Is it ok to charge to 100% with a granny charger?

[Cliff Mitchell]

I have recently purchased a MG ZS EV and have been trying to learn about it. Currently I charge with the Granny charger provided with the car. It takes a long time to charge, although normally I am in no hurry. A number of articles recommend you do not charge to 100% - is this the case, or does it generally relate to fast chargers?

I am in the process of have a 32amp dedicated circuit put into my house so that I can use a 7 kw home charger - can I charge to 100% with this charger? Any advice would be appreciated.

 

[ARealHuman]

Hello and welcome. Congratulations on your new car! The granny charger is the slowest method of charging your car, and there's nothing wrong with that if it suits your needs. I don't use it myself, but I see no reason why you can't or shouldn't charge to 100% with it - I'm sure someone more informed than me with granny chargers will respond. a 7kw home charger - known as a fast charger - will charge you to 100% no problems, this is what I use. A rapid charger - often found at motorway services and the like - will charge up to 80% fairly quickly, then the charging rate will plummet. I understand this is due to battery chemistry. Charging etiquette in these circumstances seems to be charge to 80% then leave.

There's lots of debate about fully charging or not. Your car has a battery management system (BMS) that will take care of the battery's health and balance the individual cells when it's needed. When I charge mine overnight at home, I always charge it to 100%. I don't worry about maintaining a 100% charge when the car is in use over a period of days, and will charge it when it gets low. The consensus seems to be that leaving a car with a full charge or very low charge could be detrimental to the battery, but as I said, use the car and rely on the BMS to look after the battery!

 

[Cliff Mitchell]

Thanks for the feedback. Where I come from there are very few EV owners (distance is a big issue here). Getting information about the car is from an owner is rare. Thanks again - just as a matter of interest how long have you had the MG ZS EV and how many kilometers/miles have you done?

 

[ARealHuman]

Thanks for the feedback. Where I come from there are very few EV owners (distance is a big issue here). Getting information about the car is from an owner is rare. Thanks again - just as a matter of interest how long have you had the MG ZS EV and how many kilometers/miles have you done?

You're welcome. Plenty of others will be able to offer their experiences too. I've had mine since September last year, and without double checking have only done about 1700-ish miles due to lockdown here

 

[Kithmo]

The manual recommends balancing the battery once a month, that is charge to 100% then leave the charger connected until the front MG badge goes out completely.
Mine shows 97% charge on the app, when the car says 100%, so the BMS stops you charging to 100% anyway.

 

[DaveA70]

I used my granny for a couple of months and it worked just fine and found it needed about 22 hours or so. I went ahead and had a 7kW faster charger installed so been using that.

There’s a bit to learn with your new EV but it’s straightforward and I am sure you will quickly get used to a routine that suits you.

 

[2of3]

My wife uses the granny charger every time she's at work. It's been enough so that we rarely have to charge at home on the 7kw!

Nothing beats free power!

 

[AussiePete]

I've been using my granny charger to charge since I picked up my car (new) in December. Charges fine and I've not had any issues so far. I always plug in when I get home (unless I've done a really short trip - say 10 miles) so it's always fully charged when I need it.

Only thing I'd suggest is to check the socket you plug into every now and again to see it's not getting too hot or showing cracking as some sockets aren't rated to take a continuous load of 10-13 amps

 

[AbuG]

A number of articles recommend you do not charge to 100% - is this the case, or does it generally relate to fast chargers?

.... - can I charge to 100% with this charger? Any advice would be appreciated.

There's no hard set rules, people differ on this. However its probably best to charge to about 80-90% if you don't need the full range. But will need to do full charge at least once a month so that it can do an equalisation charge. If you use lots or rapid charging it may be worth doing this more often.
The main suspected detriment is leaving the car on full charge for prolonged periods (like 1 to 2 weeks) without using at all. In this situation better to leave around 70% or so.
Obviously if you need the full range, then charge to max on AC charging.

 

[Cliff Mitchell]

I've been using my granny charger to charge since I picked up my car (new) in December. Charges fine and I've not had any issues so far. I always plug in when I get home (unless I've done a really short trip - say 10 miles) so it's always fully charged when I need it.

Only thing I'd suggest is to check the socket you plug into every now and again to see it's not getting too hot or showing cracking as some sockets aren't rated to take a continuous load of 10-13 amps

The granny charger provided with the car is limited to 8amps even though it is plugged into our basic domestic system here being 10am - 240 volts. Not sure why it is limited but there must be a reason?

 

[Kithmo]

I understood the granny was 2.2kW, which means it will draw just over 9A, similar to having a two bar electric fire on.
Just make sure the socket it's plugged into is 13A mains socket and not a spur off the (5A) lighting circuit and is capable of drawing the required current for up to 20 hours.

 

[Cliff Mitchell]

In Australia the domestic power circuits are 10amps - 240 volts The granny charger is limited to 8 amps thus we only have 1920 watts available to charge. I charge overnight and generally my power consumption has increased about 1600 watts per hour for the ten hours I am charging. For me that equates to 3.4% of battery charge per hour or about 10kms per hour.

I hope to receive my 7kw charger this week. The one I ordered has the capacity to charge at 8, 10, 16 and 32amps. This will improved my ability to charge depending on the circumstances and at the same time being able to use it at granny charging rate when necessary.

 

[ChrisR]

In Australia the domestic power circuits are 10amps - 240 volts The granny charger is limited to 8 amps thus we only have 1920 watts available to charge. I charge overnight and generally my power consumption has increased about 1600 watts per hour for the ten hours I am charging. For me that equates to 3.4% of battery charge per hour or about 10kms per hour.

I hope to receive my 7kw charger this week. The one I ordered has the capacity to charge at 8, 10, 16 and 32amps. This will improved my ability to charge depending on the circumstances and at the same time being able to use it at granny charging rate when necessary.

Where are you getting your 7kW charger from? I've been considering it (currently using the granny charger and getting 4%/hour) and have looked at the EVSE Mini Pro so I can time it solar and battery. I'd be keen to see how you go.

 

[Cliff Mitchell]

Where are you getting your 7kW charger from? I've been considering it (currently using the granny charger and getting 4%/hour) and have looked at the EVSE Mini Pro so I can time it solar and battery. I'd be keen to see how you go.

Funny you mention that, the Mini Pro (EVSE) was my first choice, but then a number of reviews indicated the timer function was not very reliable and that was the main reason for its consideration.

The solar usage facility was also enticing, (again reviews indicated this function could also be problematic) but at the moment I get more from the grid solar feed-in tariff than it costs me off-peak. So charging off peak is a better option, particularly if on occasions, I can charge more quickly.

So in the end I went for a portable type 2 charger with a flexible amperage selector and a delay feature (delays the charger from coming on for up to 6 hours). The cost was much less than the Mini Pro and installation (quote over $2,500). The 32amp circuit including the 32amp socket was around $550 - 600 and the portable charger $1,100.

Good luck with your choices.

 

[ChrisR]

Funny you mention that, the Mini Pro (EVSE) was my first choice, but then a number of reviews indicated the timer function was not very reliable and that was the main reason for its consideration.

The solar usage facility was also enticing, (again reviews indicated this function could also be problematic) but at the moment I get more from the grid solar feed-in tariff than it costs me off-peak. So charging off peak is a better option, particularly if on occasions, I can charge more quickly.

So in the end I went for a portable type 2 charger with a flexible amperage selector and a delay feature (delays the charger from coming on for up to 6 hours). The cost was much less than the Mini Pro and installation (quote over $2,500). The 32amp circuit including the 32amp socket was around $550 - 600 and the portable charger $1,100.

Good luck with your choices.

Thanks Cliff, very helpful. I'll have to check out those reviews.

I have a solar battery, don't have off-peak and my feed-in is 12c/kWh so I'd rather use the battery excess each day than give it back to the grid. My motivation is mainly to not use any grid energy for charging so it truly is a zero emissions car. I'm guessing the ~$2,000 cost will definitely have a long break even period either way.

 

[Cliff Mitchell]

Can I ask, what size battery did you get. The prices I have been quoted are unbelievably high.

 

[ChrisR]

It's an LG 6.5 kWh which was part of a whole installation with panels and inverter totaling I think $10-11k about 2.5 years ago (part of a bulk buy through Shinehub) . It's been excellent. Again the motivation was more to reduce emissions and push the transition but it's definitely paying back quickly.

 

[Martin11]

I charge on the granny lead to 100% all the time with no issues

 

[Cliff Mitchell]

I charge on the granny lead to 100% all the time with no issues

How many kilometers/miles has your vehicle covered using the granny charger to 100%?

 

[profdraper]

So what about the LFP battery on the new face lift ZS EV short range? Surely the LFP battery can be regularly charged to 100% on a hom 7kw wallbox?