I had some minor issues. And the search around finally brought me here.
I will post my findings here, but also later I will start a new thread regarding my observations with this.
First a little summary over what happened to my swedish 2017 model, 30 kWh.
It started with FOB not working, needed to hold the key close to the start button in order to start up. And a message:
« When parked apply parking brake ».
Next day on my way to buy new batteries to FOB, I noticed that the rear light was blinking, and a new message in display:
« T/M system malfunction. Visit dealer.
After a little search I found out that last message was about the original Nissan/Renault 12V battery, and this is the error code for defect battery/low voltage.
Also there comes with a bunch of DTC, because of the 12V battery is defect/low voltage.
Battery voltage 11.5V
I am not going in on those DTC, they are all covered better in other threads. But of course they are not realistic, they only are there because of the 12V battery is defect/low voltage.
So I bought a new budget 62Ah 12V silver calcium battery (brand is Biltema), only one I could find the same day, and charged it up for 24H before I installed it in the car.
Everything was OK the next 4 days.
Until the whole round with blinking rear light and warning beeps and DTC when I was on my way out the 4 day in the morning.
Battery voltage 12.1V.
And here is when I am coming to the point. The 12V behavior.
I am working with lithium batteries, mostly LiFePO4, but also the other lithium battery chemistry.
And of course lead acid batteries.
So when I see this behavior in 4 days old battery I understood that something odd is going on here.
I charged it up again for 24H, and installed it. After clearing all the DTC, including taking off the minus pole some times and wait a couple of minutes, It all started over again when I parked after driving. Nor I could charge.
OK, since this happened because of the FOB batteries beeing low, and the old Leaf original 12V battery probably did not handle this blinking and power draw, and went out, it could not be water damage in the electronics because of bad sealing wind shield. I took a quick check and took down the dashboard and checked all connections and boxes, but all looked OK. Also swapped the start relay with the blower relay. Since one of the DTC mention that. They have the same part number.
Still the same.
I know that the 12V battery is the weak link on most EVs, so I decided to check out whats really happened while in use. Using a clamp A meter is not an option, I needed more meat on the bone, so to say...
So I build up a 12.8V 100Ah LiFePO4 battery with a 100A Bluetooth BMS (I reckon it can handle 150A peak)
So this built is living its life on the border here...
And here comes the important;
I can monitor Volt, A, temperature, SOC and other parameters with my cellphone and Bluetooth in real time.
Everyone is talking about voltage here, very few about A. Because that DCDC can really deliver high power.
And can the original (or any?) lead acid battery in this size take that power? No.
You cant blow in 110A charge to a lead acid battery with this Ah size. Or draw 55A out of it, again and again.
And that is what happening here. I have measured 110A charge on the most, and over 55A draw on the most. And I am very sure that there are higher numbers than that. Because I cant log these numbers in this specific BMS.
When Leaf is on charge on the small TYPE 2 charger at home, the 12V battery goes in a 4minute cycle. Its a power draw between 2.5-3A for around 4 minutes, before it pulses 3-5 times up to over 100A charge for maybe 15-20 seconds.
Counts down the charge 3-5 times, and it starts over again. I dont know for how long, but every time I check in, it continous.
I can not log this BMS.
When driving with AC on, it can draw around 25A, before it rapidly pulses up to 110A charge for max 10 seconds, before it goes back to anything between 0A or 55A draw, for then rapidly goes up in charge again.
That poor new 12V battery I bought never had an chance. (Not the original ones either...)
Shocked to an early death...
Spec sheet says max charge 15A on this new battery I bought. And that is very common on lead acid batteries of this size.
This was a budget battery, more expensive ones will hold much longer as we know.
But finally they have to give in they as well.
This battery build is just something I mixed rapidly together, looks ****, but its safe.
I have ordered some other lithium cells, because LiFePO4 can not be charged under 0 degree C without taking damage.