Wall charger in standby mode = 140 kWh/year. - Renault Z.E. Forum
 
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post #1 of 8 (permalink) Old 09-01-2013, 12:05 PM Thread Starter
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Wall charger in standby mode = 140 kWh/year.

You may have seen, over in the 'Fluence' forum, Paul and I nattering about timers, and what a total bug it is not to have control over charge timing.

I have suggested that I might rig up a manual actuator that turns the key on and off.

HOWEVER!!...

Today I have been investigating the current drawn by the unit - originally to look at consumption of the car. However, it turns out that the unit itself is drawing 16 W all on its own, in standby mode.

(I don't usually worry too much about standby mode on appliances, because most of the year the excess waste heat generated arguably heats the house up anyway, so is not altogether 'wasted'. But this charger is in my garage, so is therefore a pure waste.)

This changes things, because that means in the course of a year it will have drawn 140 kWh, whereas I am planning on doing 6,000 miles or so to a total of 1,400 kWh - viz. the wall charger is consuming 10% of my EV's total usage, just on standby!

Paul had suggested a timer on the input power, which I thought may conflict with some grant requirement in data logging.

However, if I am stuck with a unit consuming 10% of my electricity spend all by itself, then I will do what I need to do.

I am thinking through how I would go about having someone add a relay into the circuit, a relay such as;

http://www.ebay.co.uk/itm/290624221014

(Do these need heat sinks? Is it better to use a mechanical relay, for continuous high currents?)

If I can't get what I want from the people who should be thinking through these issues for me, then I guess I'll just have to find a way to 'fix' it for myself!
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post #2 of 8 (permalink) Old 09-01-2013, 12:49 PM
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RE: Wall charger in standby mode = 140 kWh/year.

Donald, I don't think I have your problem with my British Gas Chargemaster unit. I have checked the spec sheet and there is no mention of standby current usage. My unit is mounted outside the house and has an on-off key switch on the front panel. Indoors I have an ordinary-looking switch to carry out the same function and also two isolator switches - so I have options in ensuring the system is unusable by a passing thief and is capable of total isolation, supposedly installed (at enormous expense and insisted upon by BG before they would install the unit) in case the unit needs repair! I will check with my monitor whether there is an undocumented current usage but I think not. All I'm lacking is a timer, which I now have set up with my 10A cable to do the job brilliantly and I can now get a good night's sleep - the digital timer cost me 5!
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post #3 of 8 (permalink) Old 09-01-2013, 01:28 PM Thread Starter
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RE: Wall charger in standby mode = 140 kWh/year.

I think you should make sure the timer has sufficient current rating for 10A continuous load. It's the 'continuous load' that is the reason these VMs do not recommend using any adapters/extension cords/etc..

I can turn the power off at the RCD still, but RCDs aren't designed to be switched regularly. I guess you have an older electrical installation that, itself, might be better suited to having a 'master switch' elsewhere that is more suited to regularly being switched off.

Bear in mind you are probably losing a further 10% in charging losses by using the 10A lead.
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post #4 of 8 (permalink) Old 09-02-2013, 03:40 AM
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RE: Wall charger in standby mode = 140 kWh/year.

Donald, more food for thought.

My timer is rated at 3Kw and I wouldn't hesitate to use it for a two bar electric fire which equates to the Fluence battery charge rate. I note that when the timer switches to active there is a 10 second delay before the car responds, presumably waiting for a relay circuit to respond so the switch within the timer does not suffer a current surge.
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post #5 of 8 (permalink) Old 09-04-2013, 05:26 AM
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RE: Wall charger in standby mode = 140 kWh/year.

I'd be a little worried about a Chinese one from an eBay seller.


You need to see the data sheet for the device to know if needs a heatsink and how large it needs to be.

For example, this 25A relay will need at least a 3C/W heatsink at 16 amps.

http://uk.rs-online.com/web/p/solid-...elays/0346918/
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post #6 of 8 (permalink) Old 09-04-2013, 10:09 AM Thread Starter
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RE: Wall charger in standby mode = 140 kWh/year.

Yes, thermal rating is something I have been asking about, for SSRs. I don't really understand the thermal derate information - can you explain how I use them to arrive at a heat-sink rating versus operating temp for a given current load?

I might prefer to go for a mechanical relay, which'd be OK powering up (as the charge station takes a moment to draw 16A) but powering down could be quite a current surge at cycle peak (that SSR do not experience).
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post #7 of 8 (permalink) Old 09-05-2013, 03:16 AM
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RE: Wall charger in standby mode = 140 kWh/year.

I know I'm talking here about the 10A cable for charging, but the digital timer appears to be doing its job well. The timer switches on at the appropriate time, but for disconnecting I allow the car to switch off charging at 100% - by setting the off position on the timer later than the end of charge time. Renault told me a while back that, although Nissan recommend not to charge to 100% regularly, Renault do not have any concerns over this issue.

The engineer who installed by wall charger did say that they could fit a timer in the circuit later if I needed it, I just don't think that this will be cheap and probably will never pay for the installation cost.
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post #8 of 8 (permalink) Old 02-03-2014, 09:01 AM
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RE: Wall charger in standby mode = 140 kWh/year.

Having just checked the first 3 months of my Rolec WallPod, the amount of Kw it consumed in standby was 0.001KwH no doubt to power the flashing light on the Pod and the bright LED on the meter itself.
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