v70 t5 flat battery issues
 

i have had a v70 t5 registered 2002 for the last 13 years. i go away in january for 2 months and although a friend turns it over every 2 weeks by the end of the 2 months the battery is totally flat . has any body had the same experience or any idea if this is a usual phenomenon with this model.

If the car was started and stopped a few times, without being driven to put charge back into the battery, that's probably the reason as to why its flat. Also if its the original battery, it will be passed its sell by date.

That is about 4 or 5 starts, I would expect a battery to be good for even more without being charged. Just make sure he doesn't rev the engine while running it.

With the engine running and the headlights off, measure the voltage at the battery or near the alternator ( 1 wire on the red cable 1 wire on the alternator housing). You should be getting at least 14.2V. If you read around 13.5 V the alternator is not charging properly.

Measure this first, if the value is good, then I would look either into a short somewhere (possibly the alarm siren module, just remove the fuse)

If the alternator doesn't charge, replace it first, then replace the battery because by now it has been damaged. Use ONLY an alternator for a 2001-2004 S60, do not use the alternator for 2005+ because it won't charge properly. https://www.youtube.com/watch?v=Kg-lsya-LiY

By starting the car, he's giving the battery the largest current drain possible and then most likely not allowing the battery to be replenished so it's not surprising that the battery wears down.
A healthy battery versus a correct spec current drain (35-40 mA) will comfortably last 2 months if the engine isn't started.