I fitted new batterys, now the joystick is reading low battery but no responce from the joystick.the batterys are wired red to red and black to black does the chair turn this to 24v itself, theres no diagram

There is a possibility that you have the batteries wired in a parallel circuit. This would only give you 12v and the chair should not even turn on. There was 1 time I had a customer do this and the chair would power up and when they tried to move the chair it would power down. Make sure you have 24v. The charger will not normally charge the chair without a 16v+ feedback. Some older chargers will still try to charge the batteries. The newer ones will fault and not charge until the circuit is wired correctly. Most manufacturers have taken this error factor out by color coding the harnesses. If you are unsure. Contact your local tech and they should be able to explain to you over the phone what to do

Will you don't say what chair you have and they can all be wired differently. Look under the shroud that covers your batteries and see if there isn't a wiring diagram there. If you let me know the brand ie: Pride Jazzy, Invacare M51 etc. I can give you the proper wiring for the batteries. Now you also didn't say if you charged the batteries after you installed them. Remember always charge before use. Just because they are new doesn't mean they are charged (in fact they could have sat on the shelf for a while). Make sure that they are no older than 4 months old even new batteries can be bad. Charge these puppies overnite. When you plug in the charger you should see a red and yellow light after charging overnite you should see a red and green light( indicating full charge) If when you plug the charger in you get a red and green light then something isn't wired correctly. Hope this helps