Battery failure

[Kremmen]

My main concern with the 12v battery was from previous experience that if you let it fully discharge then it's often not recoverable and needs replacing

I read the posts about using a power pack or whatever but if you can prevent it from fully discharging then that surely has to be better

[5thcivic]

It would be enough if, after turning on the car, the system simply reported, for example, "your 12V battery has dropped in voltage, please recharge it"...

An excellent simple idea assuming the control system can measure the 12V voltage before the HV regulator/relay kicks in. For owners who actually read the manual but don't have a 12V charger it tells them to do the half hour fast drive to charge things up.

[stani]

...it tells them to do the half hour fast drive to charge things up.

Hmm, but how does the user know that he is supposed to do that?...

[davejazz]

...it tells them to do the half hour fast drive to charge things up.

Hmm, but how does the user know that he is supposed to do that?...

There is a sticker on the underside of the bonnet, which instructs on how to care for the high voltage battery. Unsure if it also relates to the 12v. one.

[Kremmen]

I was intrigued by the airport parking for a couple of weeks fear

If the airport is over 30 miles away then both batteries should be fully topped up when you park, and when you do park make sure you double lock to shut down all unnecessary electrics

If less than that then maybe take a detour

If a small distance away then I'd be getting a taxi 

[5thcivic]

Hmm, but how does the user know that he is supposed to do that?...

Good point, I was thinking of the manual advice to drive for half an hour, but that is specifically for a low HV battery. However the same advice has been ususal for 12V batteries with conventional alternators for many years, and would be the same for the Jazz, although may not be well known for non-petrolheads!