Batteries keep failing

[shirley_hkg]

The right charger may not be the magic key now. It is the supply chain. They use recycled materials.
We pay £900.00 for a pair of 75Ah gel , INVACARE /OTTO BOCK.

They all last less than 6 months, nowadays. This is not isolated case.

Lead for mobility devices are hopeless.

If you can't do full lithium, a small add-on will still unleash yourself from range anxiety COMPLETELY .

16 Headway 40160 cylindrical cells are easy to diy.

[Burgerman]

If I could afford it, I would buy a new MK. And cycle it to 80% and see how many cycles it gave when correctly charged.

I suspect that it will be well within spec, and you will get 500 plus 80% capacity discharges, to an end state of above 80% of original rated capacity. In the EU at least they are not allowed to claim one thing and deliver something else. Without being liable for HUGE claims by all the hundreds of thousands of users of those batteries. It would bankrupt the company. They would need to replace millions used in solar arrays, chairs, industrial backup systems, marine and millitary use etc.

And its trivial to test. The PL8 can be configured to do 500 cycles, to the correct exact discharge voltage, and to log the capacity and rinse and repeat automatically at the 20h rate. And to the specified charge algo.

So whilst theres a lot of junk cheap recycled lead batteries coming from china. I doubt that the MK brand (deka) would want to be branded as junk and ruin their deserved reputation and possibly be sued by millions of users.

The real reason is more simple. The majority of mobility chargers are just garbage. And the increase in the weight of chairs over the last 4 to 6 years with heavy seating and faster speeds puts double the demands on the same battery. And that results in a QUARTER of the service life.

Heres one of the biggest reasons: viewtopic.php?f=2&t=9133
A chair with seat LIFT added, gains the weight of a 12 year old child. And all the recline/tilt/lift/power centre footrest, full house DOUBLES the chair weight. That alone means double the amount of discharge on the crappy lead battery. Often coupled with a smaller battery! And a shit charger...
Added to users gaining weight over the years in some cases, as well as greater use of power wasting flat free tyres etc. So its a multitude of things.

[Dan]

Vjtod are you heaver now than you used to be
How many miles do you do a day? How many hours do you use the chair for around the house? Is there a lot of stopping and starting on soft carpet? The battery gauge on the controller is not great but are you near the red when you charge the chair?
It might be a good idea to go back to the charger than came with the chair.
I would say if you weigh about 70KG and you only do a mile or two a day around the house not draining the batteries to much and charging up every night your batteries should last a year or more.
I use a fully loaded Quickie MWD around the house with 55AH batteries. After a year of being used everyday they can still make it through a day no probs. I use cheap Haze batteries from WCS.