Rechargeable battery longevity

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Stuart M

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I've just bought meself a Technolite BL-700 and some AA size Eneloops. On the subject of recharging times the idiot guide says the following:-

200 mA ~ 13 hrs.
500 mA ~ 5 hrs.
700 mA ~ 3 hrs. 35 mins.

So far, so good. I presume, though, that there's some kind of trade off in recharging consistently at the higher rate of 700mA. Am I correct in thinking that this reduces the overall longevity of the battery or doesn't it make any difference? Your thoughts, ladies and gentlemen, please.
 
I always charge mine at 200ma which I think is the default/auto setting for the b700, pretty sure I read somewhere that it's much better for the batteries so I've just always done so.
 
Hi Stuart,

I also have that charger and batteries and they work just fine!

There's no trade off in recharging them at the higher rate. In fact, 700 mAh is less then 0.5c for these batteries, so you shouldn't even recharge them using the lower rates.

Stay at 700 mAh, a full charge will show you around 2.3A, which is just perfect . ;)

edit: I meant 0.5c, not 0.5A. It's now corrected.
 
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Which eneloops did you get? Either way nothing wrong with 700ma charging rate.

Between 1c and 1/2c is the best range to be in.
 
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That's alright then. I'll keep charging them at the higher rate for the shortest possible time. Cheers!
 
PitaDaVespa said:
Hi Stuart,

I also have that charger and batteries and they work just fine!

There's no trade off in recharging them at the higher rate. In fact, 700 mAh is less then 0.5A for these batteries, so you shouldn't even recharge them using the lower rates.

Stay at 700 mAh, a full charge will show you around 2.3A, which is just perfect . ;)
Click to expand...

Why do they give you the choice of 200/500 then if you shouldn't use these charging rates ?
I always charge at the lowest as i was informed the Batteries stay cooler, Only using a higher charge rate if you are stuck for time.
It seems that the manufacturers of these products are adding pointless features then !
 
I always charge at a slow rate, unless in a rush.

I think battery tech has improved and gone are the days where rapid charging wasn't good and didn't last long.

But I still prefer slower. Even for my RC planes/helps. Only time I rush those is if I charge in the field and want more flights. Otherwise I do them slow at home. And as they are expensive, I want to keep them in good condition.
 
It does depend on the chemistry involved. Lead acid for example do not like long hard charge/discharge. It can distort the plates. They can tolerate short bursts.
Lipo can deliver silly discharge currents. But again this creates heat. And it's this that ultimately kills them.
I can't see why you'd not use 200mA as a regular charge current.
 
Slow rates are fine if your not using delta peak as your cut off, a rate of 0.5c -1c will give a strong signal to switch off charging a slower rate may overcharge the cells slightly as it takes longer to get the delta peak.
Slow rates are also fine if you can adjust the delta peak.

Slow charging was the norm before we used delta peak as the lower charge current does less damage overcharging the cells.

The charges have 200 mA because that would be the setting to use for some of the low capacity AAA batteries. Most now i thing are 900mAh so you would use about 450 mA which would be 0.5c.
 
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NikonKev said:
Why do they give you the choice of 200/500 then if you shouldn't use these charging rates ?
I always charge at the lowest as i was informed the Batteries stay cooler, Only using a higher charge rate if you are stuck for time.
It seems that the manufacturers of these products are adding pointless features then !
Click to expand...
I guess the following answer respond nicely to your question.


robj20 said:
Slow rates are fine if your not using delta peak as your cut off, a rate of 0.5c -1c will give a strong signal to switch off charging a slower rate may overcharge the cells slightly as it takes longer to get the delta peak.
Slow rates are also fine if you can adjust the delta peak.

Slow charging was the norm before we used delta peak as the lower charge current does less damage overcharging the cells.

The charges have 200 mA because that would be the setting to use for some of the low capacity AAA batteries. Most now i thing are 900mAh so you would use about 450 mA which would be 0.5c.
Click to expand...
 
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Eneloop can be charged by using a current upto 0.7C which is basically the mAH value without the "h" so for 2000mAH battery you can theoretically charge it at 1.4A or 14000mA...thats a massively fast charge.

most of the smart chargers have 700mA charge which is well within the charging current specification of these batteries.

now these smart chargers are smart because they will detect Voltage of the Battery and ramp down the current as it approaches full charge. So what it does is - the charger will use 700mA for pretty much most of the charge then gradually ramp down to 200mA and then trickle charge when the battery is full. So in short 700mA, 500mA, 200mA does nothing to your battery's longevity if you got AA batteries thats more than 1000mAH capacity. but the current will be a problem for smaller batteries where their specified capacity is 500mAH or 700mAH which means you have to use 200mA and 500mA as maximum charge current respectively, otherwise you are going to damage those batteries.
 
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