Roof box effect on range

[DaringSquirrel]

Wondering if anyone here has any experience with long journeys in the ZS when using a roof box and what effect this has on range?

The faster you go with a roof box is going to have an even bigger effect on the overall range than without, but I'd like to get a feel for how big this effect is before taking the plunge and joining the MG EV club and how many recharging stops I need to plan for camping trips

 

[Severnless]

Ohh yesss the range will be hammered!!!

We have a regular 144mile run from the midlands to Pembrokeshire, tend to go the cross country route (rather than motorway, a40) so via Builth wells and Carmarthen, lots of hills and twisty roads.
We have done it in the past in one charge, with 10 miles left..
But recently did it with a roof box, (admittedly it was a frosty day), we started of in eco but with some heat on (for the kids) and after a few miles I checked the efficiency, 2.8 miles/kWh! and by the time we got to Builth we were on 10 miles and down to 2.1 miles/kWh!
Luckily Builth have 2 new charge points but they are only type 2, Builth to Llandovery is 24 miles and Zap-Map was reporting that CCS was out of order! So we waited on the type2 until we had 30 miles range and just went for it!
Got to Llandovery CCS with no range showing!! There was no one at the rapid point and it looked like it was working, so shall we say I was doing a lot of praying when it was plugged in and it went through all the checks.
Let out a bit of a whoop when it clunked and started charging!!
Took it to 95% to make sure we could get to Tenby without any problems, which was over an hour on charge.
Got to Tenby with 20 miles showing and 1.8miles/kwh
So if you plan to use a roofbox make sure you have plan a,b,c,d for charging on the way!

 

[Mark Holmes]

Ohh yesss the range will be hammered!!!

We have a regular 144mile run from the midlands to Pembrokeshire, tend to go the cross country route (rather than motorway, a40) so via Builth wells and Carmarthen, lots of hills and twisty roads.
We have done it in the past in one charge, with 10 miles left..
But recently did it with a roof box, (admittedly it was a frosty day), we started of in eco but with some heat on (for the kids) and after a few miles I checked the efficiency, 2.8 miles/kWh! and by the time we got to Builth we were on 10 miles and down to 2.1 miles/kWh!
Luckily Builth have 2 new charge points but they are only type 2, Builth to Llandovery is 24 miles and Zap-Map was reporting that CCS was out of order! So we waited on the type2 until we had 30 miles range and just went for it!
Got to Llandovery CCS with no range showing!! There was no one at the rapid point and it looked like it was working, so shall we say I was doing a lot of praying when it was plugged in and it went through all the checks.
Let out a bit of a whoop when it clunked and started charging!!
Took it to 95% to make sure we could get to Tenby without any problems, which was over an hour on charge.
Got to Tenby with 20 miles showing and 1.8miles/kwh
So if you plan to use a roofbox make sure you have plan a,b,c,d for charging on the way!

Just as a matter of interest did you increase the tyre pressure to 42 PSI cold for a fully loaded car...

 

[Severnless]

@Mark Holmes, nope didn’t check them or adjust them, as I had a couple of tired and grumpy kids and we set off at 4.30am! Hopefully making them fall asleep, but no, awake all the way there!

 

[Mark Holmes]

@Mark Holmes, nope didn’t check them or adjust them, as I had a couple of tired and grumpy kids and we set off at 4.30am! Hopefully making them fall asleep, but no, awake all the way there!

That could make a big difference if not inflated to the correct PSI with a battery vehicle should be 42 PSI when cold about 44 - 45 when running...

 

[Gomev]

That could make a big difference if not inflated to the correct PSI with a battery vehicle should be 42 PSI when cold about 44 - 45 when running...

That's quite a leap from the 33 cold unladen.
I've been trying to find the tyre pressure recommendations in the online user manual but can only find the unladen pressures.

 

[Severnless]

That could make a big difference if not inflated to the correct PSI with a battery vehicle should be 42 PSI when cold about 44 - 45 when running...

Like I said, when dealing with young children very early in the morning the last thing on my mind is running around and changing the tyre pressure!
Besides we have done the journey before in one charge, loaded the same, so the only difference was the roof box, which this time absolutely hammered the range.
I do agree with you about the tyre pressure when loaded, It’s just life gets in the way of ticking every box in ev life.

 

[Elec Car Aust]

Like I said, when dealing with young children very early in the morning the last thing on my mind is running around and changing the tyre pressure!
Besides we have done the journey before in one charge, loaded the same, so the only difference was the roof box, which this time absolutely hammered the range.
I do agree with you about the tyre pressure when loaded, It’s just life gets in the way of ticking every box in ev life.

Lol, we agree with young kids an EV just have to fit into your normal life as best as possible. Great info on the box as I was thinking of doing similar on our next camping trip. Won't be that cold though.

 

[Evie]

@DaringSquirrel - attached is my experience on a trip from Melbourne to Sydney driving on the Hume highway where the speed limit is 110km/h. You can see the average speed in the photos... where it is around 100, I was driving at the speed limit the whole way aside from getting on/off freeway from charging stations. Others that were lower I was varying my speed a little... in particular slowing down on some of the hills.

Also I have 127cm Thule bars, which are a bit wider than standard.

 

[Elec Car Aust]

@DaringSquirrel - here is my experience on a trip from Melbourne to Sydney driving on the Hume highway where the speed limit is 110km/h. You can see the average speed in the photos... where it is around 100, I was driving at the speed limit the whole way aside from getting on/off freeway from charging stations. Others that were lower I was varying my speed a little... in particular slowing down on some of the hills.

Also I have 127cm Thule bars, which are a bit wider than standard.

Hi Evie, the photo/link doesn't appear to be working.

 

[Evie]

Hi Evie, the photo/link doesn't appear to be working.

I have added an attachment to above message instead. Sorry... noob here.

 

[DaringSquirrel]

@Evie thanks for the detailed notes on your journey. I've attempted to do some maths to work out your overall range and now my brain hurts, so I'm going back to bed.

From the photos the journey at avg speed of 99 km/h was showing 23.1 kWh/100km - which if we assume a 40 kWh useable battery (when new) gives you an overall range of 173 km.

Or 107 miles for those of us in the UK, where for some reason we still use miles for distance and mph for speed and yet sell petrol by the litre.... it's all very confusing so best to have a drink to relax.

Although when the pubs are open if you want a beer it comes in pints but all wine and spirits are sold in ml so best to just ask for vodka by the bottle, I find it makes it easier that way.

 

[Elec Car Aust]

I have added an attachment to above message instead. Sorry... noob here.

Thanks Evie, good info to know when prepping for camping trip and charging stops, particularly as we often travel in regional Australia.

 

[SCB86]

It would be better if we could fit a tow bar; you can get really good storage boxes mounted to tow bars and it doesn't affect drag anywhere near as bad as a roof box.

 

[Elec Car Aust]

It would be better if we could fit a tow bar; you can get really good storage boxes mounted to tow bars and it doesn't affect drag anywhere near as bad as a roof box.

Agree! Although I don't think those towbar mounted boxes are legal here in Aust. Anyone know?

 

[Scorpion]

@Evie thanks for the detailed notes on your journey. I've attempted to do some maths to work out your overall range and now my brain hurts, so I'm going back to bed.

From the photos the journey at avg speed of 99 km/h was showing 23.1 kWh/100km - which if we assume a 40 kWh useable battery (when new) gives you an overall range of 173 km.

Or 107 miles for those of us in the UK, where for some reason we still use miles for distance and mph for speed and yet sell petrol by the litre.... it's all very confusing so best to have a drink to relax.

Although when the pubs are open if you want a beer it comes in pints but all wine and spirits are sold in ml so best to just ask for vodka by the bottle, I find it makes it easier that way.

Would that be a 70cl or 1 litre bottle of vodka