12V battery

Gave a jump start to an ICE car today. Wondered if there would be any problems with the 12v battery, but it all went smoothly. The young man in the other car did not know how to do it, so I had show him how to make the connections.

 

I bought a cheapish jumper cable for my ICE the other day and it has a built-in voltmeter.

 

We often go away for months at a time outback touring in a diesel guzzling Mazda BT50 towing a camper. During those time the Kona will sit in the garage unattended.

Should I rely on the periodic charging of the 12v battery to occur (I have had no problems since purchase of the car 6 months ago and regularly see the orange light in the hood badge) or would it be better to disconnect the 12v battery negative?

 

My older Kona would be fine because it doesn't have any telematics function. The long-term daily 20 min (12V) charge kicks in after about 60 hours parked.

I don't think there are any issues resulting from disconnecting the 12V battery but if you have a chance to test it connected and parked for about 10 days you'll find out if it can maintain voltage. A bluetooth battery monitor (which can be bought from SuperCheap Auto) is the handiest tool to determine this. It will log and graph the voltage without disturbing the car.

https://www.supercheapauto.com.au/p/matson-matson-bluetooth-wireless-battery-monitor/594361.html

 

I don't have the telematics either (dropped in Aussie 2021 models) so, based on that, I presume I will not have a problem. Will check out the Matson device.

Is there anything to choose between the BM2 you've used earlier in this topic and the Matson device you linked to?

TIA

 

I think the Matson is just a custom packaged version of the same electronics sold worldwide under several names including BM-2. Ironically, the one product to avoid is that branded "Hyundai". It looks identical but only measures voltage, no logging.

But it's really an impressive product for the money and the current app (seemingly maintained by the same person or company for all of them) allows up to four units to co-exist within Bluetooth range and can display over 1, 7 or 15 days. I use one on both EV and ICE and check them daily.

Now that my Kona (parked for the last week) is on the longer charge schedule I can see that the 12V is slowly losing a little bit of charge but it may be fine once it reaches a new equilibrium voltage.

 

Thank you. I won't have the opportunity to test long term inactivity when I'm home as it's used daily by the missus but I'm still keen to see what's going on in the 12 volt system.

 

I installed the Matson monitor. Very nice. I cannot pinch-zoom the graph to see detail, though I can see it fleetingly on the Voltage page until it scrolls off. Can you do that (pinch-zoom) on the BM2?

 

I'm pretty sure that the app is the same. On the voltage/time screen you just touch the green line to get a readout of voltage (xx.xx) vs time at each 2 minute logging interval.

 

Thanks. Just found that.

 

This is from my 2021 Aussie Highlander, beginning when I installed the Matson monitor. This trace is different to others I have seen here. Mrs OzKona took the car shopping at 1430, returning at 1700. It's been parked, unlocked and off the charger since. The spike at 2230 may have been me switching the car on to check something, but other than that I am surprised by the frequent charging events. After 2330 it seems to have settled down to the 4-hourly top-up as reported elsewhere in this topic:

 

It would be nice if they took the same attitude with the reduction gear issues.

 

Has the 12V battery ever suffered a "dead battery" situation?
Mostly it looks completely normal.

 

No, no dead battery event. When I said I was surprised, I should have qualified that a bit. I expect it to charge while the car is in use, just like an alternator. What I thought was different to what I had seen here was the initially more frequent charging after the car was shut down.

Speaking of dead battery events, I am going to leave the tailgate improperly closed for a while (apparent cause of dead batteries reported on a few forums) and see what it does.

 

More elastic voltage excursions can be a sign of a damaged 12V battery but there's nothing untoward here, just thought I'd check.

A couple of us have done that boot experiment, myself at #349 in this thread. There are also posts somewhere from me regarding the apparent lack of charging while driving.
In short, it used to charge for the first 30 min of driving (for the day) as it still does for the first 30 min of (traction battery) charging. Since the Campaign 196 update that was carried out on all examples during 2019, it doesn't charge while driving anymore -- but it doesn't drain the battery either. It just "dithers" around, see graph below, noting that "charging" requires around 14.6 V. And, instead of a daily 20 min charge we get six a day for the first 60 hours parked then back to daily.

I think EE is correct in pointing out that a charge during driving is not reliable, the time schedule is better. I have noticed that even that can be modified if the system thinks the 12V battery has been depleted more than normal. The small device on the battery negative terminal, a 24/7 voltage and coulomb data logger, provides that info.

 

I think I'll go back and read the thread again. Now that you've pointed this out I don't see much point in going over old ground - except perhaps to see if the 2021 Aus model is different. But OTOH I'm not keen to do an exhaustive test that will flatten the 12v battery - they are never the same after even one such event.

 

This is typically what I see regarding short drives, noting I'm on "196" software. I think in this case it's a normal situation - there are no extra 12V charges to make up for start-up losses.

I'll speculate that the BMS (meaning for the 12V battery) doesn't download the 12V battery data off the IBS sensor until it wakes up and restarts the daily schedule on the 23rd at 0700. At that time it could throw in an extra 20-min charge (or 2) but instead moves to the 4-hourly schedule 2 hours later. Perhaps it's our gentle climate but the original battery is still happy after 3 years.