'Reduce charging current' option

[BusinessProOwner]

Hi there,

I notice that on the charging menu there is an option to reduce the current. Just wondering if this option needs to be on in normal domestic circumstances? In the manual it says that you may wish to reduce the current 'if several large electrical consumers are operated simultaneously via the same circuit (AC charging). Charging current is 8 A.'

We have a zappi charger and nothing out of the ordinary in the house needing a lot of electricity. Just wondering what the recommended setting is?

Thanks!

[Jono]

You should be fine leaving it off

[BusinessProOwner]

Thank you!

[Abadgermac]

With my Granny cable it charges at 9mph. If I reduce the setting it goes down to 5.

[CarterHounslow]

On a 7kw charger it reduces it to about 1/3 current, so it's only at around 2.4kw/h. There's no real reason to ever use it. The car pulls 31 amps at 7.4kw roughly, you'd have to have a lot of other stuff on in a house to be even close, and your charger probably even has something to balance the load.

Most houses can pull between 80 and 100. If you have a double even running all the time, people using high amp stuff like dryers etc then maybe think about using it. But I highly doubt you're pulling that much current.

[kaiz]

I have 3 phase 11kW charger.
It shows 15.5A in full mode and 7.4A in reduced mode.
For overnight charging I've used reduced, because my idea is, that slower charging means longer battery life.
When I need quicker charging and fuse can hold it, I clear reduced mode.

[BusinessProOwner]

Thank you!

[Deleted User 192]

slower charging means longer battery life.

I don’t believe there’s any reason on the car itself to use this setting, it is reflective of the charging situation in terms of the charge point, the electricity supply, the consumption of other devices...

[HeidiFlowerpt Driver]

Lithium batteries can be damaged by charging them very fast, right up to 100%. But we're talking about 100kW rapid DC chargers, not 7.4kW AC domestic chargers. Charging at home at 7.4kW won't damage the battery, but if you charge to 100%, best to do so just before your journey, the battery can be damaged from being sat with a full charge for a long time.

If you have solar panels, there are circumstances where it'll be useful to reduce the charge rate. For instance, if the panels are generating, say, 2.5kW more than the house is using, and you can charge your car, but at full charging rate you'll be using the 2.5kW of spare solar and also drawing 5kW from the grid, which you're paying for. But if you set 'reduced charging current' you can charge at 2.4kW and just use the excess solar, so effectively you're charging for free. If you have an export tariff, it's not quite free since you would otherwise have sold that excess to the grid, but it's more economical to use your excess than to sell it, usually.

[BusinessProOwner]

Thank you, very helpful indeed!

[kaiz]

Read various articles about Li-Ion battery charging and must agree, that this difference in amperage has minimum impact to the battery life.
Just when I was seeking for first EV, had a long debate with long-time Leaf owner who also replaced Leaf-s batteries.
He told me, that he even find a schuko in gas station to charge more slowly.
He asked, that where is the rush. Save 15 min and then do nothing.
Take a break, a coffee or tea and read a book, for what you never find time.

[G43FAN]

If you have solar panels, there are circumstances where it'll be useful to reduce the charge rate. For instance, if the panels are generating, say, 2.5kW more than the house is using, and you can charge your car, but at full charging rate you'll be using the 2.5kW of spare solar and also drawing 5kW from the grid, which you're paying for. But if you set 'reduced charging current' you can charge at 2.4kW and just use the excess solar, so effectively you're charging for free. If you have an export tariff, it's not quite free since you would otherwise have sold that excess to the grid, but it's more economical to use your excess than to sell it, usually.

In that scenario you still wouldn't use the car to manage the charge rate it would be managd by the charger so as as ( I think) been said, there seems to be no logical reason for this option to be on the car.

[HeidiFlowerpt Driver]

it would be managd by the charger so as as ( I think) been said, there seems to be no logical reason for this option to be on the car.

If you have a Zappi or similar, but some have dumb chargepoints.

[Stevep55]

I only use it when charging using my surplus solar power.

[G43FAN]

it would be managd by the charger so as as ( I think) been said, there seems to be no logical reason for this option to be on the car.

If you have a Zappi or similar, but some have dumb chargepoints.

But still in that case the car has no knowledge of the excess power available and so it's just a guess? I would also suggest that if that is the reason for th option it should be called 'ECO Charging' or some such. Given that (in the UK anyway) most Solar installations are built around a 4kWh set up with household reserved to say max 1.0kWh during the day then the option makes some sense.

[Andreas]

It’s also important in countries like Italy where the typical home power connection is only 3.something kW. So you can blow the mains fuse by running the hoover while the oven is on, when the fridge cycles.

All the best

Andreas

[bupkis]

This VW page on battery health (chart at bottom) seems to indicate that you should use reduced AC for overnight charging but doesn’t explain why and doesn’t say anything about the rates from which you should reduce the rate. If I’m charging at 7.2kW, is that a rate from which I should be reducing the speed if time allows? The page could be a lot clearer.

[SteveJ180]

If you have a 7kW home charger then this setting is probably irrelevant. I use it when charging with the granny charger - because at home I don't want to run 13A continuously all night through a standard plug circuit and when visiting the house in Spain because it only has a 16A supply for the whole house! In both of these situations, reducing the charging to 8A from 13A is really a 'safety first' issue, albeit very much a 'trickle' charge.

[Daveion]

Hi there,

I notice that on the charging menu there is an option to reduce the current. Just wondering if this option needs to be on in normal domestic circumstances? In the manual it says that you may wish to reduce the current 'if several large electrical consumers are operated simultaneously via the same circuit (AC charging). Charging current is 8 A.'

We have a zappi charger and nothing out of the ordinary in the house needing a lot of electricity. Just wondering what the recommended setting is?

Thanks!

Your Zappi should have a Current Transformer installed which will prevent you taking too much current if other appliances are taking large loads.
In your domestic charging arrangement it would be unnecessary to use the reduced current charging facility.
From My Energy
"zappi 2 – Grid Limit Function includes a built-in function to protect the grid supply from an overload. If the current measured by the grid current transformer (CT) exceeds the limit that has been set when the zappi was commissioned then it will limit the output to the electric vehicle (EV) to prevent the fuse blowing"

[duckworthsj]

Agrée that this is mainly for countries such as Italy where often the mains circuit breaker is only 16Amps.