Quick question by new hybrid owner

[Saxmaniac]

Hi all

I'm 2 days into owning a nearly new Auris Hsd estate and loving it so far. I quite often sit in a car stationary for perhaps an hour with the radio or cd playing. I'd heard this can flatten the 12v Battery quite quickly unless the system is enabled to charge it from the traction Battery. Does this mean that the correct setting is to be in ready mode and neutral or park? Or ia there another way of doing it and preserve the 12v Battery? Geoff

 

[TonyHSD]

Hi and welcome. Best way is to keep the car in ready mode and on P, parking, don’t leave it in N as when is in neutral it is not possible for the engine to charge the traction Battery. I am doing the same sometimes for hours, never had any problems. 

Regards 

[chrisgeary]

Yep, just to be clear, when in 'ready' mode, the traction Battery is engaged which is a bit like having the alternator running on a non-hybrid combustion engine. So the traction Battery keeps the 12v Battery topped up and runs all the electrics. You'll probably notice that your traction battery will have emptied well before an hour is up (even faster with the electric AC running) and the engine will kick in to replenish periodically. 

[PeteB]

I once slept in my car for 7 hours (don't ask!) from midnight to 07:00 on New Year's Day with the car in READY state the whole time.  The engine came on for 2-3 minutes about 4 times an hour to provide heating (a/c was off).  This ensured the HV Battery stayed on 7 bars all night too.

There was no noticeable difference in the miles I'd done on the tankful.  I wouldn't have entertained doing this in a non-Hybrid car, and maybe not even in an EV unless I could have it plugged in for the duration.

It was in my last (Gen 3 Prius) so at least I wasn't forced to have lights on, which would have been extremely annoying.

[Gerg]

If the car is in 'ready' mode and 'neutral', but not in 'Park', I would think that the car could easily creep forward if the engine started to charge the Battery (hypothetically).  From a safety point of view this would be a complete no-no, so the 'Park' brake must be on so the car is guaranteed not to move when a Battery charge cycle starts.  I would imagine this might be one of the Toyota design considerations on 'charging while stationary'.

The 12v Battery is a small-ish capacity, but a higher specification than a regular battery, so will suffer deep discharging better than a normal one.  The inverter /12v charge circuit is quite powerful, a figure of about 100A rating is often quoted.

The 12v battery is covered by the 5 year warranty.

If you are at a bit of a loose end, perhaps try searching 'Prius camping', which takes Pete's experiences above up another notch or two.

While you have the opportunity, it might be worth finding the 12v battery jump start location in the underbonnet fuse box.  It is mentioned in the manual, and could save you time if the 12v battery does run flat.

 

[PeteB]

When the car is READY and in N, even if the engine is running it will not charge the HV Battery.  Generally, if the engine is running when you select N, it stays running (until you take it out of N, turn off, or it runs out of petrol!), and if it's not running when selecting N, it stays off.

On the first 2 Generations of Prius Toyota people affirmed that if you left it in N long enough, it would become too weak to start the car, and would need a special charger.  At least up until 2007, there was only one such charger in the whole of Europe and the only 2 instances I heard of the HV Battery being drained (both due to being fuelled with diesel) it took up to a month in the queue for it, as it was driven from dealer to dealer as required in they order they booked it.

I've seen a couple of posts from people who've said that after a very long period in N on 3rd/4th Generation Hybrids they get a warning message to select P to charge the HV Battery.  I'm nowhere near brave enough to investigate that myself!

When I've been in P on level ground with the parking brake off (not my normal practice, but I experimented in the early days), when the engine starts the car rocks very slightly, but doesn't feel as if it's trying to move against the parking pawl.

[TonyHSD]

Not very long time before you can see the message on display to engage to P, all depends what was the charge before N was selected,  happened almost every time when cars goes through MOT or wheel alignment, mechanics keep the cars Ready and in N to be able to push them under while  inspecting them on the ramps. I think there is a sound signal too, but can’t remember exactly, but noticed how they go quickly to select P. 🙂 

[Saxmaniac]

Thanks for all those speedy replies! I'll certainly see how car behaves when it's hot weather and ac on while stationary