Not sure what you are asking as all EV’s have an on board charger. I take it you mean an upgrade to the chargers AC charging rate, if it is from 7kw AC to , say, 11kw or 22kw AC, then you’d have to ask yourself if you intend to charge away from home a lot at over 7kw AC chargers (confusingly called fast chargers by Zap Map). Otherwise it’s just wasted as home chargers are all up to 7.2kw max (unless you have 3 phase power available to you) and rapid chargers use the much higher capacity DC charging built into the car.
It depends on the cost to you to upgrade – the Ariya for instance offers the 22kw AC upgrade for around £100-200 depending on model choice. That might be worth it if your local Tesco does free 22kw charging for instance, as an hour there will give you 14kw of free energy over the cars standard 7.4kw charger. So for £100-200 its probably worth it – provided you use it.
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