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-   -   Replacing 250mAh NiMH with higher capacity (https://www.diybanter.com/uk-diy/646870-replacing-250mah-nimh-higher-capacity.html)

Grumps[_4_] March 31st 20 12:13 PM

Replacing 250mAh NiMH with higher capacity
 
Hi All
So, as per subject. This is for some solar lights that have 250mAh NiMH
1.2V AA cells, but would 2500mAh cells work too?

The Natural Philosopher[_2_] March 31st 20 12:24 PM

Replacing 250mAh NiMH with higher capacity
 
On 31/03/2020 12:13, Grumps wrote:
Hi All
So, as per subject. This is for some solar lights that have 250mAh NiMH
1.2V AA cells, but would 2500mAh cells work too?

if they are the same chemistry and fit physically yes, with the proviso
that some very cheap chargers 'expect' a certain cell capacity


--
"Strange as it seems, no amount of learning can cure stupidity, and
higher education positively fortifies it."

- Stephen Vizinczey


[email protected] March 31st 20 12:53 PM

Replacing 250mAh NiMH with higher capacity
 
On Tuesday, 31 March 2020 12:13:58 UTC+1, Grumps wrote:
Hi All
So, as per subject. This is for some solar lights that have 250mAh NiMH
1.2V AA cells, but would 2500mAh cells work too?


sure no problem. They'd last longer too as they only see part of a cycle each day. If the things contain more than 1 cell, do your best to capacity match them or they'll see repeated reverse charging which kills them much quicker.


NT

Theo[_3_] March 31st 20 02:10 PM

Replacing 250mAh NiMH with higher capacity
 
wrote:
On Tuesday, 31 March 2020 12:13:58 UTC+1, Grumps wrote:
Hi All
So, as per subject. This is for some solar lights that have 250mAh NiMH
1.2V AA cells, but would 2500mAh cells work too?


sure no problem. They'd last longer too as they only see part of a cycle
each day. If the things contain more than 1 cell, do your best to
capacity match them or they'll see repeated reverse charging which kills
them much quicker.


Beware that higher capacity cells can have lower cycle life (number of
charge/discharge cycles before they die). Given solar lights only get a
certain amount of energy per day you might find the extra capacity isn't
much use, and yet they die faster due to the lower cycle life.

For comparison, Eneloop Pro have 500 cycles life, Eneloop Lite have 3000
cycles life. So the Pro would last 1.5 years and the Lite 8 years.

Theo

Rod Speed March 31st 20 06:10 PM

Replacing 250mAh NiMH with higher capacity
 
Grumps wrote

So, as per subject. This is for some solar lights that have 250mAh
NiMH 1.2V AA cells, but would 2500mAh cells work too?


Usually, but not always. Depends on the design of the internal charger.

John_j March 31st 20 06:18 PM

Replacing 250mAh NiMH with higher capacity
 


"Chris Hogg" wrote in message
...
On Tue, 31 Mar 2020 12:13:55 +0100, Grumps wrote:

Hi All
So, as per subject. This is for some solar lights that have 250mAh NiMH
1.2V AA cells, but would 2500mAh cells work too?


Assuming they are the same physical size as the 250mAh cells and fit,
then in principle they should give you light for longer, appropriate
for early winter evenings and long nights.


Yes.

But the converse is that
they'll take longer to recharge, inappropriate for short dull winter
days.


No, you should get the same amount of charge added
and so get the same result even on short dull winter days.

Very crude simple chargers may limit the amount of
charge the cell gets to avoid overcharging so while
it will still work with the higher capacity calls, you won't
see any advantage when using higher capacity cells.


Peeler[_4_] March 31st 20 06:44 PM

UNBELIEVABLE: It's 04:18 am in Australia and the Senile Ozzietard is out of Bed and TROLLING, already!!!! LOL
 
On Wed, 1 Apr 2020 04:18:01 +1100, John_j, better known as cantankerous
trolling senile geezer Rodent Speed, wrote:

FLUSH senile Ozzietard's latest troll**** unread

Are you still not infected, senile pest? Just guess how MANY of those people
who know you are waiting for it! I suppose it's your entire neighbourhood
and all your relatives, too!

--
Pedophilic dreckserb Razovic arguing in favour of pedophilia, again:
"A lowering of the age of consent to reflect the rate at which today's
youngsters 'mature'."
MID:

Peeler[_4_] March 31st 20 06:46 PM

UNBELIEVABLE: It's 04:10 am in Australia and the Senile Ozzietard is out of Bed and TROLLING, already!!!! LOL
 
On Wed, 1 Apr 2020 04:10:49 +1100, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:


So, as per subject. This is for some solar lights that have 250mAh
NiMH 1.2V AA cells, but would 2500mAh cells work too?


Usually, but not always.


No ****, Einstein!

Depends on the design of the internal charger.


No ****, Einstein!

--
Richard about senile Rodent:
"Rod Speed, a bare faced pig and ignorant ****."
MID:

[email protected] March 31st 20 07:49 PM

Replacing 250mAh NiMH with higher capacity
 
On Tuesday, 31 March 2020 14:10:11 UTC+1, Theo wrote:
tabbypurr wrote:
On Tuesday, 31 March 2020 12:13:58 UTC+1, Grumps wrote:


Hi All
So, as per subject. This is for some solar lights that have 250mAh NiMH
1.2V AA cells, but would 2500mAh cells work too?


sure no problem. They'd last longer too as they only see part of a cycle
each day. If the things contain more than 1 cell, do your best to
capacity match them or they'll see repeated reverse charging which kills
them much quicker.


Beware that higher capacity cells can have lower cycle life (number of
charge/discharge cycles before they die). Given solar lights only get a
certain amount of energy per day you might find the extra capacity isn't
much use, and yet they die faster due to the lower cycle life.

For comparison, Eneloop Pro have 500 cycles life, Eneloop Lite have 3000
cycles life. So the Pro would last 1.5 years and the Lite 8 years.

Theo


You ignored the fact that the bigger cells won't get fully charged.

If the 0.25Ah cells are 3k cycle & the 2.5Ah are 500 cycle:

0.25Ah: 3k cycles of full charge = 3k [summer] days of life expectancy. More days IRL because winter only part charges them.

2.5Ah: 500 cycles of 1/10th charge gives 5k days of life expectancy.

These assume no reverse charging due to unequal capacity + total discharge. Hopefully the controller stops discharging before they're fully flat.


NT

Roger Hayter[_2_] March 31st 20 10:13 PM

Replacing 250mAh NiMH with higher capacity
 
Theo wrote:

wrote:
On Tuesday, 31 March 2020 12:13:58 UTC+1, Grumps wrote:
Hi All
So, as per subject. This is for some solar lights that have 250mAh NiMH
1.2V AA cells, but would 2500mAh cells work too?


sure no problem. They'd last longer too as they only see part of a cycle
each day. If the things contain more than 1 cell, do your best to
capacity match them or they'll see repeated reverse charging which kills
them much quicker.


Beware that higher capacity cells can have lower cycle life (number of
charge/discharge cycles before they die). Given solar lights only get a
certain amount of energy per day you might find the extra capacity isn't
much use, and yet they die faster due to the lower cycle life.

For comparison, Eneloop Pro have 500 cycles life, Eneloop Lite have 3000
cycles life. So the Pro would last 1.5 years and the Lite 8 years.

Theo

This is complicated by the auggestion that the number of cycles may be
geater it the cell is only partially discharged each time.

--

Roger Hayter

Theo[_3_] March 31st 20 10:41 PM

Replacing 250mAh NiMH with higher capacity
 
wrote:
You ignored the fact that the bigger cells won't get fully charged.

If the 0.25Ah cells are 3k cycle & the 2.5Ah are 500 cycle:

0.25Ah: 3k cycles of full charge = 3k [summer] days of life expectancy. More days IRL because winter only part charges them.
2.5Ah: 500 cycles of 1/10th charge gives 5k days of life expectancy.


These assume no reverse charging due to unequal capacity + total discharge. Hopefully the controller stops discharging before they're fully flat.


That's true, but it really depends on that cutoff. NiMH cells really don't like
being run flat. If the charging is 40% to 70% then you can get many
cycles on them, but if the charging is 0% to 30% then it isn't very good to
them.

Also garden lights have a habit of being alternately frozen and cooked,
which isn't ideal for the cycle life.

Theo


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