[Matt Beard]

EVs need some work on all this. There is obviously at least one microcontroller running 24/7 in the car as this does things like central locking and charge detection/timing. This should monitor the 12V level and when it is getting very low it should sip from the traction battery to recharge the 12V. Only time this should not happen is when the traction pack is close to empty. There is little point in keeping the main battery full if the car ends up on a flat-bed due to failed 12V! Sure, you can "jump" the 12V, but I bet most wouldn't.

 

[planetf1]

Another thought - whilst OVMS itself is low power, could it be keeping the CAR CANBUS alive, and causing a LOT more battery drain for the car itself, rather than the normal idle state. The leafdd reads the EV canbus instead, and it's known they behave differently.... just a thought......

 

[Paul]

Nissan (as you can see in this merged thread) are currently not accepting this as a wider problem, unfortunately as you've done what I did (charge it up) they say they can't really investigate it. You have to flatbed it.

Daft.

 

[Dave Davies]

My bet is on the car canbus

 

[planetf1]

Popped out to check and my 12V intelligent charger is reporting the 12V as fully charged.

The car now operates normally. Just reading 12.0V on the leafdd for now. Keeping a VERY CLOSE eye on this

Interestingly enough I had been having problems with the keyless entry (proximity) and start, yet the remote button unlock worked fine. I'd put it down to dodgy batteries in the remote. I wonder though if this was an early sign. These features are now working properly.

I was surprised the 12V charged in less than an hour? Not sure on capacity. I'm reckoning on it being dud.

 

[planetf1]

I'll track voltage/behaviour first with ovms in situ, then if it goes low (not critical I hope) I'll remove ovms and do again. Since I've had leafdd for about 9 months and never had the issue I think using that to display 12V voltage is ok. OVMS is a new thing I added, and is of course work in progress (including deciding whether the EV or CAR canbus works best). If voltage still bad -> replace 12C

 

[Paul]

Popped out to check and my 12V intelligent charger is reporting the 12V as fully charged.

The car now operates normally. Just reading 12.0V on the leafdd for now. Keeping a VERY CLOSE eye on this

Interestingly enough I had been having problems with the keyless entry (proximity) and start, yet the remote button unlock worked fine. I'd put it down to dodgy batteries in the remote. I wonder though if this was an early sign. These features are now working properly.

I was surprised the 12V charged in less than an hour? Not sure on capacity. I'm reckoning on it being dud.

Ours seemed to charge quite quickly, can't recall how much. Second time I just topped it up and it's seemed fine since. Nissan dealer said it seemed fine, no problems to report.

 

[planetf1]

Just to add... during that week I was away, everything was disconnected from the canbus.

 

[MK Tom]

This is 2013 Nissan Leaf Acenta.

I had the same with my 2013 Nissan Leaf Tekna. First time I thought it was because I hadnt inserted the charge connector enough the night before and this resulted in the car systems powering up waiting for pilot signal or mains power but not receiving it.. the 2nd time I have no idea though but it wasnt fully dead, just not enough for ignition to hold for the DC-DC to kick in and power the 12v electrical.
Both times i've run a cable to the Mrs car and powered up off her 12v enough to turn the Leaf on the let the DC-DC charge up.
The dealer checked my battered and did a overnight test (not the same as I charge at night so not a true test) and found no problems. They stated it might be when the main battery is below 20% the "powerup and charge 12v" feature doesnt kick in when the 12v is low but i'm sure that only accounts for 1 out of my 2 flat batteries.

Just to cover in more detail I have the car charge timer set to charge from 5am to 7.30am upto 80% (during cheap tariff) so it does normally spend time connected to charger (32a) but not charging before it kicks in at 5am.

I dont believe its possible to leave the lights on as the ignition powers these off (even when set to manual on). Also I have the solar panel but this is not supposed to charge a flat 12v only maintain (I think it counter acts the drain from TCU being constantly connected to cell tower.

So I dont really know the cause of the flat battery but I have my 12v booster pack with me just in case it happens again.

 

[Paul]

@planetf1 and others, please make sure you report these dead 12 volts to your dealer and/or Nissan CS, as I'm sure there's an issue here but the data doesn't seem to be strong enough or enabling Nissan to join the dots/raise a red flag somewhere.

 

[planetf1]

I've just been out and noticed
- after just around 3 hours idle after charge the voltage had dropped from 12.0 to 11.5 (with basic load ie accessory position)
- with the blower on (only) the voltage dropped to 11.3
- when driving the voltage read 12.9

I'm surprised to see idle voltage as low as 11.5 after just hours?

 

[planetf1]

I had a more extreme loss yesterday -- I'd been out around 7am to take my daughter to work. I didn't use the car after that. At 2037 I had an OVMS alert, and when I checked shortly thereafter LeafDD was showing 9.2V, dropping to 8.1V under load

I've just popped the car on "charge" again, but have now disconnected OVMS. I'll call breakdown/repair service if ti happens again - or indeed drops below 11V. I just want to eliminate OVMS as the cause first. I'm not removing LeafDD as it's my only other form of monitoring, and since I've had it since October last year with the car left idle for a week or two I'm pretty sure it's safe

 

[planetf1]

can left from approx 7pm until 8am .. 12V reading 11.8. probably not using the car today, so will see how it is later in the day

How are others finding their 12V voltage when the car is idle? 11.8 sounds ok so far.

I wonder if it was OVMS or at least the effect of OVMS... holding off from calling "breakdown" this morning

 

[planetf1]

Quick lunchtime check - still 11.9V

 

[planetf1]

Still 11.9 which is starting to suggest ovms may be to blame.. to check load I'm putting sidelights on. What's that? 20W?

 

[Paul]

Still 11.9 which is starting to suggest ovms may be to blame.. to check load I'm putting sidelights on. What's that? 20W?

Not necessarily, with most of the dead 12v battery instances I've seen (and my two experiences) the battery has behaved perfectly normally before and after these isolated deaths. Why? No idea.

 

[planetf1]

I only know that I it occurred multiple times, I disconnected ovms and it stopped. My plan now is to leave ovms out of the picture for a while before reintroducing and seeing if the issue returns

 

[Paul]

I only know that I it occurred multiple times, I disconnected ovms and it stopped. My plan now is to leave ovms out of the picture for a while before reintroducing and seeing if the issue returns

Sensible.

 

[Kevin Sharpe]

Sounds like OVMS is rather like one of those mobile phone apps you download that saps your battery in the background.

Tesla, Ampera/Volt, and Twizy owners are not reporting this issue. It's possible this is the result of waking the car to allow access to the relevant CAN bus which a change in the connector wiring would overcome.

OVMS support in the Leaf is in development and we should expect some challenges

 

[planetf1]

Oh I agree.. I'm not trying to "blame" ovms.. just trying to identify the cause.I've just posted to the ovms list. Of course it's early dev and more things seem to point to the EV can bus being a better candidate.