C-HR charge battery by running engine?

[mickthefitter]

Hi. New here. I've an uncle in his 80s with a C-HR, around a 2017 model I think. He doesn't do many miles. I heard on the family grapevine his car broke down. Failed to start. Having spoken to him to find out more, prior to not starting it was flashing all sorts of warnings at him while driving. Warnings about the hybrid Battery I think. Long story short, car was booked to go in, needing to be recovered on a truck, before this happened a neighbour came along and said "You need a new 12V battery", fitted one, car started and warnings went away. (My uncle is still getting the car checked anyway). 

Now - the reason why I'm here. I've got a friend, also in his 80s, with a Lexus RC 300h. He can't drive that for six months because he's had a heart operation. The Lexus is parked up, he doesn't know a lot about cars, and I was worried about HIS Battery going flat. I wanted to loan him my smart charger, but when I visited, I couldn't find the 12V Battery (I do know where it is now though). My friend however, had already been speaking to his Lexus dealer, and had been told the following - "PLANT YOUR FOOT ON THE FOOTBRAKE, PRESS THE 'START' BUTTON, WHEN 'READY' COMES UP, PUT THE TRANSMISSION IN 'D', AND REV THE ENGINE!" And he did this in front of my very eyes. I was horrified. But, the 'screen' in the Lexus displayed the engine charging the hybrid battery and my friend kept this going for ten to fifteen minutes until the hybrid battery was showing full charge. The transmission did not blow up. I've since been on a Lexus forum asking about this. Apparently, yeah, you can do this. The engine charges the hybrid battery and I believe the hybrid battery maintains the 12V battery. The Lexus doesn't have 'automatic transmission' in the normal sense. Pressing the footbrake disengages the engine from the drive wheels - the risk is, if your foot slips, you launch the car. But this is how my friend intends to maintain his batteries during his lay-off from driving. 

So my question - does anybody know, since Toyota make Lexus, whether the transmission in a C-HR works the same, and this wild method of maintaining battery charge on an unused car can be used on a C-HR?

[FROSTYBALLS]

During lockdown when people weren't using their cars much, this was Toyota's recommendation for charging the Battery. See:

https://mag.toyota.co.uk/coronavirus-toyota-hybrid-car-maintenance/

[philip42h]

So ...

1. Your uncle may well not have needed a new 12V Battery - just the existing one recharged. No harm done - maybe an unnecessary expense.
2. Putting a hybrid into Ready mode and Park will maintain both the hybrid traction Battery and the 12V auxiliary Battery. There is no need to put the car into Drive.
3. To maintain the car if it is laid up for six months:
   1. Connect a smart charger to maintain the 12V auxiliary battery - there is almost certainly a jump start point in the fuse box under the bonnet that you can use.
   2. Put the car into Ready mode and Park once a month, say, for half an hour or so just to top up the traction battery and run fluids through the engine. The engine will run until the engine is warm and the traction battery 'happy' and then stop ...

[mickthefitter]

2 hours ago, FROSTYBALLS said:

During lockdown when people weren't using their cars much, this was Toyota's recommendation for charging the battery. See:

https://mag.toyota.co.uk/coronavirus-toyota-hybrid-car-maintenance/

Hi, thank you. I've read online exactly the same sort of procedure recommended for my friend's Lexus, issued during lockdown, which further supports my belief the C-HR and Lexus RC300h share similar hybrid systems. The 'leave it idling for 60 minutes' method is the safe way to top up the batteries. The way my friend was told to do it with his Lexus is the riskier (if your foot slips off the brake) but quicker way to boost the Battery charge, because the engine was being revved at higher revs. Still not conclusive proof it's safe to stick the C-HR in Drive and rev it up, but the 60 minute method was issued by both Toyota and Lexus.... which is Toyota. So it's looking that way. 

[mickthefitter]

1 hour ago, philip42h said:

So ...

1. Your uncle may well not have needed a new 12V battery - just the existing one recharged. No harm done - maybe an unnecessary expense.
2. Putting a hybrid into Ready mode and Park will maintain both the hybrid traction battery and the 12V auxiliary battery. There is no need to put the car into Drive.
3. To maintain the car if it is laid up for six months:
   1. Connect a smart charger to maintain the 12V auxiliary battery - there is almost certainly a jump start point in the fuse box under the bonnet that you can use.
   2. Put the car into Ready mode and Park once a month, say, for half an hour or so just to top up the traction battery and run fluids through the engine. The engine will run until the engine is warm and the traction battery 'happy' and then stop ...

I'll pass this info on to my uncle. Thanks. During my further investigations into my friend's Lexus, I ended up downloading a PDF of the owner's handbook (not had chance to try that for the C-HR yet) and discovered the 'jump-start' point under the bonnet, as you say, under the fuse box lid. Also found the 12V Battery was in the boot - we did look, but not being familiar with the model, when on the scene I did not recognise where to look and what covers to remove, and it wasn't my car to mess with too much! So at the time the Battery went undiscovered. In the case of the Lexus, when I told my friend I'd finally found out where to connect the smart charger if he still wanted to borrow mine, he remained convinced the method he'd used by revving the car in 'D', with the footbrake pressed, was the way he was going to charge it! His car, his dealer had told him to do it, so I left it at that. I'll tell my uncle about the 60 minute idling method. And maybe email him the link to the 'lockdown' bulletin I was provided with in the previous reply. 

[wildtapholer]

Tell him to start the car and put the air con on hi and leave it running, it fools the car into thinking it's being driven and keeps the engine running and charging everything up.

[TonyHSD]

Omg what a suggestion for accident to happen. ⚠️
Never put the car in D and floor the accelerator while holding the brake pedal because if your left foot slip and brake is released the car will launch ahead with full power. This is actually a lunch control. ⛔️
For keeping up your Toyota/Lexus batteries in good condition all you need to do is to start the car in ready mode with parking brake on and in P , you can use hvac on or off , as you wish. Using it will charge the hybrid Battery to higher level where if car kept in ready mode without any 12v accessories used the hybrid Battery will be topped up less frequently by the engine and it will remain at lower soc. 

[mickthefitter]

18 hours ago, TonyHSD said:

Omg what a suggestion for accident to happen. ⚠️
Never put the car in D and floor the accelerator while holding the brake pedal because if your left foot slip and brake is released the car will launch ahead with full power. This is actually a lunch control. ⛔️
For keeping up your Toyota/Lexus batteries in good condition all you need to do is to start the car in ready mode with parking brake on and in P , you can use hvac on or off , as you wish. Using it will charge the hybrid battery to higher level where if car kept in ready mode without any 12v accessories used the hybrid battery will be topped up less frequently by the engine and it will remain at lower soc. 

Well this is true. While my eighty-something friend was revving his Lexus RC300h as per his dealers advice, to charge the hybrid Battery, there was a moment where he relaxed his 'brake' foot and he nearly launched his Lexus into the side of my Volvo, which because of how he had parked, I'd pulled across the front of his car. I rapidly rolled my own car out of the way in case in happened again. Any car fitted with a torque converter and transmission with clutches and brake bands, revving the car in Drive with the brakes on, well, the whole lot would have been toast. However, it worked. The Battery charged and the RC300h didn't protest. When I joined a Lexus forum to try to get some clarity on this, some people knew about it and explained the hybrids do not have torque converters but some sort of computerised CVT transmission, and with the brake on, engine power to the wheels is interrupted. I was also told about the 'idle for 60 minutes' method though. I guess being told about an alternative method, it's a question of whether my friend wants to baby sit his car for 60 minutes, or get the job done in 10 to 15 minutes by risking a high speed launch if his foot slips. When it was all over, I asked "Who told you to do this?" My friend said a man at the dealership had originally told him to leave it idling, like people here have said, but then he'd made another phone call to ask for more information and a female advisor told him about the 'in D with brakes on' method, with the caveat "I shouldn't really tell you this." My friend asked "Why not?" and the woman said "If your foot slips off the brake you could do a lot of damage." But the Lexus appears to be engineered to take this method of forced Battery charging. Since it is just a fancy Toyota, I'd imagine lesser hybrid Toyotas are made much the same. 

[philip42h]

Yes, but it's a stupid and unnecessary thing to do ...

Let's take half a step back ... the 12V auxiliary Battery maintains the car's systems when the car is switched off and will certainly run flat if left idle and unused for 6 months. The solution to that problem is a trickle charger - either a smart charger plugged into the mains or, if the car is parked outside, an appropriately oriented solar charger. If you / he can't manage either of these then leaving the car in Ready mode for 60 minutes per week will maintain the 12V auxiliary Battery as per Toyota's Covid era advice.

Being in Drive, revved hard with the brakes on won't charge the 12V auxiliary Battery any faster - he'd still need to do so for the same "60 minutes per week" - which would be really stupid and dangerous.

Being in Drive, revving hard with the brakes on will force charge more rapidly into the hybrid traction battery and so give an increased electric range when he next comes to use the car for real. But that is pointless ...

While the car is laid-up the traction battery is 'off' and not running anything so the only reduction in charge will be through internal losses. The traction battery probably won't care about being left for 6 months, but starting the engine once a month and letting it idle for a few minutes until the car decides that the engine is warm and the traction battery is in a good state is probably a good idea ...