Lights for power cuts

Power cuts are quite possible this winter. Whatever the cause, we will have to deal with it. We are not badly placed. Our gas heating won’t work as the pump is electric, but we have a multifuel burner in the living room which should keep the chill off. We have stocked up with fuel just in case. Our cooker works from gas and all we need is a box of matches as the igniters won’t work.

Rather than being completely reliant on candles and torches on phones I thought it may be a good idea to have a couple of battery powered lights. But I wanted bright ones powered from 12V batteries.

The Lights

We had a couple of old unused bookshelf lamps. These had a standard B22 bayonet fitting, and most led bulbs are Edison screw, so I bought a couple of adaptors for £1.99 each from Amazon.

I also bought a couple of bulbs, for £15.99 for two, from Amazon. These are 6W so take 0.5V from a 12V supply.  The bulb works from either AC or DC so does not care about the polarity of the source.

Out of interest, using a bench power supply, I tried lowering the voltage, and the current went up. When I raised the voltage, the current went down as the bulb tried to maintain 6W at whatever the voltage. This amounts to negative resistance, and most electronic engineers will know that this can lead to oscillations.  And it does!

I powered a lamp from a random selection of of 8 AA batteries, and after 15-20 minutes the bulb started flickering.  This is because not only had the voltage decreased from the battery bank, but so had the series resistance.  This sparked off an investigation into the state of my batteries.  I did find, after testing, that I could make up a couple of 12V battery packs that would last 1-2 hours.

The lamps worked fine of a 12V motorcycle battery or a car battery. (But the lead acid battery investigation showed that the motorcycle battery was knackered).

I won’t show pics of the lights – they look just like any other freestanding light.

Just in case the whole energy supply system goes pear shaped we also have candles.

All of this is OK for power cuts for a few hours.  For longer periods it’s another story.  The stuff in the fridge freezer will defrost and the batteries will discharge.  We will be back to the coal fire and candles. Food will be a problem! Not only our freezer will stop working but so will the freezers (and the tills) in the supermarkets.

Oh well, it serves us right collectively for voting for the Tories and Brexit (I didn’t vote for either).

what can go wrong?