Got it. Thanks for the background info, very helpful. Darryl

Seconding what Johnmeyer said above.

Maha does recommend 2 or 3 charge/discharge cycles with new NiMH batteries to develop their full capacity, but this should be done on an intelligent charger that also has the ability to dischage properly. That means taking the battery down only to a certain voltage controlled by the charger - never below that, and only at a controlled discharge rate.

After this initial conditioning sequence, no further dischaging is recommended. Lithium Ion batteries should not receive any such conditioning.

The Maha chargers are great. Here's a site that carries them (I highly recommend these people) if you need rechargeable AA batteries. There is also a technical FAQ at this site. The link actually goes to that FAQ.

Maha Chargers and Rechargeable Batteries

Thanks for that, John - valuable info and timely reminder - I have 5 shoots this week starting tomorrow - just plugging the charger in ...

They shouldn't be charged after each USE, they should be charged/discharged completely for the FIRST use. After that, normal cycling is in place. Keeping them ON the charger is a bad thing if the charger, depending on the charger.
I'm not an EE, but the Canon and Sony tech support guys have been pretty clear on this. Back in the day, we would get in trouble if we left our Bauer batteries on the charger. We'd let them sit, charge them the night before, or else use them all day and charge in the night. Leaving them on a charger, even an intelligent charger, would cause them to lose their life fairly fast.

Leaving them on a charger, even an intelligent charger, would cause them to lose their life fairly fast.

Spot, I've heard that too. Perhaps some chargers keep the trickle charge too high, and overcharge or overheat the batterieis.

However, if this were generally true, then most people's laptops would be fried, because many people use their laptop as a desktop replacement, and have it plugged into the wall whenever they don't have it on the road.

The same thing is also true of portable telephones. The battery in my portable telephone is over five years old, and it has been charging 24 hours a day for those five years. Same thing for my Dustbuster.

If you want a really extreme example, I have one laptop that I purchased in 1987 (a Toshiba T1200) that I have used since 1994 to capture all phone calls records from my telephone system (SMDR output). It has been turned on, and the batteries charging 24 hours a day, 365 days a year for ten years. When the power goes out, the batteries, which are now 17 years old, still have enough of a charge to keep the computer going (although not for as long as when they were new).

Most everyone here uses B&H Photo. Here are their battery charging guidelines for various battery chemistries:

Battery Guidelines

This page references an extremely long, technical, but useful monograph on rechargeable batteries. It is written specifically for the video professional, and can be found here:

The Video Battery Handbook

This handbook specifically warns against deep discharge, and it very specifically states that the battery should be left in the charger until just before use.

One of the most important things in this handbook -- which may explain the discrepancy between what the Sony folks may have said, and what I am saying -- has to do with what charger is used. The big problem in the early years of rechargeable batteries is that they were generall common form factors (like AA or D) and therefore could be charged in just about any charger. The problem -- which this handbook points out -- is that these chargers are often really cheap, stupid devices (often just a diode and a light bulb), and have no way to shut off, or drastically decrease the charging current when the battery has reached full charge. This causes the battery to overheat, or in the worst case to vent, both of which drastically reduce its life.

However, with a modern, smart charger -- the kind that is part of any modern video camera -- overcharging is simply not a problem.

As a result, both the guide -- and the excerpts presented on the B&H site -- specifically recommend keeping the batteries in the charger until just before use. I strongly endorse that policy and recommend that everyone do this.

Unless of course you do like we used to do (against my good advice)and turn our bank of Sony chargers off overnight with the batteries still in them, in which case we were cycling the batteries every day and then wondering why they didn't last!

Bob.

However, if this were generally true, then most people's laptops would be fried, because many people use their laptop as a desktop replacement, and have it plugged into the wall whenever they don't have it on the road.
My laptop batteries provide good service for less than 6 months, no one yet, has come up with one that lasts longer for me. I get about 60 minutes of video time on my P4 now, whereas when it was new in April, I got just over 90 minutes.
Mine is plugged in all day, and the only time it's on battery is when I'm in flight.
I'm not disagreeing overall with you, but going thru several UPS's, laptop batteries, Bauer batteries....I also have learned that what works in theory isn't reality.

Spot,

Something is definitely wrong there, although I don't have any good ideas what it would be. I have two UPS -- which of course use lead-acid batteries -- and they are still working fine after three and five years respectively. I have a Presario 1800T laptop that I bought used on eBay over two years ago, and which is connected to the wall 24 hours a day. When I go on the road, the battery -- which was old when I got it -- still gives me almost 2.5 hours, which is the spec. This is the exact same time it gave me when I first used it on batteries over two years ago.

The only batteries that consistently fail on me are the ones on my Sunpak video light, and those are almost never on the charger, and are allowed to sit on the shelf for several months at a time, during which time, they self discharge.

Oh yes, I have a boat in Wisconsin, and if the battery isn't trickle charged during the winter, I get to buy a new battery in the spring.

Oh well, do what works for you. However, having the batteries get old in only six months just doesn't sound right, no matter what you did to them.

Since you brought boats into the thread, I thought I'd mention that my little sailboat has two "deep cycle" 12v batteries in it. For years I had a conventional automotive-type automatic 12v charger hard-wired into the system, and batteries typically lasted for years. The trickle current delivered by that simple charger would cause the electrolyte to gradually boil off over time, but re-filling the wet cells every 6 months would handle that issue.

A few years ago I decided to scrap the ancient automotive charger and I bought a completely solid-state "Guest" charger. When I say solid-state, I mean it literally: the entire charger is potted inside a black slab of plastic measuring maybe 8" on a side x 2" thick. The technology of this charger is quite sophisticated.

My assumption is that battery charging technology for camcorders and laptops is equally sophisticated. Spot should be getting way more than 6 months of life from his laptop battery.