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Discussion Starter · #1 ·
After a 4 weeks of vacation the car is dead. The battery in the engine compartment seems good, reads 12.4v.

Could it be the aux battery? Where is that located? How do I access?

When I try to use the display remote it says “too far away from vehicle”


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Discussion Starter · #3 · (Edited)
Many thanks for your response. Are there videos on how to troubleshoot which one is bad? Also since the batteries are dead, how do I pop open the trunk?

I am sure I’ll have many question, appreciate your patience while I ask stupid questions.


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Discussion Starter · #4 ·
Seems like (from reading the manual) I can try to jump the car, using the terminals under the hood that I was able to locate. Wish me luck


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There is no key hole on the trunk lid, so you'll either need to reach through the trunk pass-through and try to grab the emergency release with something, or jump the car using the terminals in the engine bay.

If you have an AGM battery charger, you can also try charging the battery from those terminals, although the deep discharge could have damaged the battery.
 

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My preference- if you have the luxury of overnight- is to charge the battery... jump if you are stuck and need to move NOW.
 

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Discussion Starter · #7 ·
Thanks everyone. It took a while to jump, but power to the electrical was as soon as the jumpers were connected to seeder vehicle. I could not start the engine for a long time.

I also left the car running for about an hour.

I am planning to but a booster - NOCO Boost Plus GB40 1000 Amp 12-Volt UltraSafe Lithium Jump Starter Box, Car Battery Booster Pack, Portable Power Bank Charger, and Jumper Cables For 6-Liter Gasoline and 3-Liter Diesel Engines. https://www.amazon.com/dp/B015TKUPIC/ref=cm_sw_r_cp_api_glt_fabc_PA238VVT6SE9GJ0HKSJG

You think this will suffice?


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You may have issues with cable length on the jumper pack as the terminals in the engine bay are somewhat far apart. I would be a bit wary about using a random exposed screw as a negative terminal if you want to start the car.

Preventative charging will help extend battery life as the car doesn't continuously charge the battery when the engine is running (to improve gas mileage). I have the Noco G3500 and charge my cars every month, the current model is the Genius5 and you can leave it connected when you are away.
 

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I am planning to but a booster - NOCO Boost Plus GB40 1000 Amp 12-Volt UltraSafe Lithium Jump Starter Box, Car Battery Booster Pack, Portable Power Bank Charger, and Jumper Cables For 6-Liter Gasoline and 3-Liter Diesel Engines. https://www.amazon.com/dp/B015TKUPIC/ref=cm_sw_r_cp_api_glt_fabc_PA238VVT6SE9GJ0HKSJG
Just keep the battery charged. No need for a 'booster'

CTEK makes very good charging products

to be honest, the link provided- with their "tactical grade LED"- looks like a piece of crap
 

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Discussion Starter · #10 ·
You may have issues with cable length on the jumper pack as the terminals in the engine bay are somewhat far apart. I would be a bit wary about using a random exposed screw as a negative terminal if you want to start the car.

Preventative charging will help extend battery life as the car doesn't continuously charge the battery when the engine is running (to improve gas mileage). I have the Noco G3500 and charge my cars every month, the current model is the Genius5 and you can leave it connected when you are away.
Thanks Robin750! Shall take your suggestion under advisement.

I just noticed that in my last service record, the dealer recommended replacing the battery for 475 parts and labor. Any recommendations here?


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I just noticed that in my last service record, the dealer recommended replacing the battery for 475 parts and labor. Any recommendations here?
Did they find any faults that could be caused by the battery, or did they just recommend it based on time? There is a bulletin recommending replacing the battery as a preventative measure with every second oil change, but if you maintain the battery by charging it on a regular basis, this frequency is overkill.


$475 isn't too bad considering the usual parts markup from the service department plus an hour of labor, but you can do it yourself fairly easily. Buy the OE battery from the dealer for $200 + core charge, remove the trunk floor (if you have the spare tire option, it may be a bit more work as that needs to come out too) and install the battery, then register it using ISTA (check the coding and programming section for download link, and YouTube for how to use the service function) and an ENET cable (check eBay, should be about $20).

Since your battery went dead, there are probably a lot of other random faults stored which you can clear while you have ISTA open.
 

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$475 isn't too bad considering the usual parts markup from the service department plus an hour of labor,.
I like that... "oh, battery is usually anal rapage- so this one is 'not too bad' -just about standard anal raping, no more no less"

:)
 

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Discussion Starter · #15 ·
Yup, should work fine. There's not much to the cable itself.
Thanks Robin750! One last question, can I connect the charger to the jumping terminals located in the engine bay? I think so, but want to confirm. Thanks much!


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Discussion Starter · #17 ·
Yes, it is recommended to charge from the terminals in the engine bay.
Thanks Robin750! And I suppose both the batteries are 12V AGM batteries? Of course using the charging terminals one can only charge the main battery, but to charge the aux battery you would need to access the terminals which is quite straight forward.


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Thanks Robin750! And I suppose both the batteries are 12V AGM batteries? Of course using the charging terminals one can only charge the main battery, but to charge the aux battery you would need to access the terminals which is quite straight forward.
The auxiliary battery in the engine compartment is AGM on your car. The lithium-ion dual storage system was introduced for MY2019 that replaces the 60Ah AGM with a 10Ah lithium-ion, though I'm not sure if it is standard or only included with certain equipment like ARS.

There can be an additional auxiliary battery in the trunk on vehicles with 24V steering (I think this is only on 750i models with IAS option). Both of these batteries would have their own Power Control Units, so I don't think charging them is necessary or desirable (as the PCU would not have the correct state of charge after external charging). Even though your main battery was dead, the auxiliary battery was still fully charged, so I think you should be fine leaving it alone.

From the technical training document:

The Power Control Unit is required:
  • For charging the auxiliary battery
  • For supplying the vehicle electrical system with the auxiliary battery
The Power Control Unit (PCU) contains a DC/DC converter with a power of 500 W.

The preconditions for the direction of the energy management are calculated from the use of the
vehicle. The auxiliary battery is charged by the PCU when the engine is running. During the phases
in which the combustion engine is not running, e.g. automatic engine start-stop function, the PCU
supplies energy from the auxiliary battery to the vehicle electrical system.
 

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Discussion Starter · #19 ·
The auxiliary battery in the engine compartment is AGM on your car. The lithium-ion dual storage system was introduced for MY2019 that replaces the 60Ah AGM with a 10Ah lithium-ion, though I'm not sure if it is standard or only included with certain equipment like ARS.

There can be an additional auxiliary battery in the trunk on vehicles with 24V steering (I think this is only on 750i models with IAS option). Both of these batteries would have their own Power Control Units, so I don't think charging them is necessary or desirable (as the PCU would not have the correct state of charge after external charging). Even though your main battery was dead, the auxiliary battery was still fully charged, so I think you should be fine leaving it alone.

From the technical training document:
Thanks for that additional help insight. So this afternoon the battery went dead again. So I started the charge for the 1st time with NOCO genius10. Selected 12v AGM, and the 25% LED started to pulsate. It’s about 3.5 hours and still pulsating. Should I use force mode or 12v repair? Or wait it out overnight?


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Thanks for that additional help insight. So this afternoon the battery went dead again. So I started the charge for the 1st time with NOCO genius10. Selected 12v AGM, and the 25% LED started to pulsate. It’s about 3.5 hours and still pulsating. Should I use force mode or 12v repair? Or wait it out overnight?
Considering that the battery is 105Ah and your charger has a maximum output of 10A, you should expect at least 7-8 hours for bulk charge (constant current) on a completely dead battery. After that, the charger will switch to absorption (constant voltage), which is much slower than bulk charge, so you'll definitely need to let it charge overnight.

Since your battery is deeply discharged and potentially damaged, I would try to leave the charger on there until it turns solid green (note that it could take an entire day or more to transition from flashing green to solid green). If you need to go somewhere, wait until at least it's flashing green to avoid getting stranded.

More info here if you want to learn more about the charging cycle:

 
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