Electric Defenders Off Road
Having recently completed the electric conversion on a Defender 90 which is not destined to go to a customer right away, we’ve been taking the opportunity to put the wagon through its paces on a number of different missions. Our latest escapade has involved taking it off-road onto some green lanes around Hampshire, accompanied by two other all-electric 4x4s: A Defender 110 which we converted last year, and a VW Syncro 4x4 which was converted to electric by Sean from RetroVolt EV Conversions. In this blog we’ll take a closer look at how the three cars performed in muddy conditions.
Taking an electric-powered Land Rover off-road in slippery conditions is quite a different experience compared to driving its diesel counterpart. With its silent operation, instantaneous torque, and zero-emission capability, an electric Defender is on paper a great choice for off-roading. Our guide for the morning was Sean, a local to the green lanes in the area. Sean has completed two EV conversions from his home workshop and uses his Leaf-powered VW Syncro as a daily commuter as well as a weekend mud-basher. Being the first time out on mud for our Defenders, we were unsure how they’d perform. We were pleasantly surprised.
As it’s relevant to what we found on our trip out, let’s first-up get into some technical details about 4x4 drivetrains that will help. A differential is a component of a vehicle's drivetrain that distributes power from the engine to the wheels. It allows the wheels to rotate at different speeds when turning (vital when turning on tarmac or you could break a drive shaft), but when one wheel loses traction, all power will be transferred to the wheel with the least resistance. A limited slip differential (LSD) and a differential lock (diff-lock) are two different methods of controlling the distribution of power to the wheels.
An LSD is a type of differential that is designed to limit the difference in rotational speed between the two wheels on an axle, but for both wheels to still have power being transmitted to them. It provides for improved traction in slippery or uneven conditions, such as off-road driving. On the other hand, a diff-lock is a mechanism that completely locks the differential, forcing both wheels on an axle to rotate at the same speed. When one wheel is spinning in deep mud, a differential lock can be engaged to force both wheels to rotate together, improving traction and helping to get the vehicle unstuck. In comparison, an LSD is less extreme than a differential lock, and provides better handling and stability under normal driving conditions, and can of course be used on tarmac. However, a differential lock provides maximum traction and stability when off-roading or driving in extreme conditions and should not be used when on road unless you only ever drive in a straight line!
OK, so back to our three wagons lined up and ready to go off-road:
The VW Syncro is a very capable 4x4, designed in the late 70’s, in part for off-road military use. It is equipped with a centre diff-lock coupler that allows the front axle and rear axle to be locked together and get equal power from the electric motor. It also has remote actuated front and rear diff locks, meaning the driver can lock all three differentials (front, centre and rear) and enjoy true 4x4 power distribution to all wheels when off-road. By comparison, our Defenders are both lacking LSDs or diff-locks on their front and rear axles, a deliberate decision that we took in order to find out what they’re like off-road before we switch them over to having modern LSDs. The 110 does however have an LSD fitted in the centre of the car, installed within the Tesla Model 3 motor which is located where the old transfer box would have been. By having this, we can ensure the 110 has generous power delivery to both front and rear axles, even if power might then all end up on the left or right sides of each axle. You could say the 110 can as such only guarantee two wheels will turn if it gets stuck in mud: One from the front and one from the rear. Finally, our Defender 90 has no diff locks or LSDs at all, meaning that in really slippery mud, there’s a chance that all the power will find its way to just one wheel, resulting in poor performance (and a shout out to one of the other wagons for a tow).
Driving an electric-powered Defender off-road requires a slightly different approach than driving a diesel-powered one. The electric powertrain delivers instant torque, which can be both an advantage and a disadvantage when driving in muddy conditions. On the one hand, the instant torque helps to deliver maximum traction and control, allowing the driver to power through muddy sections of the trail with ease. On the other hand, the instant torque can also make it easy to lose traction if the driver applies too much power too quickly. Starting with a light touch on the accelerator and gradually increasing power as needed, it’s soon found to be very easy to drive. No clutch, no gear changes, not having to worry about “peak torque”, and all the while being almost silent, as a driver you can hear the noise of the tyres gently gripping the terrain. Both our Defenders use throttle pedals from a Tesla which we’ve mapped to require quite a lot of travel before significant power is delivered, really helping with putting down the power slowly and carefully.
After a short while it became obvious to all three drivers that the Defenders were keeping excellent grip, even in some quite challenging mud. There was no evidence of loss of grip, even on the 90, with its potential for one wheel spin. Clearly we were not taking the wagons into serious “competition” style routes, but we were certainly going way beyond the sort of terrain anyone would encounter if they were heading down a farm track or across a field to park up for some outdoor pursuits. We progressed along for around an hour, with a few deeper muddy water sections and were yet to find anything that could cause concern.
As expected, battery consumption while driving off-road was low. Cruising along at low speeds, with minimal wind resistance and applying only very small amounts of power, we used only a fraction of the battery capacity over the course of the morning. Had one of us needed to tow a material distance, that might have changed the dynamics, but luckily the two ropes stayed firmly stowed. We all emerged from the end of the last green lane with plenty of charge left to get home via the pub for a drink. Sean was on stand-by to offer “vehicle to vehicle” charging from his Syncro, his latest party trick on a wagon that can also deliver 240v to a kettle or coffee machine when out and about. We love this and will be investigating incorporating it into our future builds. We declined the offer of a boost, comfortable knowing we have our own party trick: Both Defenders support CCS public fast charging, which allows for up to 80 kW charge speeds on the Defender 90.
We often get asked if our EV converted Land Rovers are suitable for wading in deep water. The short answer is yes they can, with caution. The motor is fully waterproofed, as are the battery packs. Our standard conversions don’t include waterproofing of the seat boxes where some of the EV systems are kept, so it certainly wouldn’t be a good idea to wade beyond door sill height without having requested us to fully waterproof the seat boxes (a small additional job we can do during conversion). On our trip out we didn't have the opportunity to wade much beyond the centre of the wheels, but all three cars did successfully survive the jet wash afterwards.
Having returned to base safe and sound, the three of us reflected on the performance of the Defenders compared to their original diesel format. There’s a definite improvement in the ease of handling by being electric-powered and getting rid of the clutch and gear stick. The instant torque provided by the electric motor helps to deliver traction in a controlled manner, and the almost silent operation of the motor really does help you feel more connected to what you’re driving over, as well as helping you feel a little less of a disturbance to the natural surroundings. And the lack of black smoke pumping out the rear does go a decent way to helping feel more in tune with the green lanes. On the topic of LSDs for the Defenders, it’s a tough call. To do a full front and rear upgrade, moving to LSDs with uprated half shafts is around £3,000 plus labour to fit. Then the Tesla LSD is another £2,000 plus labour. We feel we proved that in base format, a Defender with no LSDs is actually fine off road, but perhaps for peace of mind and thinking of what driving on an icy incline might be like, having the centre LSD fitted into the Tesla motor is a good compromise, as per what we have in the Defender 110.
Very contented Electric Off roaders, Andy, Sean, and Julian
If you enjoyed reading about our electric off-road adventure and would like to find out more, please get in touch. We’d love to chat!