Project FrankenWalt: Refitting with LiFePO4 Batteries
 

Hi All,

I saw a couple of posts asking about lithium batteries for cordless tools so I thought telling a bit of a story was in order...

I have owned the same DeWalt 18v cordless set since I was 16... I am now 29. The first lot of batteries that came with the set lasted me more than 10 years despite being thrashed to death (try renovating an entire 150 square metre home)
Second pair of batteries I bought as replacements died much more quickly, much to my annoyance.

So to cut a long story short I decided to have a go at converting my tools to run lithium ion phosphate batteries from Hobbyking.
First try with one of these: batteries which I had previously used to power a dress for my sister.

First try was very hacky using duct tape etc. I was installing a three phase power socket in a friend's workshop which required drilling a 32mm hole through an out of reach floor joist. FrankenWalt turned out to have enough torque to chew the ends off of the setscrews in my drill extension :eek:
The drill will drill holes in concrete as if it's butter now... Just have to watch out for how hot the motor gets.

From an ecological point of view:
Lithium means not buying any more yucky nickel cadmium batteries.
The drill has so much power now that I am unlikely to need to use a generator plus power tools in the field.
From an economic and user point of view:
The lithium battery weighs about the same as a NiCad with nearly double the capacity.
And finally the lithium is about half the price of a replacement DeWalt battery.

That's all for now, I'll post an update when I've done some CAD and 3d printed the new battery case.


http://ecorenovator.org/forum/attach...rankenwalt-jpg

http://ecorenovator.org/forum/attach...-extension-jpg

http://ecorenovator.org/forum/attach...d-setscrew-jpg

What is the capacity of the original battery pack, compared to the new one? I need to do this for a Ryobi drill and flashlight set I have.

Great project Patrick. I've wanted to do this with my previous drill, but never got around to it.

Old battery was 2.4A/h
New battery is 4.5A/h

Make sure you keep an eye on the cell voltages :)

How do you know when to recharge your packs?

At the moment I just use a Cell checker to keep an eye on the voltage from time to time.
The new battery case which will be printed in ABS will have a window in it to suit the LCD. My friend has one permanently connected to his LiFePO4 race car battery and it appears to draw almost no current at all.

What are you using to charge the battery. Are you using the original Dewalt charger? I have a plethora of older Makita power tools that can use the Franken-upgrade.

Randen

I am using a Turnigy balance charger from Hobbyking. You absolutely can not use the original charger from the manufacturer.

I've also bought a small BMS PCB from eBay so will report back when I get that fitted.