Possible new multi cell Li-Ion Universal Balanced charger setup

[LuxLuthor]

As some of you may know, I have been looking all over for a way to safely charge a larger number of Li-Ion loose cells with individual voltage monitoring per cell charger slot that would provide safe balancing of pack voltages.

After spending about 25 hours searching for every place and forum that sells Lithium chargers, Lithium Batteries, Lithium Cell Balancers, LiPo Packs, and all the various RC communities....I have come to the conclusion that such a product does not yet exist...as there are only 2 slot cell chargers like the Pila or UltraFire both of which charge slowly.

I began a conversation today with the owner of a large RC supply company who saw an opportunity. I showed him the crappy DSD type cradle charger to give him an idea of a 2 slot model, even though that one is both cells charging together.

He was thinking it would not be that hard to setup a multi-slot charger with 10-12 spring loaded slots that would each have a "tap" lead that would go into a balancing charger setup.

Of course you would need a separate charger that does cell balancing, but this would be the best way to resolve all the safety issues of loose cells in packs, and would even give you the capability of 1C charging rates if you wanted.

This is fun, and he can see the huge market for this. He was stunned when he saw the number of users on this forum....although check out the 1,100 users on this other vBulletin forum for RC users.

I was thinking it would make sense to have him get a cheaper balancing solution charger & power source to combine with this setup. Also to make sure it includes the capability of charging D & C Li-Ion cells safely.

[JimmyM]

Bravo, Lux. That's a great idea.
I had planned on doing the same with my DSD for balance charging anything that would go into the DSD, but it would be connected to my eStation BC-8
It's a charger with built in balancing for up to 8 cells. I've got a couple of balancing adapters for it. I had planned on building an 8 cell rack for D cells.

[LuxLuthor]

Yeah, I'm gonna sacrifice my 3 DSD's to do the same thing, after rewiring them to be 6S, and with tap leads coming out.

But this guy had that inventor's bright light go on when he realized there was no way to charge a large number of Li-Ion cells, including the new C cells, and D cells...more than one at a time.

He plans on sending me a prototype holder to see how the various cells will fit in it.

[greenLED]

Very cool, Lux. Please keep us posted.

[gammaray1965]

Has anyone heard of Lithium-Fiber batteries?

[LuxLuthor]

Has anyone heard of Lithium-Fiber batteries?

Yeah it is on the horizon. There is also Saphion Lithium batteries that are available now, which use phosphate instead of cobalt-oxide on the cathode which makes them safe. They have a set of videos demonstrating their safety next to normal Lithium Ion/Lipo batteries here.

[PhantomPhoton]

I would appreciate a safe solution for my C's greatly. Thanks.

[gammaray1965]

It appears that the saphion technology is the way to go! It would be nice not to have to worry about something going wrong while charging some batteries up!

I'm

[LuxLuthor]

I don't know if they make a whole lineup of various cells though.

[JimmyM]

I don't know if they make a whole lineup of various cells though.

They don't. I've already approached them regarding different cell sizes.
Them as well as eOne Moli

[SilverFox]

Hello PhantomPhoton,

To properly charge your C 3300 mAh cells, the manufacturers recommend charging in the range of 0.5C to 1.0C. You will have to refer to the data sheet for your particular cells for their recommendation, but that seems to be the range of charging rates. The ideal range seems to be around 0.7C.

Doing the math, you need a charger that is capable of charging at 1650 mA - 3300 mA. The 0.7C rate works out to 2310 mA.

A 0.5C charge rate will take roughly 5 hours to charge a cell. This seems to be the rate that most consumer products use.

The charge termination is usually set to around 0.1C. This means that when the charging current drops to below 330 mA, for the 3300 mAh cell, the charge is terminated. Trickle charging and charging at very low rates is not recommended, and not healthy for your cells. It can also cause safety issues.

There is a gray area between the 0.1C cut off current and the 0.5C recommended charge current. While it is possible to charge at currents within that range, I am not sure what the safety and performance ramifications are.

Tom

[lasercrazy]

Let us know how this works out. I'm very interested.

[WAVE_PARTICLE]

I'm in.

[greenLED]

Just a random thought:

How about making this charger in a physical setup similar to the Vanson, where you pull back a metal tab to secure the cells into their positions? The choice of charging algorithm would need to be different than in the Vanson, though. Could the metal tab be wired into the charger in such a way that it "sensed" the length of the cell and that way chose a given charging rate? This could be implemented in combination with the little "sensors" the Vanson has where the (+) end of the cells contact the charger.

This is a really neat project.

[TMorita]

As some of you may know, I have been looking all over for a way to safely charge a larger number of Li-Ion loose cells with individual voltage monitoring per cell charger slot that would provide safe balancing of pack voltages.

After spending about 25 hours searching for every place and forum that sells Lithium chargers, Lithium Batteries, Lithium Cell Balancers, LiPo Packs, and all the various RC communities....I have come to the conclusion that such a product does not yet exist...as there are only 2 slot cell chargers like the Pila or UltraFire both of which charge slowly.

Huh? These have been around for at least two years. All you need is a battery holder with multiple taps to use them.

Here's links to a few:

http://www.b-p-p.com/proddetail.php?prod=h_DNCharger
www.thunderpower-batteries.com/documents/TP205.pdf
http://www2.towerhobbies.com/cgi-bin...?&I=LXPZT6&P=0
http://www.align.com.tw/shop/product...oducts_id=1574
http://www.rcuniverse.com/magazine/N...roduct_id=1644
http://batteryjunction.com/temilibachwl.htmlhttp://batteryjunction.com/temilibachwl.html

[LuxLuthor]

Just a random thought:

How about making this charger in a physical setup similar to the Vanson, where you pull back a metal tab to secure the cells into their positions? The choice of charging algorithm would need to be different than in the Vanson, though. Could the metal tab be wired into the charger in such a way that it "sensed" the length of the cell and that way chose a given charging rate? This could be implemented in combination with the little "sensors" the Vanson has where the (+) end of the cells contact the charger.

This is a really neat project.

Green, I have never seen a Vanson before, and looking at pictures at Amondo's site is not entirely clear to me how that "pull back a metal tab to secure cells" is setup. I was not envisioning making this into an automatic charger that had the capability of sensing mAh capacities of various cells based on length. My initial thought when looking at how close some of the lengths of AW's cells are, and the liklihood that protection circuit designs of various Li-Ion makers could make a given cell model have different sizes from one brand to another.

While I agree that would be a neat feature, I am pretty sure that adding those kinds of "auto sensing" features would give a lot more things that could go wrong, and significantly delay the project. With the amount of mA current that would need to be applied to various cell types (especially larger ones) in 10S to 12S quantities, I don't see a way around needing a better quality charger that does balancing. Something like the Vanson and it's transformer....just won't safely put out the current needed.

[LuxLuthor]

Huh? These have been around for at least two years. All you need is a battery holder with multiple taps to use them.

Here's links to a few:

http://www.b-p-p.com/proddetail.php?prod=h_DNCharger
www.thunderpower-batteries.com/documents/TP205.pdf
http://www2.towerhobbies.com/cgi-bin...?&I=LXPZT6&P=0
http://www.align.com.tw/shop/product...oducts_id=1574
http://www.rcuniverse.com/magazine/N...roduct_id=1644
http://batteryjunction.com/temilibachwl.htmlhttp://batteryjunction.com/temilibachwl.html

TMorita, thanks for your note. I know balancers have been around for a number of years...that's not the issue. What is missing is a loose Li-Ion cell cradle with 10-12 adjustable slots to accomodate the wide variety of Li-Ion sizes shown here (& perhaps the new C size...and maybe D Li-Ion size), and with each slot independently tap wired.

As you know, all the RC LiPo packs come with the tap wires coming out of a pack into a harness connector, ready to plug into a balancer, and having been soldered to the individual cell terminal tabs. Nothing like that exists for loose Li-Ions, or Li-Ion packs.

In researching this project, there is not even a multi-slot plastic holder that will work as a universal Li-Ion size holder to even be able to attach the taps to. I know it is hard to believe, but because there are no universal size Li-Ion holders, there is no way available to actually do multiple Li-Ion cell balancing.

None of the various serial custom Li-Ion battery holder backs have any capability of doing balance charging....let alone 0.5 to 1.0C Li-Ion cell charging with a Schultze or my Hyperion. We Li-Ion cell users are light years behind the RC LiPo crowd.

The best option right which holds most sizes (but not all) of Li-Ion cells are the 2 slot Pila or Ultrafire low current chargers. They only put out 600 mA, and do not balance...except that they independently charge up to 4.2V

This is an example (the DSD) of what we have to deal with for charging our Li-Ion cells...including having to use brass spacer plugs.

[greenLED]

Lux, that's not the "Vanson" I had in mind. Here's the link to the one I used to have:
http://www.amondotech.com/index.asp?...ROD&ProdID=277

Here's the link to the "pull back tab mechanism" I was referring to.
http://www.amondotech.com/images/nim...BC1HU_1_lg.gif

What you do is pull that metal tab back (inside the charger, towards the bottom of the pic), insert the cell, and then release the tab. A spring brings the tab forward and secures the cell in place. Depending on the cell's size, the (+) button matches with the appropriate charging channel (those small metal rectangles you see opposite to the metal tabs).


I'm not suggesting you use the internals and power supply of the Vanson, just the battery securing/size sorting idea, if anything. You're right, with a growing number of available li-ion sizes, protection circuits, and size tolerances, it'll be tricky to get all of those right automatically.

IIRC, the last incident of a cell venting was because the user had the wrong setting on the charger. Some type of mechanical or electronic system that would take user error out of the equation (or minimize it) would be a useful feature to have.

[cy]

this junky old NHM/Nicad charger looks to be a good host for a balancer mod.

looks like a balancer module for Schulze is in my future...

edit: note picture is only to show holder can take several size cells. you should only charge like cells when mod is done.

[greenLED]

Way to go, CY! That one also has those sliding metal tabs to secure the cells in place I was talking about.

[LuxLuthor]

this junky old NHM/Nicad charger looks to be a good host for a balancer mod.

looks like a balancer module for Schulze is in my future...

Yeah, that is another type of plastic holder with the sliding feature like Green was saying...and it gives a better idea of what is missing....but I want something that can do at least 6, and maybe up to 12 slots. You could do less cell numbers if you wanted...the empty slots will become irrelevant, since they are all wired in serial connections from slot to slot to the last one.

Maybe the best idea would be to have two 6-slot cradles that could be plugged into each other. The Hyperion balancer only does 6 cells, unless you network another balancer LBA-10, then you can do 12 cells. I think a one piece 12 slot cradle would be too large.

I'll show him that picture, Cy....the one thing though is I don't think we want to be charging various capacity cells at the same time....just so people don't get that idea from cy's image which is demonstrating size capability.

[cy]

opsss.... thanks and edited to reflect you should only charge like cells in finished balanced charger mod.

[JimmyM]

I really like the path this thread is taking.
The only issue I see with this (with regard to my BC-8 at least) is that the negative charging lead, of course, must be connected to the most negative connection. The positive connection is a little different.
For a 2 cell pack... the #1 tap is connected to the most negative point, #2 is connected to the battery 1/ battery 2 connection. Tap #3 is connected to the most positive end with the positive charging lead. The remaining 6 taps are left disconnected. Every time a cell is added the next tap must be connected and then the positive lead is moved. A fixed wiring arrangement would be OK for the taps, but the positive lead connection point would have to move based on the number of cells currently being charged. I was thinking that a switch connected to each of the slider mechanisms would activate a relay (MOSFET, whatever) to move the positive charging lead accordingly.

[LuxLuthor]

I really like the path this thread is taking.
The only issue I see with this (with regard to my BC-8 at least) is that the negative charging lead, of course, must be connected to the most negative connection. The positive connection is a little different.
For a 2 cell pack... the #1 tap is connected to the most negative point, #2 is connected to the battery 1/ battery 2 connection. Tap #3 is connected to the most positive end with the positive charging lead. The remaining 6 taps are left disconnected. Every time a cell is added the next tap must be connected and then the positive lead is moved. A fixed wiring arrangement would be OK for the taps, but the positive lead connection point would have to move based on the number of cells currently being charged. I was thinking that a switch connected to each of the slider mechanisms would activate a relay (MOSFET, whatever) to move the positive charging lead accordingly.

Yeah, that is a really important aspect of this, Jimmy. I suspect the issue of resistance increasing proportionate to the number of slots used, material & amount of contact surface of terminals, guage of wire, and that issue of # of taps used selection like you mentioned are all important.

This RC dealer also thought it would be good to make it a 6 slot unit, with perhaps a second 6 slot cradle that could be connected in series or parallel. It would be similar to setups like you can reproduce on this handy website with customizing diagrams.

http://scriptasylum.com/rc_speed/_lipo.html Look at the bottom set of diagrams for using two 6-slot cradles.

[JimmyM]

Yeah, that is a really important aspect of this, Jimmy. I suspect the issue of resistance increasing proportionate to the number of slots used, material & amount of contact surface of terminals, guage of wire, and that issue of # of taps used selection like you mentioned are all important.

I don't think resistance will be that big an issue. Charging is current based (it would adjust to maintain the required current) and cell voltage is monitored at the cells themselves and the tap wires would carry little current. Plus, it would only have to carry a couple of amps.
I've put together a little schematic that would perform the required switching. The only thing required would be that each of the sliding tabs have a microswitch or magnetic switch that is activated when a cell is inserted.

This RC dealer also thought it would be good to make it a 6 slot unit, with perhaps a second 6 slot cradle that could be connected in series or parallel. It would be similar to setups like you can reproduce on this handy website with customizing diagrams.

http://scriptasylum.com/rc_speed/_lipo.html Look at the bottom set of diagrams for using two 6-slot cradles.

I'd prefer 8 because I can do 8 cells simultaneously. Call me selfish.

[LuxLuthor]

I don't think resistance will be that big an issue. Charging is current based (it would adjust to maintain the required current) and cell voltage is monitored at the cells themselves and the tap wires would carry little current. Plus, it would only have to carry a couple of amps.
I've put together a little schematic that would perform the required switching. The only thing required would be that each of the sliding tabs have a microswitch or magnetic switch that is activated when a cell is inserted.

I'd prefer 8 because I can do 8 cells simultaneously. Call me selfish.

I agree more slots is better, but an option is to have an ability to plug in additional cradles. I'm only thinking of the footprint size of a universal 8, 10, or 12 slot charger though.

I also wonder if the 6 cell Hyperion LBA-10 balancer is typical of most balancing chargers or modules for chargers. The dealer's initial thought was a 6 slot would be more adaptable to existing balancers...but he just started on this.

[JimmyM]

Linking additional units using my "auto switching" design would require that there be one "high current" connector (which would be the same connector that the charger connects to while only using 1 unit) and 4 small wires to carry the "switching logic" from the second unit into the first. As far as I can see, if 2 or more units are connected, you can still use it for less than 6 cells without disconnecting the second unit.
The tap connections would be on each unit for the cells in those units. So the proper harness would have to be used depending on the charger/balancer to which the units are connected.

[cy]

Tenergy li-ion charger with load balancing with four LDC to monitor output and a 5amp 12v power supply.... all for $89 looks too good to be true. http://www.all-battery.com/index.asp...OD&ProdID=1644

I've already got a Schulze, so I'm already covered. but for someone without a suitable charger for C li-ion. this could be the base for a multi-cell balanced charger mod.

really like the (almost) fool proof wire hookups. completely different output sockets for 4, 3, 2 and one cell config.

note: cradle below show different sizes for display only.

[LuxLuthor]

Cy, because that charger/transformer package looks so nice, I'm wondering if the universal cradle project would be better served by doing it as a 4 slot size, which could then be combined with this very charger w/ easy to use transformer.

It would allow new users a more economical choice who really don't need (or want to get into) the Schultze/Hyperion type setups with balancer, 12-15V power supplies.

I think they could have an option of getting a second (or 3rd) universal cradle that would plug into first (in series) to give power users an 8 and/or 12 slot option.

What do you think?

[Alin10123]

I've actually got one in the works that's coming up here shortly. Just a few quick specs.

-Able to charge 1-6 lithiums at a time (with balance charging capability)
-Can charge 1-14 nimh/nicd cells at a time
-lead acid batteries can be charged
-charging rate of .1-5A
-discharge rate of .1-2A
-charge/discharge cycles 1-5
-10 different memory storage options so that you can program in custom packs.
-Can hook up via USB to the computer (optional)

Price should be well under $100. It would be very well under $100 depending on the amount of interest.

Thoughts?