Flat battery - Renault Z.E. Forum
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post #1 of 11 (permalink) Old 02-10-2014, 12:45 PM Thread Starter
Eep
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Flat battery

What happens if the battery loses its charge?

In simpler terms, if I bought an EV and left it in the garage over winter (and leaving battery rental issues aside for this thread), what happens if the car goes completely flat?

I've imported some Li-on smartphone batteries from the U.S. before and the low temperatures of air travel via cargo hold combined with the fact they'd clearly been left on the shelf for some years prior to eventually being sold to me resulted in them being buggered. You could not charge them. No charging unit would even recognise them as a battery.

Wondering if there is any wisdom on EVs in the same situation.
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post #2 of 11 (permalink) Old 02-10-2014, 01:45 PM
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RE: Flat battery

Wouldn't the 12v die first?

I've heard it's about 2% a month loss self discharging on a vehicle li-ion HV battery. In other words not a lot. I think the NiMh battery in the Prius was more susceptible and even then it was rare for it to run completely low.The 12v running all the ancillary equipment is more likely to fail, but is also easier to top up and easier and cheaper to replace.

Does the Fluence 12v socket switch off with the ignition or can you plug one of the solar chargers in it? If it's the latter, then you might get one of those for peace of mind?
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post #3 of 11 (permalink) Old 02-10-2014, 04:01 PM
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RE: Flat battery

Li batteries will tend to completely die if left to fully discharge. If you park it up with zero indicated charge and leave it to self-discharge further, how long before your car turns into a brick? Dunno. But it will happen if you leave it long enough.

One thing is for sure - if you've ever watched videos of Merc diesels being cranked back into life 30 years after being parked up, that just ain't gonna happen* with an EV!!

(*Well, perhaps it might if it used very low activity batteries, such as nickel-iron batteries like the Baker electrics did. Apparently, Jay Leno's Baker electric still has the original batteries!)

One way or the other, it may likely be recoverable, because the battery pack is constructed of individual cell modules that can be removed or placed. How many would actually die after X time I don't know. Keep paying your battery rental and request a replacement!....

The Leaf will start up the HV battery every 5 days and recharge the 12V battery for a few minutes. I do not know if the Renault ZEs do the same but it would seem possible if the Leaf does it.
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post #4 of 11 (permalink) Old 02-10-2014, 04:09 PM
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RE: Flat battery

I think a completely flat battery is probably the last thing anyone contemplating an EV needs to worry about. In real world use, I've experienced no perceptible loss of charge when leaving the car unused for several days. I'm guessing the "zero isn't really zero" set-up designed to limit the charge/discharge of the battery gives some protection as well.

There was an issue with the Tesla S losing charge at rest, but I believe that this was traced to a software problem that was fixed with an update.

I agree the 12V battery is a more likely point of failure, but again, probably not something to worry about too much.
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post #5 of 11 (permalink) Old 02-17-2014, 12:02 PM
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RE: Flat battery

You phone Renault as there's no way the charger will send any juice to the traction battery if it cannot determine +VE. The 12v could be charged conventionally and this might make a difference.
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post #6 of 11 (permalink) Old 10-19-2015, 06:14 PM
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RE: Flat battery

Hi there,
I noticed this a few days ago - when I turn the key to start and just before GO all the lights come on - this battery light in orange for the 12V battery has 1 bar lit up - is that normal?
I drove about 30 km parked and drove back 30 km and when I started the car again the light was still one bar. Does that mean I need a new battery or charge it away from the car or is this just normal.
I have not noticed this before, but as I am getting used to the car and really enjoy driving it - I have more time to look at other things going on. With winter approaching I do not want to be stuck somewhere. The car is from 2012 - so is it possible that the battery need replacing? It only has about 1500 km on the clock.
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post #7 of 11 (permalink) Old 10-19-2015, 07:18 PM
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RE: Flat battery

Not sure - I'll try to remember to check what mine does when I use it tomorrow. I can't recall whether the number of bars changes or whether it always just shows the same one bar.

I suspect there isn't anything to worry about unless the orange warning light stays on.

Also, even if it meant a replacement 12v battery, that's not too expensive an item compared with most things that might need replacing on a car, I suppose.

Glad to hear you're enjoying the car otherwise!
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post #8 of 11 (permalink) Old 10-20-2015, 03:03 PM
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RE: Flat battery

That's great - It was the same today again, so I'm not sure is this the norm or not, thanks for checking it out.
I certainly enjoy my car, use it every day for everything. I did the same distance in my Ford Steel as I do now, I replaced the Ford with this car. The only exception is the holidays this is always the large extra few runs during the year. But this time we just have to look for alternative use, instead of the FluenceZE. It has great comforts and I love driving it. All the extra luxuries are just great - I love it.
I still have not sorted the leasing of the battery and waiting for other things to come through, I am waiting for the electricity to install at my house the charger, a second key, the paperwork for the leasing. The Dealer insists it is in progress so I just wait patiently and annoy him with a phone call every week.
So definitely no regrets so far
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post #9 of 11 (permalink) Old 10-21-2015, 05:43 AM
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RE: Flat battery

It's the norm - the icon is a battery with a representation of low power. It is a WARNING light (not a status) and will come on when your 12v battery has a problem to show low voltage. As all the warnings illuminate at switch on, expecting this to show live 12v battery status is a bit unrealistic!
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post #10 of 11 (permalink) Old 10-21-2015, 03:49 PM
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RE: Flat battery

Thank you Buzby - Sorry to be such a fool - but great to know its an icon, I just started to get worried why it wasn't going up or down. Thanks again
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