GarageBoy
Flashlight Enthusiast
What damage CAN occur if I stick my NiMh batts into my old 3 hr NiCd charger by eveready? Thanks!
Using a NiCd charger to charge up NiMh?
- Thread starter GarageBoy
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That might be a tasty side dish with eggs in the morning.
SilverFox
Flashaholic
Hello GarageBoy,
It depends on what the charger uses as a charge termination condition.
If it is timer controlled, and you start with empty batteries, and it charges at a rate that is compatible with fully charging the batteries, it will work fine. If it charges at a slow rate, your batteries will be under charged. If it charges at a slow rate and your batteries are only partially discharged, it will cook them.
If it uses temperature control, you should be fine, within the limits stated above.
If it uses peak voltage to terminate the charge you should be fine, within the limits stated above.
If it uses - delta V, you will cook your cells.
I believe Sanyo ran a test on what happens when you charge NiMh cells on a NiCd charger that terminates on - delta V. They found that the NiMh cells heated up (cooked), but did come to a full charge state. The effect of this overcharging reduced the cycle life from around 500 charge/discharge cycles to somewhere around 20, if I remember correctly. At any rate, it was a drastic reduction in life cycle performance.
In order to answer your question, we need more information...
Tom
It depends on what the charger uses as a charge termination condition.
If it is timer controlled, and you start with empty batteries, and it charges at a rate that is compatible with fully charging the batteries, it will work fine. If it charges at a slow rate, your batteries will be under charged. If it charges at a slow rate and your batteries are only partially discharged, it will cook them.
If it uses temperature control, you should be fine, within the limits stated above.
If it uses peak voltage to terminate the charge you should be fine, within the limits stated above.
If it uses - delta V, you will cook your cells.
I believe Sanyo ran a test on what happens when you charge NiMh cells on a NiCd charger that terminates on - delta V. They found that the NiMh cells heated up (cooked), but did come to a full charge state. The effect of this overcharging reduced the cycle life from around 500 charge/discharge cycles to somewhere around 20, if I remember correctly. At any rate, it was a drastic reduction in life cycle performance.
In order to answer your question, we need more information...
Tom
wptski
Flashlight Enthusiast
I metioned this story in another thread.
My Fluke 123 Scopemeter is powered by a 4.8V Ni-CD pack but there are different firmware versions. Early units can only use Ni-CD packs while later units can use a newer Ni-MH pack.
Now they came with another Ni-MH pack that replaces all the packs and can be used on all firmware versions. The pack has four wires, one red, one white and two black wires.
I called Fluke and asked them how all of a sudden you can use a Ni-MH on all units. After talking to someone else, the answer was that they found a way to rewire the pack to make it work. This doesn't seem to make any sense, does it?
Prior to getting the scope I was given a old 1800mAh Ni-CD pack form a early version unit. Later when I got the scope, it came with a 2000mAh Ni-CD pack. There is a difference between the two though! Using a RC type charger on one pack I can use the red wire and any other wire as the negative whereas the other pack I have to use the red wire and a certain black wire. I assume that one has a diode in the wiring.
My Fluke 123 Scopemeter is powered by a 4.8V Ni-CD pack but there are different firmware versions. Early units can only use Ni-CD packs while later units can use a newer Ni-MH pack.
Now they came with another Ni-MH pack that replaces all the packs and can be used on all firmware versions. The pack has four wires, one red, one white and two black wires.
I called Fluke and asked them how all of a sudden you can use a Ni-MH on all units. After talking to someone else, the answer was that they found a way to rewire the pack to make it work. This doesn't seem to make any sense, does it?
Prior to getting the scope I was given a old 1800mAh Ni-CD pack form a early version unit. Later when I got the scope, it came with a 2000mAh Ni-CD pack. There is a difference between the two though! Using a RC type charger on one pack I can use the red wire and any other wire as the negative whereas the other pack I have to use the red wire and a certain black wire. I assume that one has a diode in the wiring.
GarageBoy
Flashlight Enthusiast
How does -delta V work? Thanks!
GarageBoy
Flashlight Enthusiast
Thank You!
