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Hi ExSpark and FFLu,

I do not have a clamp ammeter but when you turn the car off and lock the doors i hear a lot of things happening for a while that changes the voltage. At exactly 11 minutes the power to the cigarett socket gets turned off and voltmeter shows 00,00 volts. And before i read this thread i thought that 11 minutes was the end of the biggest current draws before going over to standby current draw under 100 mah. After this 11 minute period i can not hear any more action and i feel the car has vent into beauty sleep. So FFLu if you came back 1 hour later to measure maybe 11 minutes is enough waiting time?

ExSpark. Yes the voltage is 13.45V to 13.54V with dipped beams on. But here is the thing. When turning dipped beams off the voltage drops to 12.16V to 12,21V as it gets no charge. But when you roll and regenerate it charges and when pushing accelerator pedal it stops charging. And with dipped beams on and rolling and regenerating it is around 14,40V and when pushing accelerator pedal it is around 13,50V.

ExSpark - I store my new battery in my living room now at 22 Celcius. Production date was week 47 year 2019. Voltage when i got it a week ago was 12,62V. Today it is 12,60V. I do not have a charger. Ideal storage temperature is 15 Celsius. So i should move it to a colder room.

FFLu - You got your battery up to 12.50V at your first charge. What temperature do you have in your garage? And what temperature is it outside the last days? I am starting to believe that our old batteries are changing resting voltage by temperature changes. In one month the only time i had 12.50V resting voltage was the day i parked in a warm garage a couple of hours. And i believe the start stop is deactivated under a certain below freezing temperature. Here in Norway it worked with -4 C yesterday. But today at -8 C it did not work.
 

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Discussion Starter #42 (Edited)
I think the vehicle has a few different stages of sleep mode, I'm not sure exactly how many though. At a minimum there's the initial stage after locking the vehicle, then there's the low-power mode after a while longer (11 minutes could be right), and according to the manual if you wait a few days it will enter an even deeper sleep where the keyfob will no longer work, and you have to unlock with a key.

Also, temperature does have an effect on battery terminal voltage.

The start-stop system does consider a few things besides battery health, and I think outdoor temperature is one of them, as well as engine temperature, whether air con/heat has been requested, load on the electrical system, how far the vehicle has moved since last start, etc.

Edit: Just to clarify something on voltage - different sources claim different voltages for 100% SoC, and it can depend somewhat on the battery chemistry. The new Yuasa battery I got was, if I remember correctly, just over 12.8V fresh out of the box (at room temperature). Some other batteries may settle to less than this, but somewhere in the region of 12.6V to 12.8V seems normal for flooded batteries.
 

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FFLu - You got your battery up to 12.50V at your first charge. What temperature do you have in your garage?
To clarify - I measured 12.5V after my third overnight (~12 hours) charge. After the first charge I reckon I achieved ~12.3V. In the last instance I left the car to rest (as I described earlier) for at least 3 hours before measuring with a voltmeter.

My garage is of ordinary walled construction with no heating, so the temperature would have been similar to outside ~ +8C at that time.

Temperature does affect lead-acid batteries (both old and new), and available data online suggests that the terminal voltage actually increases at lower temperatures by approx 3mV/degree C (i.e. +3mV per -1C). However, lower temperature reduces the electro-chemical activity and overall the battery cranking performance reduces.

ExSpark quotes approx. 12.6V to 12.8V, and my online researches suggest these values align with ~80% and ~100% SoC for a typical lead-acid, in "good" condition, and at room temeperature (~+25C)...

Anyway, I'm not really sure if any of my info is helping you, but I'm happy to try answering any specific questions.

FFLu.
 

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You both are helpful and i have some specific questions.

Do you know when the focus is giving a low battery warning? Is it when cranking voltage get under 9.6V or something?

When you charge your battery do you disconnect it from the car? If you dont, do you first connect it to the positive pole and then to the negative chassis ground point?

When changing battery should you disconnect the negative from the chassis ground point first and then disconnect the negative pole and then disconnect the positive pole?

Also should the BMS connector be disconnected?

ExSpark - Did you reset BMS when you changed your battery?
 

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You both are helpful and i have some specific questions.

Do you know when the focus is giving a low battery warning? Is it when cranking voltage get under 9.6V or something?
I'm afraid I dont know the answer to this and have not noted anything about it in the user manual.

When you charge your battery do you disconnect it from the car? If you dont, do you first connect it to the positive pole and then to the negative chassis ground point?
Recharging in-situ is not recommended practice due to the potential risk of (costly) damage to the car electronics e.g. if there was some malfunction with the charger etc.

If you choose to charge in-situ, then I suggest you use a charger that clearly states it is suitable for doing this, and follow whatever process steps it recommends.

When changing battery should you disconnect the negative from the chassis ground point first and then disconnect the negative pole and then disconnect the positive pole?
Again, I cannot comment on absolute best practice. A major consideration for me, from a sefatey perspective, is to ensure is that the battery does not get short-circuited during removal and refitting.

[FYI on my car the battery is partly obscuredd under the engine compartment overhang and also appears to have very short leads. In this case, there would seem to be little choice but to diconnect the most accessible (+ve) lead first, and set it well aside, before attempting to extract the battery enough to disconnect the -ve lead.]

Also should the BMS connector be disconnected?
Sorry, I dont know this either.

As far as I can see on my car, once either battery post/terminal clamp is undone, all its leads come away together. So if the BMS lead is part of that, then one would think it should be sufficently disconnected in this manner.

ExSpark - Did you reset BMS when you changed your battery?
I believe ExSpark advised me earlier in this thread that BMS Reset should only be done with a replacement/new battery - not an existing one.

FFLu
 

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Thanks.

I found in the service manual that main sleep happens after 40 minutes after locking the car. So now you could measure resting voltage at the right time.
 
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