You'd be much better just going out and leaving it running for 15 mins, Your alternator will give the battery more charge in 15 minutes than a portable jump start ever can.

Then they AA bloke is a fooking idiot, I bet he never did a load test on the battery. Running a battery flat is the easiest way to kill it, yes it can be re-charged to 12.7 volts but it won't last long. The more it happens, the weaker the battery becomes.

For the short term, I'd go with the previous suggestion of a solar trickle charger or failing that, disconnect the thing everytime you're going to leave it.

This.

Incidently, about fifteen years ago my business used to be located opposite a vehicle electrician who made a living from dead batteries, I bought one from him for a three year old car on which the battery had failed, I moaned a bit over how quickly it had died but he told me that most car batteries had a two year warranty and would die between years two and three.

I'm doing quite well with the wifes low-use car after six years then (its the low usage that does for them).

That'll keep the battery topped up but it's also a sure-fire way of knackering an engine, especially a diesel engine. Engines are meant to be run under load, not sat idling. Take a look at any moored boat when it's charging its batteries, the owner will keep it tied up but also put it into gear so that the engine is working under load.

This.

You're fighting a losing battle and burning pennies trying to prolong a failing battery's life, especially buying gadgets. You'll need a new battery sooner rather than later either way.

Doesn't your battery lose 25% of its life everytime it is jumped?

Baldrick should be able to sort you out!

Go buy yourself a new battery . I will only put Bosch S3 or S4 batteries on my own cars . Some of my cars don't move for weeks at a time , but they never fail to start .
Have you had a sparky check the car for anything draining the charge such as an interior light ( especially the one in the boot) , or the radio ?
A flat battery can be boost started as many times as you want without shortening it's life , but it takes around THIRTY minutes of actually driving the car to get it fully charged . Just leaving it idling will take longer , and if you are having to do it every few days it is going to cost you more in fuel than a new battery would cost .
As mentioned above it is not a good idea to leave your car sat running . It can cause allsorts of problems .
Booster packs are a great idea , but you have to pay a great deal of money for a decent one . One I use cost nearly £400 . It is big and heavy and not really suited to be carried around in the boot though .

I drive our second car to and from the train station, and have had to replace the battery a couple of times after it went flat following periods when it wasn't being used. The last time seemed weird as the battery was only a year old and I hadn't used the car for only a about week before having to call the RACQ.

The guy tested my battery and found it was being drained way too much when everything was switched off. Without going to an auto-electrician (hardly worth it for the old thing), he suggested I disconnect the battery every time I leave the car for any time. I've been doing this for a year now and the car restarted perfectly after being left for 3 weeks. I understand with more modern cars this may be a poor solution, but in my old banger its fine.

On chargers you do have to check apparently as the one I bought a few years ago basically only 'tops up' a battery - it won't recharge it once the charge is below a certain level and apparently (according to same RACQ guy) is useless for more modern batteries. Have no idea on the technicalities of this, but chargers can be expensive, so best get the right sort.

Just to add my finale - the wifes car wouldn't start again yesterday so she called out the AA, he measured the charge in the battery and it was holding 72amp instead of 300, started it with his techno-car-starter-gizmo, measured it under charge and it was up to 120amp - she went out and bought a new one.

Dunno what juice they use, but a fortnight in a secure car park near the airport would always flatten the battery of the last car I had, and the bod in the car park who started up all the cars with dead batteries (almost a full time job that, he said!) told me that it is the car alarms with their sensors that drain the battery.