cali400h

Will the Lexus RX400h still run on gas if the hybrid battery goes out?

Weighit

Mine did straight to the dealer. All the warning lights were on, cruise inop, and felt like much less power.

ukrkoz

But was your hybrid battery 100% dead? Depleted or else, 100% non operative? Lights will come up way before it completely dies.
Amazingly, there is no straight answer for the question. Tons of articles on what happens when you run out of gas. Several saying "What happens when hybrid battery dies?" and yet, they only talk about running out of gas.
As far as I know, drivetrain will have no motive force with MG inoperable. No power to MG no go force.
yes, you can put system into Maintenance mode but that's in P or N only, as far as I know.

mswtoyota

In theory, MG1 should be able to provide enough electricity to power MG2 as long as the engine is running. I'm sure top speed and power output would also be reduced. This also assumes that there are no other major system failures, like a shorted cell in the HV battery, a bad inverter, or a short in the HV system. When Prius batteries die I've heard of people still driving them, as the car just tries to not ever charge or use the HV battery at all.

smassey321

When a Prius battery or inverter dies, the car has a single speed transmission. You can get it to the dealer as long as there is no highway involved. I assume the 400h is the same but there is not much info on failures out there.

ukrkoz

In theory, generator provides power to battery, inverter provides power to MG-s.. It is not direct MG to MG power supply. Take hybrid battery out of equation and you broke the current chain. See chart attached. No hybrid battery - no go juice for MGs. Again, hybrid battery is the best safeguarded component in the system. ECU will throw a fit and disable it way before hybrid battery dies completely. Regarding situation in post #2, and after what now - 7 or 8 years in hybrid Toyotas forums, I safely bet that though all the warnings came up on the dash, hybrid battery had enough power left in it to take vehicle to dealer. Also, that VSC, Check Hybrid System and ABS lights came up does not mean hybrid battery is depleted or even at fault. Those are generic warning lights that come up at any major issue with hybrids.

mswtoyota

I disagree. The generator IS one of the MGs (hence the term Motor/Generator - MG). All MG1 has to do is pass the current through the inverter and on to MG2, no battery involved. As your diagram shows, the battery is at the end of the chain, not in the middle.

ukrkoz

It does not matter what we agree or disagree upon. Look at the chart provided before. You can't drive without battery. Go disconnect yours with engine running and try driving. there is a disable switch in the trunk, not that hard to do. report back.

mswtoyota

I pulled the plug with the car in Ready. Ready light turned off. If you are feeling rather festive, I highly recommend you do this as it turns almost every light in the dash on very similar to a Christmas tree.
After resetting all codes, I had the car in gear with the ebrake on in Ready mode. When I pulled the plug I could feel the car relax, like it stopped trying to move forward against the e-brake. But, it only sets the same P0A0D code, which is high voltage battery interlock. So I guess we will never know, until someone kills a cell and reports back here. My vote is the car will still move.