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FAST!  Click for  BIGGER!BM3 POWERCHAIR
LATEST 2011 MK3 Version

CHARGING SYSTEM FOR ITS LITHIUM ION PHOSPHATE BATTERY
 
More info:      BM3 Home
       BM3 Lithium battery
       BM3 15 MPH
       Charging Lithium
       Construction detail  
       Roboteq controller
       PDF Summary Printable
       
Current version 2010:      BM2 Powerchair
Original version 1998:      BM1 Powerchair  

 


THESE ARE NOT YOUR OLD FASHIONED LEAD BASED (GEL/AGM) POWER WHEELCHAIR BATTERIES!

The old lead based batteries were "simple" to charge but they took forever.

Lithium Ion Phosphate batteries or LiFePO4 cells (and all lithium based batteries) are a little more complex and need very careful  management via some electronic systems.

But they can charge MUCH faster. Up to 20x faster.

Charging has to be electronically "watched" over on a lithium battery on a cell by cell basis. While charging no single cell can be allowed to go above a specific voltage.

There are for e.g. 13 parallel "groups" of cells to watch over on the BM3 powerchair's Lithium battery. Click for info!

This can be by either an ON BOARD BMS SYSTEM (Battery Management System) as the Lithium Ion battery charges OR a very intelligent charger can be used that can balance the cells during charge.

Now an ON BOARD BMS is simple for the user. But inherently less reliable and you cannot "see" graphically what is happening. Plus they add cost and complication to the powerchair. But more importantly they take control away from the user (ME!) and remove much flexibility.  So I choose to use a special charger with masses of functionality. I am a control freak after all!


 

 
 

 
 
 

Hyperion powerchair chargerTHE CHARGER I USE:

It is the unbelievably flexible & powerful Hyperion EOS1420i NET3

This things functionality, and capabilities amaze even me and I had a fair hand in it and it's predecessors development over the last 3 years.

Not only can it charge any battery of any cell count OR CHEMISTRY up to 24 cells, and up to 60 volts, and any capacity from 100mA right up to 200 Ah+ it can also graph, cell balance, discharge, capacity test, resistance test, and work IN YOUR CAR!

Its also infinitely adjustable, and can be controlled by your PC or laptop...

I cannot think of any battery type, or cell count in use, that this thing will not charge better than the charger your device came with. 

 

lithium powerchair batteryI USE THIS CHARGER TO CHARGE EVERYTHING. AND I DO MEAN EVERYTHING!

It can be powered from either a power supply indoors plugged into the wall of 12v to 28v.  Or it can be used in your car. It can be powered by your car.  It can also CHARGE your car.

It can charge everything from your watch, to your powerchair.

Any battery type or chemistry properly.

And almost any sized battery.

Lead based batteries, such as powerchairs at 12v, 24v, 36v, 48v, AGM, Gel, or any type of lead acid as it is almost infinitely adjustable. Choose your own capacity, cell count, CC/CV level, float level etc.

3 different types of Lithium batteries with fine tuning adjustments, of up to 14 cells or 60 volts max. From tiny 100mah batteries up to my huge 45v power wheelchair battery!

And Nickel based batteries like Ni-Cad, Nickel Metal Hydride and much more.

 

ORANGE & BLUE battery shown here is my LITHIUM ION NANO PHOSPHATE Hi C rate 72Ah, 45v Power Wheelchair battery >>>

 

t can also graph, test, measure power in, or out, in Ah, And balance the cells of a complex lithium battery such as the one in my powerchair shown here.

It also charges the helicopters Lithium Polymer battery pack in the background! And its RC transmitter. And my camera... And the keyboard I am typing this on.

I have 3 of these chargers! I actually helped develop the Lead acid charge algorithm and the firmware updates, as well as the PC software shown later.

Here my Lithium Ion Phosphate power wheelchair battery pack is being discharged and graphed via its PC software & its internal IR measured.

There are the usual PLUS and MINUS connections (the big red/black wires) and there are also 14 extra connections! These all go to the individual rows of cells.

There are 13 rows, so 14 wires. The charger has to manage each row of cells individually to make sure they all end at the SAME exact voltage during charge.   

An old Lead acid (Gel) or AGM battery doesn't need this careful cell balancing. It can be charged at a fixed voltage a little over its natural "full" voltage and all the low cells are just dragged up to to the full stage. The ones already full just cook a bit!  You cannot do this with a lithium battery as the cells are destroyed by such treatment. And in the case of SOME types of Lithium battery this can cause a violent fire. Fortunately my LiFePO4 battery is SAFE technology!


THE HYPERION 1420i CHARGER

Lithium Charger that I use balances all the cells to exactly 3.600v (to within a few thousandths of a volt) automatically at every charge.

However because its really designed to be balancing smaller batteries the final bit, the balance, CAN take a very long time if your cells are out of synch.

 It doesn't take long, if all the cells are well matched in the beginning, as mine are, usually just a few minutes. But if not well matched, then expect hours or days for the balance to happen at the end of a charge!  Be warned! Mine usually take 3 to 15 mins.

I carefully measured capacity, resistance, and end voltage of every one of my 78 cells, and made up "strings" of very carefully matched parallel "groups" so they are all very closely matched to one another. Not a problem if you understand and bother to do all of this. 

 

 

 

HOBBY USE

The Hyperion EOS 1420i net3 charger is actually meant for hobby use. And reasonably cheap. But unbelievably flexible!

It can also monitor your batteries, graph them on your PC measure internal resistance, cycle the cells, and store all this information automatically.

See examples below:

Charge end and balancing 13 sets of cells!

After a balance, note cell voltages in yellow... All happens as I charge and sleep. So I can SEE what's happening in the morning.

.

Overview

This charger does not need to be connected to a PC but it is very useful thing to do. It can charge from a running car, or from a power supply in your house. I have one next to my bed, connected to a PC. So as to charge and balance and graph the details every night as I sleep. Not just this battery but of my other older technology chairs too!

It can charge at up to 60v and at 550 watts and up to 14 cells. And can charge at a maximum of 20 amps. All settings, voltages, battery type, etc are user set. As in you can choose what it does.

They don't come any more flexible than this. It can also measure resistance, measure battery Ah, and graph discharge too. And store all the data for future comparison.

TO BE UPDATED DURING BUILD - probably lots!

 

Added. How to convert the Hyperion 1420i Charger to wirelessly connect to your PC via Bluetooth!

 

What's the purpose of the pages about the MK3 chair and the earlier MK1 and MK2 chairs since I don't sell them? To embarrass the manufacturers into getting with the show, and doing some real development work. And to show other wheelchair users especially Paraplegics like me, what is possible. As such there are others now doing the same or similar, many are members of my Message board.

 

RELATED

MORE

 

More info:      BM3 Home
       BM3 Lithium battery
       BM3 15 MPH
       Charging Lithium
       Construction detail  
       Roboteq controller
       PDF Summary Printable
       
Current version 2010:      BM2 Powerchair
Original version 1998:      BM1 Powerchair  

 

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