michael_99
New member
What is the best and quick way of discharging NiCd batteries before recharging them. Hook them up to a lightbulb and let them burn out, or is there something better?
Discharging NiCd batteries
- Thread starter michael_99
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wooslehunter
Active member
The question is why would you want to do this. If you have a fast charger, then it should detect when the cells are full and switch to trickle to top them up. If you don't then just trickle charge anyway.
The most important point is that you must not rapidly discharge non-vented cells. They may explode. Check first.
If this is to cycle the batteries then it's different matter. You should not discharge a NiCd cell to more than 1.0v per cell. And in fact you should discharge each cell in the pack separately to avoid cell reversal.
So the best way is to get a battery charger that includes the cycle function. If you want to do it yourself then the next best option is to discharge each cell perhaps with a bulb but make sure you monitor the voltage and stop at 1.0v under light load. The next best is to just discharge the whole pack with a bulb but still monitor and stop at 1.0v per cell. Monitor the voltage closely as they cells get close to discharge. They will operate at around 1.2v until almost flat when they drop quickly. If they go below 0.8v then you'll probably kill a cell.
Heat is also a killer of batteries, so it's best to discharge over a longer period of several hours. Of course you can discharge over 30 minutes or so but they will get hot and you also risk missing the 1.0v point & killing a cell.
The most important point is that you must not rapidly discharge non-vented cells. They may explode. Check first.
If this is to cycle the batteries then it's different matter. You should not discharge a NiCd cell to more than 1.0v per cell. And in fact you should discharge each cell in the pack separately to avoid cell reversal.
So the best way is to get a battery charger that includes the cycle function. If you want to do it yourself then the next best option is to discharge each cell perhaps with a bulb but make sure you monitor the voltage and stop at 1.0v under light load. The next best is to just discharge the whole pack with a bulb but still monitor and stop at 1.0v per cell. Monitor the voltage closely as they cells get close to discharge. They will operate at around 1.2v until almost flat when they drop quickly. If they go below 0.8v then you'll probably kill a cell.
Heat is also a killer of batteries, so it's best to discharge over a longer period of several hours. Of course you can discharge over 30 minutes or so but they will get hot and you also risk missing the 1.0v point & killing a cell.
michael_99
New member
Info on charger says charge and discharge new batteris 2 to 3 times.Info on battery packing says to fully discharge to prevent memory build up, a common problem with NiCd batteries. As I have 12 to do, one at the time would take a long time.
andy_wilson
New member
\'S obvious
First to repeat a caution, do not over discharge. The time to stop is when the device they are designed for shuts down. This is the minimum voltage they should be taken to. Any further can result in a range of ailments, see below.
To discharge them, just leave the thing turned on once a month or so, after you have finished using it. It knows when to switch off, leaving them perfectly prepared for a fresh charge.
First to repeat a caution, do not over discharge. The time to stop is when the device they are designed for shuts down. This is the minimum voltage they should be taken to. Any further can result in a range of ailments, see below.
To discharge them, just leave the thing turned on once a month or so, after you have finished using it. It knows when to switch off, leaving them perfectly prepared for a fresh charge.
ShipsWoofy
New member
I have a button on my good charger (like most in 2006 I have about a dozen chargers around the house) that discharges the cells prior to charge, it usually takes about 4-5 hours to discharge.
The charger is one of the only ones I have seen with this function and they are not cheap, though, I actually acquired this one. Ansmann powerline4
Click for link
I had a search on googleOZ but found nothing but more search engines and shops that had not updated their pages properly. These units sell for about £35 in the Uk.
hope it helps
The charger is one of the only ones I have seen with this function and they are not cheap, though, I actually acquired this one. Ansmann powerline4
Click for linkI had a search on googleOZ but found nothing but more search engines and shops that had not updated their pages properly. These units sell for about £35 in the Uk.
hope it helps
G
Guest
Guest
Re: Discharging NiCd batteries - easy answer ....
Get yourself to a good Radio Control Model Shop ..... they have chargers / dischargers specially made to "condition" NiCD's .... and they are not expensive.
But having spent many years with Radio Models and NiCD's etc. - if you are at the stage of thinking about "cycling" NiCD's - then they are probably on the way out ... unless you intend as preventive medecine ...
There are many ways to do it manually - but the light-bulb way will likely destroy the cell unless taken extremely carefully. A NiCD has a near flat-line discharge graph ... with a sharp drop at near end ... which means you have a very tiny window in which to stop the discharge and keep the cell from going zero or even -ve. Once that happens you have to then "zap" the cell with another that is full charged to revert it back ... but that also shortens life. The best way is electronic - as the gear detects the drop and faster than you can - switches to charge.
Fast chargers for NiCD's - despite what another says - are usually fast only and designed that YOU the user intervene at set time.
Did you know that cooling the battery during charge will actually get a small amount more in ? It's the trick we used to do when charging up electric race car packs .... a fan blowing on the pack while charging ... really works.
So it's Maplins / other good electronics shop or Radio Control Model Shop ... describe the pack you have - he'll sort it ...
Get yourself to a good Radio Control Model Shop ..... they have chargers / dischargers specially made to "condition" NiCD's .... and they are not expensive.
But having spent many years with Radio Models and NiCD's etc. - if you are at the stage of thinking about "cycling" NiCD's - then they are probably on the way out ... unless you intend as preventive medecine ...
There are many ways to do it manually - but the light-bulb way will likely destroy the cell unless taken extremely carefully. A NiCD has a near flat-line discharge graph ... with a sharp drop at near end ... which means you have a very tiny window in which to stop the discharge and keep the cell from going zero or even -ve. Once that happens you have to then "zap" the cell with another that is full charged to revert it back ... but that also shortens life. The best way is electronic - as the gear detects the drop and faster than you can - switches to charge.
Fast chargers for NiCD's - despite what another says - are usually fast only and designed that YOU the user intervene at set time.
Did you know that cooling the battery during charge will actually get a small amount more in ? It's the trick we used to do when charging up electric race car packs .... a fan blowing on the pack while charging ... really works.
So it's Maplins / other good electronics shop or Radio Control Model Shop ... describe the pack you have - he'll sort it ...
G
Guest
Guest
Charge discharge instructions ... common
If its a radio or other set etc. - charge it up .... switch on and let it run out .... charge up again ...
The Radio etc. normally literally switches off when cells no longer have enough to work it ... and rarely cause cell death or reversal ... so use the gear the NiCD's are supplied for ...
Like I said in another post ... I spent years flying radio models and usual practioce was to charge up radio gear ... leave switched on and let it go flat ... charge up again etc. Do it 2 or 3 times ...
Remember that NiCD's are not designed for partial discharge and recharge all the time ... repeated will cause loss of useable capacity. Try and discharge fully and then recharge at regular intervals if you can ... then partial discharge / charge at times will not hurt ...
If its a radio or other set etc. - charge it up .... switch on and let it run out .... charge up again ...
The Radio etc. normally literally switches off when cells no longer have enough to work it ... and rarely cause cell death or reversal ... so use the gear the NiCD's are supplied for ...
Like I said in another post ... I spent years flying radio models and usual practioce was to charge up radio gear ... leave switched on and let it go flat ... charge up again etc. Do it 2 or 3 times ...
Remember that NiCD's are not designed for partial discharge and recharge all the time ... repeated will cause loss of useable capacity. Try and discharge fully and then recharge at regular intervals if you can ... then partial discharge / charge at times will not hurt ...
Danny
New member
Re: Charge discharge instructions ... common
Please excuse a slight diversion but is it true that it's only NiCd cells that suffer from the 'memory' business and get to the stage where they can't supply a full dose of charge. NiMh batterys don't suffer from this syndrome, right? And is it OK to completely discharge NiMh batterys?
Please excuse a slight diversion but is it true that it's only NiCd cells that suffer from the 'memory' business and get to the stage where they can't supply a full dose of charge. NiMh batterys don't suffer from this syndrome, right? And is it OK to completely discharge NiMh batterys?
Ships_Cat
New member
What Wooslehunter says is correct but will not be allowed on this forum to stand up in the face of the rabid NiCd myth mongerering about discharging and "memory".
I suggest that you have a look at the sites of some of the main cell makers and that of professional users (those designing power packs for critical applications) for advice and ignore most of what you read here if you want good service from your batteries.
But, of course, if you find the activities promoted by the myths add excitement to your use of your batteries (after all, batteries are really quite dull if you don't have to do anything fancy to them /forums/images/graemlins/smile.gif) then go to it - the cost only being to the service you can expect from them.
John
I suggest that you have a look at the sites of some of the main cell makers and that of professional users (those designing power packs for critical applications) for advice and ignore most of what you read here if you want good service from your batteries.
But, of course, if you find the activities promoted by the myths add excitement to your use of your batteries (after all, batteries are really quite dull if you don't have to do anything fancy to them /forums/images/graemlins/smile.gif) then go to it - the cost only being to the service you can expect from them.
John
Ships_Cat
New member
Re: Charge discharge instructions ... common
Again the mythmakers will attack this but if you want a definitive answer there is plenty of good information freely available from the cell manufacturers and professional users of batteries (by professional users I mean those designing power packs for critical applications, not for domestic or hobby use).
Without getting into discussions of "memory effect" /forums/images/graemlins/frown.gif both cell types suffer from exactly the same effect. Both if mistreated can suffer from nickel precipitation resulting in loss of capacity. For both types that is reversible.
Generally the advantage of Ni-Mh is that they have more capacity for size but survive less charge/discharge cycles.The loss of capacity in Ni-Mhs is less often seen due to their lesser life in terms of charge/discharge cyles (but don't read that as meaning that they have a lesser life in terms of total energy delivered in their life). NiCds have the advantage of greater current delivery rate for size.
Again, there is plenty of professional information around, rely on that.
John
Again the mythmakers will attack this but if you want a definitive answer there is plenty of good information freely available from the cell manufacturers and professional users of batteries (by professional users I mean those designing power packs for critical applications, not for domestic or hobby use).
Without getting into discussions of "memory effect" /forums/images/graemlins/frown.gif both cell types suffer from exactly the same effect. Both if mistreated can suffer from nickel precipitation resulting in loss of capacity. For both types that is reversible.
Generally the advantage of Ni-Mh is that they have more capacity for size but survive less charge/discharge cycles.The loss of capacity in Ni-Mhs is less often seen due to their lesser life in terms of charge/discharge cyles (but don't read that as meaning that they have a lesser life in terms of total energy delivered in their life). NiCds have the advantage of greater current delivery rate for size.
Again, there is plenty of professional information around, rely on that.
John
VicMallows
New member
Re: Charge discharge instructions ... common
John,
Very well explained! ... just realised some C-cell NiCd's I'm using constantly are over 15years old...so probably treatng them OK /forums/images/graemlins/grin.gif
Vic
John,
Very well explained! ... just realised some C-cell NiCd's I'm using constantly are over 15years old...so probably treatng them OK /forums/images/graemlins/grin.gif
Vic
Danny
New member
Re: Charge discharge instructions ... common
Thanks for the explanation, John. It must have been good - I understood it!
Thanks for the explanation, John. It must have been good - I understood it!
michael_99
New member
Re: Discharging NiCd batteries - easy answer ....
Yes Nigel, it is for a R/C. I'm making a rig for my camera to be hung from a kite, which I hope to be taking pictures with when out sailing. Something like this.
I have to go to the R/C shop anyway, so I look for a discharger.
Yes Nigel, it is for a R/C. I'm making a rig for my camera to be hung from a kite, which I hope to be taking pictures with when out sailing. Something like this.
I have to go to the R/C shop anyway, so I look for a discharger.
G
Guest
Guest
Memory and discharge ...
I'm no battery expert - just used all common types of rechargeables in modesl for years ... when you have a lot of time, hard work and money tied up in that scale model flying etc. - you quickly learn to care for rechargeable's.
Memory effect - there are some who will post and say - doesn't exist ... well to them I say Tosh - There is a lot written out there in mags, articles, personal experinces etc. etc. that NiCD's when not properly cycled do suffer useable capacity loss ... I'm careful about the memory word !! The capacity is still there - it just literally stops delivering far short of where it should ...
I have had quite a few lost capacity NiCD's - as well as damaged NiCD's for other reasons - that I prefer NiMH or LIon batterys. They apparently do not exhibit the same characteristic.
In terms of discharge ......... IMHO - I would never discharge any rechargeable cell whatever its type anywhere near zero ... careful discharge to the drop point and stop .... let the cell cool down if necessary and then charge it back up fully.
having been friendly with a Mallory Battery Lab and R&D guy years ago who also ran radio models - I believe him before others who say memory does not exist ...
I'm no battery expert - just used all common types of rechargeables in modesl for years ... when you have a lot of time, hard work and money tied up in that scale model flying etc. - you quickly learn to care for rechargeable's.
Memory effect - there are some who will post and say - doesn't exist ... well to them I say Tosh - There is a lot written out there in mags, articles, personal experinces etc. etc. that NiCD's when not properly cycled do suffer useable capacity loss ... I'm careful about the memory word !! The capacity is still there - it just literally stops delivering far short of where it should ...
I have had quite a few lost capacity NiCD's - as well as damaged NiCD's for other reasons - that I prefer NiMH or LIon batterys. They apparently do not exhibit the same characteristic.
In terms of discharge ......... IMHO - I would never discharge any rechargeable cell whatever its type anywhere near zero ... careful discharge to the drop point and stop .... let the cell cool down if necessary and then charge it back up fully.
having been friendly with a Mallory Battery Lab and R&D guy years ago who also ran radio models - I believe him before others who say memory does not exist ...
G
Guest
Guest
Reversible losses ...
Having had cells lose capacity and also reverse when over discharged ... yes it is true the condition is often reversible .... but experience - my own over the many years - shows that the cell recovered is less reliable and also shortened in life ....
Looks like the thread will go for the usual head to head that NiCD posts do ... and it will fizzle out again with no solution either way ... you in one camp - me and others in other camp ... it's a great life in'it !!
FYI - I have NiCD's that go back many years ... and also NiMH ..... with reasonable treatment and regular conditioning - they last years ... usually exceeding the manufacturers stated life cycle of recharges ...
As stated before - the Mallory guy agreed and stated clearly it exists ... second I can remember him talking about "Professional" set-ups they supplied for etc. and in many cases they had built in charge - recharge + secondary / redundancy supply ... so the argument starts to show that conditioning is often built in ...
Anyway - I fall in the general camp of I shall condition any NiCD's I still have ... as they fall out of use - replacing with NiMH / LIon where possible ... the only area that NiCD's used to reign supreme is high current discharge use - such as model race packs etc.
Having had cells lose capacity and also reverse when over discharged ... yes it is true the condition is often reversible .... but experience - my own over the many years - shows that the cell recovered is less reliable and also shortened in life ....
Looks like the thread will go for the usual head to head that NiCD posts do ... and it will fizzle out again with no solution either way ... you in one camp - me and others in other camp ... it's a great life in'it !!
FYI - I have NiCD's that go back many years ... and also NiMH ..... with reasonable treatment and regular conditioning - they last years ... usually exceeding the manufacturers stated life cycle of recharges ...
As stated before - the Mallory guy agreed and stated clearly it exists ... second I can remember him talking about "Professional" set-ups they supplied for etc. and in many cases they had built in charge - recharge + secondary / redundancy supply ... so the argument starts to show that conditioning is often built in ...
Anyway - I fall in the general camp of I shall condition any NiCD's I still have ... as they fall out of use - replacing with NiMH / LIon where possible ... the only area that NiCD's used to reign supreme is high current discharge use - such as model race packs etc.
Chris_Burns
New member
NASA (as in space agency, not marine electronics) have done a lot of research into the care of NiCd batteries for obvious reasons.
Some of the information is distilled in this link: web page
Rgds
Chris.
Some of the information is distilled in this link: web page
Rgds
Chris.
geoffatstanpit
Member
Re: Discharging NiCd batteries - easy answer ....
Oh dear! I did that once and learned 2 lessons.
1. It needs a VERY big kite to lift camera, batteries, relays etc etc
2. I used a Nikonos which didn't come to any harm although the electrics fizzed merrily and dissolved when it all fell in the sea.
Oh dear! I did that once and learned 2 lessons.
1. It needs a VERY big kite to lift camera, batteries, relays etc etc
2. I used a Nikonos which didn't come to any harm although the electrics fizzed merrily and dissolved when it all fell in the sea.
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