Battery drain (10%-3% overnight) ?

[dragon2611]

Oddness continued today... Charged to 60%. Drove over 12 miles ... In this time it went UP to 61% (!) Then started to drop "normally". I'm not overly worried it's just slightly odd and makes for pretty unpredictable behaviour/journey planning etc more random. frustrating to have to build in higher tolerance for journey planning ...

Was it mostly downhill?.

Where I tend to take the dog at weekends it's mostly uphill on the way there and downhill on the way back, so I use a lot more charge getting there than I do getting back and i've seen the SOC actually go back up by 1% on the downhill stretch due to the regen.

 

[Gadget Geek]

Was it mostly downhill?.

Where I tend to take the dog at weekends it's mostly uphill on the way there and downhill on the way back, so I use a lot more charge getting there than I do getting back and i've seen the SOC actually go back up by 1% on the downhill stretch due to the regen.

That actually defies the laws of thermodynamics.

 

[frb123]

Was it mostly downhill?.

Where I tend to take the dog at weekends it's mostly uphill on the way there and downhill on the way back, so I use a lot more charge getting there than I do getting back and i've seen the SOC actually go back up by 1% on the downhill stretch due to the regen.

It was a hilly area but not excessively downhilly...

 

[dragon2611]

That actually defies the laws of thermodynamics.

I suspect the SOC going up is just because of rounding (I.e it's not a full 1%).

Also just to be clear I don't mean I end up with more charge than I started the journey with, I mean I've seen the SOC number increase by 1% between what it was showing at the top of a hill and the bottom of said hill.

 

[Tim Green]

In my Mk1, I am amazed how stable the GOM is over a period of days or even weeks. Ambient temp seems to make a difference to max charge when charging, but not thereafter.
Also, does ambient temp affect the ACTUAL miles that the car can go, rather than the GOM? Not sure how one could easily check that….

 

[dragon2611]

In my Mk1, I am amazed how stable the GOM is over a period of days or even weeks. Ambient temp seems to make a difference to max charge when charging, but not thereafter.
Also, does ambient temp affect the ACTUAL miles that the car can go, rather than the GOM? Not sure how one could easily check that….

Pretty sure it does, was travelling up the M6 on a cold/wet evening (About 5C I think it was) and car was showing 2.6Mi/Kwh

Continuing at that consumption It would have been a bit close to get home so I stopped a second time to charge. (I got better consumption for the rest of the journey likely to terrian and weather)

Also both Gridserve chargers were crap that evening, not sure if it was the chargers or the car but even the 350kw ones were only giving me 31kw.

Ideally I'd have been able to do said journey without stopping to charge but I didn't start with a particularly high SOC and the slow charging at the first location meant I didn't leave there with as high a SOC as I'd have liked.

In hindsight I should have probably tried a different charger incase I got a faulty one but it was just after getting the car so I wasn't sure how normal 31kw was given the temperatures

 

[DB Go Rex]

In my Mk1, I am amazed how stable the GOM is over a period of days or even weeks. Ambient temp seems to make a difference to max charge when charging, but not thereafter.
Also, does ambient temp affect the ACTUAL miles that the car can go, rather than the GOM? Not sure how one could easily check that….

Yes. It's already a known thing:

How Does Temperature Affect Battery Performance?

As energy storage adoption continues to grow in the US one big factor must be considered when providing property owners with the performance capabilities of solar panels, inverters, and the batteries that are coupled with them. That factor is temperature. In light of recent weather events, now...

www.greentechrenewables.com

 

[Tim Green]

What's a "known thing"?

 

[DB Go Rex]

What's a "known thing"?

You asked "how one could check that", I was just stating that degraded performance of the battery in the cold is a "known thing", so that check would only prove what was already known.

 

[Tim Green]

The question is: "Does cold weather affect the charging of the battery, and hence the resultant GOM, or does it effect the actual mileage achieved, or both?

 

[DB Go Rex]

The question is: "Does cold weather affect the charging of the battery, and hence the resultant GOM, or does it effect the actual mileage achieved, or both?

100% it affects actual mileage, that's a known property of a LiOn battery. That also has an effect on charging as the BMS will protect the battery at lower temperatures by charging it more slowly.

On the GOM, I don't know know the exact algorithm it uses to guess, but at the very least, if it's using past driving data from where it has previously been cold then that would be a yes also.

 

[Spotthedog]

Just to add my thruppence worth. The battery is your friend. I've also noticed this tendancy for the available charge to fall off a slight cliff after a long, journey when the battery has been nicely warmed up. One day over the recent winter, I parked my Trophy LR with about 17 miles range left and returned to the car just 2 hrs later to find it showing just 1 mile range. This represented a drop of around 6-7% of the cold weather range at the time. Bit of a lesson there! More recently, in warmer temps, I noticed a drop from 15% to 12% when parked for about 45 mins. I was sort of anticipating something like this after the winter experience so not really surprised. I don't see it as a problem (now that I know about it, that is!) but as something to be aware of and to add in to the mix if making longer journeys and calculating recharge stops. Probably wise to add sufficient charge as soon as you stop, ie, while your best friend is still warm and accepting a pampering.

It's a feature of the battery technology so we need to take it into consideration and live with and around it.

 

[Gadget Geek]

On the GOM, I don't know know the exact algorithm it uses to guess, but at the very least, if it's using past driving data from where it has previously been cold then that would be a yes also.

This paper is quite interesting.

Effect of Temperature on the Aging rate of Li Ion Battery Operating above Room Temperature - Scientific Reports

Temperature is known to have a significant impact on the performance, safety and cycle lifetime of lithium-ion batteries (LiB). However, the comprehensive effects of temperature on the cyclic aging rate of LiB have yet to be found. We use an electrochemistry-based model (ECBE) here to measure...

www.nature.com

 

[JCFlippen]

This is why I try to find somewhere to charge before setting off the morning after (if there is no destination charging).

E.g. drop the wife and kids off at the hotel and then drive to the charger and leave it there for 45 mins before returning for the evening.

Good plan. This is what I do as it takes away any stress, also charging when battery is warm.

 

[Sergio Almeida]

So... Completed another long journey cross country yesterday. Arrived with 10% battery and 20 or 21 estimated GOM miles (in Normal). Ambient temp I would guess at 10-12 degrees. Had nailed it, arriving with 10%, or so I thought! Surely a reasonable buffer to aim for?

Intended to get up this morning and charge nearby as my destination didn't have private charging. Ambient temp 8 degrees.

To my horror as per the title it had dropped from 10% to 3%, displaying --- on the GOM (and 6 miles on the battery screen).

This seemed like a sheer drop.
I would expect small fluctuations (ambient temp, battery temp, general weather etc) but this seems extreme - would you agree?

The first chargers I went to we're both in use ? and the second, thankfully, available. They were both within 0.5 miles or so, so no drama in that regard. But it was an unpleasant moment for sure!

Comments/thoughts/suggestions as to cause / future "remedy" (or how to avoid!) welcome!

I have the same issue with the MG ZS EV 2021. it is driving crazy because I have to plan the journey plus how many hours i will spend charging the vehicle plus sometime the GOM do get me to my destination I have to stop before I get to my destination to charge.

 

[Tim Green]

Curiously, my Mk1 zs has never shown any degradation in GOM from when it was last parked up. I was surprised at that. But the models described above are mostly long-range models with different battery technology.

 

[Data]

Interesting thread. Just bear in mind, as said by others, that temperature will affect shown range & actual range. You MAY see some small drop in shown range on the GOM as the battery cools down after a run. This will be further exaggerated if the battery isn't in an equalised state. All this can happen at anytime but especially in cooler weather in winter. So regular equalisation charging about once per month as per your owners manual is important. It preserves range & battery state of health. Further, if the battery has not been equalised for some time it can take a couple of equalisation charging sessions to bring the battery back to where it should be.