12V Battery looking low

After daytime driving and Night time driving this Autumn I have noticed this year (3rd Winter) that the Lights and wipers are affecting the range. It’s the first time I have seen this and suspect that the 12V battery does not have the same capacity that it had before and is using the traction battery to maintain it’s charge.

I’ll live like this for a while and see how it goes and hope the 12V doesn’t fail so I cannot charge.

Rather than pay Renault around £100 for a new battery I’ll start to source an alternative. Any suggestions?

Daft as it may sound, is the battery not covered on the warranty? If not, I would make sure they paid for it under it being “not of satisfactory quality” given your mileage and age of vehicle, or at least a hefty contribution to it. I would not like to fit a non-Renault battery as they will use this an a reason that any other electric or charging fault occurs and won’t pay for those repairs.

Just a thought.

It’s surprising that it would make that noticeable a difference. Does a Twizy 12V battery charge while the Twizy is being charged, or does it *always *charge from the traction batteries when the “ignition” is on? Ours is also coming up to 3 years old and it looks like we’ve lost maybe 5% of our traction battery capacity - the first “bar” on a full “tank” now disappears after about 3.5 miles, though the others are still counting down at 4 to 5 miles a bar depending on temperature. I’ve been assuming that this is just normal degradation after 9500 miles. The (wall) watt-hours per mile don’t seem to have changed by much, though this will presumably degrade a bit over time as well.

I would assume but will check that the 12V battery is a consumable item and expected to need replacing like tyres. Looking at it like that then I did not fit Renault Tyres or replace light bulbs with Renault ones, have I now messed up the warranty? I suppose it is also like Brake pads.

I have only done 8000 miles and still get a full 5 miles from the first bar if not using lights and wipers - again depending on temp.
The 12v Battery charges during charge and if required from the traction battery. Hence I don’t see the effect for a few miles with lights on as the 12V battery has some capacity to power the lights on it’s own. Actually thinking about this, the little 12V battery cannot power the lights on it’s own for long. Drawing around 10amps from the 12V battery will flatten it very quickly so it must be being topped up whenever the lights and ignition are on. Worse still if the wipers are on.

I’m obviously just over concerned. I’ll have to pull it out and check it off the car.

A consumable item must still be fit for purpose, 2 years and 8,000 miles is not the expected lifetime of a quality part.
Good luck!

Quite. It may only be a motorbike battery, but you’d expect it to last a lot longer than that. But motorbike and car batteries are only designed for pretty shallow discharge because the alternator takes most of the load (on a motorbike, it wouldn’t even have to manage the high starter current). I wonder what the charge/discharge regime for the Twizy battery is?

I have also noticed a drop in range since this darkness arrived, I was wondering if the traction battery is getting weaker. Way I see it th batteries are leased, so if they fail, I want a new one , traction or 12v :slight_smile:

My range at these temps is as previous years, just appears lower when I use the lights and wipers.

I would agree, but wonder how the lease is worded, if 12v battery is part of car not leased?
If leased, should be replaced, if owned, is not fit for purpose and should be replaced, end of!

The traction batteries will certainly lose capacity over time. I think Renault would only regard them as having failed if the capacity drops below 75% of the original during the lease period. The lead acid 12v battery shouldn’t discharge to the same extent as the traction battery, because I don’t think it would last very long at all if it did. I’ve always assumed that the non-traction electrical load while the car is running is actually taken largely by the traction batteries, which are designed for deep discharge. If it’s not that simple (and for example if the 12V battery is mainly re-charged when the traction battery is) then maybe there are grounds for concern.

The 12V battery is charged during charging and from the Traction battery when required (ignition has to be on). ie. All the time when lights and wipers are on. This should stop it becoming discharged below say 50% where it becomes damaged but …

I posted some time back about upgrading the 12v battery. Someone gave all the measurements, it looked like I could almost get a double AH capacity battery that would fit, better if you a running a stereo.