You waste energy every time you charge to full

[Petriix]

I did a test and made a video. Same journey from full used 1.2kWh more to recharge...

 

[AbuG]

1.2kwh is probably the equalisation charge.. 0.3 for 4 hours...that costs less than 16 pence on a home charge. Should be done once a month.

 

[greentangerine]

6p on my Octopus Go tariff.

We have an MG5 and ZE50 Zoe and plug whichever needs the charge more in overnight on a 00:30 to 04:30 time slot to match the cheap tariff.

We use the heated seats, the air con and the heater if we feel they are needed.

We charge to 100% with abandon.

We don't have sleepless nights over battery equalisation.

We drive them exactly as we used to use our petrol and diesel ICE cars and the sooner people stop stressing about the cost (both in terms of financial and range) of using standard features you wouldn't even consider not using in an ICE vehicle and range anxiety (irrelevant for average car use if you have easy access to a charger) the more you can stress about things that might actually matter in life and instead treat your car as it is i.e. a means of getting from A to B and presumably back again and appreciate that is costs much less to run and is a lot more fun.

 

[Petriix]

1.2kwh is probably the equalisation charge.. 0.3 for 4 hours...that costs less than 16 pence on a home charge. Should be done once a month.

The balance charge was a bit quicker the second time so about 800wH with 400wH due to the limited regen when fully charged.

 

[Petriix]

6p on my Octopus Go tariff.

We have an MG5 and ZE50 Zoe and plug whichever needs the charge more in overnight on a 00:30 to 04:30 time slot to match the cheap tariff.

We use the heated seats, the air con and the heater if we feel they are needed.

We charge to 100% with abandon.

We don't have sleepless nights over battery equalisation.

We drive them exactly as we used to use our petrol and diesel ICE cars and the sooner people stop stressing about the cost (both in terms of financial and range) of using standard features you wouldn't even consider not using in an ICE vehicle and range anxiety (irrelevant for average car use if you have easy access to a charger) the more you can stress about things that might actually matter and instead treat your car as it is i.e. a means of getting from A to B and presumably back again and appreciate that is costs much less to run and is a lot more fun.

A lot of people do charge to full every night. There's no criticism of that. It's just for information. I've not seen any analysis of the wasted energy before.

 

[Frank]

Guys,

Am I missing something here. As far as I know the user (at least for the MG ZS EV, don't know about the MG 5 but I don't think it will be any different) can't initiate an equalization charge as it is the BMS that will tell you on the screen if and when it is required.

I, as you know are one of those strange creatures who plugs in my car every night and just let it do its own thing. Not once in the time I have had the MG ZS over a year did it say to do this, and I have NEVER had any battery related problems with either of the car's batteries.

I am also not convinced about efficiency (I did watch your video ,nicely shot and presented by the way) as no matter how hard you try it is impossible to exactly replicate two drives the same and the amount is not worth the hassle factor for me to change my habit even if it was true.

As stated in my last post I am not advising anyone to follow my habits, everyone to their own.

Have a good weekend.

Frank

 

[Frank]

6p on my Octopus Go tariff.

We have an MG5 and ZE50 Zoe and plug whichever needs the charge more in overnight on a 00:30 to 04:30 time slot to match the cheap tariff.

We use the heated seats, the air con and the heater if we feel they are needed.

We charge to 100% with abandon.

We don't have sleepless nights over battery equalisation.

We drive them exactly as we used to use our petrol and diesel ICE cars and the sooner people stop stressing about the cost (both in terms of financial and range) of using standard features you wouldn't even consider not using in an ICE vehicle and range anxiety (irrelevant for average car use if you have easy access to a charger) the more you can stress about things that might actually matter in life and instead treat your car as it is i.e. a means of getting from A to B and presumably back again and appreciate that is costs much less to run and is a lot more fun.

With you a 100% percent.

Frank

 

[greentangerine]

A lot of people do charge to full every night. There's no criticism of that. It's just for information. I've not seen any analysis of the wasted energy before.

I'm not convinced yet it is wasted energy as (ignoring the wife's Zoe which clearly has as different charging strategy which never seems to obviously balance) I've found what I assume is the balancing' portion of the charge takes longer proportional to how much lower the original lower battery capacity the vehicle started at.

I use emoncms to monitor basically everything electrical in my house and my charger is OpenEVSE so it links into that and have full data at 10s intervals since we've started charging cars last October.

In the end, if the BMS is requesting charge, it is presumably going into the battery. Where else is it going? The MG5 profile is similar to the charging of my 20kWh battery pile that timeshifts the grid usage of my house. Again, my wife's Zoe is different and I've no idea why - but neither do I care.

I'm certainly not knocking the investigation that started this thread but in the end I'm not convinced it's either necessary or worth the effort to intervene.

 

[Petriix]

I'm not convinced yet it is wasted energy as (ignoring the wife's Zoe which clearly has as different charging strategy which never seems to obviously balance) I've found what I assume is the balancing' portion of the charge takes longer proportional to how much lower the original lower battery capacity the vehicle started at.

I use emoncms to monitor basically everything electrical in my house and my charger is OpenEVSE so it links into that and have full data at 10s intervals since we've started charging cars last October.

In the end, if the BMS is requesting charge, it is presumably going into the battery. Where else is it going? The MG5 profile is similar to the charging of my 20kWh battery pile that timeshifts the grid usage of my house. Again, my wife's Zoe is different and I've no idea why - but neither do a care.

I'm certainly not knocking the investigation that started this thread but in the end I'm not convinced it's either necessary or worth the effort to intervene.

The wasted energy is lost as heat. The balancing process uses switched resistors to protect the cells which are already up to maximum voltage and the friction brakes lose energy to heat when regen is limited. It's all in the video.

 

[Petriix]

Guys,

Am I missing something here. As far as I know the user (at least for the MG ZS EV, don't know about the MG 5 but I don't think it will be any different) can't initiate an equalization charge as it is the BMS that will tell you on the screen if and when it is required.

I, as you know are one of those strange creatures who plugs in my car every night and just let it do its own thing. Not once in the time I have had the MG ZS over a year did it say to do this, and I have NEVER had any battery related problems with either of the car's batteries.

I am also not convinced about efficiency (I did watch your video ,nicely shot and presented by the way) as no matter how hard you try it is impossible to exactly replicate two drives the same and the amount is not worth the hassle factor for me to change my habit even if it was true.

As stated in my last post I am not advising anyone to follow my habits, everyone to their own.

Have a good weekend.

Frank

The battery will balance every time you charge to full if you leave it plugged in.

 

[greentangerine]

Yes, accepted. Certainly the regen is the noticeable aspect.

But given the MG BEVs don't have the software to control the charge limit, the resolution requires manual intervention and that's exactly what adoption of BEVs doesn't need.

I suspect my wife's Zoe is a bit more savvy and only balances every so often; I need to look at the charge profiles over the last few months (it is usually charged five nights a week from around 68% to 100%) to see if there are any occasional differences.

And I'm not discounting the cumulative energy usage - once BEV adoption starts rising exponentially, it will add up, which is why the BMS software needs to improve, and it will I'm sure.

But for most of us, it really doesn't matter re: the minimal financial cost as convenience wins every time.

 

[Petriix]

I totally understand the convenience thing. There is an argument about battery health, but that's also likely to be small margins if anything. It's just that I'd never seen it discussed before. It's a the equivalent of leaving a 60w light turned on 24 7. Not a massive deal.

Some of us like to maximise our efficiency. I just noticed that my miles per kWh was always lower when driving with a full battery. I find it all quite fun.

 

[thefunkystoat]

Let’s not forget the extra 2.5 micro grams of mass in a full battery. Doesn’t sound like much, but it’s probably enough to break that boot floor

 

[Petriix]

Let’s not forget the extra 2.5 micro grams of mass in a full battery. Doesn’t sound like much, but it’s probably enough to break that boot floor

Maybe I should make another video about the difference between driving on a full or empty stomach...

 

[Petriix]

Maybe I should make another video about the difference between driving on a full or empty stomach...

I suspect that my 'hanger' will make me drive faster (and less efficiently). But then I'll be able to spend more time charging for free at Lidl while eating their baked goods. But then I'll be fatter so every subsequent journey will be less efficient. But then my range anxiety will lead to weight loss...

 

[Davloc]

Some of us like to maximise our efficiency. I just noticed that my miles per kWh was always lower when driving with a full battery. I find it all quite fun.

I have noticed this as well. My short journey to work achieves 3 miles per kWh below 80% but only 2.6 if above 80%. Full level 3 regeneration coming off the dual carriageway shows -125 amps ( the same as I've had from a 50kW rapid charger) below 80% charge but maxed out at 70 or 75 when above 80%. Didn't check the rates at 95%.

I now try to avoid charging above 80%. I like having full regen braking available and don't need to charge to 100%. I'm only using about 50% capacity a week at the moment.

 

[Kithmo]

Not really an accurate test, same journey yes, but same traffic ? same wind direction ? etc.
It needs to be run several times for each scenario (100% v 87% charge) and each scenario on the same day and over a period of several days to prove anything.

 

[Davloc]

All other variables being equal, the regeneration available and hence, recovered energy, is lower above 80% SoC than below. I'm assuming this is reflected in the miles per kWh the car displays.

 

[Petriix]

Not really an accurate test, same journey yes, but same traffic ? same wind direction ? etc.
It needs to be run several times for each scenario (100% v 87% charge) and each scenario on the same day and over a period of several days to prove anything.

Yes, it would be great to run the same test several times. It occurred to me that the battery was warmer at the start of the second test so that might have made it more efficient. The wind was pretty similar in both tests but the traffic and run of the lights were different.