Battery power reduced by a third carrying 4 mountain bikes

[djr]

Hi all,

I’m new to the forum and the proud owner of a 3 year old MG ZS EV exclusive (2020 model 44.5 KWh), which I’m very happy with overall, despite a few niggles. I’ve owned the vehicle for 3 months and it's my first EV. I’ve had a couple of holiday trips to North Wales and it performed well and all was fine with range and charging.

Just recently, I had an interesting (and scary) experience, which I would like to share with the forum in the hope that it will be useful to others and may lead to answers to some of my questions.

Basically, I had to do a 25 mile round trip to a mountain bike park and prior to starting the trip I had 70 miles showing on the battery. Unfortunately, the trip led me to almost run out of power. In the final few miles, my battery display went down to 8 miles and then the display went to 3 dashes (replacing the 3 digits) and I thought that was that (there was no 7, 6, 5, 4, 3, 2, 1). Thankfully I did manage to make it home.

Here are some extra details about the journey:

• About three-quarters of the journey was on the motorway and I drove at 55-60 mph on the outward journey and 50 mph on the return journey.
• I was carrying 3 adult mountain bikes on the roof and one in the boot.
• Nobody else was in the car other than myself.
• I drove through a flooded area of road twice (outbound and return journeys). The flooded area was about 5 m long, with the deepest part about three-quarters of the way up the wheel. I didn’t want to do this, but had no choice as I wanted to transport my son’s and his friend’s bikes to the bike park.
• The weather was mild and there wasn’t much wind.

So my questions are:

• Did the drag of the 3 mountain bikes have such an effect on the battery to reduce power by a third (each mountain bike weighs less than an adult, so I doubt the weight was the issue)?
• Does driving through flood water have any effect on the battery (or cause long-term damage)?
• Has anyone else experienced the 3 dashes before?

 

[Jomarkh]

Hi and welcome to the forum.
The GOM is just that a guess it is better to see what m/kWh you are getting. During the summer about 4 is good nearer 3 in the winter.

 

[Gadget Geek]

Hi there and welcome to the world of EV driving.

Aerodynamic drag has a profound effect on any vehicle no matter what fuel it uses. You tend to notice it more in an EV because the range is less than that of an ICE vehicle, so yes, 3 bikes on the roof will reduce your range.

Water will drag at the wheels and body of the vehicle as water is far more dense than air, so yes, driving through water (even rain) will reduce your range.

Speed is a range killer, although your stated speed was very reasonable. I got 3.6m/kWh at 65mph on a journey this week.

I tend to look at the miles per kWh to give me a better idea of how each journey is doing for efficiency, as the Guess-O-Meter averages over your previous journeys. 3.5 m/kWh is a reasonable average, 4+ on the flat or downhill, and less than 3 on uphill stretches.

Mr EV on YouTube did a video on the effect of a roof box on range. Worth a look.

I hope this puts your mind at rest.

 

[dannyf123]

Our anecdotal experience of 4 bikes on the roof is that it decreases the range by about a 3rd. Was expecting a range hit but it was far worse than we thought it would be. We've got a towbar on ours so for long hauls I'll be popping them on a rack on the back.