Instructables

14.4v Rechargable Battery Power Supply ^updated with Banana Terrminals

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The goal of this Instructable is to make it convenient to use my supply of 14.4 volt rechargeable batteries in prototyping projects.

This is a very simple but useful adaptation of the charger that strips away all the components except those which hold the battery and connect to it two (pos & neg) terminals. It's nothing more than a socket for the battery with easily accessible output leads.

For my outputs I chose to use a two foot length of paired wires with insulated alligator clips at the end. In hindsight, some type of plug or jack mounted on the case would provide even more flexibility. With most of the components removed from the circuit board there is plenty of space for adding new components.

I have a drill and a circular trim saw, each with a few batteries and charger. I really only need one charger in my life so the second one became the doner for this project. I still have an intact charger to keep all the batteries charged.

 
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Step 1: Opening the case

This particular model has a two-part case secured with 'triangle' head screws that are hidden under plastic foot pads on each corner. The foot pads can be I opted for drilling out he heads rather than buying or making an appropriate screw driver.

Should you need to drill out the screws, a 3/16 inch drill will do.


Don't forget the fifth screw located down inside battery socket.


Step 2: Inside the case

Picture of Inside the case
Once all the screws have been removed the top case should lift off freely. There are no electronic parts or wiring attached to the top case. The AC cord coming into the case routs through a serpentine channel in the bottom case to provide a cord strain-relief.

This is a good opportunity to check out all the components that make it a charger.
now all you need is another battery recharger to juice the battery back up
busidit (author)  MACKattacksnipe3 years ago
Indeed. Because I get a charger with every tool I have an excess of chargers. And by the number of lone chargers I see at pawn shops, so do most cordless tool users.
Thanks for looking and for your comment.
jimmykat4 years ago
hello, I have 2 dewalt and 1 black & decker chargers known as superchargers. They were able to charge differt brands of batteries. I think there was some leagal dispute over it and quit making them early. They had different contacts in the slot the batteries went in. I used a old dead dewalt battery and connected wires to the nose of of old battery and am able to charge many different size battery packs . It automaticaly switches to trickle charge or fast charge. I wish someone could disect one and figure out how it works. If you are able to come across one buy it because it can charge alot of different sizes and brands of batteries
busidit (author)  jimmykat4 years ago
i don't know enough about different charging cycles on batteries. do you know if the output voltage and current of the charger changes during the cycle or is it constant? i think some or maybe all niCad chargers have a feedback circuit that monitors the current from the battery to let the charger know when to stop. the dewalt charger says it works for batteries 7.2 to 14.4 volts so the charger would need to measure each battery's capacity. i need to read up on this and proceed with caution.
thanks for your comment.
richms4 years ago
I would chuck a lighter socket on the case as well, handy for plugging in all sorts of car chargers etc for phones and GPS and stuff.

A fuse and a switch would be worthwhile additions to the thing too.

When I wanted to open my charger to see what had gone bang in it, I used a set of reverse drills that got the screws out nice and easy. Stupid "tamper proof" stuff.
kill-a-watt4 years ago
Ah, had to read it twice, "take an old broken battery charger, strip the guts, and make a holder for a rechargeable battery to power projects". Clever.

I thought at first this was "pull out the leads of this battery charger, and use it to charge other brands of batteries". One of DeWalt's chargers (at least one of them) will auto-sense the voltage and switch to the right program to charge a wide range of battery pack voltages. You could bring out the leads and charge other brands of batteries, if the thermistor is the same across packs (that's the third terminal, and no, I don't know if there's a standard among different brands)
busidit (author)  kill-a-watt4 years ago
That would be great to make a universal charger. I'm thinking about adding a pair of terminal blocks to make the outputs more versatile. The gator clips are handy but I would like have other options.

Thanks for your comment.