<div class="pull-right"><img src="https://storage.googleapis.com/steemimgimgs/2016/10/24/Electric_batteriesb50b8.jpg"><br><a href="https://simple.wikipedia.org/wiki/File:Electric_batteries.jpg">image credit</a></div><b>First that you need to know that you should beware of cheap dumb battery chargers</b> (God save the Queen from buying dumb chargers!)  I’ve had three (!) dumb chargers before I found out that it eventually would cost me more to buy a new pack of rechargeable batteries every each time they start to fail charging then buying ordinary batteries. I was buying different brands of rechargeable batteries hoping that the next pack will be better in terms of lifetime. Once I realized that I’m constantly literally throwing money away.

# What is the problem?



**The problem is that a cheap charger never knows if an individual battery is full or not and continues to charge them all together, will leads to either undercharging or what is worse to overcharging a battery that shortens it’s lifetime greatly. Also, never buy ultrafast chargers–they will kill your batteries very fast too!**

On the contrary to dumb chargers, smart chargers:

-	stop charging right after the batteries are full, so they do not overcharge and live much longer;
-	charge each battery individually giving it exactly the power it needs;
-	allow you to mix bad and good batteries in one charger;
-	allow you to mix different sizes (like AA with AAA);
-	have other smart functions, like discharging, testing and slow charging.

# How to know if a charger is smart?

**Basically if any charger’s description doesn’t contain the word ‘smart’, than you can presume that it’s a dumb charger.**

**Here's [Bluejay's Law of Battery Chargers]( http://michaelbluejay.com/batteries/charging-tips.html)**:

> Any charger that's not described as being a smart charger, is definitely a dumb charger. Conversely, any charger that's indeed a smart charger, will definitely be described as such.


# La Crosse Technology BC-500



The charger I’m using currently is [La Crosse Technology BC-500](http://www.lacrossetechnology.com/bc500) (depicted below). It’s not produced anymore and lacks some functionality of his bigger brothers, but you still can find it around as cheap as [$28 with free shipping](https://www.amazon.com/product-reviews/B0031ERMO4) and it’s very handy charging the batteries. Bought just to prove the concept it helped me to resurrect 3 packs of 4 AA batteries, which made me extremely happy given the price of a single battery pack.


https://storage.googleapis.com/steemimgimgs/2016/10/24/DSC_43946bbe7.jpg

https://storage.googleapis.com/steemimgimgs/2016/10/24/DSC_44109fba5.jpg

# How to resurrect a dead battery?

**Even if you fancy smart charger tells you that the battery is dead there is a chance to resurrect it**. The simplest method I use: find a metal surface and stand the batteries (a dead battery and a good fresh one) on it, then connect positive terminals with some metal thing, like a screwdriver or a paperclip. If you don’t have a metal surface around simply stand both on a metal paperclip and then connect the positive terminals of the both batteries for a second (see the picture below). Try charging your bad battery with your smart charger after the procedure, repeat if this didn’t work. | **Disclaimer**: *I haven’t heard of any problems, like explosions or whatever, but use this method at your own risk!*  


https://storage.googleapis.com/steemimgimgs/2016/10/24/DSC_4420d3263.jpg

Needed assistance while making a shot, hence that fancy manicure above

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**Update from the comments to this post**:
  
> @dgiors57
I have a couple of LaCrosse chargers. A year ago I got an Opus BT-C2000 charger and it's a keeper. It rejects fewer batteries in their deep discharge state.
BTW I keep one of my old "dumb" chargers around for refreshing a "dead" battery. The one I have charges a pair of batteries. 5 minutes in there won't risk over charging but gives enough juice they can be transferred to one of the smart chargers.
*Thank you @dgiors57 for your valuable comment!*

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**Useful links:**

[Best battery chargers](http://michaelbluejay.com/batteries/chargers.html)
[Battery Charging FAQ](http://michaelbluejay.com/batteries/charging-tips.html)
[What does mAh in a battery mean](https://www.quora.com/What-does-mAh-in-a-battery-mean)
[A simple step to revive a dead Ni-MH battery](http://www.instructables.com/id/A-simple-step-to-revive-a-dead-Ni-MH-battery/)
[La Crosse Technology BC-500](http://www.lacrossetechnology.com/bc500)
[La Crosse Technology BC-700](http://www.lacrossetechnology.com/bc700)
[La Crosse Technology BC-1000](http://www.lacrossetechnology.com/bc1000/)
[Why we shall not throw batteries into a trash can](http://distractify.com/old-school/2014/08/05/things-you-dont-throw-in-the-trash-1197777136)

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**Thanks for reading!**

**Sincerely yours, 
@richman**