Friday, 23 May 2014

Collecting - Cable

I said it would only be a matter of time before I added to the cable collection.  I was right,  I just got an absolute bargain on eBay for a piece of the first transatlantic cable with silver plated ends .  I have come up with design for a display rack, so once I have a few more I will start that project in earnest.

Sunday, 11 May 2014

Collecting - Cable

Some people collect things, I have never really been one of those, but I think that might be changing. Now my parents would disagree and say the large quantity of vintage computers mainly BBC Micro's filling there loft is a collection, I would say its just some useful equipment I have collected over the years, oh bugger maybe it is a collection.

So what have I started collecting?  Well I have started collecting cable and when I say started I have two pieces which is I guess the minimum to count as a collections but a have saved an eBay search so its only a matter of time before I have more.

I first purchased a piece of collectable cable in 2007 from the Hoover Dam whilst on a lads trip to Las Vegas. It was a pen holder made out of a short length of hollow high voltage conductor cable, designed to carry 287500 volts across the Mojave Desert.  The cable is hollow to save weight, this is possible because most of the electricity flows through the outer surface at high voltages, it is referred to as skin effect.  The construction of the cable is ten interlocking tongue and groove strips on a slight spiral, this enables the cable to expand and contract. Sorry to geek out but I do think its a cool design.

It was a Seven years later I was browsing eBay looking for a Morse key (another project I will write about some day) and I saw a whole lot of undersea telegraphy cable sections for sale.  So I bid on them, all of them.  Luckily I was outbid on all but one of them, if I have won them all I would of been in for a couple of thousand dollars.  The one I won ended up costing me just under £50 including postage so it has not broken the bank.  The only problem I have is that I do not know where or how to display them, maybe I should make some form of display rack...

Monday, 5 May 2014

Makita 18v LXT Battery Dismantling & Testing

So I have four failed batteries and decided to find out what has gone wrong each of them.  First step is to get the cover off.  This is held on by four T10 Anti Tamper screws, on newer models there may be a white plug covering one of the screws.  I have found that the easiest way to remove it is to drive in a small wood screw and pull it out with a pair of pliers. I was surprised how much dust had made its way into the batteries.

Below is a description of the fault on each battery.
  1. Battery One: Fails to charge with a over temperature alert.  Also the plastic at the side of the release button has bubbled. It is showing 7.99v across the whole battery which is way to low and 0.04v, 0v, 3.96v, 0.04v and 3.97v across each of the cell pairs respectively. Upon opening up the battery there is obvious damage to the second pair of cells.
  2. Battery Two: Fails to charge with classic red / green flashing lights. It is 12.84v across the battery and 3.2v, 0v, 3.22v, 3.22v & 3.21v across each of the cell pairs respectively.
  3. Battery Three: Fails to charge with classic red / green flashing lights. It is 15.54v across the battery and 0v, 3.89v, 3.89v, 3.89v & 3.89v across each of the cell pairs respectively.
  4. Battery Four: Fails to charge with classic red / green flashing lights. It is 18.15v across the battery and 3.62v, 3.63v,3.6, 3.63 &3.62v across each of the cell pairs respectively.
By way of comparison a known good battery seems to measure around 20v when freshly charged.

So I think my best option to end up with an extra working battery is to use the board from Battery One and fit it to the cells and temp sensor from Battery Four.  Changing the board should be pretty simple it just requires de-soldering.  Fixing the other batteries is going to be a little more challenging. Up until recently replacement circuit board were not available so once you had seen the red / green flashing lights three times your battery was bricked.  However recently they have become available for a round £10 which is certainly much cheaper than a replacement battery.

That still leaves the failed cells and whist it is possible to solder cells together the heat required to solder them risks damaging the cells. Having investigated purchasing a spot welder I feel that is out of my budget but I may have a go at making a capacitor discharge one.

Saturday, 3 May 2014

Nest Thermostat after 28 days.

It has now been four weeks since I installed my first Nest thermostat in my house and since then I have added two additional Nest Thermostat, one to control the kitchen and one for the upstairs, making a total of three. Currently they are all on Nest stands although I will hard wire a couple of them when I am next going to decorate as I will have to chase in new cables.

Over the last few weeks I have had several days when in some of the rooms the heating has not been required at all.  With my old system I would of carried on heating the area.  I have noticed that the auto away seems to be a bit strange about when it triggers, some times it cuts in fine but other days it does not. I am wondering if it might be down to sun light hitting the sensor?

On the client side, we have now installed several for clients with all types of heating systems and so far everyone is really happy.  I just wish the Nest Protect was available, just about every client we have installed a thermostat is keen to get a couple.  Hopefully they will get there issues sorted soon.