I saw this:

<snip>

My question is why use a transistor at all? Why not just use resistors to lower the current to the 63mA or w/e?

 

because. duh...

Actually I dont see anything...

 

The link in the original post has been removed. The projects were not valid, nor was the site one we would care to have members exposed to just because of the language.

The Op is going to get more useful information from the link - http://www.batteryuniversity.com/

Notice that alkaline batteries are not in the list of rechargeable batteries. http://en.wikipedia.org/wiki/Alkaline_battery

There are some alkalines that are rechargeable, though - http://en.wikipedia.org/wiki/Recharg...kaline_battery
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Well if you don't want that site because of language here is another:

http://www.i-hacked.com/content/view/207/44/

This guy claims it works also.

 

You must not attempt to recharge primary batteries like alkaline, carbon zinc, etc. You will receive poor performance, and there is a risk of fire/explosion, or the battery case otherwise rupturing and ruining the device it's used in.

A constant-current charger is just too simple for rechargeable battery charging. The charger should change modes from current-limiting to voltage regulated when the battery approaches fully charged. Failing to do so will result in overcharging and short battery service life.

 

Well it wasn't so much that I wanted to build that circuit as much as I was curious as to why it was built the way it was. If anyone knows the original circuit and wants to explain I would appreciate it.

 

Using a constant current supply makes the charging rate steady, as in, same amps, all the time. Using a resistor would make the charging current decrease as the battery gets filled up. That might be a good thing when trying to charge a battery that isn't meant to be charged!

 

Using a constant current supply makes the charging rate steady, as in, same amps, all the time. Using a resistor would make the charging current decrease as the battery gets filled up. That might be a good thing when trying to charge a battery that isn't meant to be charged!

Why does the current get less with a resistor setup? As the battery fills, does the battery itself have more resistance?

 

Why does the current get less with a resistor setup? As the battery fills, does the battery itself have more resistance?

Yes. The internal resistance changes as the battery charges and ages.