(T) Punto 75 SX '98 battery & electronic check problem

I have Punto 75 SX from '98. I was a great car till start showing two problems.
1. First and greatest is battery emptying problem. In fact, very often (aprox. 2-3 times/month) I can't start the engine because of empty battery. I bought new one, but the problem remains. The good thing is that when problem occur I swap the batteries and charging the empty on AC charger out of car for the next swap. Electrical charging on the car seems to work OK - on long trips battery remains full even on night driving under light and with car stereo on.
2. Second problem is electronic check light. Often (3-4 times/week) whet I try to start the engine electronic check light remains to light (red) and ignitions is weighty. In this situations engine fan switch on and blow. After few kilometers everything go back to normal - engine work normal, check light and fan switch off. Nothing changed after replacement of temperature sensor.

Any advise will be very helpful.
Thanks in advance

OK problem number 1 sounds like you have got a drain on your electrical system.
To check undo your negative lead off your battery and wire a 12v test light between your battery lead and your negative post on your battery.
With your ignition OFF see if the light is iluminated the brighter the light the bigger the drain .If you have got a volt meter you can wire it the same as your light and it will tell you how many volts your drain is.
To find out what the drain is first start with stereo and alarm disconnect them if light or volt meter goes out you found your drain.If not head for the fuse box take out fuses one by one check to see if light goes out.(only remove one at a time then replace it before taking the next one out) When the light goes out you check what the fuse is for then you've found your drain.If your light is still on find the relays and remove those one by one the same as the fuses.
Hope you find your drain good luck.

Check your fan relay first sound like it F#*ked that may drain your battery to.

Dodgy alternators can cause this too.

Pete.
Cinq sporting 1242cc
http://mysite.freeserve.com/close_to_cracking_up/