Almost any battery charger.

Thread Starter

hp1729

Joined Nov 23, 2015
2,304
How about a battery charger that does just about any AA battery? NiCad, NiMH, rechargeable alkaline, NiZn, LiFePO4 ... maybe even LiIon batteries. I haven't tried one yet but it is in the voltage range I think. A "good" battery charger it may not be. It doesn't note the voltage drop indicating a proper full charge. It does note peak voltage, adjustable to meet the needs of various batteries. When peak voltage is reached it shuts down and lights a light.
Other than not noting that voltage dip it breaks a few other rules. Power is about 7 V. This voltage also runs the 74LS74 TTL chip.

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Lestraveled

Joined May 19, 2014
1,946
You have designed a nifty circuit that charges at a constant current until a voltage is reached and then it shuts off and a led comes on. Unfortunately, the world does not need another bad battery charger. Wal-Mart has beat you to it. They sell some of the worst chargers in the world. Most of the those chargers do pretty much what you have designed. Please learn about the battery chemistry before you design your next charger. Each type of battery has its own charge profile. If that profile is not followed, then not only will the battery be poorly charged, but will fail prematurely.

Yea, my above language is a little strong, but you are a feisty kind of guy and you can deal with it. It took me a while to figure out the difference between a good battery charger and a bad one.

Thread Starter

hp1729

Joined Nov 23, 2015
2,304
You have designed a nifty circuit that charges at a constant current until a voltage is reached and then it shuts off and a led comes on. Unfortunately, the world does not need another bad battery charger. Wal-Mart has beat you to it. They sell some of the worst chargers in the world. Most of the those chargers do pretty much what you have designed. Please learn about the battery chemistry before you design your next charger. Each type of battery has its own charge profile. If that profile is not followed, then not only will the battery be poorly charged, but will fail prematurely.

Yea, my above language is a little strong, but you are a feisty kind of guy and you can deal with it. It took me a while to figure out the difference between a good battery charger and a bad one.
You are quite correct it is another less than perfect battery charger. I opted for a trade off of one charger instead of many different chargers. I couldn't find a charger at all for the rechargeable alkaline.
No offense taken. Your analysis was correct. The objective was one instead of many.
Maybe the next evolution will be a smart charger that handles each type correctly.

Dr.killjoy

Joined Apr 28, 2013
1,196
You are quite correct it is another less than perfect battery charger. I opted for a trade off of one charger instead of many different chargers. I couldn't find a charger at all for the rechargeable alkaline.
No offense taken. Your analysis was correct. The objective was one instead of many.
Maybe the next evolution will be a smart charger that handles each type correctly.
They do make chargers for this purpose and pretty cheap for a quality charger..
I tend to stay away from chargers and such cause these built unit should be watched in the event of a failure or design error and other safety concerns.. I mean look at Julian Llett with his solar chargers that are starting to show failures errors .

MrSoftware

Joined Oct 29, 2013
2,015
Thread Starter

hp1729

Joined Nov 23, 2015
2,304
That looks like it is for a special package design, not a AA. My objective was one charger that would do any / many AA batteries, even if it were not an ideal charger for any of them.

MrSoftware

Joined Oct 29, 2013
2,015
That's a list of multiple chargers that charge multiple chemistries. The leads connect to whatever package you have. You can probably find the guts of many of those as open source somewhere, I believe they just use a little micro processor to control the output.

Thread Starter

hp1729

Joined Nov 23, 2015
2,304
That's a list of multiple chargers that charge multiple chemistries. The leads connect to whatever package you have. You can probably find the guts of many of those as open source somewhere, I believe they just use a little micro processor to control the output.
And a very nice list it is. My charger was made from stuff on hand. Cost $0 to build. Lestraveled Joined May 19, 2014 1,946 @hp1729 Why don't you design a charger that correctly charges NiCad/NiMH and LiPo in the AA case size. Both battery chemistries benefit from temperature sensing. It is just a matter of adjusting crossover points. A simple switch is all that is needed. Learn each charge profile and translate it into electronics. Now, that would be cool!! ronv Joined Nov 12, 2008 3,770 And a very nice list it is. My charger was made from stuff on hand. Cost$0 to build.
Dare I say you may want to think about a micro. Good sensing of Nicad and NiMd is tricky. Hard to do with just hardware.

Thread Starter

hp1729

Joined Nov 23, 2015
2,304
@hp1729
Why don't you design a charger that correctly charges NiCad/NiMH and LiPo in the AA case size. Both battery chemistries benefit from temperature sensing. It is just a matter of adjusting crossover points. A simple switch is all that is needed. Learn each charge profile and translate it into electronics. Now, that would be cool!!
A good suggestion. Maybe in the next version. This one was thrown together as a dumb controller. The operator supplies the smarts. It would take me more than the hour this design did. I have a few options of processors to work with. I figure a 10-bit ADC is needed to note the 5 mV dip at the end of the charge cycle, assuming operation from +5 V. A stable voltage source, MZ4614 diode (1.8 V) with an LM334 constant current source should be stable enough.

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