How long do NiMH batteries hold their charge?


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dnaxe

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#1
(and does anyone know the current contact details of sanyo energy in Singapore?)
 

genegoh

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#2
I think this varies from battery to battery.
The Sanyo eneloops can hold charge for up to 6 months, whereas other brands and types may not last as long.
 

dnaxe

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#3
ok, to be clearer - I'm referring to the normal formulations, rather than long lasting nimh battries such as eneloops and recykos...

Mine discharge completely after 3 days, and i'm wondering if this is normal.
 

ipin

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Nov 21, 2005
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#4
My PowerEx could hold their charge for more than 2 weeks. :think:

How old are your batteries? Maybe their are either nearing their lifespan or they just need refreshing.
 

lkkang

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#5
I think this varies from battery to battery.
The Sanyo eneloops can hold charge for up to 6 months, whereas other brands and types may not last as long.
I design / customise battery pack for a living...

Normally, we will take a 25%/month self-discharge rate as a norm. meaning that if you fully charge a re-chargeable battery cell . in 4 months time, the remaining capacity will go to ZERO.

As for the case you are facing, 3day to empty, you can throw the cells away already... it is already dead...
 

zac08

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#6
ok, to be clearer - I'm referring to the normal formulations, rather than long lasting nimh battries such as eneloops and recykos...

Mine discharge completely after 3 days, and i'm wondering if this is normal.
Nope... not normal...

I keep my PowerEx batteries on my shelf for periods up to a month or so... and the drop in power is negligible.. ;)
 

dnaxe

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#7
eeks.

the cells are about 10 months old, and have been charged about 30 times.

Perhaps I shouldn't use this 15 minute charger I have. >.<
 

lkkang

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#8
eeks.

the cells are about 10 months old, and have been charged about 30 times.

Perhaps I shouldn't use this 15 minute charger I have. >.<
hi dnaxe, you are quite right actually. Fast charge also means shorter lifespan. I will not go into the technical explaination ... very boring.

We did design some batteries specially for remote control car racing purpose. They can be recharged in 5~10 minutes and the output instantanous power is very very high. However, they only can re-charge about 5 times, after that, the capacity drops to almost ZERO.

If recharge time is not very critical, I would recommend that you do a slow charge or overnight charging ( about say 10~ 15hours slow charge, using very small current ). We call this formatting the cells. Maximum lifespan + Maximum cell capacity is achieved.
 

deckard

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Oct 13, 2006
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hi dnaxe, you are quite right actually. Fast charge also means shorter lifespan. I will not go into the technical explaination ... very boring.

We did design some batteries specially for remote control car racing purpose. They can be recharged in 5~10 minutes and the output instantanous power is very very high. However, they only can re-charge about 5 times, after that, the capacity drops to almost ZERO.

If recharge time is not very critical, I would recommend that you do a slow charge or overnight charging ( about say 10~ 15hours slow charge, using very small current ). We call this formatting the cells. Maximum lifespan + Maximum cell capacity is achieved.
so quick chargers are actually bad?
 

kiwi2

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#10
Is it really true the rechareable batteries can recharge for 500 or even 1000 times that the advertisement says? I find this like too good to be true! Based on my usage of say 1 or even less than 1 charging per week, I could use the batteries for at least 10 years!! :bigeyes:
 

Jan 14, 2005
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#11
Is it really true the rechareable batteries can recharge for 500 or even 1000 times that the advertisement says? I find this like too good to be true! Based on my usage of say 1 or even less than 1 charging per week, I could use the batteries for at least 10 years!! :bigeyes:
In ideal conditions, it is possible. But the performance of batteries also decrease with age. I don't think you can still use the batteries as it is after 2 or 3 years.

BC
 

deckard

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Oct 13, 2006
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#12
one thing I want to ask...

is keeping batteries in the fridge good for the batteries?

I heard from people, cold temperature will extend the life of the batteries... :dunno:
 

dnaxe

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#13
hi dnaxe, you are quite right actually. Fast charge also means shorter lifespan. I will not go into the technical explaination ... very boring.

We did design some batteries specially for remote control car racing purpose. They can be recharged in 5~10 minutes and the output instantanous power is very very high. However, they only can re-charge about 5 times, after that, the capacity drops to almost ZERO.

If recharge time is not very critical, I would recommend that you do a slow charge or overnight charging ( about say 10~ 15hours slow charge, using very small current ). We call this formatting the cells. Maximum lifespan + Maximum cell capacity is achieved.
You tempt me into buying a wizardOne. ;)
 

lsisaxon

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Nov 29, 2004
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#14
ok, to be clearer - I'm referring to the normal formulations, rather than long lasting nimh battries such as eneloops and recykos...

Mine discharge completely after 3 days, and i'm wondering if this is normal.
Do you have the faulty Sanyo 2500mAhs? I'd say a safe figure would be about a week or 2 but not 3 days, I did have some Sanyos and Energizer 2500 which only lasted 2-3 days. Gave up. I am using Eneloop and Recyko+ now.
 

lkkang

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#16
Is it really true the rechareable batteries can recharge for 500 or even 1000 times that the advertisement says? I find this like too good to be true! Based on my usage of say 1 or even less than 1 charging per week, I could use the batteries for at least 10 years!! :bigeyes:
Typical recharge cycle is between 300 ~ 500 cycles. However, it should be noted that this figures are based on slow charging and slow discharge rate. Meaning that if you discharge the cells too fast ( for example ... completely discharging the cells in 1/2 hour) or charge the cells too rapidly ( fast charge in say 1 hour ), the number of recharge cycles will drop accordingly.

To make things more complicated, the operating temperature also makes a difference.

As a consumer... don't be bored by these figures... you just buy and then use... no capacity then you buy new cells, thats how we earn our living.. he he he...
 

lkkang

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#17
so quick chargers are actually bad?
I will not say that they are bad. It is actually a demand and supply matter. If there is a demand for the user to recharge the cells in 10minutes due to situation arise. Then it will be a plus point to use 10 minute charging.

It is exactly the same synario as driving a car. If you ramp your car from 0 km/hr to 100 km/hr in 3 seconds everyday, the engine is going to wear off very fast. However, if there is a dying person lying in the car and you are going to fetch him / her to the hospital, then making stepping the accerlator makes the a lot of difference to a person life.
 

arpinkor

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May 13, 2005
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#18
so quick chargers are actually bad?
Fast chargers are only good for emergency use. Not only do they shorten the lifespan of the batteries, but you can't completely charge the batteries within that short time.
 

dnaxe

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Oct 5, 2006
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#19
Do you have the faulty Sanyo 2500mAhs?
I'm using Sanyo 2500mAhs - but I'm not sure if they're faulty... I doubt mine in late sept 2006, which seems to be well after the faulty sanyo battery batches.
 

dnaxe

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#20
Typical recharge cycle is between 300 ~ 500 cycles. However, it should be noted that this figures are based on slow charging and slow discharge rate. Meaning that if you discharge the cells too fast ( for example ... completely discharging the cells in 1/2 hour) or charge the cells too rapidly ( fast charge in say 1 hour ), the number of recharge cycles will drop accordingly.
One hour is a fast charge?!? Hmm.

Isn't too slow a charge also a bad idea, though?
 

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