Wednesday 10 September 2014

Its time to go to the mattresses...

The fall of Professor Ashton, detailed here amongst several other blogs, has struck a blow into the very heart of the establishment. Whilst its true that he more jumped than was pushed, either way its hard to see him keeping his position as President of the Faculty of Public Health. And whether we were responsible for it or not (clue: not), we are going to take the brunt of the retaliations and finger pointing from academia and the public health industry.

Dont ever doubt that his loss* is a massive one for the triumvirate forces arrayed against us. This is a man at the very apex of the public health world, to borrow a term from Clive Bates. They're angry, they're shocked, and they're even a little scared. This is not how things work. The twittering classes do not get to rock the boat. Ever.

So the gloves are off. They may be angry and scared, but they also smell blood. They can get a lot of mileage out of portraying us as threatening louts, as bullies and as trolls. Especially as trolls. They will attempt to use whatever leverage they can get from this to take the conversation away from us, to remove whatever hard-won sympathy we have garnered, and break the few links we have with the powers that be.

Their tactic will be to troll. They will play the victim, as the ever suffering Martin McKee has already done in the Times article, the man who includes long sections in his speeches about how horrible we all are to him, and introduces himself at conferences as "I'm Martin McKee, and vapers hate me".


We must rise above it and let it burn itself out. Make no mistake, we are being tested, and this may be the harshest test we have ever faced. The one thing we have always done is to speak out - and that is what we cannot afford to do now. With no reaction from us, they cannot maintain the illusion that we are constantly attacking them whenever they speak out.

If you do see a highly provocative post, it will have been put there for the express reason of provoking us into saying something stupid. Stop. Think. Dont let your anger sway you. If you are in any doubt whatsoever, leave the post alone and dont respond to it.

Stand firm and ride it out folks. If we use our heads now more than ever, we will prevail.

PS. I have removed a couple of the more hard-hitting posts from here which, whilst cathartic for me and written with a humourous intent, I am aware could be used against us. Did someone say "chilling effect"?

* I speak about him like hes dead, dont I? He's not dead. He's just 'taking a break from Twitter'

Edit: Okay, it seems some clarification is in order. Professor Ashton hasnt officially "fallen". He is facing several official complaints which, according to the FPH complaints procedure will be forwarded on to the relevant authority, either the GMC or the UKPHR - the UK Public Health Registrar. This body will decide whether the complaint is upheld. Should this be the case, Ashton may have his membership of the FPH revoked, and may face further sanctions from the UKPHR's independent Fitness to Practice panel, including the setting of conditions, suspension or indeed erasure. It also ensures that a permanent record of complaints is kept. The operative word in all this is "may", however this has given us enormous leverage over Ashtons influence in the debate, and in this sense I maintain he has as far as the purposes of this post require, "fallen".

Tuesday 2 September 2014

E-cig charging, and why USB aint so universal

We've all seen the news articles about exploding e-cigs. Its published so often you'd think you were taking your life in your hands every time you  hit the go button on your eGo. Of course, we all know that isnt true, but fires and explosions do happen. And they happen for a variety of reasons.

There are three parts to your eGo e-cig system, all of which are required to charge it, and any of which may fail and/or cause fires. They're electrical devices. They can fail.

1. The battery

The standard eGo style battery contains a small circuit board which may or may not contain a battery charging circuit, depending on the manufacturer. It has no vent holes to exhaust the hot gases should the internal battery go into thermal runaway - a process where a stressed battery heats up, which further stresses the battery leading to more heat in a feedback cycle that leads to catastrophic failure of the battery. The principle method of protection should this happen is by the base cap, the metal or plastic end of the tube at the bottom of the device which is press fitted into the tube, and is designed to pop off under pressure to relieve the build up of gases contained in the tube.

As this relies on the correct manufacture of the press fit, and as some manufacturers are better than others (never buy cheap, people!) this can sometimes fail to pop out, leading to a build up of pressure in the tube which can eventually fail, exploding outwards quite dramatically.

2. The charger 

There are 3 types of charger generally used for this sort of e-cig. Firstly, you get the small type that plug directly into your USB port, which are typically designed and supplied for charging cigalikes. The next two look virtually identical, with a USB plug, a length of wire, and the small charger box on the end onto which you screw your device. The difference is in the current rating of the devices - one type will supply typically 120mA, the other will supply typically 420mA. The lower current rated charger is intended for charging cigalikes and very low capacity eGo batteries. The higher is for your everyday >600mAh type eGo. Some may have charging circuits in them, intended for batteries that do not, others may not have those circuits and rely on the battery to regulate the charge.

3. The supply

The chargers have a USB plug, and connect to a suitable USB port. Normally this would be a "wall wart" type power supply which plugs directly into your mains socket, however you can also connect them to anything with a USB socket.

So what can go wrong?

Oooh, lots of things. Firstly, you need to understand how a lithium battery charger works. Unlike standard NiMH or NICAD battery chargers, they dont simply pump voltage into the battery until you unhook it. They typically charge the battery in 4 stages, as shown below:

As your battery and components have a certain resistance, varying the input voltage will change the supply current, and this is what is provided to the battery at stage 1. The charger varies the voltage to maintain its rated supply current.

Once the charge in the battery reaches a certain level (determined by the charger), it switches from constant current mode to constant voltage, so now the charger is supplying a fixed voltage to the battery with a varying current. It will monitor the current drawn by the battery until it reaches a set level, typically 0.1C or 10% of the capacity of the battery, at which point the battery is fully charged and the charger circuit will cut off (stage 3). 

If left connected to the charger, it will periodically give the battery a small top up charge to keep it up to spec (stage 4).

Bearing this in mind, consider our system. 

If you have a 180mAh cigalike, and you screw it in to a charger that is going to supply a constant current of 420mA, the chances are high that your battery will fail and/or explode as the charger will be supplying a higher current than your device can handle. The little cigalike batteries typically don't have a charge control circuit, and would be unable to regulate the supply down to  a safe level.

If you plug a battery that has no charge circuit into a charger that also has no charge circuit, you're going to be applying an unregulated voltage to your battery, which may cause it to fail catastrophically.

If you plug a charger with a circuit into a battery with a circuit, well, you're probably going to be okay, but I still wouldn't advise it unless that was the charger the manufacturer specified!

Now this is where most people stop. They dont consider the third variable in the system, the supply. The power supply is just as capable of failing catastrophically as either the battery or the charger, and for the same reasons. Overloading a power supply by attempting to draw more power from it that it is rated to supply will cause the unit to heat up and can cause melt downs and fires, the same as any other piece of overloaded electrical circuitry.

USB is a set standard that includes not just the shape and pinout of the connector, but also the current demanded from the devices that will be connected to it. It has also gone through several revisions, each of which has increased the current rating of the port.

Great, right? Unless you happen to have a supply that is specified to the lower standard, and are expecting it to be able to safely supply a much greater current than that for which it is designed. The unit will overheat, and eventually fail, potentially in flames.

USB 1, the original standard, set a maximum unit load of just 150mA - just 0.75W.
USB 2 raised it to 100mA per load, with up to 5 connected loads, giving a maximum supply current of 500mA.
USB 3 raised it again to 150mA per load, with 6 loads, giving a maximum of 900mA.

Connecting a charger that is designed to give a constant current output of 420mA to a supply socket that is designed to deliver a maximum of 150mA would overload the supply port causing overheating, and may lead to, you guessed it, an eventual failure and/or fire.


Your charging system is just that - a system. If one part of your system is stressed or over loaded, the entire system is likely to fail, and the stressed part of it may fail catastrophically. You need to ensure that your eGo battery is connected to the correct type of charger and that the charger is connected to the correct power supply unit. If you mix and match without knowing the exact specifications of each part, you are taking a risk, and that is something you do NOT want to do with lithium batteries.

And eventually I come to the point of this article. USB may be a convenient and common connection standard, but when you are connecting devices to it that may far exceed the specifications to which your supply was built, you are playing - literally - with fire. And that is why I dont think the USB connector is a suitable standard for this application. If a dedicated connector was designed for each class of device, then only those devices that required that type of charger/supply would be able to connect to them. This would massively reduce the risk associated with e-cig charging, and might even get the press off our backs for 5 minutes.


Whilst I have made every effort to ensure that the information contained in this post is accurate, it is your responsibility to ensure that the equipment you use is safe, and is operating within its specifications. If in doubt, contact the manufacturers. Do not sue me if your house catches fire. I'm broke, you wont get anything anyway.