MG4 & Ohme Home Pro Charging Rate?

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FlyingDutchman

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Hi all, I just wanted to see what KW other MG4 owners were getting with their OHME Home Pro (OHP)

I had the OHP 8m tethered installed with this configuration:
  1. 6mm Doncaster EV cable ~ 10m from the box.
  2. 100A into the house, 80A RCD Type A with a 80A Type C MCB.
  3. Set at 32A max, with Load balancing turned on (60A). CT clamp active.

When charging the MG4; the OHP is showing 30.8A however, the MG seems to be continuously cycling between 6KW and 6.4 KW in the car? Never goes above 6.4KW.

Battery heating isn't turned on and the current is not limited.

Thanks, Jan
 
FlyingDutchman said:
Hi all, I just wanted to see what KW other MG4 owners were getting with their OHME Home Pro (OHP)

I had the OHP 8m tethered installed with this configuration:
  1. 6mm Doncaster EV cable ~ 10m from the box.
  2. 100A into the house, 80A RCD Type A with a 80A Type C MCB.
  3. Set at 32A max, with Load balancing turned on (60A). CT clamp active.

When charging the MG4; the OHP is showing 30.8A however, the MG seems to be continuously cycling between 6KW and 6.4 KW in the car? Never goes above 6.4KW.

Battery heating isn't turned on and the current is not limited.

Thanks, Jan
Click to expand...
The car shows what it is putting into the battery after all the system loses are taken into account from losses due to heat in the circuit to loses in the conversion of AC to DC by the onboard charger.
 
Ayoull said:
The car shows what it is putting into the battery after all the system loses are taken into account from losses due to heat in the circuit to loses in the conversion of AC to DC by the onboard charger.
Click to expand...
Thanks for the reply - and you're probably correct. Looking at a few online sources, anywhere between 5 and 15% loses is normal. It'd be interesting to see what other MG4 owners are getting from their Ohme Home Pro :)
 
I've shared this previously: the efficiency calculation is based on kWh stored in the battery (calculated from the %age charge) vs kWh delivered from the charge point (measured/stated by the charge point/app).

1679858117853.png
 
Similar setup, I have a 100 yr old cottage, with very old wiring, both in and out. So needed a new electricity pole, new dropwires, a TN-C earth system, and then a new isolator, henley blocks, meter tails & meter, Doncaster EV cable (10m from meter), CT clamp & ohme pro etc..

Cost = £600 (May 22)

my background charge rate, according to the smart meter is 7.27Kw (consistantly appears at 4am-5am), which includes 20-50w from the house baseload
 
Last edited:
Tig170 said:
Similar setup, I have a 100 yr old cottage, with very old wiring, both in and out. So needed a new electricity pole, new dropwires, a TN-C earth system, and then a new isolator, henley blocks, meter tails & meter, Doncaster EV cable (10m from meter), CT clamp & ohme pro etc..

Cost = £600 (May 22)

my background charge rate, according to the smart meter is 7.27Kw (consistantly appears at 4am-5am), which includes 20-50w from the house baseload
Click to expand...
Wow, a bit of work eh! What KW is the MG4 showing on charge?
 
Omg all this is so alien to me, after driving sporty petrol cars all my driving life, current being a remapped megane RS, but trading it in for an MG4 trophy, is there any website or forum group that’ll teach me what I need to know about charging etc?? 😵‍💫
 
cb15035 said:
Omg all this is so alien to me, after driving sporty petrol cars all my driving life, current being a remapped megane RS, but trading it in for an MG4 trophy, is there any website or forum group that’ll teach me what I need to know about charging etc?? 😵‍💫
Click to expand...
You'll be fine! - its not that bad being a virgin! - its like caravaning in that every one talks to each other when charging, and helps each other out! (at least in Wales, scotland / north of england)

You'll also never need to "remap", as the power band is 0-100% accross the "rev" range - I've come from "semi"-sport cars too (XR2, RS1600i ), and (must be getting old), but the power band is silly.
 
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cb15035 said:
Omg all this is so alien to me, after driving sporty petrol cars all my driving life, current being a remapped megane RS, but trading it in for an MG4 trophy, is there any website or forum group that’ll teach me what I need to know about charging etc?? 😵‍💫
Click to expand...
There's a pretty good beginners guide on electrifying.com that covers everything you'd need to know on EVs - Download our Beginners' Guide to Going Electric | Electrifying

If in doubt, we're all here to help too :)
 
Thanks for sharing your OHP numbers! My MG4 is charging right now with 6.6kw.
54A72F66-C9AF-47E4-BE49-AF518572244D.png


Interesting though, the car / app is out of sync and keeps crashing on refreshes or requests. I always set my target to 80% but to my surprise: It’s set at 100% above. You can see below where the app almost ‘remembers’ it should be 80%.
D4FAC45C-00EC-46F0-9F0E-C68A2FD0D10D.png


E2125679-B700-4BD0-B8C0-263A8EAE02EC.png
 
siteguru said:
I've shared this previously: the efficiency calculation is based on kWh stored in the battery (calculated from the %age charge) vs kWh delivered from the charge point (measured/stated by the charge point/app).

View attachment 16320
Click to expand...
Hi siteguru, great table. Can I ask what type of charger are you using for the 34p charges - granny or 7kW wall box or a mix? And are the differences in efficiency due to temperature or different chargers?
Finally, are your stored kWh figures a measurement or a calculation?
Thanks
 
All the questions you've asked have previously been answered. :) (Green cells in my spreadsheet are user-entry cells - white cells contain formulae).

34p = home wallbox charges (except for one time using the granny lead at my cousin's - that was the lowest efficiency. Some low-efficiency wallbox charges will be when BMS balance has happened)
79p = DC rapid charges

Efficiency depends mostly on the charge source, as the charge has fixed and variable (related to charge source) losses. Fixed losses are a higher percentage, the lower the charge power you use. So a granny lead will tend to have lower efficiency than a 7kW wallbox, and that will be lower than a DC charge source (as the AC/DC converter in the car's charger isn't needed).

Stored kWh are calculated based on the End-Start % figures x Usable Capacity (50.8kWh in my case).
 
Thanks siteguru and sorry if you had to repeat yourself.

Very helpful explanation. I had noticed that the cable to the charger and the charger to the car gets warm charger and that the rate of charge on the charger display is lower than the charging power shown on the MG app and this now gives me an idea of what's happening - and why.
 
siteguru said:
All the questions you've asked have previously been answered. :) (Green cells in my spreadsheet are user-entry cells - white cells contain formulae).

34p = home wallbox charges (except for one time using the granny lead at my cousin's - that was the lowest efficiency. Some low-efficiency wallbox charges will be when BMS balance has happened)
79p = DC rapid charges

Efficiency depends mostly on the charge source, as the charge has fixed and variable (related to charge source) losses. Fixed losses are a higher percentage, the lower the charge power you use. So a granny lead will tend to have lower efficiency than a 7kW wallbox, and that will be lower than a DC charge source (as the AC/DC converter in the car's charger isn't needed).

Stored kWh are calculated based on the End-Start % figures x Usable Capacity (50.8kWh in my case).
Click to expand...
This is actually very interesting because you can manage how fast the car is charged with the Ohme Home Pro.

With intelligent octopus, I charge between the hours of 2330 and 0530. So, I normally set a target (of +30-40%) and the OHP spreads it over that time period.

The OHP also has a setting to be ‘eco’ where it tries to charge when more green energy is being produced.

Right now, the OHP is charging at 3.7kw with the car registering 3.3kw. Around 11% loss.

So, I changed the schedule to trick the OHP into max charging. The OHP charged at 7.1 kw with the MG registering 6.6kw. That is a 7% loss.

To put it in context, I put around 25kwh (on avg.) of juice in the car each night from the OHP. That is for all year round.

Charging at max charge: 1.75kwh loss per night
Charging at eco rate: 2.75kwh loss per night

A nice 1kwh difference means 3.6 miles for me! Multiply it by 365 days and 10p p/kWh and I’ve got a £36.50 saving.

Not a lot in it to be fair, but a pound saved is a pound earned! :)
 
Interesting how the same car and the same charger can have a spread of efficiency. I am beginning to notice a similar trend with our Zappi as in Eco mode it only draws about 1.4kW and then adds in any surplus power from our solar panels. It appears (more trials needed) that on fast charge the Zappi shows 7.1kWh and the car 6.5 (8.4% loss) while on Eco the figures are 1.5kWh and 1.2 (20% loss).
So while the sun was out yesterday I started charging the car on Eco (to last all day) and when the panels went into the shade I switched to Fast (which can be done while charging). The total charge shown on the Zappi was 30.5kWh. During that period the panels produced 8.7kWh - none of which was exported but we did use the washing machine and dishwasher during the day.
Looking at the graphs, I reckon maybe about 5kWh went into the car. That's 15-20 miles of free motoring.
Happy days.
 

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