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Northampton Handyman
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Discussion Starter #1
I wrote the following to Renault Customer Services:

"I have just bought a 2011 Renault Kangoo ZE. I charge it each night using an occasional usage charging cord (aka “granny cable”) plugged into a standard 13 amp domestic socket. To avoid wear and tear on my charger I have installed it in a waterproof wall-mounted box so its physical arrangements are the same as a tethered charger.

My Kangoo has leased batteries and I have now received a lease agreement from RCI Financial Services Limited. Section 12.1 of the agreement specifies that “The Battery may only be charged in accordance with the Manufacturer Recommendations: (a) at a charging station; or (b) by using your home charging point (being a wall box recommended by the manufacturer and installed by a suitably qualified electrician).” I asked RCI to modify the terms of the agreement to include my charging arrangement but they replied “we are unable to make amendments to our Terms and Conditions, as this clause states it must be in accordance with 'manufacturers' recommendations we would advise you contact Renault UK directly for further assistance.”

In referring to the occasional charging cord 4 the handbook recommends that “This cord 4 should only be used for occasional charges in accordance with the installation conditions set out above.” This recommendation will require me to either spend £1,500 (that I don’t have) to install a wall charger (that I neither want nor need) or to break the terms and conditions of my battery lease agreement with RCI Financial Services. Are you able to explain why you make this recommendation? If my granny charger is safe to use on one night why is it unacceptable to use it every night?"

Renault replied "I understand it is a better option for yourself to continue charging at home using a granny cable however this is only a occasional use charging cable and constantly charging the battery with this cable is not recommended and may damage the battery. The occasional charging cable is a low voltage cable intended for occasional use."

Is it true that my 240 volt AC granny cable is a "low voltage cable"? If so, what voltage do charging stations use? And how might a slow charge every night damage the battery?

I'd be grateful for any input before I reply to Renault.
 

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Complete rubbish...at least, the "may damage the battery" bit is. As discussed ad nauseam elsewhere, there are potential safety risks (primarily overheating) associated with granny cable use, but to suggest that low-rate charging is liable to damage the battery is rot. Again, lots of references (and debate, and opinion) available elsewhere, but in general what damages batteries is time, cyclic use, high rate charging (heat) and leaving for long periods at very low or very high states of charge. Low rate charging is about as kind as you can be.
 

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Ioniq
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I thought the main reason Renault don't supply a granny charger is that the efficiency of their charging mechanism falls off a lot at low power, to something like 60% or so, so they would much rather you use a "proper" 7kw wall box.

The "low voltage" bit is nonsense too, AC charging on the UK is always 240v, each phase of a 43kw rapid is still 240v.
 

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So you are now stuck with an unsatisfactory response that contains irrelevant inaccuracies. :unsure: What's your next move as you have potentially flagged up to them that you aren't treating their battery correctly under their terms? :eek:
 

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Renault ZOE R135 ZE50 GTLine July 2020 (Sold: R90 ZE40 i Dynamic Nav June 2017)
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Note that there is no similar clause that limits charging the battery when you own the battery, instead of leasing it. So apparently, a leased battery has different requirements from an owned one.

It's all Chinese whispers in the marketing departments of Renault and RCI. I'd simply ignore it. The technical situation (as I understand it):

  • Charging batteries slowly is good for them, as @electricdriver says.
  • The ZOE uses its motor windings as part of its charger circuit, instead of a separate on-board charger, thereby saving weight and supporting 3 phase AC charging. But it is optimised for higher charging speeds, and the design trade off is that low speed efficiency is poor. Charging with a granny does cost a bit more, but its still a lot cheaper than petroleum.
  • House wiring should be checked carefully if using a 13A socket. Old sockets and a loose connection anywhere in a 13A ring can cause excessive heat. (It's easier to get a rep to say "Don't use one" than to say "get your wiring checked".) If I was using a granny regularly, I'd consider installing a cable for a charge point immediately with a top quality 13A socket or commando socket on the end. It can be fused for 10A charging with a granny and be very safe. And it's a sensible investment, being ready for a charge point to be installed when one is needed.
  • As @Phil Himsworth says, the granny charger is not "low voltage" in any way.
 

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The only risk I could see is if the car is exceptionally cold (-10C or lower), the granny charger may not be able to supply enough current to run the battery heater, if equipped. This may cause the car to run flat despite being on a charger - which could cause battery damage if this was the case for many weeks of inactivity.

Really, all considered that would be quite an unusual situation, and I doubt you'd ever get that circumstance in the UK.
 

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Northampton Handyman
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Discussion Starter #7
That's creative thinking Tom! I hadn't thought of that. The handbook says that the battery charging must be finished before the automatic heating function will work, that the heater will start an hour before the programmed time and automatically terminate 30 minutes after that time. So even if the heater consumes a huge 3kW then on the coldest of days with the windows open it would only deplete the traction battery by 4.5 kWh. My 22 kWh battery is down to 70% state of health, so it's a 15.4 kWh battery. It's not going to run flat because the automatic function has turned the heater on. I suppose there's a danger that I could do it manually: open the windows on a cold day, turn the heater on and leave the keys in the ignition so that it stays on all day, but then we'd have moved away from charging technology issues into the mental health arena.
 

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They mean lower current, not lower voltage.

The main issue is that continuous* use of a granny cable on old/dirty/tarnished 13 amp sockets with old wiring in the corner of a damp garage that hasn't been used for years is likely to see the plug top overheat at some point. They don't want to deal with your warranty claim when that happens, hence they don't recommend it.

* you should also make sure that the 13 amp plug is disconnected and reconnected relatively regularly (every few weeks, maybe), to keep the contact surfaces clean - so called "self wiping".
 

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That doesn't justify the statement made by Renault reported by
constantly charging the battery with this cable is not recommended and may damage the battery
 

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That's creative thinking Tom! I hadn't thought of that. The handbook says that the battery charging must be finished before the automatic heating function will work, that the heater will start an hour before the programmed time and automatically terminate 30 minutes after that time. So even if the heater consumes a huge 3kW then on the coldest of days with the windows open it would only deplete the traction battery by 4.5 kWh. My 22 kWh battery is down to 70% state of health, so it's a 15.4 kWh battery. It's not going to run flat because the automatic function has turned the heater on. I suppose there's a danger that I could do it manually: open the windows on a cold day, turn the heater on and leave the keys in the ignition so that it stays on all day, but then we'd have moved away from charging technology issues into the mental health arena.
In this case I would be talking about the battery coolant heater. I am not sure if Zoe is equipped with that. It's not necessarily the same as the cabin heat but in some cases the same heater is used for both.

The only reference I have is my Golf GTE. The coolant heater is up to 7.5kW. However the battery is not heated during charging, at least not as far as I could tell - I am not sure what the car would do if the battery is cold. Probably not charge, as it's a hybrid so that's probably their logic.
 

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I thought the main reason Renault don't supply a granny charger is that the efficiency of their charging mechanism falls off a lot at low power, to something like 60% or so, so they would much rather you use a "proper" 7kw wall box.
That is true for Zoe. -- Charging a Zoe from a Granny lead wastes a lot of power and money.


I'm not sure about Kangoo. It uses a different on-board charger than Zoe that doesn't have the big dropp off at 2.2kW. However, if Kangoo runs battery cooling during charging that would also be a big chunk of the 2.2kW. If that is what happens then charging from a granny lead will use a lot of power and money compared to a 7kW wall box.
 

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I'm not crazy, the attack has begun.
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There's no battery heater.

There's no loss of efficiency (this isn't a Chameleon charger, for which that is true).

It's all complete bollocks.

Just tell them you are charging using a charge point, just don't mention it's your 3-pin socket.

Carry on, all is well. The granny charger does not emit red electrons, they will have no possible possible not the remotest way of telling.

However, what you should do is check the plug is not getting hot; every couple of charges, go to it after an hour and just place your palm on the back of the plug, make sure it is no hotter than the last time you checked. If the temperature feels like it is creeping up (or is already hot) then the receptacles in the 3 pin socket might be weakening over time and through use.

THIS WILL HAPPEN IF YOU USE THE SAME 3 PIN SOCKET LONG ENOUGH, DON'T ASSUME IT'S FINE BECAUSE YOU HAVE USED IT 100 TIMES BEFORE.

(Capitals so everyone else notices that too .... ;) )

Worth swapping the socket out for a new high quality make at that point, because they 'will' notice if the plug is all melted and charred when you return it!!! ;)
 

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£1500 sounds steep for a wall charger install. Podpoint are offering installs for £450 at the moment. Is yours a particularly difficult install setup?
 

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30KW Tekna (2017)
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I was just about to say the same as @donald ....... they cannot tell your using the granny vs other home charger!

And depending on your setup as above you can buy cheaper off the shelf charge points than what you’ve been quoted.

Another cheap and safer option than the U.K. socket granny is buying a commando version, and having a socket installed. Not perfect but safer than 3 pin plug and 16 amp charging As a bonus!
 

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Ioniq
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Apart from when they interrogate the logs and ask why your wall charger is turned down to 10 amps. ;)
Because it's a zappi or something like that throttling down to use just your solar PV, or because your DNO says you can't draw any more, or or or...
 

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Northampton Handyman
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Discussion Starter #17
Thank you all for your helpful comments. No, it's not a difficult installation at all. My preferred location for a charger would be on the other side of the wall from the consumer unit installed in 2019. I got two quotes for 7 kW chargers: £1,500 and £1,900. Since my old Kangoo can only charge at 3.3 kW it made much more sense to buy a 2.2 kW granny charger for £170. I'm encouraged to learn from donald that it isn't a less efficient way of charging.

I run the supply to it with an app-controlled switch so it's only live during economy7 tariff hours. The 13A plug and socket are both brand new and well protected, but I appreciate the warning about the danger of them heating up. To remove that from the equation I may just cut the plug off and wire the granny cable directly into the wifi-controlled switch.

Since Renault Customer Services is unable to explain how charging at 2.2 kW may damage the battery I have asked them for contact details for one of their battery engineers. It'll be interesting to see whether they will give me access to somebody in the company qualified to confirm that it's hogwash.
 

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THIS WILL HAPPEN IF YOU USE THE SAME 3 PIN SOCKET LONG ENOUGH, DON'T ASSUME IT'S FINE BECAUSE YOU HAVE USED IT 100 TIMES BEFORE.

(Capitals so everyone else notices that too .... ;) )

Worth swapping the socket out for a new high quality make at that point, because they 'will' notice if the plug is all melted and charred when you return it!!!
@donald - the issue is generally with the plug rather than the socket itself, and the socket is normally the victim of heat build up from the fuse holder in the plug. Hence why the issue is always with the Live pin despite the same current flowing in the Neutral line.
Another cheap and safer option than the U.K. socket granny is buying a commando version, and having a socket installed. Not perfect but safer than 3 pin plug and 16 amp charging As a bonus!
Good advice on two fronts - this does away with the fuse holder in the plug and forces you to have a safer arrangement. Even if you stick with 10 Amp charging there's a greater safety margin.
Do not cut the plug off, many granny leads contain thermal sensors in the plug.
This means you can not simply change the plug.
Sadly true. It may be more cost-effective to sell your current granny lead and buy one with 32Amp socket already fitted.
 

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Renault ZOE R135 ZE50 GTLine July 2020 (Sold: R90 ZE40 i Dynamic Nav June 2017)
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I got two quotes for 7 kW chargers: £1,500 and £1,900.
These seem very expensive for a standard domestic EVSE, especially for such a straightforward installation. Here's one totally random (not recommended, but not untypical) example for £599 (£350 if you can get the grant, which I think you could): ChargedEV
access to somebody in the company qualified to confirm that it's hogwash.
Here's access to a battery scientist: Euan McTurk. But I don't think he answers your question on why it's safe to charge slowly. The point is that batteries get damaged by heating them up by charging too quickly.
 
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