Monday, October 20, 2008

SoniCare battery replacement

Replacing batteries in consumer devices shouldn't be hard. If you're using a Phillips SoniCare toothbrush though it's a royal pain in-the-ass. SoniCare toothbrushes are good in maintaining oral hygiene but not good for the environment since they are built with Nickel Cadmium batteries that are difficult to access and therefore, similar to an IPod, have planned obsolesce built into the unit. Once the battery is dead you need to throw out the whole unit. Isn't that silly...

Background:
Our family generally liked our SoniCare we had a couple of bodies and several heads that each family member would screw-on when they wanted to brush. I'm not sure why now, but we stopped using the brushes for about a year and then we decided to get back into them. Therefore the units sat idle for about a year. Not good...

After a twenty-four hour period of recharging the batteries in the charging cradle, both units wouldn't hold a charge. They would go on for about ten seconds then turn off, thirsty for more power, waiting for another charge. Clearly there was some battery related problem.

After looking for a simple battery access cover on the unit, not finding it, and then searching the net for answers. I found that the batteries were difficult to access and this was going to require a bit of work to fix. Since I wanted to learn more about the SoniCare and how it worked I took on the challenge and decided to change the batteries myself (Pictures coming shortly).

I found two techniques for getting to the batteries on the Net:

1) Depending the the model of SoniCare you have they recommend inserting a screwdriver into the body twisting and separating the unit into two nice pieces. From the SoniCare website (http://www.sonicare.com/owners/help/help_cleaning.asp): "How do I replace the batteries in my Sonicare Advance toothbrush? The batteries inside your Sonicare Advance toothbrush can't be replaced. We encourage you to recycle them instead. To do so, insert a flat-head screwdriver in a slot between the 2 halves of the handle at the threaded end to break them apart. "

Huh...wait a minute..."Insert and flat-head screwdrive in a slot...break them apart..." That didn't sound good.
This method didn't work so well for me as I kept feeling like the handle was going to snap and break into about five pieces not two. Others have seemingly had more luck than I in various postings around the net.

2) Others recommended using a Dremmel with a cutting wheel to cut the body in half extract the NiCad batteries and then replace them. (http://www.instructables.com/id/Repairing-your-Sonicare/)

Power tools are cool...
I like power-tools and have many of them. They sound badass, get stuff done quickly and are generally fun to use. Therefore any excuse to use my Roto-zip (Dremmel like tool) worked for me and avoided cracking the base into several pieces prying it with a screwdriver.

Getting started:
I used a Dremmel cutting wheel attachment and cut the SoniCare housing. To do this, I secured the unit in a vise and carefully followed the seam that ran down from the threads around the body, unscrewed the vise, turned the unit over and then worked back up to the threads. It was really hard to follow the seam neatly and I gained a new found respect for those who can draw a perfectly straight line or cut a perfectly straight cut with the Roto-zip. It's definitely an acquired skill I haven't mastered yet.

Always wear protective eye wear when using power tools...
I managed to cut my way up the unit following the seam as neatly as possible leaving only a mild gash here and there in the base plastic. It is very important to note that when cutting the unit hot plastic goes flying as the cut precedes, therefore it is really import that you wear protective eyewear when using any power tool and especially relevant for this project. Never make exceptions to this rule as protective eye wear is inexpensive and your vision is not.

Next I pried open the unit and located the old Ni-Cad batteries. The unit's circuit board is mounted above the batteries so rather than desoldering the circuit board above the batteries, I cut an access opening for a battery door.

The batteries were tough to get out. I needed to pry them out of a plastic/resin-like material which was a process that took way to long and several times I was sure I had ruined the old solder connections to the circuit board.

Note: The batteries in the SoniCare were *Nickel Cadmium (Ni-Cad) batteries both bad for our landfill and have the downside of having a memory. Rather than inviting back the same problems in a year or two by replacing with Ni-Cad batteries again I changed them out for Lithium Ion ( Li-Ion) batteries.

Note: When testing the unit after the batteries were removed I used alligator clips connected to the battery posts and then connected that to two Duracell AA batteries. The result was a blinking light on the push-button. With a push of the button we could hear the motor vibrating against the top of the base and knew the old batteries had been removed successfully and I hadn't damaged the logic board.

I puchased new Lithium Batteries (Li-Ion) batteries and taped them together so the positive post and the negative end were flush. I sanded all four battery terminals so the solder would stick and carefully soldered two-ends with a small wire so the batteries were in series and then the posts to the correct battery terminals. I was careful to keep the soldering iron and solder only on the batteries when absolutely necessary as excessive heat can damage Li-Ion batteries.

I pushed it all back into its housing and light was blinking when I pushed the body back into the charger.

But it now looks a bit mangled since my opening procedure sucked therefore here's how I plan on making it look and feel a bit better:
  • Take 3/4" pipe insulation and cover most of the brush we hold (with a hole for the switch)
  • Use a handle bar grip.
or... just wait till my family complains :)

All in all, this project shouldn't have even been a project. It should have been as simple as open battery compartment and replace batteries. Both Phillips, and Apple - with their IPod/IPhones, should seriously rethink this idea that the batteries shouldn't be easily accessed and replaced. This strategy is bad for our environment, is expensive for the consumer and in the end is seems uncessary.

I wouldn't recommend this project for most people. Unless you are comfortable with electronics and their voltages, cutting-tools and working carefully with hot-solder I recommend investing the same time into writing a letter to Phillips to help change their policy of not putting a battery door on the SoniCare and then recycling your current unit.


* Ni-Cad battery recycling in the U.S.:
http://www.recycleyourbattery.com/
http://www.batteriesplus.com/t-batteries-plus-recycles.aspx

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