The chair won't power on and the batteries won't charge. I know the charger works because I have tried it on another chair. When I plug the charger into the chair the light stays green and nothing happens on the controller, no lights go on, nothing. I have changed the batteries and still the same issue. With the charger plugged into the chair if I press the power button on the controller then the lights go on streaming across the speed display and the horn works but the charger doesn't charge. What could it be? Is there a fuse somewhere which may have blown?

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! 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!

That's exactly what it was, the batteries, which were new, sat idle for months. I have bought a new set ot batteries and now I know to charge the batteries once a week if we don't use the chair.

Is there any way to get the batteries, which sat idle, back to use again? That's exactly what it was, the batteries, which were new, sat idle for months. I have bought a new set ot batteries and now I know to charge the batteries once a week if we don't use the chair. Is there any way to get the batteries, which sat idle, back to use again?