on the edge

computers & technology, books & writing, civilisation & society, cars & stuff

Greg Black

gjb at gbch dot net
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If you’re not living life on the edge, you’re taking up too much space.

FQE30 at speed

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Worthy organisations

Amnesty International Australia — global defenders of human rights

global defenders of human rights

Médecins Sans Frontières — help us save lives around the world

Médecins Sans Frontières - help us save lives around the world

Electronic Frontiers Australia — protecting and promoting on-line civil liberties in Australia

Electronic Frontiers Australia


(Coming soon…)


(Coming soon…)

Software resources

GNU Emacs


The FreeBSD Project

Tue, 26 Jul 2005

Battery charger lessons

Late last year, I wrote about an attempt to preserve my BMW’s battery with a solar-powered trickle charger. Prior to that, I had found batteries tended to last about seven months before dying completely.

So, how did it work out? In a word, not too well. Last week, I went to start the car, only to find that the battery was so far gone that the clock had stopped, the immobiliser LED was out, and my volt meter showed something less than 1 volt. It was so bad that attaching jumper leads to a much bigger battery in a car that had its engine running did not suffice to crank the engine.

Before rushing off to buy yet another new battery, I decided to try a different kind of charger—as I now have power in the garage. I bought a device that has semi-intelligent electronics so that it can give a heavy duty charge until the battery is up to a normal level, and then gives a lower charge until full charge is achieved. It then sleeps until it senses a need for more charging. I wasn’t sure how well it would go, but it seemed worth a try.

It took a couple of days to bring the battery up to normal, but then the car started immediately. This seems to be promising, so I’ll monitor things more closely for the next few months and see how it goes.

No doubt, the abuse given the battery when it was allowed to go dead flat will have shortened its life—but if it keeps working for a few months, I’ll feel as though I’m on a winner and will buy the next battery with better grace.

As a minor point of interest, one of the features the new charger boasts is that it avoids the bad effects of trickle chargers…