[LeakingElectrons]

We took delivery of our ZS EV a few weeks ago and have had to rapid charge a few times. The rapid charging is oddly slow compared to the Nissan Leaf that we used to own. It doesn't matter what I do, it always seems to max out at about 20-30kW. Even when the battery charge is low (e.g. 20%), and even if we've already driven a good distance, so the battery isn't freezing cold, I can't get above 30kW. Temperatures have been about 10 degrees on each occasion, so not hot but not freezing either.

This is happening on different chargers (Ecotricity and Instavolt), and I'm using the correct CCS connector.

Is this typical - is the car just not very good at rapid charging, or have we got a lemon?

 

[Maxit]

I posted a screenshot last week as I wasn't sure how to work out what I was getting from a rapid - a member worked it out as 39kw, it was during the cold snap so definitely not close to 10c

 

[WalkingBootWeather]

Coldgate is definitely a thing with the ZS (and quite a few other EVs). There appear to be definite thresholds in terms of state of charge and battery temperature, below which charging seems markedly slower than you might expect. Unfortunately we don't know what these threshold values are. Lots of stories about drivers hammering down the motorway to arrive with single figure SoC and battery that is warmed to 30 degrees plus then getting impressive charge rates but that isn't practical for everyone in the real world.

Anecdotally things do seem a little better since the most recent (Jan 2021) BMS update but other than that the best advice I can give (when driving in cooler months) is:

• Avoid rapid charging if you can. If you can fully charge at home overnight then do that.
• If you are undertaking a long journey then leave with a full battery if you can, drive as far as you dare, ideally arriving at single figure SoC (or at least after first battery warning message displayed when down to last 'blob')
• Rapid charge while battery is still warm. Better to charge as approaching destination than shortly after departing on a return leg)

Note the above may improve charging speeds slightly but in reality I generally charge when most convenient and accept it might take a bit longer than advertised. Things do improve in the warmer summer months.

 

[LeakingElectrons]

Thanks for the advice - I'll wait until it warms up a little and see if the speed improves. Disappointing though, we never had slow charging in the Leaf at those temperatures (I suppose the trade off is when it got too hot and the charging speed went right down!)

 

[Sandy]

What network was the charger on? And what model/make of charger? MG does seem to dislike at least 1 network. Instavolt seem to give the best results for 50kW, Alfa give good results on above 50kW.

 

[MikeProcter]

The ‘problem’ with the MG is that it is water cooled. Driving fast down a motorway at 70mph speeds doesn’t significantly increase the temperature of the battery.

There is only one way to increase the temperature of the battery and that is to rapid charge it! the second rapid charge of the day should be quicker.

Whereas the Leaf only has passive air cooling, so it just gets warmer and warmer until you cook the battery. I had a 24kWh and then a 40kWh that suffered from #rapidgate from day 1 on a 270 mile journey back home from the dealer. On the 3rd charge it throttled right back.

I had the fastest speeds at an instavolt 125kW rapid last summer on my 2nd rapid of the day, it peaked at 72.6kW, having started at 14% SOC whereas the first rapid of the day was on a 150kW BP Pulse charger and I only managed around 35kW, even though our SOC was in the low 20’s%.

the MG doesn’t charge fast with a high SoC when rapid charging or a cold battery.
However with the new BMS it is better.

 

[LeakingElectrons]

Thanks for the advice, Mike. Do you think it would be worth asking the dealer to upgrade the BMS?

 

[MikeProcter]

Personally I would. It would protect the battery long term as not charging as high a voltage and as it gives more regen when full and also improves the rapid charging speed.

 

[LeakingElectrons]

Just an update. Thanks all, you were correct, the problem was the 'cold' temperature. When the weather was nice last week I had no problem jumping straight up to 45-ish kW on the first (PodPoint) rapid. The second rapid, which was an Instavolt 125kW unit jumped straight up to 70kW.