Put Your 12V Tools on Steroids

[BrianWillan]

Greetings Fellow Woodworkers

I believe I have found a good solution to the scurge of cordless power tools. Batteries that do not hold a charge. The problem being that if you use your cordless power tools infrequently (probably not the case for most here) they will lose their charge and be useless for that quick job of wanting to drill a couple holes or drive some screws. I have also found that leaving your battery packs on the charger all the time doesn't work either and tends to kill your battery packs faster due to overcharging and heat issues.

So, in my case, I have a couple of 12V cordless drills and I just picked up a new B&D 12V impact driver (lovely little tool) so I decided to do something about the problem of weak batteries.

Some background, for my day job, I am a photographer and was sick and tired of having to constantly change my AA batteries in my flash. The solution to that problem was found over here. There Al uses a 6V SLA battery with a 5AH capacity. Using this solution has solved the AA battery changing issue for me. I can get 1500 plus flashes with this battery and it is still going strong. The best part about SLA batteries is that with an intelligent charger, you can leave you battery on the charger indefinitely. So when you need your battery, it is always charged and ready to go.

So I said to myself, SELF, what if we take this idea with the SLA battery for camera flashes and apply it to cordless power tools batterys... Light bulb moment.

So that is what I did. Here are the items I used for my project.

1) 12 V 5AH battery such as this one
2) Smart Battery Charger such as this one
3) 2 0.187" spade connectors
4) Length of 16 guage outdoor lighting kit wire (Home Depot has it) I used 6' for mine.
5) A bit of solder and 45 minutes of time later.

How to.

Step 1) Disassemble the old pack. Most battery packs are just screwed together and will come apart easily.
Step 2) Remove the old cells be sure to save the plastic part that holds the metal tabs that make connection to the drill motor
Step 3) Drill a hole in the back of the battery pack to insert the new wire
Step 4) Strip off the wire ends and solder to the appropriate positive and negative metal tabs on the plastic part you saved in step 2.
Step 5) Reassemble the pack. Now this will require some ingenuity here. I used a piece of 3/4" dowel to to hold the plastic piece with the metal tabs in place. I cut it to fit to so that it holds against the bottom of the inside of the pack
Step 6) Strip the other ends of the piece of wire and crimp on your spade connectors.
Step 7) Attach to battery and be sure to match polarity. If all went well, the tool should work.

Now, for general use, you will want to find a case to house your new battery, I found my camera case that I have for my small digital camera does the job and it has a belt loop so that it can be worn on my belt when doing a task.

Now this is just the easiest way of doing it. The next variation of this would include a locking connection to the battery base so that the cord to the battery could be removed. So far, I have not found that to be necessary.

The end result is that I now have a 12V 5Ah SLA battery that will give enough juice to drive screws or drill holes all day long and then some.

Cheers

Brian Willan

P.S. I could take some pictures of the various steps if someone wants to see the steps in more detail.

[Jaden]

That sounds like an ingenious idea, would love to see the step-by-step photo's posted..

Steve

[bigstick509]

Sounds Great

Pictures would be great, I'm having a hard time visualizing the finished product.

[pirinst]

Wait a minute.....did you just convert a cordless to a

Corded tool?

Just guessing by the description, but that's what I think I'm reading.

Other than shutting off faster than wall outlet corded drivers, what's the
advantage in carrying around a battery with wire??

Excellent thinking outside the box, by the way. I love solutions people on these forums come up with.

[LCHIEN]

...

Other than shutting off faster than wall outlet corded drivers, what's the
advantage in carrying around a battery with wire??

...

Semi-corded. 6' Cord goes to bigger battery pack on belt.
5AH instead of 2AH. Same volts.

[Russianwolf]

So if you ran three of the 6 volt SLA batteries in parrallel you could do the same for the 18v tools right?

[LCHIEN]

So if you ran three of the 6 volt SLA batteries in parrallel you could do the same for the 18v tools right?

series ---- not parallel, to get 18V

The only problem I have with this (external battery pack) is that the wire is too small at 16 Ga.
Depending upon how powerful a motor we are talking about the wire will not allow full power to be developed.
Considering a corded drill often uses 600W at fill load, a 12V drill delivering the same power
will also require 600W, with a 12V battery some 50A needs to be delivered. While NiCad batterys may deliver close to this when wired properly, 6 ft. of 16 ga wire pair will drop 5 volts at that current leading to major undervoltage at the motor. So while it will work for light jobs it will not be able to handle big jobs at full performance (where the battery pack is wired with a few short inches).

[BrianWillan]

Project Pictures

Hey Guys

Thanks for the comments so far. Here are the pictures of the steps involved.

As for the size of the wire, I choose 16 Ga as that was recommended in the reference guide that I use for my battery solution for my camera flash. Given that it is unlikely that you will get more than the 5Ah out of the battery, I doubt the under voltage issue will be a problem as mentioned by others. Also the original wires for the NiCd pack were not that large in comparison and that pack is only providing 2Ah at most.

If you are thinking of doing this idea for 18V tools, 3 6V batteries in series would work as would a 12V and a 6V in series. Just note that if you do this with a 6V battery in the mix, the charger I linked to in the original post is 12V only. So you will need to account for that.

Appologies in advance for the out of focus picture on the one showing the wires attached to the plastic piece that holds the metal tabs. I took these pictures quickly.

Cheers

Brian

[LCHIEN]

As for the size of the wire, I choose 16 Ga as that was recommended in the reference guide that I use for my battery solution for my camera flash. Given that it is unlikely that you will get more than the 5Ah out of the battery, I doubt the under voltage issue will be a problem as mentioned by others. Also the original wires for the NiCd pack were not that large in comparison and that pack is only providing 2Ah at most.

Its not 5AH that causes the drop.
5AH is the capcity, like the size of the bucket 10 gallons.
If you put a 1/4" hole in the bucket and a 1/4" drain tube, the bucket cannot deliver 10 gallons per minute if you needed it.

Likewise too small a cord limits the Amps the battery can deliver right now. A 16 Ga wire 6' long is too small to deliver much more than 5-10Amps. This may not be apparent if you don't load the drill heavily. But if you do load it to 20-30-40 amps the drill will feel a lot less powerful.

Photoflashes have a voltage upconverter that stores high voltage in as big as a beer can sized capacitor. Like a compressor. With the energy stored in the capacitor, energy for the flash is delivered from the capacitor. The delivery wire from the battery needs not be so big, tho it can affect how fast the flash will recyle.

Now an effective design would be to have a smaller battery pack in drill, say 1aH cells and have the cord go to your belt pack with 5aH. The local batteries would provide the high amps for a short time and the belt batteries would continuously keep the local batteries full. A lighter cord and smaller battery pack - in exhcnage for a belt pack... a compromise but how many people would go for that?

[Russianwolf]

series ---- not parallel, to get 18V

Had it right in my head (drill to -, + to -, + to -, + to drill) but used the wrong word.