NiCad/NiMH- Whats the difference??

NiCad are the earlier version of the rechargeable batteries and have an issue with memory retention.

NiMH are a later version and can be recharged from any point in their cycle with no memory effect at all. Essentially if you do not let the NiCad fully discharge, they will get a "memory" at some point and will only then charge to that point.

Does that make sense? This is what I understand, although perhaps people such as Mainey will be able to shed a more technical explaination on it for you.

Check that your devices will work with rechargeable batteries before spending a bundle on spare batteries - I have some LED Petzl headlamps that I bought NiMH AAA batteries (1.2V) for, and the headlamp is designed for 3 alkaline batteries (1.5V) - the headlamp sucks the juice out of the NiMHs in no time because they're designed for 4.5V, and they're only getting 3.6V with the rechargeables.

Most devices work (I use NiMH in almost everything that takes AA/AAA/C/D cells), but the Petzls don't like them. End up having to use alkaline in them.

Another tip - even if you've got an in-car charger for NiMH, have at least two sets of batteries for everything, so you can rotate batteries - charge the flat ones while using fresh ones.

Hi, I have found that any rechargables dont seem have a very long life ( 6 months). last trip with new camera I found that they were only lasting a few days , what with checking shots etc , and bought a set of Energiser Lithium AA's ( advertised to take 600 shots ) for $13.50) on the way to WA, that was last August and I have just replaced them,( battery icon showed up when the flash was recharging) took over 500 odd shots and some video etc on that trip( 5 weeks ), plus all the editing while we were away ,and have been using it regularly since then .
I have since shelved the charger & 3 sets of batteries.
Very happy with these, just my experience.
Cheers Des.

Terminal voltage is the same for both - approx. 1V2

NiMH cells have a greater energy density against volume so they come in larger capacities.

NiCads have a far lower self discharge rate than NiMH so if you can't recharge them for a couple of weeks NiCads (even lower capacity ones) may be a better bet.

NiCads will provide a higher maximum current than NiMH.

Beware: NiMH cells above 2000mAh capacity have a 0.2mm larger diameter than other cells - generally won't matter but sometimes it does - Garrett Infinium gold detector for example.

The "Memory Effect" is a myth (spacecraft aside) - these is a condition know as "charge depression" but don't worry about it.

Mike Harding

Get some Lithium batteries for the camera. They last for ages.

Are Lithium Ion rechargeables available in AA? Remember looking for them ages ago but couldn't find anything. Reckon they would be the ducks nuts if they came in 1.5V.

After having tried many different brands of AA and AAA batteries and looked after them in very expensive chargers/conditioners, the ONLY ones I will buy from now on will be Sanyo Eneloops.

"Memory" is a very bad name for the fact that NiCd and NiMH batteries will lose capacity if you don't discharge/recharge them AT least once every three months.

No, this doesn't apply for Lead-Acid batteries, but then their chemistries are totally different.

I have given up on rechargable batteries. There are a few issues one being that rechagables have a slightly lower voltage. Equipment designed for alkaline batteries can then act like the batteries are getting flat quite quickly, particularly if it is very cold. However equipment designed for rechargables are usually fine. The other problem I have had is some of the chargers seem to kill the rechargables. I am happy to stand corrected on this point but the last time I used rechargables I had 8 AA less that 12 months old and 8 new AA's. After a 10 week trip only 4 still accepted any charge.

Steve

The other issue is environmental - Cadmium is pretty toxic and people dump them in normal waste. Just another reason why NiMh are preferred.