Thought i would add this to help others changing batteries is quite easy , read through before starting a couple of times
Raise chair slightly a few inches if you can unless its stuck somewhere fair enough
1. First turn off charger
2. Turn of key
3. turn off red power switch
4. turn off white main power switch rear of chair you may have to feel for it
5. lower the foot rest remove the plastic cover
6. remove the metal cover
7. behind cover will be wires and three allen key nuts DO NOT TRY AND REMOVE CENTRE ONE
8. Two allen key bolts are one below centre and one right of centre loosen them, the chair will now title left and right, you may need to remove the one on the right or bottom completely to allow more movement if needed, again DONT try and remove centre bolt
9. Remove left side cover by undoing two silver screws
10. remove right hand cover again two silver screws and cover will slide out
11. you may need to tilt chair left and right to get covers off
12. batteries will be revealed
13. NOTE WHERE CABLES GO AS CABLES ARE DONE IN A CERTAIN WAY TAKE A PICTURE IF YOU HAVE TO
14. remove both batterries
15. Install new batterries
16. Refit in reverse order , you may need a small level to level the seat out before doing up allen key bolts
almost forgot batterries you need will cost about £25
any 12v 7ah type average size Dimensions: 151mm in Length, 65mm Width, 95mm high
approximate sizes
Hope this helps
al yeti, July 2014