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Old Feb 19, 2008, 08:12 PM
Tim Wescott
Guest
n/a Posts
Hey Red! (was: Re: NiCd and NiMH charging (and Dewalt))

Vladimir Vassilevsky wrote:
>
>
> Tim Wescott wrote:
>
>> On Tue, 19 Feb 2008 13:08:51 -0800, Neil Kalo wrote:
>>
>>> Is there much difference in a circuit designed to charge NiMH versus
>>> NiCD batteries? How does the circuit tell what is attached? In
>>> particular Dewalt brought out a completely new range of NiMH/NiCd
>>> chargers when they introduced NiMH batteries. Was there any real need to
>>> do this?

>>
>>
>> Yes, they did. NiMH batteries are more touchy about charging than
>> NiCd batteries. If you charge a NiCd battery using the optimal NiMH
>> procedure you'll get a slightly less than optimal charge; do it the
>> other way around and you'll get a damaged battery and possibly a fire.

>
> I think this is an urban legend.
>
> BTW, the Lacrosse BC700 battery charger does not distinguish NiCd and
> NiMH. It is a very good charger indeed.
>
> http://www.discovergadgets.com/product.asp?itmky=492702
>

(From sci.electronics.design)

So, oh battery expert -- who's right?

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html
Old Feb 19, 2008, 08:40 PM
The Natural Philosopher
Guest
n/a Posts
Re: Hey Red!

Tim Wescott wrote:
> Vladimir Vassilevsky wrote:
>>
>>
>> Tim Wescott wrote:
>>
>>> On Tue, 19 Feb 2008 13:08:51 -0800, Neil Kalo wrote:
>>>
>>>> Is there much difference in a circuit designed to charge NiMH versus
>>>> NiCD batteries? How does the circuit tell what is attached? In
>>>> particular Dewalt brought out a completely new range of NiMH/NiCd
>>>> chargers when they introduced NiMH batteries. Was there any real
>>>> need to
>>>> do this?
>>>
>>>
>>> Yes, they did. NiMH batteries are more touchy about charging than
>>> NiCd batteries. If you charge a NiCd battery using the optimal NiMH
>>> procedure you'll get a slightly less than optimal charge; do it the
>>> other way around and you'll get a damaged battery and possibly a fire.

>>
>> I think this is an urban legend.
>>
>> BTW, the Lacrosse BC700 battery charger does not distinguish NiCd and
>> NiMH. It is a very good charger indeed.
>>
>> http://www.discovergadgets.com/product.asp?itmky=492702
>>

> (From sci.electronics.design)
>
> So, oh battery expert -- who's right?
>

My understanding is that the delta peak is much smaller on Nimh..so many
NiCd chargers 'missed' it and could destroy the batteries through
overcharging.

OTOH a NiMh charger will easily detect a NiCd delta peak.
Old Feb 19, 2008, 08:42 PM
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Old Feb 19, 2008, 08:47 PM
Ray Haddad
Guest
n/a Posts
Re: Hey Red! (was: Re: NiCd and NiMH charging (and Dewalt))

On Tue, 19 Feb 2008 17:12:47 -0800, I said, "Pick a card, any card"
and Tim Wescott <tim@seemywebsite.com> instead replied:

>Vladimir Vassilevsky wrote:
>>
>> Tim Wescott wrote:
>>
>>> On Tue, 19 Feb 2008 13:08:51 -0800, Neil Kalo wrote:
>>>
>>>> Is there much difference in a circuit designed to charge NiMH versus
>>>> NiCD batteries? How does the circuit tell what is attached? In
>>>> particular Dewalt brought out a completely new range of NiMH/NiCd
>>>> chargers when they introduced NiMH batteries. Was there any real need to
>>>> do this?
>>>
>>> Yes, they did. NiMH batteries are more touchy about charging than
>>> NiCd batteries. If you charge a NiCd battery using the optimal NiMH
>>> procedure you'll get a slightly less than optimal charge; do it the
>>> other way around and you'll get a damaged battery and possibly a fire.

>>
>> I think this is an urban legend.
>>
>> BTW, the Lacrosse BC700 battery charger does not distinguish NiCd and
>> NiMH. It is a very good charger indeed.
>>
>> http://www.discovergadgets.com/product.asp?itmky=492702
>>

>(From sci.electronics.design)
>
>So, oh battery expert -- who's right?


Tim,

From memory, I believe NiCad batteries are charged at a constant
1/10 rate of max current while NiMh are charged using a 1/30
diminishing rate with a requirement of heat sensing to fast charge.

Sensing can be done by first measuring the cell voltage then using
the NiCad rate on both for 15 seconds. Check the voltage level again
and determining from that which type is present. NiCad will have a
tiny increase in voltage over uncharged while NiMh will not.

As I stated, this is from memory, not actual specs.
--
Ray
Old Feb 20, 2008, 01:50 AM
The Natural Philosopher
Guest
n/a Posts
Re: Hey Red!

Ray Haddad wrote:
> On Tue, 19 Feb 2008 17:12:47 -0800, I said, "Pick a card, any card"
> and Tim Wescott <tim@seemywebsite.com> instead replied:
>
>> Vladimir Vassilevsky wrote:
>>> Tim Wescott wrote:
>>>
>>>> On Tue, 19 Feb 2008 13:08:51 -0800, Neil Kalo wrote:
>>>>
>>>>> Is there much difference in a circuit designed to charge NiMH versus
>>>>> NiCD batteries? How does the circuit tell what is attached? In
>>>>> particular Dewalt brought out a completely new range of NiMH/NiCd
>>>>> chargers when they introduced NiMH batteries. Was there any real need to
>>>>> do this?
>>>> Yes, they did. NiMH batteries are more touchy about charging than
>>>> NiCd batteries. If you charge a NiCd battery using the optimal NiMH
>>>> procedure you'll get a slightly less than optimal charge; do it the
>>>> other way around and you'll get a damaged battery and possibly a fire.
>>> I think this is an urban legend.
>>>
>>> BTW, the Lacrosse BC700 battery charger does not distinguish NiCd and
>>> NiMH. It is a very good charger indeed.
>>>
>>> http://www.discovergadgets.com/product.asp?itmky=492702
>>>

>> (From sci.electronics.design)
>>
>> So, oh battery expert -- who's right?

>
> Tim,
>
> From memory, I believe NiCad batteries are charged at a constant
> 1/10 rate of max current while NiMh are charged using a 1/30
> diminishing rate with a requirement of heat sensing to fast charge.
>


Usual bollocks from resident idiot.

Nicads are chraged at 20 minute current rate, NiMh are charged at hourly
rate. Fast charging relies on a FALLING voltage with time to signal a
lowering internal resistance (possibly due to heat), but the heat is
never measured directly.

The FALLING voltage is a negative differential with respect to time,
hence the term 'Delta PEAK'


> Sensing can be done by first measuring the cell voltage then using
> the NiCad rate on both for 15 seconds. Check the voltage level again
> and determining from that which type is present. NiCad will have a
> tiny increase in voltage over uncharged while NiMh will not.
>


It is not necessary to sense pre-cahrge: Stuff a constant high current
in and wait till the voltage stops rising and starts to FALL that is the
delta PEAK, and the charger then switches to trickle mode. Its just a
smaller drop with Nimh, tyhats all.

Pack ready to fly..well as far as a Nickel pak AN fly. Heavy thiugs at
the bet of times.

> As I stated, this is from memory, not actual specs.
> --
> Ray

Old Feb 20, 2008, 12:07 PM
Red Scholefield
Guest
n/a Posts
Re: Hey Red!


"The Natural Philosopher" <a@b.c> wrote in message
news:1203471639.63015.2@despina.uk.clara.net...

>My understanding is that the delta peak is much smaller on Nimh..so many
>NiCd chargers 'missed' it and could destroy the batteries through
>overcharging.
>
> OTOH a NiMh charger will easily detect a NiCd delta peak.


This is correct.

The Lacrosse BC700 battery charger is junk IMHO, designed
for the mass market consumer who wouldn't have a clue as to what his battery
performance is.

--
Red S.
Red's R/C Battery Clinic
http://www.rcbatteryclinic.com
Check us out for "revolting" information.



Old Feb 20, 2008, 04:04 PM
Ed Forsythe
Guest
n/a Posts
Re: Hey Red!

You really shouldn't hold it in, Red - Tell us how you really feel. ;-))

> The Lacrosse BC700 battery charger is junk IMHO, designed
> for the mass market consumer who wouldn't have a clue as to what his
> battery
> performance is.
>
> --
> Red S.
> Red's R/C Battery Clinic
> http://www.rcbatteryclinic.com
> Check us out for "revolting" information.
>
>
>



Old Feb 20, 2008, 04:26 PM
Ray Haddad
Guest
n/a Posts
Re: Hey Red!

On Wed, 20 Feb 2008 06:50:09 +0000, I said, "Pick a card, any card"
and The Natural Philosopher <a@b.c> instead replied:

>Ray Haddad wrote:
>> On Tue, 19 Feb 2008 17:12:47 -0800, I said, "Pick a card, any card"
>> and Tim Wescott <tim@seemywebsite.com> instead replied:
>>
>>> Vladimir Vassilevsky wrote:
>>>> Tim Wescott wrote:
>>>>
>>>>> On Tue, 19 Feb 2008 13:08:51 -0800, Neil Kalo wrote:
>>>>>
>>>>>> Is there much difference in a circuit designed to charge NiMH versus
>>>>>> NiCD batteries? How does the circuit tell what is attached? In
>>>>>> particular Dewalt brought out a completely new range of NiMH/NiCd
>>>>>> chargers when they introduced NiMH batteries. Was there any real need to
>>>>>> do this?
>>>>> Yes, they did. NiMH batteries are more touchy about charging than
>>>>> NiCd batteries. If you charge a NiCd battery using the optimal NiMH
>>>>> procedure you'll get a slightly less than optimal charge; do it the
>>>>> other way around and you'll get a damaged battery and possibly a fire.
>>>> I think this is an urban legend.
>>>>
>>>> BTW, the Lacrosse BC700 battery charger does not distinguish NiCd and
>>>> NiMH. It is a very good charger indeed.
>>>>
>>>> http://www.discovergadgets.com/product.asp?itmky=492702
>>>>
>>> (From sci.electronics.design)
>>>
>>> So, oh battery expert -- who's right?

>>
>> Tim,
>>
>> From memory, I believe NiCad batteries are charged at a constant
>> 1/10 rate of max current while NiMh are charged using a 1/30
>> diminishing rate with a requirement of heat sensing to fast charge.

>
>Usual bollocks from resident idiot.


Sadly, you're the last person here who would know.

>Nicads are chraged at 20 minute current rate, NiMh are charged at hourly
>rate. Fast charging relies on a FALLING voltage with time to signal a
>lowering internal resistance (possibly due to heat), but the heat is
>never measured directly.


Not for a fast charge. Look it up.

>The FALLING voltage is a negative differential with respect to time,
>hence the term 'Delta PEAK'


Which is what I stated below.

>> Sensing can be done by first measuring the cell voltage then using
>> the NiCad rate on both for 15 seconds. Check the voltage level again
>> and determining from that which type is present. NiCad will have a
>> tiny increase in voltage over uncharged while NiMh will not.

>
>It is not necessary to sense pre-cahrge: Stuff a constant high current
>in and wait till the voltage stops rising and starts to FALL that is the
>delta PEAK, and the charger then switches to trickle mode. Its just a
>smaller drop with Nimh, tyhats all.


It's the safe way, though. Something you probably don't concern
yourself with.

>Pack ready to fly..well as far as a Nickel pak AN fly. Heavy thiugs at
>the bet of times.


I'm sure that means something to someone here. But who?
--
Ray
Old Feb 20, 2008, 04:45 PM
Lyman Slack
Guest
n/a Posts
Re: Hey Red!

You mean no more 'Warm and fuzzy' replies? <snicker, grin>

Lyman

"Ed Forsythe"
> You really shouldn't hold it in, Red - Tell us how you really feel. ;-))



Old Apr 03, 2009, 02:06 PM
Jim
Guest
n/a Posts
Re: Hey Red!

Aw Lyman, you know Red! hehe.

"Lyman Slack" <lyslack@bellsouth.net> wrote in message
news:sb1vj.92713$_m.13461@bignews4.bellsouth.net.. .
> You mean no more 'Warm and fuzzy' replies? <snicker, grin>
>
> Lyman
>
> "Ed Forsythe"
>> You really shouldn't hold it in, Red - Tell us how you really feel. ;-))

>
>



Old Apr 03, 2009, 02:07 PM
Jim
Guest
n/a Posts
Re: Hey Red!

You guys spend too much time 'sweatin the small $hit'! Why don't you go
fly?


"Ray Haddad" <rhaddad@iexpress.net.au> wrote in message
news:ri6pr39n7m08uiqsg2l67fbkat9d9oiri4@4ax.com...
> On Wed, 20 Feb 2008 06:50:09 +0000, I said, "Pick a card, any card"
> and The Natural Philosopher <a@b.c> instead replied:
>
>>Ray Haddad wrote:
>>> On Tue, 19 Feb 2008 17:12:47 -0800, I said, "Pick a card, any card"
>>> and Tim Wescott <tim@seemywebsite.com> instead replied:
>>>
>>>> Vladimir Vassilevsky wrote:
>>>>> Tim Wescott wrote:
>>>>>
>>>>>> On Tue, 19 Feb 2008 13:08:51 -0800, Neil Kalo wrote:
>>>>>>
>>>>>>> Is there much difference in a circuit designed to charge NiMH versus
>>>>>>> NiCD batteries? How does the circuit tell what is attached? In
>>>>>>> particular Dewalt brought out a completely new range of NiMH/NiCd
>>>>>>> chargers when they introduced NiMH batteries. Was there any real
>>>>>>> need to
>>>>>>> do this?
>>>>>> Yes, they did. NiMH batteries are more touchy about charging than
>>>>>> NiCd batteries. If you charge a NiCd battery using the optimal NiMH
>>>>>> procedure you'll get a slightly less than optimal charge; do it the
>>>>>> other way around and you'll get a damaged battery and possibly a
>>>>>> fire.
>>>>> I think this is an urban legend.
>>>>>
>>>>> BTW, the Lacrosse BC700 battery charger does not distinguish NiCd and
>>>>> NiMH. It is a very good charger indeed.
>>>>>
>>>>> http://www.discovergadgets.com/product.asp?itmky=492702
>>>>>
>>>> (From sci.electronics.design)
>>>>
>>>> So, oh battery expert -- who's right?
>>>
>>> Tim,
>>>
>>> From memory, I believe NiCad batteries are charged at a constant
>>> 1/10 rate of max current while NiMh are charged using a 1/30
>>> diminishing rate with a requirement of heat sensing to fast charge.

>>
>>Usual bollocks from resident idiot.

>
> Sadly, you're the last person here who would know.
>
>>Nicads are chraged at 20 minute current rate, NiMh are charged at hourly
>>rate. Fast charging relies on a FALLING voltage with time to signal a
>>lowering internal resistance (possibly due to heat), but the heat is
>>never measured directly.

>
> Not for a fast charge. Look it up.
>
>>The FALLING voltage is a negative differential with respect to time,
>>hence the term 'Delta PEAK'

>
> Which is what I stated below.
>
>>> Sensing can be done by first measuring the cell voltage then using
>>> the NiCad rate on both for 15 seconds. Check the voltage level again
>>> and determining from that which type is present. NiCad will have a
>>> tiny increase in voltage over uncharged while NiMh will not.

>>
>>It is not necessary to sense pre-cahrge: Stuff a constant high current
>>in and wait till the voltage stops rising and starts to FALL that is the
>>delta PEAK, and the charger then switches to trickle mode. Its just a
>>smaller drop with Nimh, tyhats all.

>
> It's the safe way, though. Something you probably don't concern
> yourself with.
>
>>Pack ready to fly..well as far as a Nickel pak AN fly. Heavy thiugs at
>>the bet of times.

>
> I'm sure that means something to someone here. But who?
> --
> Ray



 


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