4WD

[vmanthani]

Hi All,

Two days ago due to M4 closure I happened to use B roads & A roads to reach home. And these roads had steep turns and was becoming very difficult to drive in the night and to maintain the speed.

Then I switched on 4WD and amazing, car handled the curves very easily. And even the roundabouts are very easy to maneuver.

My question is can I keep 4WD always on? Will it consume more battery (I believe it shouldn't be as this is handled by CPU itself)?

Thanks

 

[jkh112]

As I understand it there is no technical reason why you cannot keep 4wd engaged all the time. It will consume more battery though as it means both electric motors (or the petrol motor and the rear electric motor) will always be live even when it would be more efficient to use just one motor.
Having said all that I have previously tried using 4wd for an extended period at both low and high speeds and did not notice any increase in battery use. I did not find such a marked change in the car's behaviour as you seemed to.

 

[maby]

I'm surprised that you noticed a difference under these circumstances. It is in permanent 4WD at speeds below parallel hybrid mode (40 to 45mph) and, in practice, in 4WD most of the time above that up to 65 or 70mph. The "4WD" button simulates the differential lock that you get on more conventional 4WD vehicles - only really does anything useful if you are losing traction on one or more wheels. You really should not need it on any tarmac road unless there was significant amounts of mud or snow on it.

 

[jaapv]

Both electric motors are always live, no matter what. Engaging 4WD lock does not alter that and it will only function at lower speeds, distributing power evenly over all 4 wheels.

 

[jkh112]

Both electric motors are always live, no matter what. Engaging 4WD lock does not alter that and it will only function at lower speeds, distributing power evenly over all 4 wheels.

One thing I did notice while using 4wd lock at high speed was that when the power flow meter showed the petrol engine directly to the wheels (say 80mph) with no flow from the battery, switching on 4wd lock would start a flow from the battery and turning off 4 wd lock would end the indicated flow from the battery. From this I thought that at those speeds the 4wd lock button engages the rear motor to give 4 wd, and if it was not in 4wd lock mode then the petrol engine was only driving the front wheels.

 

[maby]

Both electric motors are always live, no matter what. Engaging 4WD lock does not alter that and it will only function at lower speeds, distributing power evenly over all 4 wheels.

One thing I did notice while using 4wd lock at high speed was that when the power flow meter showed the petrol engine directly to the wheels (say 80mph) with no flow from the battery, switching on 4wd lock would start a flow from the battery and turning off 4 wd lock would end the indicated flow from the battery. From this I thought that at those speeds the 4wd lock button engages the rear motor to give 4 wd, and if it was not in 4wd lock mode then the petrol engine was only driving the front wheels.

that is my experience too. Reportedly, the control systems always feed some power to the motors but at speed this is reduced to a level that is sufficient to counteract the drag of the motor but not actually drive the car.

 

[maby]

Both electric motors are always live, no matter what. Engaging 4WD lock does not alter that and it will only function at lower speeds, distributing power evenly over all 4 wheels.

One thing I did notice while using 4wd lock at high speed was that when the power flow meter showed the petrol engine directly to the wheels (say 80mph) with no flow from the battery, switching on 4wd lock would start a flow from the battery and turning off 4 wd lock would end the indicated flow from the battery. From this I thought that at those speeds the 4wd lock button engages the rear motor to give 4 wd, and if it was not in 4wd lock mode then the petrol engine was only driving the front wheels.

that is my experience too. Reportedly, the control systems always feed some power to the motors but at speed this is reduced to a level that is sufficient to counteract the drag of the motor but not actually drive the car.

 

[jaapv]

Yes, but the motors are powered up and can be activated instantly by the anti-yaw system.