Battery Exhaustion

[jow104]

I have a digital camera which uses 2100 x 4 AA mAh type rechargeable batteries.
I want to exhaust the batteries and recharge two sets fully before commencing my holiday in the near future.

I thought I could place the batteries in one of those small flashlight torches and leave switched on until battery exhausts.

IS THIS A GOOD IDEA?

What would be the time span to exhaust two batteries (I assume 1 &1/2 amp bulbs)

[Sturdee]

John,

That is what I do with the batteries of my cordless drills before recharging to make sure they fully recharge.


Peter.

[CHJ]

I thought I could place the batteries in one of those small flashlight torches and leave switched on until battery exhausts.

IS THIS A GOOD IDEA?

Fine.

Sony recommend leaving my camcorder on in playback (VTR) mode to do this,(propriety format)
rarely have the need as they get run down easily enough anyway.

If you have a variety of rechargeables it might be worth checking out some of the more intelligent chargers on the market, they not only cover Ni-Cd and Ni-Mh batteries but will have a discharge function built in that automatically takes care of the complete discharge before recharge.

[jow104]

just come in right for that posting chas. (forum says message posted 2 m9ns ago.)
Thanks again for info

[CHJ]

just come in right for that posting chas. (forum says message posted 2 m9ns ago.)
Thanks again for info

That’s Ok. It's P**ing down here and resorted to a quick browse, can't work up the enthusiasm to heat up workshop and do something useful.

The model Charger I have was procured in Germany (another bargain buy) so do not think model no. would be of any use to you.

[Iain]

When you do arrive you can purchase a 12v charger that will fill the said batteries in a couple of hours, cost about $25-30AU.
I carry one in the car with me for my N mH AA's.
My camera has a discharge function but I rarely use it as the camera seems to discharge the batteries sufficiently for recharging.
I am using 2400mah batteries but if they ever come in L Io I will change over to them as there is no memory at all.

[jow104]

I'll be OK if the van has a cigar lighter I've got a lead for my own charger setup. Trying to keep weight down and avoid bringing the large transformer with me.

[wonnie]

if they are NiMH then there is no 'memory effect' on these batteries so it is safe to recharge at any time, however if they are NiCad then try to fully discharge the things.

The main reason why some people dont go for NiMH, even with the 'no memory' is that they take longer to charge you camera between shots. I use NiMH but i do find that the capacitor in the camera takes longer to charge between shots takes longer than NiCad, especially with a flash on.

[bsrlee]

Don't do it! Fully discharging a NiCd battery can completely stuff it! Its one reason that NiCd battery packs can die quickly - not all cells in the pack are quite the same quality (specially in cheap packs, which is why they are cheap) and some cells reach zero before the rest, 'collapse' and will not re-charge again, so the pack is trying to work one or more cells short.

The other way to stuff NiCd's is to overcharge them a lot - it takes a while to have a deleterious effect, and it is difficult to tell the difference from cell collapse by discharge - the battery appears to take a full charge but it goes flat sooner than it used to.

There is no cure for either condition once it happens - just recycle bin the battery & get a new one.

There has been a tremendous amount of research into rechargeable batteries over the years. NiCd's can sustain high discharge rates better than their more modern counterparts, as Wonnie has noted, which is one reason they are so common in cordless power tools. They are also cheaper, but are less 'evironmentally friendly' supposedly - but lithium is toxic too, as is nickel.

Just use the batteries until they show signs of slowing down, remove them from the tool/whatever & LET THEM COOL DOWN. Then recharge them in a modern battery charger that cuts off when it detects full charge. Remove them from the charger as soon as you realise that they are finished & again - let them cool down before use. Some chargers are designed to 'trickle charge' a battery pack and are clearly marked and marketed as such - usually for walkie-talkie radios and emergency equipment.

Jow104:
We all use 240 volts here in Australia & you can buy a wall plug adapter for a few dollars - say a pound each - from almost any big electrical store such as Dick Smith/Powerhouse/Tandy - all one company here with different store names. Also Woolworths & Coles/K-Mart have them. Don't but from a Duty Free or other tourist trap. Cars have the same cigarette lighter fitting the world over, just ensure that it is connected in your hire vehicle before you drive off - I think some companies disconnect it to discourage inconsiderate smokers littering their vehicles.

[jow104]

Thanks for tips, I'll try and remember the one about hire companies.

[CHJ]

Don't do it! Fully discharging a NiCd battery can completely stuff it! Its one reason that NiCd battery packs can die quickly - not all cells in the pack are quite the same quality (specially in cheap packs, which is why they are cheap) and some cells reach zero before the rest, 'collapse' and will not re-charge again, so the pack is trying to work one or more cells short.

Jow104 was initially talking about individual AA cells, and using a small single cell flashlight, (Quote “until battery exhausts”) as long as he stops discharging when no perceivable light is seen in bulb and does not leave it in situ for to long he should not have reached 'rock bottom'

Modern chargers/dischargers for individual cells take care of this base threshold but may not cover the full charge cut off if left connected indefinately(all mine are on a time clock in case I forget to switch off)

Cars have the same cigarette lighter fitting the world over, just ensure that it is connected in your hire vehicle before you drive off - I think some companies disconnect it to discourage inconsiderate smokers littering their vehicles.

Jow104: If it is an 'Estate' as we would call it or a people carrier it may have one in the rear for cooler etc. which may still be live even if Cigy lighter is dissabled.

[jow104]

in the back,

Thanks thats another good tip to remember.

[Iain]

if they are NiMH then there is no 'memory effect' on these batteries so it is safe to recharge at any time, however if they are NiCad then try to fully discharge the things.

NiMh do have a memory effect, just not as pronounced as NiCad and may be recharged prior to full discharge.
One disadvantage with NiMh is that they will not endure the same number of charges as a NiCad, I believe their useful life is about half that of a NiCad.