If the battery is disconnected and it’s ventilated you can charge in the boot directly on the battery posts.
Not sure when they started using them or of Z3/Z4 have them but cars now have a current sense on the battery connection. It’s a short metal bar of known resistance, so, by measuring the voltage drop across it you can determine the current flowing.
If you charge directly on the battery posts then the cars electronics doesn’t know about the charge you’ve put in the battery and so may incorrectly set the alternator output voltage incorrectly causing the battery to be overcharged causing damage.
BMWs conveniently have a +ve and -ve post to connect to under the bonnet. Should be used for charging and jump-starting. This avoids by-passing the ever increasingly clever electronics that manage the battery and confusing the battery management.
When using a conditioner I put it under the bonnet and using a long extension feed the cable right at the corner of the front above the headlight. The cable isn’t pinched so won’t suffer damage. The bonnet can be closed fully and the car locked. There’s no exposed mains socket so it doesn’t matter if it rains.
Not sure when they started using them or of Z3/Z4 have them but cars now have a current sense on the battery connection. It’s a short metal bar of known resistance, so, by measuring the voltage drop across it you can determine the current flowing.
If you charge directly on the battery posts then the cars electronics doesn’t know about the charge you’ve put in the battery and so may incorrectly set the alternator output voltage incorrectly causing the battery to be overcharged causing damage.
BMWs conveniently have a +ve and -ve post to connect to under the bonnet. Should be used for charging and jump-starting. This avoids by-passing the ever increasingly clever electronics that manage the battery and confusing the battery management.
When using a conditioner I put it under the bonnet and using a long extension feed the cable right at the corner of the front above the headlight. The cable isn’t pinched so won’t suffer damage. The bonnet can be closed fully and the car locked. There’s no exposed mains socket so it doesn’t matter if it rains.
