You are here:

Electrical Engineering/Simple configuration question.

Advertisement


Question
Hello.

I'm much on the ignorant side of the electrical world & have a simple goal I'm trying to achieve but would like knowledgeable feedback before I proceed.

I'm looking to get 36v DC on a zero budget. I'm wanting to use that to zap rechargeable tool batteries to revive them. From what I gather through multiple youtubes, several short zaps from a 36v DC source will burn off the built up dendrites in a battery. This revives the battery's ability to charge/recharge.

Since I don't have a 36v source, I was wondering if I could wire 3, 12v DC wall charger power supplies/adapters in series to get the desired end output voltage. Will that work or will the chargers' connecting to each other create an undesirable result?

Thank you in advance.

Answer
This applies only to NiCad (Nickel Cadmium) batteries  -  which are not used so much anymore due to their lower capacity per ounce and size and their memory loss (caused by dendrite build up).

But if that is what you have you can indeed restore the battery to its formerly life - at least to some degree - with a discharge/recharge cycle.  This is done by totally discharging the NiCad battery and then charging it back up; maybe repeating it a couple of times.  The trick here is to discharge the battery completely.  In normal use the user does not actually discharge it all the way which invites the dendrite build up.  So, you must find away to totally discharge the battery by leaving it connected to some equipment that will run it down totally. Often if you think it is run down and wait 30 minutes you will find there is still some energy that has rebuilt up and the battery will run the apparatus again for a short while.  Then, when totally discharge, connect the charger and charge it up all the way.  This is the safe way.

The trick of adding the higher voltage to the battery terminals is tricky because if you leave the overcharge on too long it can cause an explosion - and harm to the user.  It takes a certain voltage and certain current rating to accomplish the voltage charge.  You must know important characteristics of the battery in order to determine the voltage and current rating necessary.

The problem with series connection of wall pods is you don't know the current rating for sure and they mostly don't have dc ripple smoothing filter therefore the voltage output is really a dc truncated ac signal.  And, the grounds may be difficult to keep isolated from each other.  If you could give me the battery model or basic character and the make or model number of the chargers maybe we could figure something out.  But, I recommend the first method of revitalizing the battery since it is easy to do, costs nothing and is not dangerous to the user.

Let me know more if you have further questions.

Hope this helps.

PS: If you are working with Ryobi there is a trick that is even easier for them;  just plug the battery into the recharger and shut of the power to the charger and back on for a few cycles and it should bring the battery back to the full charging state.  

Electrical Engineering

All Answers


Answers by Expert:


Ask Experts

Volunteer


cleggsan

Expertise

All technical areas of Electronics Engineering.

Experience

BSEE, MBA, Design, R&D, University Research.
Senior Life Member of IEEE. Life Fellow of AES.

Organizations
IEEE, Consumer Electronics Society, Audio Engineering Society.
Broad teaching experience; work experience mostly in consumer electronics and conversion from analog to digital technologies. Pioneer in digital audio at all levels.

Education/Credentials
BSEE (Equiv) BYU BSEE University of North Dakota MSBA (MBA) Illinois State University Graduate Studies in Computer Science - Bradley University Graduate Studies - Ohio University Graduate Studies - University of Missouri Kansas City DeVry Tech - Electronics

©2016 About.com. All rights reserved.