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Nimh battery question
- Thread starter John(Tx)
- Start date
doindadiggin
New member
Hi john mate all rechargeables will loose 1% per day so keep them charged if possible
grumpyolman
New member
Doesn't make any difference. It's always better to store a battery with a charge in it, rather than drained dead, but Nimhs don't develop a memory like the NiCads. Sanyo makes a Nimh, the Eneloop, that they claim will retain 80% of it charge sitting on the shelf for a one year period. That's not all Nimhs that do that. But there is technology that some, and their's more than Sanyo, are using that provides that advantage. I know it's frustrating to have a pack of Nimhs sitting there and you stick them in the device and they die fairly quickly cuz you forget when you last charged em. If you think you might be heading out in a day or so, put em on a 'good' charger. Won't hurt them and they won't develop the memory. jim
Charged is best and in a cool place. Then you should turn them regularly to stop the electrolyte pooling in one place.
The long life batteries Grumpy mentions are sold under different names but often have the marking LSD NiMH to show they are the improved type.
The old NiCad v NiMH arguement ie NiCad develops memory effect and NiMH doesn't has been proved to be untrue. To create true memory effect the charge and discharge cycles have to be same (some say exactly the same). The effect that people think is memory effect is voltage depression caused by cheap chargers and funnily enough its NiMH's that suffer more from this as they don't cope well with overcharging.
The long life batteries Grumpy mentions are sold under different names but often have the marking LSD NiMH to show they are the improved type.
The old NiCad v NiMH arguement ie NiCad develops memory effect and NiMH doesn't has been proved to be untrue. To create true memory effect the charge and discharge cycles have to be same (some say exactly the same). The effect that people think is memory effect is voltage depression caused by cheap chargers and funnily enough its NiMH's that suffer more from this as they don't cope well with overcharging.
An extract from http://www.powerstream.com/Storage.htm
Storage recommendation for various battery types in the manufacturer's words.
NiMH (Nickel Metal Hydride) Battery Storage
Duracell NiMH Battery Storage
Ni-MH batteries can give years of safe and reliable service if they are used in accordance with recommended procedures and are not abused. Batteries should be kept clean and dry both during use and storage. They can be stored for many months in a charged or discharged state without any detrimental effects as long as they are not exposed to extreme temperatures for any long period of time. After periods during which the battery has not been used, the battery should be charged before being placed in service. Extended overcharging or overheating of the battery should always be avoided.
Varta NiMH: Battery storage in any state of charge is possible. Storage temperatures between -20 and +35 are recommended, relative humidity approximately 50%. In case of long term storage cells must be recharged once a year.
Sanyo NiMH: Under the recommended storage conditions (-20 C to +35 C) the Twicel can be stored indefinitely in either a charged or uncharged state. Recovery may take several cycles. If a battery is stored for a prolonged time connected to a load, electrolyte fluid will leak, the battery will begin to deteriorate, and capacity will be impaired after storage. During long time storage battery deactivation may tend to occur, and for this reason charging may stop early during recharging after storage. This problem can be solved by charging and discharging the battery several times.
Sanyo NiMh Battery Storage: Generally speaking, a loss of voltage and capacity of batteries due to self-discharge during storage is unavoidable. The factors inducing this self-discharge of Nickel-Metal Hydride batteries is listed below:
1. The inside of the cell is a hydrogen atmosphere at low pressure, which gradually reduces the active materials at the positive electrode, resulting in a drop of cell capacity. Accompanied by this, the negative electrode which is thermodynamically unstable in its charged state gradually gives off hydrogen gas, thus reducing cell capacity.
2. The active materials at the positive electrode in its charged state self-decompose, causing the cell capacity to decrease.
3. Impurities within the cell, especially nitric ions, are reduced at the negative electrode and diffuse to the positive electrode where they are oxidized. This results in a lowered cell capacity.
The factors (2) and (3) also apply to Nickel-Cadmium Batteries. As discussed above, the self-discharge of Nickel-Metal-Hydride Batteries during battery storage causes a loss in stored energy. However, once recharged, this lost portion of the capacity will be almost completely restored. The self-discharge characteristics of Nickel Metal Hydride batteries is affected by storage temperature. . . If the battery is stored at high temperatures, the self-discharge will be accelerated. Also, the longer the storage period, the more the cell capacity decreases. As mentioned above, since the capacity of Nickel Metal Hydride batteries lost by self-discharge can be restored by recharging, there are virtually no noticeable adverse effects of battery storage. However, prolonged storage at high temperatures may deteriorate or deform the gasket or the separator, and should be avoided. Either fully charged or discharged, Nickel Metal Hydride ( NiMH ) batteries may be stored indefinitely. . . In either cased (charged or discharged) the capacity is recovered within two or three charge / discharge cycles.
Panasonic NiMH Battery Storage
Because long term storage can accelerate battery self-discharge, and lead to the deactivation of reactants, locations where the temperature ranges between +10
Storage recommendation for various battery types in the manufacturer's words.
NiMH (Nickel Metal Hydride) Battery Storage
Duracell NiMH Battery Storage
Ni-MH batteries can give years of safe and reliable service if they are used in accordance with recommended procedures and are not abused. Batteries should be kept clean and dry both during use and storage. They can be stored for many months in a charged or discharged state without any detrimental effects as long as they are not exposed to extreme temperatures for any long period of time. After periods during which the battery has not been used, the battery should be charged before being placed in service. Extended overcharging or overheating of the battery should always be avoided.
Varta NiMH: Battery storage in any state of charge is possible. Storage temperatures between -20 and +35 are recommended, relative humidity approximately 50%. In case of long term storage cells must be recharged once a year.
Sanyo NiMH: Under the recommended storage conditions (-20 C to +35 C) the Twicel can be stored indefinitely in either a charged or uncharged state. Recovery may take several cycles. If a battery is stored for a prolonged time connected to a load, electrolyte fluid will leak, the battery will begin to deteriorate, and capacity will be impaired after storage. During long time storage battery deactivation may tend to occur, and for this reason charging may stop early during recharging after storage. This problem can be solved by charging and discharging the battery several times.
Sanyo NiMh Battery Storage: Generally speaking, a loss of voltage and capacity of batteries due to self-discharge during storage is unavoidable. The factors inducing this self-discharge of Nickel-Metal Hydride batteries is listed below:
1. The inside of the cell is a hydrogen atmosphere at low pressure, which gradually reduces the active materials at the positive electrode, resulting in a drop of cell capacity. Accompanied by this, the negative electrode which is thermodynamically unstable in its charged state gradually gives off hydrogen gas, thus reducing cell capacity.
2. The active materials at the positive electrode in its charged state self-decompose, causing the cell capacity to decrease.
3. Impurities within the cell, especially nitric ions, are reduced at the negative electrode and diffuse to the positive electrode where they are oxidized. This results in a lowered cell capacity.
The factors (2) and (3) also apply to Nickel-Cadmium Batteries. As discussed above, the self-discharge of Nickel-Metal-Hydride Batteries during battery storage causes a loss in stored energy. However, once recharged, this lost portion of the capacity will be almost completely restored. The self-discharge characteristics of Nickel Metal Hydride batteries is affected by storage temperature. . . If the battery is stored at high temperatures, the self-discharge will be accelerated. Also, the longer the storage period, the more the cell capacity decreases. As mentioned above, since the capacity of Nickel Metal Hydride batteries lost by self-discharge can be restored by recharging, there are virtually no noticeable adverse effects of battery storage. However, prolonged storage at high temperatures may deteriorate or deform the gasket or the separator, and should be avoided. Either fully charged or discharged, Nickel Metal Hydride ( NiMH ) batteries may be stored indefinitely. . . In either cased (charged or discharged) the capacity is recovered within two or three charge / discharge cycles.
Panasonic NiMH Battery Storage
Because long term storage can accelerate battery self-discharge, and lead to the deactivation of reactants, locations where the temperature ranges between +10
grumpyolman
New member
I respectfully have a different opinion with UKBrian about the differences in NiCads and Nimhs. This issue has been hotly debated by the real field experts in battery technology and that's the HAM radio community. I may be in error but operate on the evidence presented to me, as a HAM, and believe the Nimh is a superior battery.
Brian and I do agree on the good charger issue. You just aren't going to do your batteries justice by using the transformer plug it in the wall power supply. You don't have to spend $100 either. If you get a good charger it will calculate the amount of capacity in the battery and will perhaps discharge the battery, at a rate that it's designed to accept, and then recharge it. I would expect to pay in the $40-70 price range. These chargers will handle most any battery in the AAA, AA, C, etc. If you plan to move into the lithium batteries make sure the charger has a setting for those. Some don't.
I have a MAHA and it will charge anything that I can get the + & - terminals connected to it. It also tells me how many milliamps it was able to put back into the battery. That's important becaue if I have a pack that is acting up, and can recharge one battery at a time and find the one that's defective and just replace it. However, with the price the Nimhs are these days. I'd keep those for spares somewhere and get a new set.
It's smart to get a battery with the largest milliamp hour rating you can. They run from 1600mah to 3200mah. Depends on how and who built them. Think of the mah as the size of the fuel tank in your vehicle. Do you want to carry 32 gallons with you or 16. An arguement can be made for both sizes. jim
Brian and I do agree on the good charger issue. You just aren't going to do your batteries justice by using the transformer plug it in the wall power supply. You don't have to spend $100 either. If you get a good charger it will calculate the amount of capacity in the battery and will perhaps discharge the battery, at a rate that it's designed to accept, and then recharge it. I would expect to pay in the $40-70 price range. These chargers will handle most any battery in the AAA, AA, C, etc. If you plan to move into the lithium batteries make sure the charger has a setting for those. Some don't.
I have a MAHA and it will charge anything that I can get the + & - terminals connected to it. It also tells me how many milliamps it was able to put back into the battery. That's important becaue if I have a pack that is acting up, and can recharge one battery at a time and find the one that's defective and just replace it. However, with the price the Nimhs are these days. I'd keep those for spares somewhere and get a new set.
It's smart to get a battery with the largest milliamp hour rating you can. They run from 1600mah to 3200mah. Depends on how and who built them. Think of the mah as the size of the fuel tank in your vehicle. Do you want to carry 32 gallons with you or 16. An arguement can be made for both sizes. jim
JOHNMARKHAM
New member
i keep mine with a charge on them and in a cool dry place and i use a battery cycler to charge and cycle all my packs..
good luck
hh
john
good luck
hh
john
Information is all over the forums and when this was debated (because there's so much disagreement) on the U.S. Friendly Forum about three years back I found the report that had been created by one of the U.S. Universities to try and get a definitive answer. The only variation from what I said in my post below was that the ultra fast charge/discharge carried out with remote control cars meant they were a bit of a special situation but detectors don't come under that heading and also what they called very high drain situations which also doesn't apply.
My old Deepstar P.I. battery (Ni Cad and like a small brick) was supposed to provide at least five hours detecting time but on the average beach could just manage six hours now manages six and a quarter and its over nine years old. This is by only charging when the inbuilt battery meter is half way into the red, no topping up and never running totally flat. Still fine for general use but is shedding charge far faster when in store. To go even further off topic (sorry John) I had no end of problems with lithium-ion from setting my laptop alight to repeat replacements in my E-book and portable T.V. These all charge on board and its a screwdriver job and a fiddle to get them out. My camera also uses lithium which give no problems at all and can be dropped out in seconds if they did, sods law I suppose.
My old Deepstar P.I. battery (Ni Cad and like a small brick) was supposed to provide at least five hours detecting time but on the average beach could just manage six hours now manages six and a quarter and its over nine years old. This is by only charging when the inbuilt battery meter is half way into the red, no topping up and never running totally flat. Still fine for general use but is shedding charge far faster when in store. To go even further off topic (sorry John) I had no end of problems with lithium-ion from setting my laptop alight to repeat replacements in my E-book and portable T.V. These all charge on board and its a screwdriver job and a fiddle to get them out. My camera also uses lithium which give no problems at all and can be dropped out in seconds if they did, sods law I suppose.