Do you have an M340i Xdrive MHT and Bimmerlink?

[sjb993]

If so, I would be grateful if you would let me know what Bimmerlink shows as your 12 volt battery's state of charge.

TIA.

[steve_n]

MHT means nothing here. That's just the state of charge of the regular 12V battery, as with any other car.

[sjb993]

Thanks for the response.

I know what it is, but I'm interested in what state of charge figures others get.

[steve_n]

OK. My point was it doesn't make a jot of difference what others say. The battery for the MHT is totally separate and one will not charge the other. 74% is just a reflection of how your car has been used and my guess is not very much in the way of regular and longer stints?

[sjb993]

steve_n said:

OK. My point was it doesn't make a jot of difference what others say. The battery for the MHT is totally separate and one will not charge the other. 74% is just a reflection of how your car has been used and my guess is not very much in the way of regular and longer stints?

BMW Service Information Bulletin 61 01 21 seems to disagere with you:-

Prolonged used of the “Emergency charging function” causes the 48 V battery to become totallydischarged. This occurs when the 12 V battery is not properly maintained and the SOC of the 12 V battery drops below the critical threshold value while the vehicle is in sleep mode. The vehicle is woken up and recharged from 48 V battery. If the 12 V battery is not properly, maintained this cycle repeats until both batteries become totally discharged.

[steve_n]

I stand corrected. Either way your 12V battery needs charging and if it's got like this then a more regular charge is likely to be needed. With only 74% charge you'd guess that the 48V battery is empty.

I don't use my 535i very much so I put the CTEK on every couple of weeks. Makes the battery last much longer.

If you are using the car a few times a week for more than just short journeys it might indicate a problem.

[sjb993]

The SIB I quoted also states that a charger rated at >20A is needed (I have a CTEK Pro25). Whilst the charger indicates the charging has completed successfully (green LED) and the CTEK battery monitor I have hardwired to the 12V battery shows SoC 100%, Bimmerlink shows SoC 74%. I am wondering whether Bimmerlink isn't handling MHT correctly.

Hence my question.