On Fri, 15 Sep 2000 19:26:01 -0700 Mark Willis <[EMAIL PROTECTED]> wrote:
>> > Scary numbers: With 6mA charging a 360mAh NiCad pack, it'd take about
>> > 60 hours for a full charge. Probably longer, all things considered.
>> > <G>
>> That is correct for a 360 mAh battery pack.
>> My calculation is for a 60mAh NiCad pack, as originally stated, not a
>> 360mAh NiCad pack. Only 10 hours for a 60 mAh battery pack.
> Whole idea's to solve MY (and others') problems with some computers
> here, I thought? <G>
I guess I didn't make myself clear. My calculation is for a 60 mAh
battery pack as originally stated by YOU. Maybe you meant to write
360 mAh, but 60 mAh is the figure that appeared in your original post.
>> I was making the calculation for the simple installation of a
>> current-limiting resistor connected between the 5V source and the 3.6 V
>> NiCad pack. I don't see the need for the diode if you simply disconnect
>> your 5V source after your 3.6 V NiCad pack is fully charged. IMHO, a NiCad
>> pack should be charged, then discharged almost completely, and then charged
>> again. I don't think it is a good idea to keep a NiCad pack on continuous
>> trickle charge all the time.
The above statement about not keeping a NiCad pack on continuous trickle
charge the time applies to a battery pack for a device that is not used
frequently. For a device that sees frequent use, then trickle charging
is a good idea. According to the FAQs I have read, a NiCad battery will
last longer if fully charged, then deeply discharged and then re-charged.
If discharged only slightly after each use then it will become accustomed
to short discharge-recharge cycles and it won't be able to perform for very
long when needed for a long discharge period. For this reason I do not
trickle charge the NiCad batteries in my flashlight. I do not use my
flashlight very often. When I do need to use it I will want the power to
be available for a long period.
> I don't plan to leave the computer on for 60+ hours, then open the case
> and remove the jumper for 5V power, when a diode'll do the same thing
> (5V power supply drops to 0V, battery drains at 30mA or so i.e. 12 hours
> to DEAD, then have to charge for another 60+ hours again and re-enter
> all the CMOS values? I need the NiCad pack to LAST for a few months
> between times I need these rarely-used computers working; the last
> thing I need's more work! <G>
OK, then I agree that a diode will be needed for a circuit designed for
providing a *continuous* trickle charge. By *trickle* charge I mean a
slow charging rate. A trickle charge may be applied only occasionally or
continuously, depending on your battery's needs. I might connect my car
battery to a trickle charger when parked overnight during a spell when the
weather is especially cold. During a night when we are experiencing only
the normal winter temperature ranges, I do not need to use the trickle
charger.
If you want the battery pack in your rarely-used computers to hold a
charge for only a few months then you should not need to have the
batteries on continuous trickle-charge.
BTW, while composing this post I decided to power up an old Toshiba
laptop that I have had in storage and unplugged since November of 1999.
The date and time needed to be reset. All the other CMOS settings were
still OK. I checked a few other things out and it seems to be Y2K
compliant. This is the first time this computer has been powered up in
the current millenium.
The trickle charger I suggested was not for applying a *continuous*
charge, just an initial charge for the battery pack prior to installation.
For this reason I did not see the need for a diode. I agree that you will
need a diode to provide a *continuous* trickle charge. I believe the
motherboards of most computers have a continuous trickle-charge circuit
already built-in. I think that as long as the computer remains plugged in
to the 120V AC supply, and even though the computer is powered off, a
continuous trickle charge is fed to the CMOS batteries. Am I not right on
this point? Somebody please correct me if I am wrong, because on this last
point I am not sure.
> Trickle charge on NiCad's is not a problem, read the battery FAQs. Far
> worse to HARD charge a NiCad continuously; Slow charging at c/10 isn't
> bad at all, at under c/10 would happen in my design <G>
If by HARD charging you mean *fast* charging, then this is really *bad*
for any kind of battery. I agree that charging at c/10 or less is the
most recommended charging rate.
<snip>
All the best,
Sam Heywood
-- This mail sent by Arachne, www graphical browser for DOS
-- Visit the Arachne DOS Browser Home Page, http://home.arachne.cz
To unsubscribe from SURVPC send a message to [EMAIL PROTECTED] with
unsubscribe SURVPC in the body of the message.
Also, trim this footer from any quoted replies.
More info can be found at;
http://www.softcon.com/archives/SURVPC.html
