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Mixing NiCd and NiMH batteries in scanner

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john_p_bowen

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Is it OK to mix NiCd and NiMH AA batteries in my scanner?
I do not charge them in the scanner I have a battery charge and know you have to charge them separately.
I have three NiCd and one NiMH battery and wondered if it would be OK to use them in my scanner together.
 

hertzian

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Very BAD idea for in-scanner use. Keep the chemistry the same for the "pack". Ideally, they should be used as a "pack", and not just grabbed randomly from other devices - that way they will have similar usage characteristics and you won't run into the problem of having 3 good batteries, and one that is going bad, reducing performance.

As for the charger, unless it charges each cell individually, mixing the chemistry is also a bad idea.

Is the battery charger you are using actually rated to handle NIMH, or is it an old hold-over designed for Nicads only? Using NiMH in an older charger designed for Nicads is also not recommended as the charging characteristics are different. Using nicads in a modern charger designed for NiMH should be ok - but check the manual to make sure.

I think it would be best to start out with a fresh set of nimh's, and a modern charger designed to handle them.
 

Rt169Radio

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Its never a good idea to mix batteries in scanners.I would stick with using all NIMH batteries in your scanner.
 
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I agree with all comments thus far but to learn a bit about the rationale behind the answers provided, actually go to some websites of companies manufacturing both types of technologies (NiCd and NiMH) and see how their recommended charging techniques/procedures differ. As a follow-up to that would be the question of what charging scheme does the radio use. Is it constant current? If so, what is the amount of that current. You might find that the value of current used (if constant and/or constant for so many hours then shut off, etc.) might be acceptable for both battery chemistry types. I hope this gives you some understanding of WHY most of the comments you've been provided are accurate and I also hope that it will give you something to research on your own to learn more about rechargeable batteries and their differences.

Ken
 

gewecke

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Well.... would you mix ... bleach and ammonia ? :(
Same diff!

73,
n9zas
 

jackj

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As others have said, it's a bad idea to mix Ni-Cd and NiMH cells in the same device. There is a big difference in battery capacity between the two types. NiMH cells usual have about 3 times the current capacity of Ni-Cd's which means that the Ni-Cd's will discharge first. Unless you watch your battery voltage very closely, you will probably reverse charge the Ni-Cd's ruining them.

Mixing them for recharging is also a bad idea. If your charger charges two or more cells at once, the Ni-Cd's will recharge first because of their lower current capacity, overheat and pop their vents ruining the cells.

Use either all Ni-Cd or all NiMH, never mix them.
 

CoolCat

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Is it OK to mix NiCd and NiMH AA batteries in my scanner?
[sarcasm] If you like expensive paperweights, then yes, it is a great idea. mix away! :lol: [/sarcasm]

But seriously, it's never a good idea to mix different battery types in anything (even a simple flashlight). Chances are there would never be any serious issue (just shorter battery life, or premature shutdown of the device due to insufficient battery voltage and/or current), but it is not worth taking a chance. ;)
 
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majoco

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You shouldn'y even mix batteries of the same type with different capacities say one 1600mA/H with three 2400mA/H - the low capacity one will discharge first and then start being charged in the reverse polarity by the others in the pack. Pretty soon the low capacity one grows a whisker (usually cadmium) across the electrolyte and then it's useless. There are schemes to rejuvenate them but they don't last for long - better to avoid the problem in the first place.
 
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