12v Battery Best Practices

[EEEE]

This is the bm2.

https://www.ebay.co.uk/itm/125189489000

[FDAD]

I'm pretty sure the charging only starts when the drivers door is closed.

Nope... It can start in accessory mode, door open, closed it doesn't matter...

I think if you open the car, sit in, press the power button, put the seatbelt on but don't close the door, the 12v charging will not start.

I used to think like that, I was wrong.

The system usually charges below 30% the problem is... you need at least 1h for it to top up, so if you don't happen to begin your trip at the 20% mark or drive 1h every day it wont charge it properly.
After some time like I've seen happen to me the system will start the charge at 20% and i arrive my destination 5 minutes latter... the result is 8h with the battery at 20% or lower... that will repeatedly damage the battery after time.

The thing is.. the car can actually hold a charge ex: it depleted 50% in 8h but as soon as it hits 20% it takes double that to deplete, but it can't charge it without the key + accessory mode.

I've bought a BM6 https://pt.aliexpress.com/item/1005005057800182.html the insight is truly remarcable.

[Verone]

I'm actually thinking of buying one of those belt buckle alarm stoppers just for this, so I can leave the belt unplugged and just slot that in when I'm washing the car or cleaning the interior.

I can say with certainty that the system will charge the 12v even in accessory mode.
I thought that wouldn't happen but i have see it multiple times with a battery monitor.

Oh that's really good to know then - do you know what conditions it'll start charging when in accessory mode?

[FDAD]

I'm actually thinking of buying one of those belt buckle alarm stoppers just for this, so I can leave the belt unplugged and just slot that in when I'm washing the car or cleaning the interior.

I can say with certainty that the system will charge the 12v even in accessory mode.
I thought that wouldn't happen but i have see it multiple times with a battery monitor.

Oh that's really good to know then - do you know what conditions it'll start charging when in accessory mode?

I'll try and record a video of it but I haven't had a definitive answer.

[FDAD]

Below you can see that it begins to charge as soon as I'm seated, the car turns on automatically, it doesn't need to be ready to begin charging even the seatbelt:
I tested with leaving the car for one hour without being near it and it just stayed on charging. Just taped the screen when opening the dor to tell it not to turnoff when leaving.

Below is a typical 3 day charging cycle. From my understanding it just begins charging as soon as I'm seated/driving.

Turning off the infotainment (Via fuse 19 removal) did not stop the usual battery drain.

[EEEE]

SOC is not useful to you.

All 12v battery charging required a 'head' of voltage above the battery voltage in order to push the charge into the battery. By looking at SOC, you are limiting your observation to what it believe the SOC is. As far as I can work out, you cannot work out the SOC whilst it is charging.

I think if you change the graph type to Tensao (Tension/Voltage?) you should see better data.

Without seeing the voltages I couldn't say for sure, but it appears your battery discharges quite quickly. If you have never had trouble, then this probably isn't true.

Does the app have a way to set battery chemistry type? Can you pinch/zoom the graph - its hard to tell if you have lots of high drain loads bursting, or a gradual decline (The graph looks like it has lots of streaks hanging down from the line , but I have no idea if that's real data or a visual placebo).

[FDAD]

SOC is not useful to you.

All 12v battery charging required a 'head' of voltage above the battery voltage in order to push the charge into the battery. By looking at SOC, you are limiting your observation to what it believe the SOC is. As far as I can work out, you cannot work out the SOC whilst it is charging.

I think if you change the graph type to Tensao (Tension/Voltage?) you should see better data.

Without seeing the voltages I couldn't say for sure, but it appears your battery discharges quite quickly. If you have never had trouble, then this probably isn't true.

Here it is... taken just now. Unfortunately pinch to zoom not available but I could get de CSV file, if you're interested.

Does the app have a way to set battery chemistry type? Yes, you can select Lead, AGM and Li-on.Can you pinch/zoom the graph - its hard to tell if you have lots of high drain loads bursting, or a gradual decline (The graph looks like it has lots of streaks hanging down from the line , but I have no idea if that's real data or a visual placebo). It is visual placebo.