HEV 12V Battery investigations

[PhilHornby]

The last post also contains this document from Hyundai about lithium hybrid batteries :-
https://www.hyundaimotorgroup.com/story ... 0000002069
I haven't read thru it all but there may be some help in there if you haven't seen it before.

That's the one that I previously linked to, that I clearly hadn't bothered reading properly

Referenced from "Sport Mode" thread, I found a reference to the May 22 Update thread, which is probably also required viewing, for anyone interested in this topic.

[PhilHornby]

Test Description: Car was placed in Sport Mode and in driven in 'manual mode' for a few miles, to charge the Traction Battery to almost 100%. The Parking Lights were turned on and the car closed and locked.
When the Battery Voltage reached 12.75V (estimated to be 25% charge), the car was unlocked, the lights turned off and then re-locked. It was allowed to just stand for 1.5 hours afterwards.

I got an alert from Bluelink informing me that the "Sidelights were on, but the car off". When I eventually accepted its offer to turn them off, it said: "Not supported on this vehicle"

Looking at the graph, opening the doors lowered the battery voltage slightly below my target (to 12.56V min). This condition only lasted 4 seconds, but that was very close to the voltage at which the cutout operated on my first 'parking light' test (12.41V).

The 12V Battery Cutout did not operate. When I turned the car back on, the Air con and trip computer settings were lost

(The Traction Battery level had dropped by a 'smidge'...)

[PhilHornby]

Some observations:-

The discharge curve is quite different to the first time I did this (Parking light test). At the first attempt, I made no effort to charge the Traction Battery, though I guess it was reasonably high (it usually is, when I arrive home). Also, it has had an update applied since then (and a service...).

This is is the first time I have captured the "loss of settings" without the 12V cutout operating. Assuming for minute that module(s) had turned themselves off to save the battery, there is no sign that they achieved anything by it

FIRST PARKING LIGHT TEST

[PhilHornby]

Probably my last update on this - since the 'new' Tucson Hybrid seems to have some different control modules on board (if the change of navigation system is anything to go by). Presumably whatever the 'old' Tucson Hybrid has, it will be stuck with them now.

Since I've been 'home alone' for a few days, I did a longer term battery monitoring test. (I bought something on eBay, but it was useless, so I built my own ).

The test involved turning the car ON (but not "ready") and engaging Main Beam (along with Aircon etc). The first session was for five minutes and I subsequently repeated the test at (random) intervals - though only for 2½ mins at a time. It was obvious from each test, that the battery voltage was dropping lower each time, during the test - and although it recovered somewhat, it recovered to a lower value than it started.

I saw no signs of background charging from the Traction Battery (disappointingly), but I did see the Infotainment System power off before my very eyes. Strangely, it allowed me to power it straight back on again, but of course, it had lost its dynamic settings. My theory remains that its 'brownout detection' operates at a slightly higher voltage than the rest of the 12V system - producing those odd glitches, even when the car is "off".

It was obvious that with each test, the car was getting more agitated about the state of the 12V battery; it started with warning messages on the main dash, then on the infotainment screen (before it powered off!) On my very last entry into the car, the car unlocked as normal, but the effort of doing that and folding the mirrors out etc, triggered the '12V Cut-out' and I had to press the Reset button, to start the car.

The Traction Battery level was still on 2/3 at the end of the test.

[alan sh]

Interesting stuff. But what does it show in reality? Nothing we can influence by the looks of it.

[PhilHornby]

I agree that discharge curve doesn't show anything particularly unusual - but equally, it doesn't show the "30 minute background check, with charging if required" that I found in the document linked to in Post #36

It does imply though - that unless you have some 3rd party accessories causing a drain - there should be no obvious reason for the 12V Battery cut-out to operate, if the car is left unused for an extended period.

Something else that I missed in that Hyundai document, is that the 12V Lithium battery "only" weighs 4Kg. 4Kg = four bags of sugar ... now that is not a small battery

(I found plenty of LiFePO4 12V batteries for sale that were rated at 50Ah and weighed around that figure. This shouldn't really come as a surprise; this battery demonstrably has a lot of 'oomph' - it can run all the accessories (air con, power steering pump, seat heaters, lights etc) for an 'appreciable' amount of time.

As for the 'Infotainment system' powering-off/losing its dynamic data: there may be a case for doing that pre-emptively, just before the 12V cut-out operates (The screen itself, GPS etc might be considered a significant enough load). I can see no such justification for doing it when the car is "off" - so maybe, it's just poorly implemented

[alan sh]

Yes, my car can stand for over 2 weeks and start up normally. I just reset the aircon and centre display (and live with the fact that the miles since fill up has reset) and off I go.

Alan

[PhilHornby]

Just to square the circle, one owner was told that frequent 12V Battery Disconnects were caused by a faulty 12V battery and "they'd not seen it before".

I wonder...

[Philr]

That sounds like dealer billy bs to me.
If I had a pound for every time a dealer has " not seen that before" I'd be richer than a rich man. Let's face it if the dealer hasn't seen that before how would they know it was a faulty 12v battery?
They may as well say that there's an r in the month so it's bound to happen.
(And yes my opinion of main dealers is not terribly high)

[howitis]

The 12v battery sometimes doesnt get enough oomph from the traction battery, which is what is supposed to charge it, and on occasion it can catch you out with regard to maintaining what you expect it to do, particularly if you do have other bits running off it like some cameras and possibly if you sit in it using the phone at the end of the day to finalise the days business. I blame that last piece of work for messing up a diesel e class merc I was using for a living nearly 20 years ago. That had 2 batteries, I dont know what was supposed to keep the one responsible for the central locking and the rest of the gubbins charged up but it regularly ended up needing using the hidden key in the fob to get in to start it and so did my boss in his 500SL. 55 years ago I used to meet up with Jag road testers at a cafe just off the M5, all they did all day was put miles on up and down the M5. It's in the real world we catch the manufacturers out despite them running the things up to the North pole etc.