RExes in existence

Hi Guys,

it can't be that I'm the only REx-er around here. Fellow buzzers: who has got one and how are you getting on ?

Regards, Steven

I have one!

I have yet to use the REx for real; let it automatically start on a flat battery. In fact, I need to force this situation soon as I'm a bit nervous it won't work! However, I have used the hold charge function on a motorway run. It's very quiet - drowned by wind and road noise. In fact I couldn't hear it and had to use the energy flow screen to confirm it was running and generating.

I think it's a good solution to the fact batteries are always going to have limited range.

I have a longish journey tomorrow; 100 hilly miles in total. I'm wondering what the best strategy is:

i) charge up and just drive it - letting the REx kick in when the battery is drained, or
ii) manually fire up the REx and save the battery for later.

I'll need the REx at some point but want to finish up at home with a full petrol tank - I can fill up with electrons at home but filling up with fuel means a stop at a petrol station so I'd rather get that out of the way.

I'm thinking I might do the second half of the outward journey on REx and the second half of the return journey on REx. This means I can top up the petrol tank on the way home.

Hi,

what I did, so far, in the flat Dutch polders if I can't charge long enough along the way, is to activate the REx as early as possible (~75% soc) when on the highway, then drive a little on electricity at the destination, if needed. Then, again if needed, some little bit of REx-ing on the way back as soon as possible and where it is the least inconvenient (mostly on stretches where max 100 km/h (60 mph) is allowed to keep the revs down) until I'm positive I'll be reaching home with a few km of battery left.
I'm really interested to know how the little REx is going to behave in hilly terrain.

Regards, Steven

Idiot that I am, I forgot to zero the trip computer or to record any detailed figures such as initial predicted range, battery remaining etc.

However, I think it all worked as planned.

In total I drove approximately 102 miles and used 40 miles (maybe more) worth of REx and returned home with 20 miles of battery left. The route was hilly (for the UK - the "Hampshire Alps"!) and I used a mixture of country lanes (at 40 mph and under) and the A3 (at rarely more than 60mph). A mix of comfort and eco-mode.

I started on battery (not that you have a choice when it's full) and timed my RExing to allow me to fill up on the way home and then get home on battery. Tomorrow I'll have two full "tanks" and a predicted combined range of around 140 or 150 miles, I think.

Hi fellow RExer

Good to read your RExperiences. I'll be very interested in the fuel consumption in hilly terrain !
Ho'w the engine noise in the hills ?

Regards, Steven

Stevei3 said:

Hi fellow RExer

Good to read your RExperiences. I'll be very interested in the fuel consumption in hilly terrain !
Ho'w the engine noise in the hills ?

Regards, Steven

Click to expand...

I don't think I'm going deaf - but I have yet to hear it. Probably because I've only really used it on faster roads and I had the radio on when I was in the country lanes.

I used the REX on my test drive to see exactly how noisy it was. When we were driving on main roads in excess of 40 mph I could not hear it at all while sitting in the rear seat. When driving at less than 30 mph I could hear the engine from the rear seat but my wife. who was driving, did not notice it.

Hi, I have a Rex but to be honest I haven't tried it yet. I only picked the car up a couple of days ago and haven't had time to try everything but will fire it up in the next day or two just to make sure it works and to see how noisy it is when running.

My parents live about 50 miles away which would be a nervous round trip of 100 miles on just batteries. Whilst I know that this is possible it would make for a stressful journey and the Rex just takes the worry away and allows me to enjoy the journey. As it's a trip I plan to do on a regular basis it really made the Rex an easy decision for me.

Regards

Jon

Hi Jon,

welcome to the i3 Motor Club
I'm looking forward to your experiences regarding your REx.

Regards, Steven

Not sure if this information will help anyone but I did my first REx test on Sunday:

I left home and drove around 11 miles on battery to reach the motorway..... after about another 4 miles I activated REx (battery at 75%), I then carried on using the REx for 82 miles until it ran dry, then let the battery take me another 17 miles. The battery at this point was at 50%, so I refilled with petrol turned on the REx and drove the same route back home. The REx again cut out at 82 miles and remaining battery got me home (32 miles) with 4 miles showing remaining.

It was driven mostly at 71mph using cruise on the motorway section. The conclusion is 41mpg (UK gallon!) at 71 mph and a 66 mile battery range. I left home with a full battery, full fuel tank and managed a 228 mile round journey with one fill up of petrol midway. I'm very pleased with that overall.

I don't live in the flattest part of the UK so this journey is reasonably hilly in places but not mountainous.

Good stuff Paul. I've got a 190 mile motorway journey on Thursday which I'm hoping to do with just one fill-up so if it goes as well as your test it should be fine.

Hi Plug,

I think you will be absolutely fine, I will be very interested to hear how your results compare to mine.

I will confess to slowing up a little bit on the motorway at the end.... 62-65 mph for the last 15 miles of motorway as slight range anxiety started to kick in.... , had the heating/vent on too but the AC was off and it was daylight and no rain.

Just a quick note is that the REx seemed to cope well at keeping the battery at correct state of charge at 71mph, it seems to drop a few miles when you first switch on then maintains it and even catches back up again on the long downhill sections.

Got another long journey planned at the weekend.... may even try 75mph!

Paul

Did you run the Rex until it had actually run out of fuel. If so did the car just continue on the main batteries without hiccup?

Yes I just kept going, have to say I was wandering what would happen too.

It simply counted down to 0 miles then "---" to go then it just stopped and car continued on as if nothing had happened.

I filled up, which amazingly took 8.94 litres, then once on the motorway again selected the REx and it fired up instantly without any fuss....... I don't know why but I guess I was expecting some coughing and spluttering..... BMW seem to have got this just right, it didn't splutter out of fuel, the engine seemed to know exactly when to stop.

I've done 160 m-way miles on pretty much exactly 1 tank and 1 charge. It was cold and we were 4 up plus luggage - but I wasn't going fast (65 - 70, I'd guess).

I've also tried both versions of "running out"; I've drained the tank and seamlessly gone over to battery only - and equally seamlessly gone back to REx after a top up. And I've run the battery flat and seen the REx fire up as promised once down to 2 miles (gulp) of range.

I was a bit nervous about all these evolutions first time around. I'd half expected coughing, spluttering and other side effects of running the tank dry. Not a bit of it - unless you were watching the screens like a hawk (as I was, of course), you'd not be able to discern the various transitions.

I don't think you're allowed to run it dry - I believe it's a pressurised fuel system like a hybrid.

I was told with my Lexus RX Hybrid that you must never run it bone dry - or it would be a recovery job.

For that reason it apparently had the normal "low fuel" warning plus a later secondary emergency warning if you got really low - though I never reached that.

SanSerif - Thats interesting. Others have said that if they let the battery get so low that the Rex will not maintain the power. In fact I understand a local owner managed to run his battery down to 0 then tries to get the Rex to work - that was a recovery job.

Paul1886 - Thanks for the info. I guess from what you say (and Jeremy’s info) that the Rex switches off before it gets totally dry otherwise there would have been some spluttering. Which is surely the right way otherwise we would risk getting contaminates into the engine.

Hi Mike.... absolutely right... as far as I can tell it is really smart and has a very accurate fuel gauge/remaining mileage system that stops the engine before the pipes empty out.

It put a smile on my face when the petrol pump showed 8.94 litres..... I figured it must have F1 type fuel monitoring!

82 miles on 8.94 liters works out to 35 mpg (US) at 71mph. Sweet!

Thanks for taking the time to give us some real-world numbers!