B4P Mild Hybrid Jump Start

[KeithR56]

If the mild hybrid engines have a 48 volt starter motor, do I correctly assume that they can’t be jump started with a 12 volt external booster pack?

[Snow man]

Yes you can jump start with another 12v,the manual explains how to,like most modern cars not directly to the battery but the dedicated terminals in engine bay.

[KeithR56]

the manual explains how to

Thank you Snow man. That’s good news. I didn’t see anything in the manual earlier, but will have a proper look later.

I’m not in a flat battery situation right now, but the thought occurred to me when I was putting my jump starter on charge this morning.

[Snow man]

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[blaurelena]

If your mild hybrid is packing a 48-volt starter motor, trying to juice it up with a 12-volt booster pack won't do the trick. It's like trying to fit a big pizza into a small box – just ain't gonna work, my friend.
Speaking of car woes, I remember when my trusty old ride broke down on me. It was one of those "Oh no, not now!" moments. Lucky for me, I had the number of a road assistance crew saved in my phone. They came to the rescue faster than you can say "stranded."
In the meantime, if you ever find yourself in a sticky situation like that, you might wanna check out https://stuck.solutions/. These folks really know their stuff when it comes to getting you out of a jam.

[Itsme]

If your mild hybrid is packing a 48-volt starter motor, trying to juice it up with a 12-volt booster pack won't do the trick. It's like trying to fit a big pizza into a small box – just ain't gonna work, my friend.

My manual states that the mild hybrid XC40 can be started via a 12volt battery and jump leads, see attached screen grab.

I suspect that the starter motors are 12 volt and that the Hybrid auxiliary Battery is the 24volt element in the car which; may have confused or been miss understood by the OP in their original post above.

[ChrisLF]

Before making statements like that you should check the manual!

States use 12 volt battery to start and go nowhere near the 48 volt system.

Posts overlapped.

[ChrisLF]

The starter motor must have some power though as it moves the car off whilst starting the motor.

[Felindre]

Think this is again down to Volvo's previous terminology: They used to call the 12v battery the 'starter battery' and the little 12v one the support (?) battery. They may still be referring to jumping just the 12v battery but calling it the 'starter battery'

My understanding is the motor alternator is 48 volt, driven by and charging the 48 volt battery in the boot. This charges the 12 volt system and battery by a voltage step down circuit. So you can't charge it going the opposite way.

[gedger]

My understanding is the motor alternator is 48 volt, driven by and charging the 48 volt battery in the boot. This charges the 12 volt system and battery by a voltage step down circuit. So you can't charge it going the opposite way.

I understood that the DC - DC converter is bidirectional so the 48v battery can be topped up although slowly. However, I can find no definitive documentation to confirm...