Rechargeable Batteries - Best operation regime

[davehu]

What use regime is best for ensuring the best life for rechargeable batteries for use in GPS, cameras, torches etc

It seems that the situation with Li-on batteries the best is to leave it on charge all the time you can, and leaving it without use in a fully charged position does it no harm.

What about Ni-Cad and NiMh types, Keeps then working full to flat ? if not being used for a long period leave flat or fully charged?

All thoughts Appreciated.

 

[LadyInBed]

See this thread

 

[William_H]

Ni cad and NiMh are happy left discharged and if left fully charged will self discharge relatively quickly.
One thing Nicad do not like and I expect NiMh are the same is being discharged under load to the point where some cells in a series go to zero and are actually charged in the reverse direction by discharge current. so the more cells in a Nicad battery the more trouble you get from this effect. The way to minimise this problem is to completely discharge each cell individually to zero with ultimately a short circuit for an hour or so, so that when batteries are charged they are all hopefully equally charged. It gives the charger a shock for a few minutes with 0 battery voltage. Some chargers may even refuse to charge.
In a sealed battery you should watch the voltage and not discarge lower than about 1.1v X number of cells or about 90% of the rated battery voltage. Note it is the actual discharge at high current that damages, natural discharge won't hurt them. olewill

 

[andy_wilson]

Short way to total failure?

When used in electronic equipment designed for re-chargeables, it will shut down when the correct low voltage indication is reached. Discharge below this may ensure they will at best be resistant to re-charge, at worst will not accept re-charge.

I can't think of one good reason to flatten them manually, and certanly no good reason to short circuit them.

Equalising the state of charge in all the cells in the array is easily acheived by 2 or 3 complete normal discharges followed by extended re-charges (16 or so hours).

 

[William_H]

Re: Short way to total failure?

Hello Andy certainly on wet NiCad batteries used for aircraft starting the process of discharging individual cells and in fact leaving shorted for 24 hrs (deepcycle) is a battery maunnfacturers requirement as regular maintenance at periods of approx 6 months. Now tthese batteries while low capacity at about 20 AH are discharged at 900 amps for about 10 secs on start and are recharged at several hundred amps initially using a voltage regulated charger (and are usually temperature monitored.
However I believe that small Nicad cels can benefit also from this treatment. olewill