Ultimate Lithium Add-on for dummy users .

[Burgerman]

What voltage is the supply?
12A max, @ 26.8V to XLR? Would be about right?

So you need a CC/CV charger that will work from a higher voltage like 36?

[shirley_hkg]

12A max @28.2V via XLR .

Supply battery voltage between 29.4---23.0V

[Burgerman]

Then it will need to be a buck and boost system like the PL8...

28 OR MORE IS TOO HIGH. iT WILL WASTE A TON OF POWER TRYING TO CHARGE A SET OF 95% FULL BATTERIES AT cv, AND BE WASTING ALL ITS ENERGY IN GASSING AND RECOMBINATION. Sorry about caps!!! You want it to contribute range not to desulfate the batteries idealy. The charger can do that later on.

[optical10]

This is really worth watching.
Tesla batteries.


youtu.be/TdUqQZC2dcE

@Burgerman Thanks, well worth the watch, way to shake up the car industry in only 15 years https://youtu.be/lyyeY8jO5UM, off to watch part 1.
If only tesla made a PowerChair or Toyota iReel https://www.topgear.com/videos/top-gear-tv/richard-hammond-drives-toyota-ireel-series-12-episode-2....off to tweet elon musk

[shirley_hkg]

I've made 10 of these compact powerbanks for wheelchairs.


24V50A, hup on hop off anytime , any chair .

[Burgerman]

Interesting.

[fishinjunky]

Impressive looking good

[shirley_hkg]

They are popular and need more units to meet the demand. I want to make 5 sets this time, with 21700 cells(6P7S), going after slim outfit.

Gonna pick a cutoff voltage.What will be the difference in DOD with 3.3V and 3.6V respectively ?

Discharge to lowest 3.6V (3.7V for safety which will be about a weeks use earlier)

[Burgerman]

Lifespan (unknown but very significant) and around 10% range.

[shirley_hkg]

Or you can use say 8S and 4p 21700 cells and build a physically small firework 20Ah 35V battery in a small bag carried on the chair push handles. And use this, to give say constant 27V and 3 to 5A limited CC/CV charge via XLR all day long. So adding 50% or 60% to the range. https://www.ebay.co.uk/itm/226087828265

Been planning to build one to lend out myself for years. Never get around to it!
It would extend the lifespan of lead by a long time, maybe double or better if set as suggested above.
4 or 5 Amps isnt enough for continuous rolling. But it would still more or less keep up as it catches up when you stop for a few mins or eat etc.
Remember that 4A charge is 20Ah restored every 5 hours. About the rate most people use up the battery. So low DoD average.

Thank your advice.

Sticking to 24V is to cater for recharging with stock charger of one's own.

A buck-boost inverter is used. It has small footprint of 80*55*20(mm), 5-48V/0-20A