Gerard Maas Blog

… or why you need a *really* smart battery charger.

If you are into the small flash business, then all your great speedlite features and, therefore the success of your shoot, are completely dependent of the power delivered by these unassuming little power containers… batteries.
The newer NiMH type of rechargable batteries offer an affordable and environmentally friendly means of feeding the power hunger of your flash.

Intelligent vs Smart

The process of recharging your batteries is crucial to ensure a reliable source of power. Many battery chargers are labeled as “intelligent”. In most cases, this “intelligence” refers to the capability of the charger to stop charging the battery when they reache their full load and therefore avoid overcharge damage. Also, in most cases you will have a basic indication of when the batteries are full. Probably a led changing from red to green or stop blinking.

This indication of “full” only says that the battery cannot be charged anymore and doesn’t say much on *how good* the battery was charged. Consider these two sets of batteries:

Both sets are full, so we are good to go, right? Here is were the really ‘smart’ features of a good charger come into play.
One of these battery sets was dying on me giving me very poor performance. 50 shots and a dead flash. So you change the batteries in a nervous movement before your model says “didn’t you change the batteries one click ago?” and gives you ‘that’ look. Well, now you are back at home with a pocket full of empty batteries and they all look the same.

The total charge indicator

The really key feature of a smart charger is the total charge indicator, or the total amount of electrical energy stored in the battery. It’s indicated in Ampere-hour (Ah) or often found as mAh in batteries: mili Ampere-hour. Think of it literally like how much juice can you fit into the battery: 2Ah think of 2 litres, which is equal to 2000ml juice, or going back to electricity, 2000 mAh.

When comparing these two battery sets at the total charge indicator, you can clearly spot the bad apple. There are two poor performing batteries in the blue set. The most damaged battery used to hold 2850mAh of juice, but now it can only hold 49mAh. That’s 1.7% or pretty bad in my book.

Once this bad*tery goes flat inside my flash, the total voltage will drop too low to for the other batteries to provide charge to the flash. Result? Black frames. Ashamed face. Lost moment. Hell awaits.

How to use a Smart Charger?

In the normal mode, a smart charger will to the same that all other chargers: will fill the battery up until it’s full, regardless of its current level. It’s like refilling your drink: your glass can be empty, half full or half empty. If you imagine a battery like your glass, the total charge indicator will show you how much drink it was needed to fill it up; it might be a little, or might be a lot but the charge measurement won’t tell you anything useful.

If you want to check how good your batteries are, and know their full capacity, you need to empty the glass first. The best feature of a Smart Charger is ‘discharge’. This will first completely empty the battery and the fill it up with fresh energy. After a complete discharge->charge cycle, the total charge indicator (in Ah, remember?) will tell you how much your energy fits in your batteries. This is a number you can trust and will give you confidence that your speedlites will have all power needed for a successful shot. Great light. Pretty faces. Happy customer. Heaven.

BTW, I’m using a LaCrosse Smart Battery Charger RS-900.
Here’s a good review of this charger. Thanks to PetePixxx for the link.
-Gerard.