Strange charging problem MG4 51

[T1 Terry]

Woken up this morning with the MG beeping its horn in a regular pattern. Turns out that the MG supplied granny charger has died after 2 weeks use It had been plugged in for 2 days, the screen said it was charging, but it was still at the same 74% it was at 2 days ago.

Dug out the Aussie made unit that can charge from 10 amps or 15 amps, charging commenced and I, quite by accident, discovered that a double tap on the charging section on the home screen opened up a page dedicated to charging. This also showed it was charging, but zero going into the battery .....

Messing around in there, I found a charging limit, tried the 6 amps, still nothing, 13 amps ..... charging at 300w .... Back to the Aussie unit, it said it was putting in 2kw .... WTF

Turned off the air con, bingo, now it read 1.3kw .... so the air con uses 1kw but where was the other 700w between the Aussie charger adapter that read 2kw and the screen reporting 1.3kw ...... is this normal, or do I have a problem already .... I was hoping for a honeymoon period at tad longer than 2 weeks ......

 

[ReintjeWA]

I too get about 1.4 kW when on the MG granny charger (and an extension cord).

 

[Martinonline]

Sorry to hear about your MG Granny Charger. Mine worked well for a year before I got an EVSE.

You should need only one tap on the battery level tile on the home page to get you to the next level.

As you say there are losses in the system and, also, different reports of power being supplied. Thus from my power meter in the image below the App reported 1.95kW rather than the 2.25kW the power meter said was being supplied.


But, from another charging session, the App reported higher than the car:

Confusing or what?

 

[siteguru]

Car reports what's going into the battery - app reports what's going into the car?

 

[Martinonline]

Could be. But then again there is the difference between what the power meter shows and that on the App, ~300W in the first image. If the losses are consistent then the total losses would be ~500W between mains and battery.

 

[T1 Terry]

Mine reports a 700w loss, that's a lot of wasted energy when it takes 20 hrs plus to recharge the battery. I certainly need to do some more testing and research to determine if AC charging is even feasible from the motorhome solar and battery, maybe I need to research into direct DC charging, even if it would be the slowest ever DC fast charger as Coulomb suggested on another forum

T1 Terry

 

[decrep]

ours, shows 1.75 coming from the grid. car says 1.4 into battery

 

[pollenface]

It's quite normal to have some efficiency/heat losses during an electrical charging process. Typically more power is consumed from the grid than what reaches your HV battery.

ours, shows 1.75 coming from the grid. car says 1.4 into battery

That would imply that it's charging at 80% efficiency at that given point in time.

I certainly need to do some more testing and research to determine if AC charging is even feasible from the motorhome solar and battery

I intend to do the same from a 300ah Lifepo4 battery in the back of my diesel 4x4, when we take both cars camping. I estimate I could provide about 15-20kms

 

[T1 Terry]

I will have to investigate further, the 700W variation between what the magic box says and what the car says means a lot of solar power would be wasted. I'd much prefer to waste the solar on running the air con rather the creating heat in the MG charger box.

I just finished the first part of swapping out the Full River 120Ah lead acid door stop for the 600Ah Sodium ion. As of about 15 mins ago, we are running off the Sodium ion batteries ..... the lights no longer flicker when the water pump runs, so that's a plus

T1 Terry

 

[decrep]

I will have to investigate further, the 700w variation between what the magic box says and what the car says means a lot of solar power would be wasted.

That's twice the difference we get I suspect something is wrong. We have a very similar car

 

[T1 Terry]

That's twice the difference we get I suspect something is wrong. We have a very similar car

Maybe it takes more electricity because it's generated from renewable sources, not as concentrated as the coal fire stuff

T1 Terry

 

[pollenface]

I will have to investigate further, the 700w variation between what the magic box says and what the car says means a lot of solar power would be wasted.

I've observed a few different charge rates between 1.5-3.4kW at different SOC/temperature/etc. It seems to wander between 68-86% efficiency with 230-700W loss.

 

[T1 Terry]

I've observed a few different charge rates between 1.5-3.4kw at different SOC/temperature/etc. It seems to wander between 68-86% efficiency with 230-700w loss.

Thank you for that, at least I know I'm not alone with this savage drain, I wonder what causes the variation in efficiency ..... I know to turn the air con off, that's a kW on its own, but 700W loss between the ac in and the dc into the battery is savage when there is only 2kW to start with .... maybe the ac voltage might be something to do with it ..... I'll check that out when I have the solar and 5kVA inverter installed, that will supply a constant 240VAC if I tell the inverter that's what I want ....

T1 Terry

 

[pollenface]

Okay, my grid feed AC power varies depending on time of day, i see 219V at night and up to 252V during the day when everyone's solar is feeding the grid.

Agreed 700W @ 2kW does seem savage. I think it would be hard to challenge that point with the service centre unless the AC charging system was critically failing.

 

[TonyF]

According to iSmart, my XPower charges on granny at 1.3 to 1.6kW. Usually 1.4-1 5.

My solar app tells me charging draws 1.5 to 1.9kW. I assume peak charging occurs at peak draw, so ~2-300W are lost. All figures approximate.

 

[T1 Terry]

Okay, my grid feed AC power varies depending on time of day, i see 219v at night and up to 252v during the day when everyone's solar is feeding the grid.

Agreed 700w @ 2kw does seem savage. I think it would be hard to challenge that point with the service centre unless the AC charging system was critically failing.

Our supply is often down around the 218VAC, the factory that was on this site before we bought it was a very heavy power user and they had to chip in towards a new supersized transformer on the poles at the front gate. As soon as that factory type work ended and it returned to more of a workshop, SA Power pulled the supply links for that transformer, yet the joiner workshop beside us has installed even bigger more equipment that sucks the power, so the voltage drops ...... even though we have a mega solar farm less than a km from our back fence ...... seems all that power goes into the interconnector to be sold interstate

T1 Terry