[Col-Bimmer]

Been lurking for a bit, with an occasional post here and there. This past January I took delivery of an alpine white M235. Loving the car.

Because I don't drive the 235 all the time, I purchased a battery tender. So where am I suppose to connect the terminals of the tender? The gap between the two battery tender alligator clamps is not large enough to reach the positive and negative terminals under the hood of the car. So, is it safe to connect the tender directly to the battery located in the trunk of the car?

I have the same question regarding an air compressor. I would like to purchase a small compressor for the car (to fix flats or adjust tire pressures while on the road). There are two options. A compressor which connects directly to the cig lighter (provided the cig lighter can handle the amperage), or connect directly to the battery in the trunk.

[dan99]

I connected my tender directly to battery from the trunk. As far as air compressor, iv used the cig before on my e46 many times and no issues of blown fuse.

[nike001]

Pull the positive & negative wires apart from each other, it should separate the 2 wires bound together to give you some more stretching room.

[DanG]

You have an air compressor in the trunk. The M mobility kit works great. Just don't plug in the goop.

I've use it to blow up the tire after getting a flat from a nail. It plugs into the cigarette lighter.

[NEUE02]

I bought the cigarette lighter connector adaptor (you can get this separately) and use this all the time. Very convenient.

If your car has run flats you will not get an OEM compressor in the trunk. You can buy this from the dealer. Also, Sears sells a very high quality mini compressor which will also fit in the storage are in the trunk.

[Pyewacket69]

I have a 235 and I use CTEK battery tenders. I connected the charging pigtail directly to the battery, mounting the pigtail ends (lugs) to the upright threaded posts that are used to tighten the battery post clamps. Just remove the tightening nut, place the cable end on the stud, then reinstall the nut.

CTEK also sells roughly 1-meter long extension cables, and if you don't like having to lift the trunk floor panel to connect the charger you can connect one of these extensions, which gives plenty of length to route the other end where it will lie in the trunk, on top of the battery access panel, for easy connection.

You can simply close the trunk on top of the charging wire, as the trunk rubber seal has more than enough room to compress, so that the charging cable isn't pinched.

I also have this setup on my 2010 328, and it's worked beautifully for me since I bought both cars new.

CTEK also has a great warranty program, and really stands behind t heir products.

[krhodes1]

You don't necessarily need to reach the negative post under the hood. Any grounded bit of metal will do. On my 3-series I just use one of the shock tower bolts near the positive post - and I am not 100% sure that car even has an "official" negative post under the hood. It probably spends half the time on the charger, since I am away for work so much.

I would NOT muck around with the battery itself, lest you make the IBS unhappy. Assuming a 2 has an IBS.

[nike001]

Originally Posted by krhodes1

You don't necessarily need to reach the negative post under the hood. Any grounded bit of metal will do. On my 3-series I just use one of the shock tower bolts near the positive post - and I am not 100% sure that car even has an "official" negative post under the hood. It probably spends half the time on the charger, since I am away for work so much.

I would NOT muck around with the battery itself, lest you make the IBS unhappy. Assuming a 2 has an IBS.

The shock tower bolts are said to not be a direct route to the chassis. This is the correct negative post:

[krhodes1]

Originally Posted by nike001

The shock tower bolts are said to not be a direct route to the chassis. This is the correct negative post:

Anything metal that is attached to the body/engine should be grounded enough for a trickle charger. The tower bolts work just fine on an e91, but if the 2 uses a fully rubber mount they could very well not be grounded. With a good charger you will know instantly anyway.

Since there is an official post on the 2, I will just use it, my C-Tek charger cord will easily reach that far. Poor thing will also spend 50% of the time on the charger.

[Col-Bimmer]

Originally Posted by nike001

Pull the positive & negative wires apart from each other, it should separate the 2 wires bound together to give you some more stretching room.

Thank you all for the help and advice. I ended up doing what was advised in the quote above. It worked like a charm.

Thanks again.