please explain? charging question
 

Newbe! I had my 1st 6 flights about 3 weeks ago and I'm charging up for tommorow night

I'm using a converted power supply (11.4v) to feed a hobbyco quick field charger MKll.
I'm charging a NiMH 4.8v 1200mah, battery is in the plane.

Battery indicates 1st charge at 100 - 125 ma for 16 to 20 hours
trickle charge at 25 - 50 ma

what is a " safe " range for charging?
I have over night so I'll set it for 35ma....it should stop charging when its done?

If I was at the field and wanted to " push " it what could I do? charger will do 2.0 amps...

I just started charging:
After 10 minutes the charger beeps 7 times and starts flashing indicating it is going to trickle mode.
Is that short a time normal?

Also when I put a meter in the meter ports what exactly am I reading?
with everything hooked up but turned off I read 5.22v
turn on the PS and charger and I read 5.69v
its been 1 hour and it reads 5.55v

How do I use this info?

I'm going to reread the manual but it doesnt help much

TIA


Pop

RE: please explain? charging question
 

Let's talk about the battery first. A 4.8V battery won't read 4.8 when it's fully charged since 4.8 is nominal voltage. A full battery will read around 5.4V. When the battery discharges to 4.7, below nominal voltage, it's going to be dead soon and needs a recharge.

Okay, charging. At first, a battery should undergo a series of slow charges at a rate of one tenth its capacity. Therefore, your 1200mAh battery should be slowly charged at around 120mA. After a while you could "push" it at the field to 1C, or 1.2A; that's as fast as I'd go. It will complete the fast charge in an hour. Remember, this fast charging should not be done with a new battery. I usually don't fast charge my batteries just to play it safe. I don't want to lose 1K+ worth of aircraft just because I'm impatient.

Checking the battery. Just hooking it up to a voltmeter tells you very little about the state of the battery. Without a load, an almost dead battery can appear almost full. Therefore, you must load the battery when testing. Products like the Hobbico Digital Voltmeter will load the battery if used properly. This will insure an accurate reading. Remember, a full battery will be around 5.4 volts and a "dead" battery will be below 4.8. Please note that voltage as a function of capacity is not a linear relationship. Basically, this means that if you had a battery whose voltage was exactly between 5.4 and 4.8 it would not be half used. It would actually be less than half used since the voltage tends to drop off fast to begin with and hover around 4.8 for a while. After the voltage hovers below 4.8 a bit it will suddenly drop off.