I can not reach the AC power charging recepticle on the back of my m51 pronto. Other people might get out of the chair and walk to the back but I can not walk at all. I need the AC charger in the front where I can reach it while seated. Is there an extension or something?

It seems to be a known issue. Is it the black disc by the axle in this image?
https://www.monsterscooterparts.com/brands/invacare/models/pronto-m51/motor-and-gearbox-for-the-invacare-pronto-m51-and-pronto-m61-power-chairs.html

I would put a large hose clip around it. If you have the old one, you can probably get a replacement from Home Depot, or contact the company for a free one.

http://www.invacare.com/cgi-bin/imhqprd/contact.jsp

More info and manuals etc

https://www.google.com/search?q=Invacare+Pronto+M51+gearbox+grease+oil+plug

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You will need to contact a service tech in your area to do this. They should have a special programmer box that can adjust the settings on the chair to improve the chairs performance.

use locktite on the threads

Morning,its people like yourself that i am here.Please visit:www.alldatasheet.com

The chair needs to be off when you charge it. If you do leave it on by accident that is OK also.

Eduardo After using your chair and the battery level lights are down with yellow or red lights showing just plug the chair into the wall socket and let er rip. Now really after using your chair during the day and you are ready for bed just plug in the charger and let it charge over night. In the morning unplug the charger and you should be set for the day. If you don't use the chair everyday always put it up with a full charge and about once a week plug it in and let it charge overnight. Never leave the chair plugged in all the time and never leave it for more that 24 hours. The charger has two lights on it one red and one yellow or green that are hard to see because they are under the rear cover. When the chair is fully charged the yellow light turns green and you can unplug the charger and you should have a full charge. Hope this helps you

Jo, nope you are safe. Most of the chargers are designed to cut off and go into trickle charge once they sense that the batteries are fully charged. The problem with overcharging comes after 18 hours or so. You should never leave the charger plugged into the chair for more than 24 hours. On the M51 the charger is built into the chair so just plug it in when you go to bed and unplug it when you get up and you'll be ok. You can check for full charge by looking at the charger there should be a red light and a green light when fully charged. Hope this helps

Have the batteries load tested. It sounds like the batteries need to be replaced.

the batteries were dead

Margie,   Yes you may charge it overnight. If you use it everyday,charge it every night. Once the charger senses 24 volts it stops sending a charge,so they cannot be overcharged.  I suggest when you go to bed put on the charger and unplug it when you get up in the morning.