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Nuclear engineer
02/2012 X5 35d M57Y CPO 110K miles NOKIAN WR G3 25K miles
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21,385 Posts
Read your owners manual page 9 indicating Step 3 BULK charge is limited to 20 hours. 20 hours X 4.3 Amps = 86 Ampere-hours and not enough to fully charge a > 90 AH nominal battery.

There is nothing wrong with interrupting a charge at any time. Consider it an interrupted charge and restart when it is convenient for you. Charge until you get to Step 7 FLOAT or an error describe on page 11.

If you have loads on the charger other than the battery then the charging current will be divided and not charge the battery at 4.3 Amps. 4.3 Amps is the maximum that the CTEK 4.3 MUS will putout.
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 110K miles NOKIAN WR G3 25K miles
Joined
·
21,385 Posts
Thanks Doug but not sure that's it. I'm using the same way as on my Z4 and did not have this issue. Why on the M440i?
What “that’s it”?
 
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