Can you help estimate battery health for me?

[Ian Robinson]

I've picked up a 2023 MG4 SE Long Range with 17k miles. The sales company were unable to get a battery health check as AFAIK later software will not report battery health on the tools they use. I would like to check the battery is healthy bafore the 1 week trial on the vehicle ends. I drove it 38 miles home with a lot of 30,40mph and some 60mph roads and it got 4.7mi/kWh and was showing 216miles range remaining. (88% battery) So total range is 254 miles and 254miles/4.7 (kwh/miles) = 54.1kWh available but it should be 61.7kWh useable... The trip meter was re-set before the trip and was 100% charged. Could other users post their trip summaries so I can work out if mine is normal - many thanks in advance.

If there is another (better way) to find battery health let me know - all MG dealers around me are busy for the next 3 weeks...

 

[Alb]

Get yourself an OBD2 Scanner and the Car Scanner App.
You'll be able to read Battery SOH for yourself.
If you do a search, you'll find lots of recommendations on which scanner to buy.

 

[Tight Git]

I've picked up a 2023 Mg4 SE Long Range with 17k miles. The sales company were unable to get a battery health check as AFAIK later software will not report battery health on the tools they use. I would like to check the battery is healthy bafore the 1 week trial on the vehicle ends. I drove it 38 miles home with a lot of 30,40mph and some 60mph roads and it got 4.7m/kwh and was showing 216miles range remaining. (88% battery) So total range is 254 miles and 254miles/4.7 (kwh/miles) = 54.1kwh available but it should be 61.7kwh useable... The trip meter was re-set before the trip and was 100% charged. Could other users post their trip summaries so I can work out if mine is normal - many thanks in advance.

If there is another (better way) to find battery health let me know - all MG dealers around me are busy for the next 3 weeks...

Let it run down as far as possible and then do a single continuous AC charge - you should be able to get a very rough estimate from that.

 

[Ian Robinson]

Get yourself an OBD2 Scanner and the Car Scanner App.
You'll be able to read Battery SOH for yourself.
If you do a search, you'll find lots of recommendations on which scanner to buy.

Thanks I already had a scanner and tried it today - says SOH is 97% which is very good! I'm very happy with that, I was concerned since the car did so many miles in the 1st year I assume that meant a lot of charging to 100% and a lot of rapid charging at motorway services. From my figures though is a 250mile range expected if I'm getting 4.7 miles/kWh ?? Is it just that the range estimation is very bad? (or efficiency calculation is bad also)?

 

[Ian Robinson]

Let it run down as far as possible and then do a single continuous AC charge - you should be able to get a very rough estimate from that.

By the amount used to recharge it?

 

[Coulomb]

By the amount used to recharge it?

Basically, yes. But it's impractical to discharge to 0% usable SoC, so take the remaining SoC into account as well. But then there is charging efficiency to take into account as well. So it's much easier to just accept the car's SoH estimation instead.

 

[Ian Key]

It sounds like you aren't getting your Trophy from a main dealer so it might be worth a quick email to [email protected] with the registration number asking when the next service is due. The service intervals are 12 months or 15,000 miles which ever comes sooner.

 

[GoElectric]

It really depends on % of throttle used. The closest to 60kWh+ is when driving slowly - up to 55 mph with a very light foot and flat terrain or city driving where you can greatly benefit from regen.

As soon as you get out of these parameters the kWh capacity drops somewhat.

You will notice this especially if you commute daily and track the numbers. At 80% on the screen (20% spent), sometimes you will notice 12kWh spent, sometimes 13-14 kWh spent. Depending on outside temperature and % of power used. The longer you were in the regime above 28% of throttle (fast driving, hills), the lower the number for the 20% spent. Usage will be between 11-14 kWh. And that's normal.

Batteries are not like a fuel tank with a fixed volume. Their capacity fluctuate daily, they're changing due to OAT, % of throttle used, cell imbalance, age.

Considering the description, I'd say your battery is fine.

EDIT: Maybe a link to read up on batteries to help you get acquainted with EVs.

 

[hojnikb]

It's true that batteries have internal losses, that result in lower net capacity, when you drain the battery faster. Also when it's cold, there's going to be less capacity as well.

But as far as drain speed vs capacity is concerend, those losses are a few % at worst, not 15%+. The issue here is SOC, which is not perfectly linear, so using SOC to determine capacity at half charge is just plain inaccurate as hell.

The best way to determine battery capacity is to fully charge it and then fully discharge it to as near 0% as possible and check the energy spent (minus regen benefits) to get a rough idea of net usable capacity.

Or reset the trip computer, drive it from 100% to 0%, check milage and consumption and calculate capacity. Also a decent way to do it.

 

[Tuareg]

Gasoline/Petrol also varies in what energy it can provide. Increase any elevation and more fuel is used per km (unlike an EV), humidity has the same effect (unlike an EV). The difference isn't noticed on an ICE because the fuel gauge isn't in 1/100th segments as on an EV. I would like the EV gauge to be configurable, so it can show 8 segments on the gauge instead of the pointless 'percentage'. After 15% consumption on an EV with an 8 segment gauge it would still show all 8 segments.