I Hve a dell 9100 and the barttery light dose not come on hence the battery is not charging any suggetion I have been on to dell who say Battery or Mother booard is there a way of checking

If you have access to another 9100, swap batteries.

It could very well be your power adapter. Same situation happened with me on that model. They make that adapter so heavy and the wired parts to it not well constructed that it is bound to happen if you move that thing around at all.

Works fine on mains your right about the weight, since I brought it I have biceps like a boby builder

just because it works fine that way means nothing..It will work with ac power and still be an issue with charging the battery..it did happen to me

How old is the battery? I have a 9100 and the first battery only lasted about a year before it couldn't hold more than 10 minute charge. It is quite possible the battery will not hold a charge at all anymore and you just need a new one.

If there was a problem with the AC adapter, the charge light would not come on when the computer is plugged in and the battery is low. I've had to replace the AC adapter on this laptop twice. The first time something inside shorted out. The second time the wires became exposed at the stress thing by the main "brick" of the adapter. Neither time did that really affect my battery.