Sonicare Hack?

[shintashi]

I've been thinking about the Sonicare toothbrush, ever since I got one years ago it has reminded me of some kind of laser device. Two things fascinated me about this tool, 1) it has a really nifty blinking LED charge indicator with bars; 2) it doesn't actually require physical contact to recharge.

The second aspect - wireless recharging absolutely fascinates me. I was also rather impressed by how much power the sonicare appeared to produce, and I still wonder if I attached dremel tools, would it be a functional grinder or mini saw?

So here i am years later wondering if anyone has tried or thought about the power supply of the sonicare, and the idea of wireless recharging. Perhaps this thread could act as a spring board for hacking one.

here's what one guy on Amazon said:

Since the warranty expired, I took a Dremel tool to the Sonicare and opened it up. To my delight, I noted that the batteries employed by the unit were two standard, albeit unbranded AA NiCad cells. I removed and replaced them with two 600mah Sanyo cells, closed the handle and sealed it shut with silicone. It's been over a year now and my Sonicare is working as well as it did the day I bought it. For the gear heads out there, the Sonicare consumes about 1.3 watt hours and lasts about 14 days between charges when used twice a day. This equates to about 56 minutes of total run time, which means that the original batteries installed in the Sonicare were ~600 mah. I considered replacing the batteries with 2000mah NiMH cells, but opted against this option as the cells would probably self-discharge before I depleted the cells from normal use.

I disagree with another reviewer and do not believe the Sonicare should use Li-Ion or Li-Poly cells. Li-Ion and Li-Poly cells require sophisticated charging and discharging circuitry. They also last fewer recharging cycles than NiCads. Conversely, NiCads take a lot of abuse and in an application of this size, they provide more than enough storage capacity. For the bean counters, NiCads are cheap to source. However, the cadmium in NiCads is highly toxic and not exactly the most environmentally friendly option for batteries. Compared to NiCads, Nickel Metals would be a better environmental choice but would provide little performance benefit

 

[Kmor2004]

I'm not 100% sure, but I doubt it would work using induction charging with a majority of the pointers we use, due to most of the host's being a solid chunk of metal, which would interfere with the wireless transfer of energy, not to mention that even if it could work it's less electricaly efficent then just pulling the batterys out and recharging or plugging in a charging adapt like some lasers have.

 

[shintashi]

I'm not 100% sure, but I doubt it would work using induction charging with a majority of the pointers we use, due to most of the host's being a solid chunk of metal, which would interfere with the wireless transfer of energy, not to mention that even if it could work it's less electricaly efficent then just pulling the batterys out and recharging or plugging in a charging adapt like some lasers have.

The metal limitation is definitely an issue, although I think the aesthetic in terms of inductive recharging vs. taking the batteries out is a smaller consideration, which is probably why Sonicare did it in the first place - then again, the argument could be made that all induction devices are actually intended to be part of "planned obsolescence" forcing customers to buy more. My main concern isn't how fast, but how full the recharging process could be. For instance, can a book or kite sized solar panel be rigged to produce the necessary current to recharge such a device?

I guess that's something off topic, but the question isn't so much about "sonicare", as whether induction is a functional means of recharging something in the 200+mW range.

The Sonicare device is interesting as a host for three reasons: it's similar in size to many LPF hosts; it has a charge indicator - something I would find extremely useful on a laser; and it uses induction.

How much "non metal" does an induction device need? I mean if just the lower half inch were a plastic cap, would the rest of the body being made of metal still conflict? (I'm new to the idea of induction).

 

[Kmor2004]

The best reason I can think of for metal hosts is the increased thermal dissipation area, I could be wrong so somebody with more experience would have to chime in.

As for using a plastic tail cap, how long do you think it would last if you dropped the laser and that region hit first ?

In terms of using a solar cell to charge....well you could use a gerbel or a hamster runnning in their little wheel spinning a motor, as for how long it would take to charge....a rather long time.

 

[shintashi]

Inductive Recharging?

Check this out:
Airnergy WiFi power system gives RCA a reason to exist (video) -- Engadget

I've been looking into this wireless thing on and off for a couple of years, and it seems to me there's no logical reason aside from space and cost that would prevent you from putting in both a "cellphone charger" style connection and a wifi charging induction system in the same device.

Cons:
it will cost more
it will take up more space
the host may not be as nearly indestructible (is carbon fiber any good?)
the host won't be as efficient as a heat sink

Pros:
you can recharge your batteries two different ways
you can recharge your batteries wherever there's a wifi signal
it makes a good conversation piece

My limited understanding of the new wifi charging theory is that people already have these devices turned on. For instance, at schools, computer labs, and at homes. In apartments, multiple boxes are going off. That's essentially "free" energy that could be slowly recharging your laser batteries while you are asleep.

I'm not where near advanced enough to start fiddling with this - i barely understand half the parts in a normal laser - but I think it's worth exploring.

 

[rhd]

I would be interested to know whether a non-magnetic metal still interferes with inductive charging. To my knowledge, neither copper nor aluminum are magnetic

 

[Benm]

The metal limitation is definitely an issue, although I think the aesthetic in terms of inductive recharging vs. taking the batteries out is a smaller consideration, which is probably why Sonicare did it in the first place - then again, the argument could be made that all induction devices are actually intended to be part of "planned obsolescence" forcing customers to buy more.

There is only one reason for using the induction charging on electronic toothbrushes and similar devices: Since they tend to get wet during normal use, metal contacts would corrode or get a lot of calcium/grout/toothpaste/shite on them, causing the device to malfunction quite rapidly.

As for the power transfer: these things generally charge their cells quite slowly, requiring overnight charging to go from completely empty to full. This is no problem for a toothbrush sitting on its stand every night, but may be annoying otherwise.

The NiCd cells are chosen for a good reason too: they are capable of providing considerable current relative to their capacity. Perhaps such a toothbrush would expend all of its charge in 10-15 minutes, but that is no problem since few people brush their teeth for that long.

Having a laser or tool that runs for 10 minutes and then requires 10 hours of recharging would not be that practical, i think

 

[Kmor2004]

Well copper wire is used in generators, as they spin through magnetic feilds, I imagine that a copper body would interfere with an Electro-magnetic feild from a induction charger.

I could very wrong with this information especially since I'm not an induction expert nor am I all that interested in induction experiments, the only reasons I stated a metalic host might cause an issue is because I've seen some induction based projects, done by hobbyists and as far as say a SS host + some HF HV induction add in a healty dose of current and an M6 bolt can get mighty bright.

 

[Benm]

The operating principle of these things is not that difficult: Essentially the coils in the base and brush unit from a transformer. The difference with an ordinary mains transformer is that the coils are very loosely coupled, which ultimately results in a very narrow frequency range of operation.

A metallic host would shield both coils from eachother and render the transformer useless - the connecting part must be made of a non-conductive material, though there is no reason the rest of the unit (say, 1 inch from the coils) could not be metallic.

 

[shintashi]

induction and charging options?

I get worried about my 1W laser overheating after just a few minutes, so we don't use it but a couple of minutes a day before putting it into storage, which ironically is in a black bag about 8 inches from my wifi box.

perhaps the host could be set up to still allow rapid access to the batteries, or some kind of rubber cap from an old cellphone and then you could plug it in that way, by drilling out a small hole on the side of your host and then tapping in the cellphone charger input?