Dewalt DC9360 Disassembly

14th September 2007

 

Why would someone do this!?

A company in the US called A123Systems recently developed a very high performance Lithium Iron Phosphate battery which they call the "ANR26650M1". (Click here to view the datasheet.) This battery currently powers Killacycle, the world's quickest electric vehicle. A123Systems are currently moving into the automotive arena with their batteries, including a recent agreement with General Motors to co-develop a battery system for the Chevrolet Volt project.

Unfortunately, as is so often the case with such things, it is not easy for the general public to get their hands on the cells. You can sign up for an evaluation pack which gets you 6 cells for US$120 - not cheap! Fortunately, if you're handy with a screwdriver, there is an alternative..

Power tool manufacturer Dewalt is one of the first commercial users of this battery, having used them in the DC9360 battery for their cordless power tools. Each pack contains 10 cells, and is usually available for around US$100 on eBay (or similar). The first crowd to start taking these packs apart were the radio controlled aircraft enthusiasts, for use in high performance planes. Even at US$10 each, pricing is still a bit high for use in BEVs (its almost three times the price of ThunderSky, for example!), but the technology is perhaps a glimpse at things to come in the battery arena!

Generic disclaimer: This is for information purposes only, perform at your own risk. And it will definitely void your pack's warranty! So don't sue me :)

So without further ado..


The pack before disassembly, blissfully unaware of it's imminent demise.

The screws holding the top on are Torx T-10 with centre pin. It's a somewhat rare type, just to make it a bit harder for us to take apart!

The screws at the back are recessed, I had to grind down the case a little to get access. YMMV.

With all the screws removed, the yellow top comes off easily. To the left is the latch and spring which also comes free.


The silver/cream unit on top is the battery management system (BMS), which I disconnected. Taped on to one cell you can see the thermistor for temperature protection.


The batteries are basically jammed into the bottom shell - quite tightly. Using a screwdriver or similar you can carefully lever the cells out bit by bit.

The black frames on either side fall away easily. They're just there to keep the cells orderly and include the contacts for the BMS connections to each cell.

A closeup of the text printed on each cell.

So what's next?

The main reason I wanted to get my hands on some of these cells was for performance testing. I will be publishing my results soon, but suffice to say they are living up to their reputation!

They are way outside my price range for use in a full-sized car (which requires about a 10kWh pack or larger), but they could feasibly be used in electric bicycles or even up to a motorcycle, which would only need a 1-2kWh pack. I'm considering using them in a small (and very quick) scooter sometime.

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