I put four AA Ni-MHs on a Power Supply to Recharge Them

  • Thread starter Watson A.Name - \"Watt Su
  • Start date
W

Watson A.Name - \"Watt Su

Guest
... and I cranked up the current control to 300 mA or so. The four are
in series and are 1700 mAh capacity. I've seen chargers that charge the
Ni-MHs at C/10, for 15 hours. I have another charger that charges them
in 5 hours. So if I charge them at about C/5, should I charge them for
7.5 hours? Or is there some difference in the time when the charging
rate goes up?

Thanks.

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
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Don't be ripped off by the big book dealers. Go to the URL
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@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
 
"Charles Schuler" <charleschuler@comcast.net> wrote in message
news:RPmdnZwpspWu-RzcRVn-vQ@comcast.com...
"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com
wrote
in message news:10o16b0g9lce3d2@corp.supernews.com...
.. and I cranked up the current control to 300 mA or so. The four
are
in series and are 1700 mAh capacity. I've seen chargers that charge
the
Ni-MHs at C/10, for 15 hours. I have another charger that charges
them
in 5 hours. So if I charge them at about C/5, should I charge them
for
7.5 hours? Or is there some difference in the time when the
charging
rate goes up?

1.4 to 1.6 x AH capacity usually works. 1.4 x 1700 = 2380. 2380/300
= 6.3
hours

7.5 hours should be good, too.

Yes, slower charging rates work differently. One must consult the
manufacturer's specifications.
Click to expand...
Thanks. I've had four sets of four Ni-MHs in my digital camera case for
awhile and I found that they were nearly discharged after a few months
of not being used. So I have to keep up on maintaining them in a
relatively fully charged condition. I think I should get another
charger or two, just to keep on hand so I can drag out all four sets and
charge them overnight. Or else use the ol' bench PS, like I did this
time. ;-)
 
"DAW" <davew@joink.com> wrote in message
news:cls7gn0169d@enews2.newsguy.com...
As charge rates goes up the battery warms, hence a portion of the
charge
current goes to heat the battery rather than charge it. This is main
reason
a C/1 rapid charger usually does not charge "rapid charge" for one
hour, the
thermal sensor shuts it back to about C/10 with the batteries at about
80%.
There are ways of getting around this so batteries can be charged to
almost
100% in as little as 15 minutes, but it makes for a fairly complicated
charger.

C/5 should be fine, but you might check the battery temp around 5 or 6
hours. If warm to touch, you might want to back the current down a
little.
If they are only slightly above room temp then let them go at 300mA.
Click to expand...
Thanks. I think I'll buy a few more chargers, since the newer ones all
seem to have a timer and cut off automatically. Makes for a safer
stuation. I could go off and forget to remove the cells from my bench
PS and that might not be a good idea. :)


"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com
wrote
in message news:10o16b0g9lce3d2@corp.supernews.com...
.. and I cranked up the current control to 300 mA or so. The four
are
in series and are 1700 mAh capacity. I've seen chargers that charge
the
Ni-MHs at C/10, for 15 hours. I have another charger that charges
them
in 5 hours. So if I charge them at about C/5, should I charge them
for
7.5 hours? Or is there some difference in the time when the
charging
rate goes up?

Thanks.

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
Click to expand...
 
On Thu, 28 Oct 2004 00:03:53 -0700, "Watson A.Name - \"Watt Sun, the
Dark Remover\"" <NOSPAM@dslextreme.com> wrote:

.. and I cranked up the current control to 300 mA or so. The four are
in series and are 1700 mAh capacity. I've seen chargers that charge the
Ni-MHs at C/10, for 15 hours. I have another charger that charges them
in 5 hours. So if I charge them at about C/5, should I charge them for
7.5 hours? Or is there some difference in the time when the charging
rate goes up?

Thanks.
Click to expand...
In theory yes but there's more chance of damage if overcharged using a
higher current. With NiCads, if I remember correctly, you can
overcharge at C/10 for a few hours and at C/15 for 100 hours.
Can't be sure about NiMh but I would be caution if you want long life.
 
"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com> wrote
in message news:10o16b0g9lce3d2@corp.supernews.com...
.. and I cranked up the current control to 300 mA or so. The four are
in series and are 1700 mAh capacity. I've seen chargers that charge the
Ni-MHs at C/10, for 15 hours. I have another charger that charges them
in 5 hours. So if I charge them at about C/5, should I charge them for
7.5 hours? Or is there some difference in the time when the charging
rate goes up?
Click to expand...
1.4 to 1.6 x AH capacity usually works. 1.4 x 1700 = 2380. 2380/300 = 6.3
hours

7.5 hours should be good, too.

Yes, slower charging rates work differently. One must consult the
manufacturer's specifications.
 
As charge rates goes up the battery warms, hence a portion of the charge
current goes to heat the battery rather than charge it. This is main reason
a C/1 rapid charger usually does not charge "rapid charge" for one hour, the
thermal sensor shuts it back to about C/10 with the batteries at about 80%.
There are ways of getting around this so batteries can be charged to almost
100% in as little as 15 minutes, but it makes for a fairly complicated
charger.

C/5 should be fine, but you might check the battery temp around 5 or 6
hours. If warm to touch, you might want to back the current down a little.
If they are only slightly above room temp then let them go at 300mA.

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com> wrote
in message news:10o16b0g9lce3d2@corp.supernews.com...
.. and I cranked up the current control to 300 mA or so. The four are
in series and are 1700 mAh capacity. I've seen chargers that charge the
Ni-MHs at C/10, for 15 hours. I have another charger that charges them
in 5 hours. So if I charge them at about C/5, should I charge them for
7.5 hours? Or is there some difference in the time when the charging
rate goes up?

Thanks.

--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@
Click to expand...
 
On Fri, 29 Oct 2004 03:58:44 -0700, "Watson A.Name - \"Watt Sun, the
--- cut---
Thanks. I've had four sets of four Ni-MHs in my digital camera case for
awhile and I found that they were nearly discharged after a few months
of not being used. So I have to keep up on maintaining them in a
relatively fully charged condition. I think I should get another
charger or two, just to keep on hand so I can drag out all four sets and
charge them overnight. Or else use the ol' bench PS, like I did this
time. ;-)
Click to expand...
NiMh self discharge faster than NiCads.
About 1 month for NiMh and 3 Months for NiCads. Some 9v PP3 NiCads
will last for many months, I use them in Fire Detectors but I see NiMh
are not recommended in that application.
Sadly that's the price you pay for reducing the so called 'memory
loss' of NiCads.

Can't win 'em all...!
 
On Fri, 29 Oct 2004 16:35:58 +0100, the renowned NOSPAM@easily.co.uk
wrote:

On Fri, 29 Oct 2004 03:58:44 -0700, "Watson A.Name - \"Watt Sun, the
--- cut---
Thanks. I've had four sets of four Ni-MHs in my digital camera case for
awhile and I found that they were nearly discharged after a few months
of not being used. So I have to keep up on maintaining them in a
relatively fully charged condition. I think I should get another
charger or two, just to keep on hand so I can drag out all four sets and
charge them overnight. Or else use the ol' bench PS, like I did this
time. ;-)



NiMh self discharge faster than NiCads.
About 1 month for NiMh and 3 Months for NiCads.
Click to expand...
I don't think it's nearly that bad. Four months to about 50% remaining
charge for the ones I use. That's at 20°C. At 40°C you can get down to
25% in a month.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
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