My Invacare TDX SP has died on me and someone told me of a trip switch on the batteries..Anyone know where this switch is as all I can see are bolts and metal?

SOURCE: power chair lights

The problem was a bad joystick. A local company came out to replace it and it works fine now.

SOURCE: WHAT MAKES THE CHAIR NOT MOVE WHEN CHARGING?

You cannot make a powerchair operate while it is charging. For safety purposes the power cuts out when charging batts. The only power is going to the batteries.

SOURCE: My brother-in-law's chair has a new battery and he

Contact the person who sold him the battery as it is under warranty. That person should be able to check out that battery for you.

SOURCE: all lights are flashing, and chair won't move when I try to use

The flash codes for the VSI controller used on this chair are located here:
http://www.pgdt.com/scenter/diagnostics/diagvsi.html
These will tell you what the fault is; repost with more information.

SOURCE: The chair won't power on and the batteries won't

After you changed the batteries, did the power chair sit unused for several weeks? It sounds more like a battery or fuse issue than a charger issue. If there are blinking lights when you try to turn the power chair on (not while attached to the charger), or it comes on then goes back off by itself quickly, there may be something else going on.
1- The green light on the charger is telling you that the batteries are not accepting any more power, either they are fully charged or they have oxidized/gone solid from sitting without being put on the charger for too long.
2-The scrolling lights on the controller when the charger is plugged in just confirms that the chair is connected to the charger, so it sounds like everything is connected properly and working. The horn will work fine when it is attached to the charger as it is getting power from the wall outlet.
3- If it was a fuse issue, the lights would not come on at all when the charger is NOT attached, even after the battery has been fully charged, which is what it sounds like is going on. The fuses can blow if you operate the chair on a slick surface or one of the drive tires spin out. The batteries will be fully charged but because the circuit is not complete, the chair will not power on.

I recommend checking the fuses and changing them if necessary. You are in luck because this is a relatively easy and inexpensive fix as they are standard automotive fuses found at any auto parts store or even Walmart for around $2 each (you need 2). The fuses are located inside the gray battery covers under the seat, attached to the leads connected to the battery cables. The straps holding the covers on the batteries are tight, you may want to use a flat head screwdriver to help release the clips. While you are down there, inspect the tread on the tires, if it is worn or slick it may need to be replaced for safety.
I hope this information is helpful to you- good luck!