I think you'll find that battery technology hasn't changed too much over the years and that anything over 14.5V starts to over heat the battery and cause the electrolyte to "boil" off. I think you'll find that 'most' cars are actually 14.5V when tested with a quality meter.

That Solar panel idea sounds good. Got any links on how to build one?

Edit.

Found this one...

http://cgi.ebay.com.au/ws/eBayISAPI....link:middle:au

thoughts?

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RS Liberty - Because WRX's are only good for parts...

Just had a look at the Jaycar ones, the biggest one with a regulator will set you back about $350, not too bad I suppose, beats buying new batteries every year.

Does it need to be the biggest one though? Aren't they for running camper vans and such?

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RS Liberty - Because WRX's are only good for parts...

If your car is going to sit outside in the sun most of the day you'll only need something that puts out 10W or so (Ebay one is a bit small). Make sure it has a charge regulator as well (Can be inbuilt, but mostly sold seperately).

If you want a flexible panel (generally more expensive, but can be thrown in anywhere) give the 12 Volt Shop a call. They are up Kewdale way. Ask for flexible Uni Solar panels (not sure if they make these anymore though).

But otherwise, any no-name brand panel from Jaycar (5 - 10W) should do the trick.

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TD06 - Oink.

Nah, it doesn't. The Jaycar ones need to have a regulator to go with them, all up for a similar one as the ebay one would set you back about $65, couldn't hurt. At least you would get a warranty from Jaycar!!!

The Largest panel from Jaycar only puts out 2A, which would suit a slow battery charge rate

mate same problem i have becuase i dont drive often or far enough either and i thought my battery was fucked.
but was just not charging enough.
so basically every couple months should just stick charger on it over night

If you were worried about current draw draining the battery you could always fit a battery isolator switch, just means you'll have to set the clock and radio every time you turn it back on!!! Bad idea???

Other wise maybe get an auto elec to do a current draw test on your car and try to find a culprit for the battery drain? Maybe not due there hourly rates!! You could have a crack yourself, just buy a cheap Multimeter and start playing.

yeah i know my car draws a bit plus having ezitrak with constant anti tow away on. is constantly searching for gps signal... but mine seems ok i drive enough

Normally anything between 14 and 15V is a good charging rate. Above or below this and you have problems. It's quick to find out if you have a battery drain... undo the negative terminal on the battery, place and Ammeter between the negative post on the battery and the negative terminal, check the reading. Above 0.5A and you have a problem.
Also try and drive the car a bit more... leaving your battery in a slightly discharged state for long periods of time causes the cells in the battery to go hard and therefore the battery will not charge properly because the chemical reaction taking place inside the cells will not occur properly. Meaning you will have to buy a newer battery sooner... = $$$ =