Radio specific battery charging question
 

Radio... Degen DE1102
Batteries charge in the radio via a procedure
described on p.3 of the English manual.
One selects a number of hours to charge
depending on the capacity of the batteries by
pressing the 1...9 number keys.
My problem... I don't know how to implement
this. The included rechargeables are 1100 mAh.
I want them fully charged, but don't want to
overcharge. And if I switch to my own 1800 mAh
batteries I'd want to charge them fully as well
without damage to the batteries or radio.

Can anyone help me figure this out?
I posted the same question in the
Kaito-Degen1102 yahoo group, so hopefully
I can find out today.

Thanks everyone.

"Sanjaya" wrote in message thlink.net...
Radio... Degen DE1102
Batteries charge in the radio via a procedure
described on p.3 of the English manual.
One selects a number of hours to charge
depending on the capacity of the batteries by
pressing the 1...9 number keys.
My problem... I don't know how to implement
this. The included rechargeables are 1100 mAh.
I want them fully charged, but don't want to
overcharge. And if I switch to my own 1800 mAh
batteries I'd want to charge them fully as well
without damage to the batteries or radio.

You would want to find out the various charge rates per key selected.
IE: 100ma, 500ma, etc...In general, a slow charge is rated as charging
with 1/10 battery capacity for current, for 15 hours. So if you had
the 1100 mah battery, you would want to charge at appx 110 ma, for 15
hours. The 1800, 180 ma for 15 hours. But the current used is not
critical. It will just vary the overall time it takes to get a full
charge. The best way to determine full charge is by watching the
voltage. If the batteries are nicads, you will see about 1.4 volts per
cell when you have a full "float charge". The normal resting voltage
with the charger unhooked will be about 1.2v per cell. So lets say you
have a battery
that is a total of 7.2 volts. "six 1.2v cells". When charging, the
voltage will gradually rise while charging. When fully charged, the
voltage will rise to appx 8.4 volts or so. The battery is fully
charged, and should be disconnected to avoid overheating. The nickle
hydrides are slightly different. The charge voltages are about the
same, but when they are fully charged, the voltage peaks, but then
slightly drops off a bit. This indicates full charge. This is why they
have separate chargers, or switchable ones that do both types for
nicads vs nickle hydride. A voltmeter is the best way to check charge,
and avoid overheating. But if you know the exact charge rates, you can
guestimate it and get pretty close. The battery will be warm when
fully charged. Thats one "caveman" method of estimation...:/ You have
to really start to overheat one before it will be damaged. You could
leave it a while extra, and it's not going to kill it. It's also
simple to build a charger that will limit current when the battery is
fully charged. Works about the same as a trickle car battery charger
that tapers off as it gets to full charge. I've built simple ones
using diodes.
What voltage battery is it? Probably 7.2, 9.6, or 12 volts. The
respective full float charge voltages would be appx 8.4, 11.2, or 14
volts. MK

Mark Keith wrote:

The nickle
hydrides are slightly different. The charge voltages are about the
same, but when they are fully charged, the voltage peaks, but then
slightly drops off a bit. This indicates full charge. This is why they
have separate chargers, or switchable ones that do both types for
nicads vs nickle hydride.

The nickel cadmium (NiCd) battery is the kind that reaches a peak
voltage and drops off a little when it's fully charged. The NiMh don't
do this.


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"Mark Keith" wrote
What voltage battery is it?

Sorry. I wasn't very clear in my original post.
The radio uses three 1.5 volt NiMH AA batteries.
It came with three 1100 mAh double A's
To charge them in the radio one follows a procedure
of selecting "charge", then a number of hours to
charge by pressing 1 through 9 on the number keys.
Pressing 8 charges for 8 hours, etc. This is done
with the radio "off" and plugged into the wall outlet.

The radio came with a converter to change my 110v
to 220v so I can use it here in the U.S.

I posted the same question in the yahoo Kaito-Degen1102
group and was told that dividing the capacity of the batteries
by the charge current would give me the number
of hours to charge. 1100 / 220 = 5 hours

starman wrote in message ...
Mark Keith wrote:

The nickle
hydrides are slightly different. The charge voltages are about the
same, but when they are fully charged, the voltage peaks, but then
slightly drops off a bit. This indicates full charge. This is why they
have separate chargers, or switchable ones that do both types for
nicads vs nickle hydride.

The nickel cadmium (NiCd) battery is the kind that reaches a peak
voltage and drops off a little when it's fully charged. The NiMh don't
do this.

Sure they do. http://data.energizer.com/batteryinf...al_hydride.htm
But I do notice they seem to indicate temp monitoring is preferred to
voltage for overcharge cutoff. But for the average user, voltage is
probably easier to measure. MK

"Sanjaya" wrote in message

I posted the same question in the yahoo Kaito-Degen1102
group and was told that dividing the capacity of the batteries
by the charge current would give me the number
of hours to charge. 1100 / 220 = 5 hours

Fairly close. But it may take more like 7.5 hours, if they used a .1C
rate for 15 hours as the "standard". IE: 110ma for 15 hours. If you
double the current to 220ma, I might expect 7.5 hours instead of 5.
But I'd watch the voltage to get an idea when full charge really
occurs. It will vary per battery and condition of the cells, etc...
MK

On Thu, 5 Feb 2004 2:03:50 -0600, starman wrote
(in message ):

Mark Keith wrote:

The nickle
hydrides are slightly different. The charge voltages are about the
same, but when they are fully charged, the voltage peaks, but then
slightly drops off a bit. This indicates full charge. This is why they
have separate chargers, or switchable ones that do both types for
nicads vs nickle hydride.

The nickel cadmium (NiCd) battery is the kind that reaches a peak
voltage and drops off a little when it's fully charged. The NiMh don't
do this.


They do on my charger (info by the digital readout built into the charger).

/gray/

Mark Keith wrote:

starman wrote in message ...
Mark Keith wrote:

The nickle
hydrides are slightly different. The charge voltages are about the
same, but when they are fully charged, the voltage peaks, but then
slightly drops off a bit. This indicates full charge. This is why they
have separate chargers, or switchable ones that do both types for
nicads vs nickle hydride.

The nickel cadmium (NiCd) battery is the kind that reaches a peak
voltage and drops off a little when it's fully charged. The NiMh don't
do this.

Sure they do. http://data.energizer.com/batteryinf...al_hydride.htm
But I do notice they seem to indicate temp monitoring is preferred to
voltage for overcharge cutoff. But for the average user, voltage is
probably easier to measure. MK

The smart chargers I have monitor the voltage rise and dip of a NiCd to
terminate the fast charging rate, then it goes to trickle charge. With
the NiMh it tappers to a trickle charge when it senses peak voltage.
There is no temperature monitor for either kind of battery.


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starman wrote in message ...


The smart chargers I have monitor the voltage rise and dip of a NiCd to
terminate the fast charging rate, then it goes to trickle charge. With
the NiMh it tappers to a trickle charge when it senses peak voltage.
There is no temperature monitor for either kind of battery.

You sure you don't have that backwards? It should be the other way
around. Or most are anyway. I've used and charged both varieties using
homebrew chargers. I only used the voltage dip method for NiMh. There
may also be a small dip on the nicads, but I never really noticed it
that much. All the nicads I had usually peaked voltage, and hung there
until the charger was disconnected. Most commercial chargers are
opposite from how you describe yours. Or the ones I've seen anyway...
MK