Near-dead Canon batteries - do you short them out?

I would be wary of shorting out the battery, only do it if you are certain that you know what you are doing. I also have a totally dead 300D battery and plan on getting 2 new ones over the web soon enough.

Dave,

Try and get the 1800mA batteries. I have them and they are very good. I get nine hours of continuous use during the summer (with the LCD off) using my battery power pack.

Either Canon has grotesque mark-ups or the Chinese have really cheap labour

I bet the Canon ones are made in the same factory by the same people!

Quote:"You'll often hear discussions about the so-called 'memory effect' exhibited by NiCad cells. This refers to the claimed tendency of cells not to deliver their rated voltage when placed in a charger before being fully discharged. Belief in the existence of the 'memory effect' is widespread amongst users of NiCad batteries. However, textbooks and data from battery manufacturers make little or no mention of it. Believers say that to prevent it batteries must be discharged to 1 volt per cell before charging. Non-believers say that this discharging merely reduces cell life.

Evidence suggests that true 'memory effect' is rare. It was first noticed in communications satellites where cells were discharged to precisely the same discharge point every time. In casual amateur use batteries are most unlikely to be discharged to the same point after every use. Much of what is mistaken for the 'memory effect' is voltage depression, which is caused by long, continuous overcharging, which causes crystals to grow inside the cell. Fortunately both the 'memory effect' and voltage depression can be avoided by subjecting the battery to one or more deep charge/discharge cycles.

Another term you will hear is 'cell reversal'. This can occur when a battery of cells is discharged below its safe 1.0 volt per cell. During this discharge, differences between individual cells can lead to one cell becoming depleted before the rest. When this happens, the current generated from the remaining active cells will 'charge' the weakest cell, but in reverse polarity. This can lead to the release of gas and permanent damage to the battery pack.

NiCads can short circuit due to the build up of crystals inside the battery. The use of a fully-charged electrolytic capacitor placed across the cell can effect a temporary cure. Over-discharging of batteries invites short circuiting. Batteries should be stored charged. A lifespan of 200 to 800 charges is typical for NiCad batteries.

Nickel metal hydride (NiMH)
Like NiCads, nickel-metal hydride cells provide 1.2 volts per cell. Battery makers claim that NiMH cells do not suffer from the 'memory effect' and can be recharged up to 1000 times."

Paul,
your descriptions above are good, and think that's what I was on about.

Peter,
thanks for the extra info.

Seanie.

Continuing on, I have another question.

Again, for my near dead battery, IF I WANTED TO, can I simply take a long duration exposure with the les cap on to try and drain the battery? Will this affect the chip at all? Things like hot pixels don't matter for this kind of exposure, but do they do any damage?

Sorry for the stupid nature of my questions, but if I don't ask, I'll never know.

Seanie.

Seanie,

A quick and easy way to drain the battery is to leave the camera on ... no photos but just on as if you were preparing an imaging session. Also, if you have any images on the flash card, preview them on the LCD screen since the LCD is the greatest source for battery consumption.