You can also use a 4.2v Lithium battery. I've done it hundreds of times--but you should only let it touch it NOT for 10 seconds, but only for 1 second at a time, keep checking the voltage or til the charger will recognize it. I've done it with a 12 volt battery too, but the batteries were 1.2v and like 4000mAH. Again, only touching MOMENTARILY until the dead one "wakes up". If you don't see a little spark, you got a dead/high resistance/open/ bad battery.
ok let me get this straight (non english speaker) : if i use another NIMH 1.2v batterie to revive the "DEAD" i have to hold the wires for 10-15 seconds; if i use a 3.7v/4.2v lithium or 12V battery to revive a nimh i must hold for 1-2 seconds; is this correct ?????
I would not recommend using Lithium-Ion batteries for this, or using this method on them. The biggest disadvantage with Li-Ion batteries is that they can cause explosive fires easily that are hard to put down. If you remember certain Samsung Note phones, hoverboards not being allowed on airplanes, or saw some fires with EV car batteries, Those are lithium based batteries. They normally have protective mechanisms but less reputable ones might not. By doing this operation you cause a huge current (about 2A, there was a video where another person is showing this method and he got 6A) to go through (it's the biggest at initial connection then goes down) which can rapidly heat the battery and if you're unlucky trigger fire. Even without fire this will put huge stress on on Li-Ion which was not designed for high current so you might be saving one battery at the cost of another.
Wow! It worked! I was able to revive a 20-year-old 6-cell ni-cad battery pack for my old RC car by doing your method. It's like jump starting a dead car battery!
Havent tried it yet,but I got put all my old rechargables that I saved for some reason.ALL have said hhis works,and the same response from viewers on similar videos. I believe it will work and thank you ahead of time.You and others offering this technique across TH-cam are saving folks a lot of money. 2 thumbs up bud.👍👍
Thank you so much. I know great deal about batteries but this never occurred to me. I threw 2 x DEAD 1.2v 1300mah niCd batteries in the bin. after seeing your video, Both now charging and working fine now. Thank you for making this video.
isn't this just a voltage effect? Can't you apply 1.2v or so, from any source to revive these individual cells? The dead cell doesn't know anything about the chemistry of the donor cell :)
It worked! Dead battery had 0,120 V and charger marked is as faulty. I connected it to good battery and after 15 seconds or so, I put dead battery into charger and it started charging it, thank you so much.
This worked for me. I have the PowerEx MH-C808M charger and had some dead (0v) NiMH D cells. The charger simply wouldn't recognize that I inserted them. I used a new alkaline D cell to "jump start" as shown, except I held the wires for 30 seconds rather than 10. Then the charger at least recognized the D cells. I ran the cells thru a "condition" cycle, a feature of the charger, which took a few days, and the batteries seem good now.
very nice video!!!Sure we would like the reassemble video of the battery pack. let me know ,did you use the same cell for reviving each one of the dead ones?or did also exist and another cell with enough voltage too which you used in addition?
My varta NiMh AA batteries are able to be charged normally but not with quick charge mode. What is the problem of these batteries? They were quick charging before without a problem but they now only charge with normal charge mode.
Great presentation, Saiyam. I have two Roomba battery packs dead due to long use interruption. Before disassembling them, I would like to see how the cells are rebuilt after the charging. Could you do a short video of that too.
Thank you! I will try my best to make a video of that. Although the cells are spot welded with nickel strips and I don't have a spot welder with me so I'll just try to solder them together (which is actually not recommended) and let's see if it works.
@@SaiyamAgrawal Would be interesting to see how you reassembled the pack back. I was opening the pack today too - but i realized as they were all in series, there is no need to separate them from nickel strips - went pretty smoothly charging one by one (nickel strips are nice to clip crocks on). Now i would be mostly interested how to restore the shrink wrapped cover (although it is mostly aesthetic issue only)
NIce video.. ihave a battery pack of two batteries..one seems to be death and the other not , do i neeed to remove plastic cover in order to try this? thanks
my 9v PP3 rechargeable batteries charge up fine but lose half their power after about 12 hours , they have never been used and just put in a drawer for a few years
hello . nice video. how can we deal with memory effect of these dead cells? after reviving and allowing them charging regularly , they still have memory effect and dont go up to their highest capacity. Is there a trick for this? I sometimes do a discharge and charge cycles but didnt get success
I just reconditioned 2 RC 6 cell battery packs after the charger read error. After cycling them for 3 days I got them from 250mAh to 1400mAh but they will not hold a charge over night. Complete waste of time.
great , thank you!! May I ask a question, I have a couple of dead AA NIMH batteries that I want to revive, my other working batteries are D cells of the same type, can I use a D cell to revive an AA cell?
I am not sure if that will work. However, dead cells have high internal resistance so you can go ahead and try it as there won't be much of a risk. Just make sure you don't connect them for more than 10-12 seconds. If it doesn't work after 10-12 seconds then it's not going to work. For more safety you can use a diode to avoid reverse flow of current.
@@SaiyamAgrawal Maglite said I need a new battery. I used a normal D cell & it revived my Maglite battery! It wasn't working for years, now it's perfect. Really happy. Thanks.
I was hoping that maybe it is possible to just connect to each inter-cell busbar in turn, without breaking the connections. The cells are all in series, right? But how much "stripping" is needed for that?
What's the theory behind why the chargers won't charge them initially? It seems like they've set them up that way intentionally. Is there a reason? Based on the flashing lights, the charger certainly recognizes that there's a battery there, but just doesn't want to charge it. I would wonder (in my ignorance) whether they think it's a safety concern, or whether they think the battery won't be any good in the long term (e.g., it may take, but will no longer hold, a charge)
It's because the chargers cannot recognize the battery and do not know whether it some random object which is holding very little charge or whether it's just a dead battery. I think it's for safety purposes.
There is a certain voltage for each kind of batteries below which they can be declared dead. So it recognizes the cell, if finds its voltage to be too low and thus shows an error. Might be a safety concern.
An extreme example would be if you had a lithium cell at 0.1 volts and it tried to charge it as if it was a NiMH; such a lithium cell would be a fire hazard. If it detects 1.0 volts it can assume NiMH or NiCd and start charging; using ‘hobby chargers’ it is possible to charge anything; for example an 8.4 volt 6-cell electric vehicle pack that was at 0.01v for the whole pack!...
@@SaiyamAgrawal hey I need your help I recharged 150 mah aaa 1.2v rechargeable with 2.5 v and 2A is it dangerous the battery was 0v it holding it change for about 2 days and now its need recharged I had not used it voltage is 1V
Yes, voltage will decrease if you don't charge them just after reviving. The process of reviving is only enough for increasing the voltage of a dead cell so that it can be charged normally.
Depends on how old the batteries are and how many charge cycles they had already completed before being revived. Obviously after this process they won't work as if they are brand new.
For NiMH cells, a cell-voltage reading below 0.98 volts to 1.0 volts is a sensitive electro-chemical zone where excess current can permanently damage the cell, even shorting it out permanently. The typical manufacture requirement for very low charge cells (between zero and 1 volt, when the cell is at room temperature) is to trickle charge them slowly to above 1.0 to 1.1 volts, then do a normal charge at 1/10 the mAh capacity. In other words, normal charge rates for NiMH for a 700 mAh cell would be one-tenth, or 70 ma. It the cell is hot from recent use, charge or discharge you need to wait till it is at room temperature to measure it, or the cell voltage will not indicate state-of-charge. if you just discharged it at high current so the cell is hot, wait until it is cool so your charger can make good decisions. Shorting the dead cell to a charged cell is a desperation procedure -- if you force charge into the cell this way, you will reduce the number of future charge cycles available from that cell. And you might kill a cell that would be recoverable with the trickle-charge procedure. If someone uses a fully-charged cell they might cause enough gassing in the dead cell to blow it up an injure themselves. The NiMH cell is typically not damaged by sitting around and self-discharging to a very low voltage, as long as you slowly bring it up to the safe normal charge voltage for about 1.0 to1.2 volts a room temperature. This trickle-charge start-up process is built into quality commercial and industrial NiMH chargers, and ones I have designed for electronics products all work that way. A reliable circuit uses a magnetic-latching relay to disconnect and lock out the cell from the device when the per-cell volts falls below 1.0 volts. When power is restored, the charging circuit charges the cell or cell-pack slowly until each cell is above 1.0 volts, before switching to regular charge until about 1.2 volts per cell. Then the latching relay is un-latched to connect and power up the device. This logic can be performed with a cheap 70-cent microprocessor that spends over 99% of its time sleeping. Why don't OPUS snd Nitexxxx implement this trickle charge for NiMH? I don't know, but it may not be compatible with the requirement to automatically recognize the chemistry-type of cell in the charger (NiCad, NiMH LiFePO, Lithium-ion, etc.).
![ร้อยพ่อพันแม่ - WanMai [Official MV]](http://i.ytimg.com/vi/XY2pNYASEbg/mqdefault.jpg)
You can also use a 4.2v Lithium battery. I've done it hundreds of times--but you should only let it touch it NOT for 10 seconds, but only for 1 second at a time, keep checking the voltage or til the charger will recognize it. I've done it with a 12 volt battery too, but the batteries were 1.2v and like 4000mAH. Again, only touching MOMENTARILY until the dead one "wakes up". If you don't see a little spark, you got a dead/high resistance/open/ bad battery.
Oh, thanks for the tip! I just don't like to mess around with lithium batteries :')
ok let me get this straight (non english speaker) : if i use another NIMH 1.2v batterie to revive the "DEAD" i have to hold the wires for 10-15 seconds; if i use a 3.7v/4.2v lithium or 12V battery to revive a nimh i must hold for 1-2 seconds; is this correct ?????
I would not recommend using Lithium-Ion batteries for this, or using this method on them. The biggest disadvantage with Li-Ion batteries is that they can cause explosive fires easily that are hard to put down. If you remember certain Samsung Note phones, hoverboards not being allowed on airplanes, or saw some fires with EV car batteries, Those are lithium based batteries. They normally have protective mechanisms but less reputable ones might not. By doing this operation you cause a huge current (about 2A, there was a video where another person is showing this method and he got 6A) to go through (it's the biggest at initial connection then goes down) which can rapidly heat the battery and if you're unlucky trigger fire. Even without fire this will put huge stress on on Li-Ion which was not designed for high current so you might be saving one battery at the cost of another.
@@tkd128 its fine as long as you do it for a little bit, you can short any lithium ion cell but as long as it doesnt become too hot its fine
Wow! It worked! I was able to revive a 20-year-old 6-cell ni-cad battery pack for my old RC car by doing your method. It's like jump starting a dead car battery!
Was it NiCD?
Havent tried it yet,but I got put all my old rechargables that I saved for some reason.ALL have said hhis works,and the same response from viewers on similar videos.
I believe it will work and thank you ahead of time.You and others offering this technique across TH-cam are saving folks a lot of money.
2 thumbs up bud.👍👍
Thanks! I hope it works for you as well 😄
You saved my life bro.. 3 sets of 5000 mah was about to be thrown away. They are charging now.. Thanks alot.
Good to know :)
Thank you so much. I know great deal about batteries but this never occurred to me. I threw 2 x DEAD 1.2v 1300mah niCd batteries in the bin. after seeing your video, Both now charging and working fine now. Thank you for making this video.
isn't this just a voltage effect? Can't you apply 1.2v or so, from any source to revive these individual cells? The dead cell doesn't know anything about the chemistry of the donor cell :)
Ideally, it should work but I haven't tried :')
It worked! Dead battery had 0,120 V and charger marked is as faulty. I connected it to good battery and after 15 seconds or so, I put dead battery into charger and it started charging it, thank you so much.
Great! :)
This worked for me. I have the PowerEx MH-C808M charger and had some dead (0v) NiMH D cells. The charger simply wouldn't recognize that I inserted them. I used a new alkaline D cell to "jump start" as shown, except I held the wires for 30 seconds rather than 10. Then the charger at least recognized the D cells. I ran the cells thru a "condition" cycle, a feature of the charger, which took a few days, and the batteries seem good now.
Thank you for the guidance. I was able to restore mine. Cheerssss
very nice video!!!Sure we would like the reassemble video of the battery pack.
let me know ,did you use the same cell for reviving each one of the dead ones?or did also exist and another cell with enough voltage too which you used in addition?
My varta NiMh AA batteries are able to be charged normally but not with quick charge mode. What is the problem of these batteries? They were quick charging before without a problem but they now only charge with normal charge mode.
Can you make a video on how to disassemble and reassemble the roomba battery? That’s the part I’m nervous about.
I have already disassembled the pack so can't make a video of that but for the reassembly, I'll surely try.
Is it still OK if I buy AA nimh with production date Oct 2020? Thank you
Awesome tip Saiyam! Shukria! I am going to try reviving my old cells now.
You're most welcome :)
good vid! how do tell the difference from + or + wire? And do make a reassembly video of the Roomba pack.
if you connect a wire to + then its a + wire
it's not something unique to the wire
Could anyone give me description about the science of it? Why does it work? Thank you for your video!
I used the same trick on my 3.7v lithium batteries, except I put them in a 18650 flashlight with a good battery. Same trick but a lot safer.
Great presentation, Saiyam. I have two Roomba battery packs dead due to long use interruption. Before disassembling them, I would like to see how the cells are rebuilt after the charging. Could you do a short video of that too.
Thank you!
I will try my best to make a video of that. Although the cells are spot welded with nickel strips and I don't have a spot welder with me so I'll just try to solder them together (which is actually not recommended) and let's see if it works.
@@SaiyamAgrawal Would be interesting to see how you reassembled the pack back. I was opening the pack today too - but i realized as they were all in series, there is no need to separate them from nickel strips - went pretty smoothly charging one by one (nickel strips are nice to clip crocks on). Now i would be mostly interested how to restore the shrink wrapped cover (although it is mostly aesthetic issue only)
NIce video.. ihave a battery pack of two batteries..one seems to be death and the other not , do i neeed to remove plastic cover in order to try this?
thanks
I don't have dead batteries but for some reason when I charge them they drop back down too 1.25-1.27 volt. I have 20 GP D cell 1.2v 9000mah batteries
Great work brother, keep it up!!!
Thanks!
thanks for saving my antique phone battery the phone charges but cant hold the charge so thanks
my 9v PP3 rechargeable batteries charge up fine but lose half their power after about 12 hours , they have never been used and just put in a drawer for a few years
hello . nice video. how can we deal with memory effect of these dead cells? after reviving and allowing them charging regularly , they still have memory effect and dont go up to their highest capacity. Is there a trick for this? I sometimes do a discharge and charge cycles but didnt get success
I just reconditioned 2 RC 6 cell battery packs after the charger read error. After cycling them for 3 days I got them from 250mAh to 1400mAh but they will not hold a charge over night. Complete waste of time.
The packs are 15 years old.
great , thank you!! May I ask a question, I have a couple of dead AA NIMH batteries that I want to revive, my other working batteries are D cells of the same type, can I use a D cell to revive an AA cell?
I am not sure if that will work. However, dead cells have high internal resistance so you can go ahead and try it as there won't be much of a risk. Just make sure you don't connect them for more than 10-12 seconds. If it doesn't work after 10-12 seconds then it's not going to work. For more safety you can use a diode to avoid reverse flow of current.
@@SaiyamAgrawal thanks a lot!
thank you, it works!
Arre mast! Mere TV remote ke cell bhi charge karde bhai 😂😜
😂
Can I use a normal D cell to revive my Maglite rechargeable battery pack ?
If both of them are rechargeable and of the same type/size (D type as you said), you're good to go.
@@SaiyamAgrawal Maglite said I need a new battery. I used a normal D cell & it revived my Maglite battery! It wasn't working for years, now it's perfect. Really happy. Thanks.
Nice video! I have the same problem with my roomba! I would like to see the resemble of the battery
And isn't it possible to revive them without tearing apart the whole battery pack?
Sure, I will try to post that video
@@randykuipers4743 not sure about that. I don't think that is possible.
@@SaiyamAgrawal , waiting eagerly for the reassembly presentation.
I was hoping that maybe it is possible to just connect to each inter-cell busbar in turn, without breaking the connections. The cells are all in series, right? But how much "stripping" is needed for that?
Can I revive my NiMH batteries with Zn Carbon battery or do I have to do it via charged NiMh one
Do not connect different types of batteries. Do it only with charged NiMH one.
Hmmmm...good job ! It worked on 5 year dead batteries....
You are best
Thank you so much 🙏🏻
Awesome video. Keep making such helpful videos🙏.
Thank you so much! 🙏🏻
What's the theory behind why the chargers won't charge them initially? It seems like they've set them up that way intentionally. Is there a reason? Based on the flashing lights, the charger certainly recognizes that there's a battery there, but just doesn't want to charge it. I would wonder (in my ignorance) whether they think it's a safety concern, or whether they think the battery won't be any good in the long term (e.g., it may take, but will no longer hold, a charge)
It's because the chargers cannot recognize the battery and do not know whether it some random object which is holding very little charge or whether it's just a dead battery. I think it's for safety purposes.
There is a certain voltage for each kind of batteries below which they can be declared dead. So it recognizes the cell, if finds its voltage to be too low and thus shows an error. Might be a safety concern.
An extreme example would be if you had a lithium cell at 0.1 volts and it tried to charge it as if it was a NiMH; such a lithium cell would be a fire hazard. If it detects 1.0 volts it can assume NiMH or NiCd and start charging; using ‘hobby chargers’ it is possible to charge anything; for example an 8.4 volt 6-cell electric vehicle pack that was at 0.01v for the whole pack!...
@@SaiyamAgrawal hey I need your help I recharged 150 mah aaa 1.2v rechargeable with 2.5 v and 2A is it dangerous the battery was 0v it holding it change for about 2 days and now its need recharged I had not used it voltage is 1V
@@SaiyamAgrawal it took 1min to change it I used 14C so I guess it has less recharge cycles now?
Nice.
Awesome it worked!!!
Glad to know that :)
pfhahaahahaha
Ek saal baad video bhai video banana start rakh
Ok this video shows how to charge a flat Nimh. Like anyone really needs showing that ! & nothing about reviving dead cells.
But in 5min there voltage is Dicricse why what is the reason behind
Yes, voltage will decrease if you don't charge them just after reviving. The process of reviving is only enough for increasing the voltage of a dead cell so that it can be charged normally.
And what capacity do they have after that procedure?
Depends on how old the batteries are and how many charge cycles they had already completed before being revived. Obviously after this process they won't work as if they are brand new.
B.S.
For NiMH cells, a cell-voltage reading below 0.98 volts to 1.0 volts is a sensitive electro-chemical zone where excess current can permanently damage the cell, even shorting it out permanently. The typical manufacture requirement for very low charge cells (between zero and 1 volt, when the cell is at room temperature) is to trickle charge them slowly to above 1.0 to 1.1 volts, then do a normal charge at 1/10 the mAh capacity. In other words, normal charge rates for NiMH for a 700 mAh cell would be one-tenth, or 70 ma. It the cell is hot from recent use, charge or discharge you need to wait till it is at room temperature to measure it, or the cell voltage will not indicate state-of-charge. if you just discharged it at high current so the cell is hot, wait until it is cool so your charger can make good decisions.
Shorting the dead cell to a charged cell is a desperation procedure -- if you force charge into the cell this way, you will reduce the number of future charge cycles available from that cell. And you might kill a cell that would be recoverable with the trickle-charge procedure. If someone uses a fully-charged cell they might cause enough gassing in the dead cell to blow it up an injure themselves.
The NiMH cell is typically not damaged by sitting around and self-discharging to a very low voltage, as long as you slowly bring it up to the safe normal charge voltage for about 1.0 to1.2 volts a room temperature. This trickle-charge start-up process is built into quality commercial and industrial NiMH chargers, and ones I have designed for electronics products all work that way.
A reliable circuit uses a magnetic-latching relay to disconnect and lock out the cell from the device when the per-cell volts falls below 1.0 volts. When power is restored, the charging circuit charges the cell or cell-pack slowly until each cell is above 1.0 volts, before switching to regular charge until about 1.2 volts per cell. Then the latching relay is un-latched to connect and power up the device. This logic can be performed with a cheap 70-cent microprocessor that spends over 99% of its time sleeping. Why don't OPUS snd Nitexxxx implement this trickle charge for NiMH? I don't know, but it may not be compatible with the requirement to automatically recognize the chemistry-type of cell in the charger (NiCad, NiMH LiFePO, Lithium-ion, etc.).