.  The trickle charge is well under 0.1 C rate for 80's
vintage C-cell batteries, with capacity on the order of 1000-1200 mah.
That should be well below what is safe for your 1900s if left on
trickle indefinitely.

Ok, but a basic peak detecting charger won't cost you much, and your
batteries will probably last longer.  You can probably get a basic
peak detecting charger for a little more than the cost of another
battery pack.  (There are several for sale, aimed at the car crowd but
will be fine for you, that cost about $40, for example.)

Don't use discharge at all.  There's little point -- you're not likely
to have a `memory' problem since your battery is probably mostly
discharged for every flight.  Using the discharge function just uses
up the finite number of cycles your batteries have during their
lifetime.

Also, if it ever discharges your battery fully, the weakest cells will
probably be reverse charged, making them even weaker.

If you do use the discharge function, do what the other poster
suggested -- monitor their voltage (HFT meters are great for that, and
they're $3-$4 on sale) and stop when it hits 6 volts or so.  But the
problem with having to monitor the state of your charge is that you'll
inevitably forget or get distracted ... in the long run, you want a
charger that will do it all for you.

Depends on the charge rate and how far discharged the battery was.
One thing you must do -- STOP CHARGING when your batteries get hot!
If they get hot, that tends to mean that they're already fully
charged.  Fast charging already fully charged batteries is bad.

6 cells x 1.4 volts = 8.4 volts, so yes.  A full charged NiCd or NiMH
cell reads about 1.4 volts.

A few hours of trickle charging won't hurt.  Weeks might.

Of course, I don't know how fast `trickle' charging is for this
charger.  If it's a true trickle charge (like C/50 or C/100 or so)
then you can do it forever.  If it's really a slow charge, like C/10,
then you shouldn't do it for a long time, but a few hours won't hurt.