Plus when you search for the original part number or generic size code, you
get nimh batteries that claim to be drop-in replacements for the
size/form/terminals code.
They can't know the details of every possible circuit the original parts
were used in, and yet they feel safe saying that the new nimh battery is a
replacement, because what they DO know is the exact behavior and specs of
the original batteries, and of the new battery, and implies that any
charging circuit that was correct for the original nicd part is also at
least within tolerances for the new part.


On Mon, Mar 12, 2018 at 5:29 PM, Mike Stein <mhs.st...@gmail.com> wrote:

> Agreed.
>
> There are some differences between NiCd and NiMH charging recommendations,
> but according to the Panasonic literature the standby* Trickle charging*
> currents are exactly the same.
>
> m
>
> ----- Original Message -----
> *From:* Fugu ME100 <b4me...@hotmail.com>
> *To:* m...@bitchin100.com
> *Sent:* Monday, March 12, 2018 4:21 PM
> *Subject:* Re: [M100] batteries...
>
> Where is that stated about Trickle Charging,  I don’t see it in the M102
> manual?
>
> I can find the section on pg 1-7 where it says "Charging current 1.2mA
> (typ)".   Which is in line with an average current however it will vary
> considerably depending on charge state of the battery.  Fully charged the
> current will be 300uA it cannot be more.
>
> So the impact will be well below any but the worst quality batteries – which
> may have other issues :)
>
> From: M100 <m100-boun...@lists.bitchin100.com> on behalf of George
> Michael Rimakis <grima...@gmail.com>
> Reply-To: <m...@bitchin100.com>
> Date: Monday, March 12, 2018 at 12:11 PM
> To: <m...@bitchin100.com>
> Subject: Re: [M100] batteries...
>
> The M102 service manual says the trickle charge is at 1.2mA, and some
> batteries may not be as tolerant.
>
> On Mon, Mar 12, 2018 at 3:54 PM, Fugu ME100 <b4me...@hotmail.com> wrote:
>
>> I swapped to NiMH for my replacements mainly because NiCd was hard to
>> find.  Before doing so I did some research on manufacturer
>> recommendations.  This doc is pretty good http://data.energizer.com
>> /pdfs/nickelmetalhydride_appman.pdf
>> <https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdata.energizer.com%2Fpdfs%2Fnickelmetalhydride_appman.pdf&data=02%7C01%7C%7C12fc6249c1734290265408d588556cc2%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636564822832910764&sdata=UIq70Tlu4EJ9vC%2BbMgbj6VduM%2F1%2BWfZJ5KjwHUpPCn0%3D&reserved=0>
>> If you look at the Recommended Charging Rates section (pg 11) it gives
>> this recommendation on trickle charging:
>>
>> '*Finally a maintenance (or trickle) charge rate of less than
>> 0.025C (C/40) is recommended. The use of very small trickle charges is
>> preferred to reduce the negative effects **overcharging*.’
>>
>> The NiMH and NiCd self-discharge very badly so if the trickle charge <
>> self discharge rate things should be fine.
>>
>> Looking at the charge circuit on the M100 it is basically a series diode,
>> resistor (1.8K) and the battery.  If the battery is at 0V the max current
>> is ~2mA,  at full charge (3.7V) the current is ~300uA.   Based on the
>> recommendations of Energizer the charge should be <C/40 for a trickle
>> charge. The battery is ~60mAh, which gives ~1.5mA trickle or maintenance
>> charge well above that produced in the M100, in fact the NiMH might sell
>> discharge at that rate.   So I went ahead and updated the batteries.
>>
>> If you trickle charge at very high rates then NiMH might fail earlier but
>> so too would NiCd.   The initial charge might be slower for NiMH compared
>> to NiCd but that is not really an issue in this application it is merely
>> acting as a backup battery.
>>
>>
>>
>> From: M100 <m100-boun...@lists.bitchin100.com> on behalf of George
>> Michael Rimakis <grima...@gmail.com>
>> Reply-To: <m...@bitchin100.com>
>> Date: Monday, March 12, 2018 at 10:10 AM
>> To: <m...@bitchin100.com>
>> Subject: Re: [M100] batteries...
>>
>> The thing about NiMH, is the level of trickle charge that they can
>> tolerate is a bit less than NiCD. Might not be good in the long run.
>>
>> On Fri, Mar 9, 2018 at 5:00 PM, Jim Anderson <jim.ander...@kpu.ca> wrote:
>>
>>> > -----Original Message-----
>>> >
>>> > This brings up an interesting point.  Having just replaced my NiCad I
>>> > think I'm going to use my label maker to leave a note about when it was
>>> > replaced under the battery door.
>>>
>>> I like to do this anyway (and not just with m100s), because I find
>>> myself struggling to remember later which machines have which things
>>> replaced, and when they were done...
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>         jim
>>>
>>
>>
>


-- 
bkw

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