Flat 12v battery - built-in key.

[Jazzik]

Just a question (out of curiosity):
Has anyone experienced whether you can open the car with the built-in key when the 12v battery is completely flat?

[ColinB]

Surely the whole point of the physical key is to be able to open the car when the electrics are dead? If it won't do that, why is it there?

[5thcivic]

Surely it must do that to open the bonnet and change/charge the battery.

[Jocko]

I have always been able to lock and unlock the driver's door with a physical key even without the battery connected. On a couple of cars with remote locking, I used to take the battery in occasionally to charge up and I could lock the car up and unlock it again in the morning. There is a mechanical lock in the driver's door the same as any "old fashioned" car had.

[Jazzik]

I asked the question, because the manual says:

"The built-in key can be used to lock/unlock the
doors when the keyless remote battery
becomes weak and the power door lock/
unlock operation is disabled."

I can't find if it also works if all systems are "dead" due to a flat 12v battery.

[Jocko]

With the car unlocked and the bonnet open disconnect the battery earth, then try and lock and unlock the car. That will prove it for you.

[Kremmen]

I think the question is trying to ascertain whether the door lock is mechanical, so the key should work, or whether it triggers a solenoid that may not work with no power.

[Jazzik]

Indeed!

[Neil Ives]

I had to use the physical key yesterday. My wife had got out of the car and wandered off;  she was out of sight. The car was refusing to auto lock. I went round reshutting the doors but still no locking. I had an idea that wifeys key might be in the car. Sure enough I found her key inside the car in her jacket pocket. I now had two keys in my hand. Pressing each in turn, the car would not lock. I was desperate for a pee so I removed the physical key from mine and it locked the car. The mirrors stayed out but the doors locked.

I now believe that Janet had opened the car with her key before we set off, so even though I tried turning her key off to try to get my key to work, 'the car says no'. If I'd turned my key off and used hers I believe the car would have locked.

[Lord Voltermore]

If it were a solenoid  and the car cannot be opened  with  the physical key  if the 12v battery is dead (or missing)  you would need a way of releasing the bonnet  from the outside.  Not something they normally include in owners manuals.   

[Jocko]

The solenoid works the mechanical lock not the other way round.

[John Ratsey]

I can confirm that the physical key can open the driver's door when the 12V battery is flat (but not the other doors - so don't keep an emergency battery in the boot). When I tried to unlock my HR-V this morning it was completely unresponsive (this was 9 days after a 160 mile trip). I was able to unlock the driver's door to unlock the bonnet and discover that the 12V battery was reading 2.8V. I connected my smart charger which wouldn't do its job because the voltage was so low. Hondacare (=AA) first tested the battery and concluded it needed replacing before doing a jump-start so I could drive the vehicle to the dealer for investigation.

[Hugh R]

When I tried to unlock my HR-V this morning it was completely unresponsive (this was 9 days after a 160 mile trip).  Hondacare (=AA) first tested the battery and concluded it needed replacing before doing a jump-start so I could drive the vehicle to the dealer for investigation.

I find (these rather often) complaints disturbing.  While mine has behaved well after non-use, now and then, of a week or so, I can't help wondering what the root cause could be.  Any ideas?

[Lord Voltermore]

When I tried to unlock my HR-V this morning it was completely unresponsive (this was 9 days after a 160 mile trip).  Hondacare (=AA) first tested the battery and concluded it needed replacing before doing a jump-start so I could drive the vehicle to the dealer for investigation.

I find (these rather often) complaints disturbing.  While mine has behaved well after non-use, now and then, of a week or so, I can't help wondering what the root cause could be.  Any ideas?

I think its the long shipping time from Japan  ,plus maybe  delays at each end . A few cars may  flatten their battery  for too long and they get damaged.  Probably not that many overall, since Honda seem to prefer the cost of replacing a few under warranty, than  the cost of keeping them all charged up in transit. 
Once replaced with a brand new battery it should restore the status quo. 

But the fact remains  the 12V battery in virtually ALL new cars  are now at risk  if its  only used occasionally or  for short journeys . Unless precautions are taken to keep it charged  or to drive it regularly.  . Ideally a smart charger, but if thats not possible a solar charger may suffice. 
 Modern cars  have various computer systems, alarms,keyless signals  etc running 24/7 which have a big drain on the  battery. This is not just a problem with Honda or Hybrids with their relatively small 12v battery.   . Even conventional ICE cars with a full sized starter battery can completely flatten their battery in 4 weeks,risking permanent damage , or only  2 weeks down to 50% charge and a reasonable chance of still starting.


I've not  had any problem with my EX    And I once   left it unused  for over 2 months in January and February on a solar charger. It started no problem.
I have also taken a belt and braces approach  of carrying a small power bank 12v  jump starter.  They claim to be able jump start an ICE engine so should be enough to power up a hybrid computer system . That remains charged for about 3 months, so I will have to remember to keep it topped up. I hope never to need it ,although it can also be used a  usb power bank for phones, cameras etc and as a torch.      I also carry a replacement button battery for the keys . 
   
 

[Kremmen]

With the colder months and my very low usage my CTEK will be used every 2 weeks.