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Comment by seanmcdirmid | Hacker News Reader

How would they maintain a water proof seal if they allowed for a user replaceable battery? Wireless charging allows the battery to be charged without allowing for any gaps in the toothbrush, but achieving water proofness disallows letting the user take it apart and still have to considered to be in working condition.

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It's a shower proof seal for a toothbrush, literally just need an o-ring, you know like the one that keeps the water in the pipes. The parent said the old one had a replaceable battery and worked for 10 years, seems like they had already solved the water ingress issue.

Yes, but you never used those old style electric toothbrushes in the shower right? An O-ring would just confer water resistance, not water proofness. You couldn’t really submerge it and expect it to continue working. There is a huge difference between hermetic sealing an an O ring or a gasket.

I washed my old toothbrush. It gathers toothpaste gunk if not properly washed. It worked just fine for a decade. The motor finally gave up.

No way is this new tooth brush going to last me 10 years.

And people making excuses - do you know that kids electric tooth brushes have replaceable batteries? Shouldn’t that be a bigger problem? Here’s the kicker - kids electric tooth brushes don’t have replaceable brush heads.

Yeah - this is nothing but planned obsolescence.

Kids toothbrushes aren’t designed to be used in the shower.

As a child, I had a $20 plastic submarine that was powered by AA batteries. It could sit at the bottom of a pool for days on end, without water ever getting into the battery compartment of the engine module (which was sealed with a rubber o-ring).

I bet there are hundreds of counter-examples to your claim that water-proofing with an o-ring is an engineering challenge of the utmost difficulty.

> An O-ring would just confer water resistance, not water proofness.

The comment you replied to explicitly said:

> > an o-ring, you know like the one that keeps the water in the pipes.

> You couldn’t really submerge it and expect it to continue working. There is a huge difference between hermetic sealing an an O ring or a gasket.

No, there isn't. O-rings and gaskets are exactly what one uses to make stuff waterproof.

> How would they maintain a water proof seal if they allowed for a user replaceable battery?

So many things are water proof and user serviceable: Piping, engines, transmissions, water cooling (for pc or car) and those electric toothbrushes that have replaceable batteries.

This isn't a technical problem. We figured out how to make things water tight a long time ago.

None of those things are consumer products the size of an electric toothbrush. The old electric toothbrushes simply couldn’t be submerged or used in the shower at all, they were just water resistant.

If you want a simple example then take a watch. Waterproof for decades, and batteries are replaceable.

GoPro has replaceable battery, sd-card, charge-port, hdmi-port, 3x microphones and a replaceable lens. It is smaller than a toothbrush and can be submerged.

Further up in the thread here, there's a comment that people will rabidly defend manufacturer's horrible decisions with false arguments. I think your comment is a perfect example of that.

A toothbrush is cylindrical, like a pipe. We know gaskets exist. A threaded cap on the end with an o-ring would suffice to allow easy access to the internals while keeping even pressurised water out.

In fact, the majority of electric toothbrushes fail due to water entering the head end, and they don't have a good seal there.

> Further up in the thread here, there's a comment that people will rabidly defend manufacturer's horrible decisions with false arguments.

That in itself is an incredibly ideological remark. "These arguments are false/invalid/insincere! There is no cost/manufacturing/reliability/usage benefit to completely sealing a toothrush, gaskets/o-rings/re-welding are just as good!"

Ya, I get it: you'll make us buy the toothbrushes that became outdated 10 years ago through some sort of top-down government regulation, and we will grudgingly like it because all of our arguments otherwise for preferring the newer things are invalid.

You seem to be totally stuck on insisting, against incontrovertible evidence to the contrary, that waterproofing small electric gadgets while still retaining repairability and user-maintainability is some huge insurmountable problem. Even in the face of myriad examples of cheap, reliable, long-existing solutions.

Why is that; where does it come from? Is it some weird fetish you have, or what?

How do submarines work if you put some door for people to enter in, or how do submarines can fire torpedo without getting flooded? The answer is some engineers found a way to do it, there are videos and articles that will explain it if you are really curious and not trying to find the most stupid excuse possible (there are many electronics with replaceable batteries that work under water)

Aren’t you just making my point? If they have to get a reactor out of a nuclear submarine, they have to cut the whole thing open. Engine work is either done inside shell is cut open and they just reweld it back. It isn’t cheap at all.

> you are really curious and not trying to find the most stupid excuse possible

This sounds like you are trying to make a Reddit comment rather than an HN one.

>Aren’t you just making my point? If they have to get a reactor out of a nuclear submarine, they have to cut the whole thing open. Engine work is either done inside shell is cut open and they just reweld it back. It isn’t cheap at all.

Nope. My point was that you can have things in hyper hard conditions, underwater at high pressure and salt and you can still say shoot torpedo.

Do I need to send you video proof that tooth brushes with replaceable batteries exists or you can google it yourself? My son has one that is almost 10 years old too , it uses 2 AA batteries , brand is Oral-B .

Considering their previous one with a replaceable battery lasted a decade, something tells me that's a terrible excuse you are giving them.

Please don't excuse wanton waste. It's not a good look.

Think about it - my last tooth brush lasted 10+ years. Would it have if it wasn’t water proof?

It is quite trivial to make it able to be easily disassembled while also making it waterproof. A rubber gasket on the bottom with a few screws would work just fine.

Waterproof mechanical watches have been a thing for over a century now. They are small, serviceable and have no glued parts. It unfortunately seems the knowledge of watchmakers past hasn't made it into the phone industry yet (same for smartwatches, sadly).

Such knowledge had made it there: waterproof phones with headphone jacks and replaceable batteries did exist; examples are mentioned in the thread. People are just pretending it has been forgotten while in actuality deliberately ignoring it.

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