четверг, 23 августа 2012 г.

How a Trivial Technical Problem Turns into a Major Hazard

These days portable devices are EVERYWHERE. Phones, computers, power tools have decent mileage on batteries these days.


Now mileage is not always decent ENOUGH and so you'll often want a spare battery or two. This applies to all kinds of devices the number one being Android and number two being power tools.


Unlike other devices most professional power tools come with two batteries. You charge both, then you use one of them until it goes empty. The empty one goes to the charger, the second one goes to the tool. If you have to use the tool where there's nowhere to plug the charger – you may want to have more batteries with you.

Anyway at some moment there's a battery that is not connected to the tool and is likely not connected to the charger. It is on its own.

Have you heard that a battery has TERMINALS? You know, the metal thingies which connect the battery to the tool. Do you have an idea of what happens if there's a direct electrical contact between the terminals?

That's called a SHORT CIRCUIT. This is FUKKEN BAD for teh battery – it will spark, overheat, explode, hell will break loose. Search for "battery explosion" on YouTube for details.

Do companies who produce phones, laptops and tools know about that?

Sure they do. Let's open a manual for ... say... Bosch GDR 10,8 V-LI power impact wrench. Page 14 says this:

When battery pack is not in use, keep it away from other metal objects, like paper clips, coins, keys, nails, screws or other small metal objects, that can make a connection from one terminal to another. Shorting the battery terminals together may cause burns or a fire.

This is how companies typically "solve" the problem. A warning in the manual.


Suppose I'm packing tools into a bag. I want several screwdrivers, wrenches, pliers, a hammer, some wire and maybe some screws. And finally I want a power tool and a second battery pack for that tool.

You see, if I put the battery pack right into my bag there's risk that the wire or the screws or some combination thereof will get to the terminals of the battery pack and cause a short circuit.

Looks like I'm screwed.

Not really. There is a solution. It is wrapping the battery into plastic film. Most likely that will be a plastic bag.

Yes, a plastic bag. The tool costs several hundred bucks but you have to put its battery into a plastic bag because otherwise it can short circuit and then hell breaks loose.


Let's looks at it in details. Suppose you want to design a phone, a computer or a power tool. You will have requirements – maximum weight, maximum size, minimum performance, maximum heat dissipation, duration of runtime off the battery and many many others.

You see, these requirements are conflicting big time. If you want a bigger battery you get a bigger heavier device. If you want more power you'll have problems dissipating that power.

Now you spend months and years putting all that together – you choose all the right components and pack them the right way so that your device is powerful enough and small enough and lightweight enough and lasts on one charge enough.

You're so FUKKEN PROUD of yourself. You hire a ton of marketing specialists who market ur device everywhere talking about its sleek design and its amazing power and lots of irrelevant crap like number of screen colors of a phone and voltage of a power tool, but...

... your user buys your device for several hundred dollars and has to pack the second battery into a plastic bag to avoid a short circuit ...

... and all you can do is put a warning into the manual listing all kind of metal and other conductive crap that can cause the short circuit?


Here's what to do. Next time you design a battery design a protective cover for the terminals.

If you design a power tool – that's very easy. The battery typically connects to the tool handle. Clone the part of the handle the battery connects to, then cut off all the extra plastic which forms the tool body, form the rest into a plastic cap. You've got a plastic cap that fits to the battery in the most secure way possible and protects the terminal against short circuit.

If you design some other kind of device at least provide a tiny plastic box.

Never ship second batteries without a protective cover. Make protective covers available through your service centers in case your users lose covers – sell them dirt cheap.

Now go to your device manual and change the warning to say "dude, hell breaks loose if there's a direct contact between the terminals, to avoid this put the protective cover onto the battery when the battery is not connected to the device or the charger".


Bonus points – you have less lawsuits, easier public relations and maybe you can save a bit on marketing your device. Less risk of short circuit sounds FUKKEN GOOD...

It's a SAFER DEVICE and everyone likes safer devices.

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