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Thread: Tech Tricks: Homemade Balance Charging Cradles.

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    Flashaholic* Conte's Avatar
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    Default Tech Tricks: Homemade Balance Charging Cradles.

    Some of you might recognize one of these units.



    It's a typical multifunction hobby charger.
    It's a great investment to the avid flashlight enthusiast as it can pretty much intelligently charge any battery or pack we'd have in our arsenal, from NiCD to LiFepo4. This particular model can be had on the Bay for about $50. I power it with an IBM laptop adapter that gives me plenty of voltage and current for most all my charging needs. 16v 4.5a to be exact.

    One disadvantage is that it has but a single main output. This is not a problem for charging assembled packs that are designed to have the cells gang charged, but when you want to top off your set of Li-Ions so that your ROP or Mag 11 is ready to rip later on, you are pretty much limited to doing it one cell at a time.

    If you can connect more then one at a time, you can charge them together, but as most battery geeks will tell you, better they each get their own attention. I've noticed the new LiFepo4 cells in particular can be sensitive, yielding different state of charge readings, fresh of the charger when charged together in series.



    Most of the good hobby chargers will feature these special connectors, designed to establish control over each cell in a specially made lion/lipo/life pack. The pack will have a special charge connector to plug into these sockets.

    Using grade school arts and craft skills, and some basic soldering skills, I have exploited this feature, effectively turning my charger into bank charger.



    Here I have a set of 3 LiFe cells charging using the Balance charge function.



    I took 4 C-Cell battery holders, cut them in half and glued them to a sheet of acrylic spacing the halves to accommodate 65mm cells.



    I then wired the leads and the charge connector across this terminal strip. It has some nice lugs for me to connect my chargers alligator clips to while selecting the number of cells I wish to charge. As labeled, the Common Negative is the the left. Then from left to right I can select 1s, 2s, 3s, and 4s.



    The festivities do not end there. As the cradle is sized for 65mm cells, it can also be used to bank charge 18650 lions. Seen here it's topping off my IMR for my EDC. You can unplug the balance connector and select 1s for single cell operation.

    NOTICE: Make sure you read your chargers instruction manual, and double check your connections. As you are manually selecting your cell configuration there is a margin for error, and some chargers REALLY won't appreciate being hooked up wrong. For example, my chargers manuals warns that you might damage it, if you attempt to start a charge with the balance connector plugged in, but without the alligators connected properly.



    Today I want to make a cradle to accommodate my shiny new AW IMR26500 cells that I just got in the mail to power my Megalennium 2x26500.

    The ingredients are: one charge connector, a 3 point terminal strip, 2 C-Cell holders, and piece of acrylic.



    Acrylic is pretty easy to work with. In Canada you can usually purchase it from your local Home Hardware for not lots of money.
    To cut it you use a metal straight edge and a sharp knife. I'm using a pen knife.

    When you figure out where you want to make your cut you run the knife along the straight edge to give it a nice score mark. If you can, run it over a few times.



    Once you have your nice score mark, simply locate the mark along the edge of your desk or work bench like so, and snap it off.

    Easy Peasy.



    I originally attempted to construct these units using Hot Glue, aka: Glue Gun Glue. This did not work very well. Though it seems to stick to acrylic really well it did not hold up in use. The terminal strip on my 2x50mm cradle came loose, and the first two most used slots on my 2x65mm also fell apart during a charge.

    I rebuilt the units using epoxy, it really is the best way to go for this setup.



    Once we get it all together, it's ready for wiring.
    This step will require basic soldering skills. If you are not confident soldering, I recommend lobbying the services of someone who is.
    After all, sloppy work here could cost the lives of your batteries or your charger, and who knows what other collateral damage.

    If you are new to soldering and can do a decent job, this may very well be a good beginner project. Just make sure to check and double check your work before using it, and maybe run a multi meter over it checking for continuity and resistance to confirm there are no cold solder joints. Also, if you are using the same kind of terminal strip as I am, watch out when you solder to the lug that is also used for mounting as it may soften the glue and come loose on you.

    TIP: Soldering is like buttering toast. You use the knife the apply the cold butter to Hot toast, causing the butter to melt into the toast. You DO NOT, use a Hot knife to melt butter onto cold toast.

    The idea with soldering is that you are using the iron to heat up the lug and the wire, then touch the solder to it, thereby the heat of the lug and wire causes the solder to melt and fuse to it. A common beginner mistake is to melt the solder with the iron and attempt to apply it. The correct method will almost always assure a good solder joint.



    Here is the Wiring Diagram provided in the chargers manual. It lays out for you, pretty clearly (at least to an experienced tech like Me), how to wire up our charge connector. I imagine your charger manual might also feature such a schematic. This particular schematic SHOULD apply to most chargers as the balance Charger connection is a Industry Standard.



    Here is the finished product. I used the centre lug as the common negative, and the adjacent lugs on either side for 1s and 2s connections, then labeled it as such.

    If you prefer, feel free to stick to a more linear layout, it's jsut tech instinct to assign the common negative to the mounting lug.

    The terminal strip I used is alot smaller then the one use on my 65mm 4s cradle, so I will use caution to make sure the alligator clips do not touch each other or any contacts they are not supposed to.

    When sourcing out charge connectors, I recommend getting some that can accommodate the maximum amount of cells you may be building a cradle for. Chances are they will come in a lot.

    I got a 10 pack for about $5.
    The sockets in my particular charger are backwards compatible, and don't much care how many cells are plugged in at a time, as long as they are in proper order. You can remove extra pins from the connector and tailor it to your needs.

    In my case, I bought a lot of 4s connectors off the Bay, and removed two pins to make a 2s connector, and my charger doesn't' mind that it is plugged into the 4s slot.



    Here I have successfully built a 2 bank charger for my IMR cells.

    All parts were sourced from Ebay:
    The Battery holders were about 6 for $5.
    The connectors were about 10 for $5. Search "balance charger plug".
    I forget how much I paid for the Acrylic at Home Hardware.
    And the terminal strip could be found in lots for about $1 each. Search: "terminal strips".

    One of these cradles likely costs less then 5 dollars. Once you have a lot of supplies as I do, you could build all sorts to accommodate your various battery charging needs.



    Seen here I chopped a single D-Cell holder, into 3, to create a cradle to charge five 1/2D cells, for dropping 6volts into a 3D Mag, for running Magcharger or Wa1160 bulb.

    IMPORTANT SAFETY NOTICE:

    These designs have no official safety certification, as such their limits are unknown. It is up to the individual user to verify and monitor their safe operation. Many CPF members will have the experience necessary to construct and safely use these units, and this post is for their benefit.

    If used incorrectly or overloaded they could very well pose a fire hazard. For this reason, I advise you build and use one of these units at your own risk.

    Unless you have a good idea of the limitations of the particular components used in one of these builds I would recommend limiting the applied current battery holders with stock leads to 1amp. As the leads that came with my battery holders are very flimsy, chances are this current spec will be safe for any other variation of this build.
    In use I've noticed some mild warmth coming from the battery holder leads when 2amps is applied. This does not last long, as no matter what current level I would set, the smart charger would throttle down the current to about 1.1amps, and did not seem to want to push any more then that through the flimsy leads.
    I can only imagine the charger detected insufficient plumbing and compensated.

    Upgrading and Revisions.


    If you like this design, and use it regularly . . . AND are confident with your soldering skills, you may consider upgrading the leads to up the charge rate and assure an overall safer operation. I found this necessary as I was unable to get the charge rates I wanted with the stock battery holder leads.

    This requires some quick and confident solder welds as the plastic of the holder is likely to melt very easily.
    I'm upgrading my cradles using 18 gauge solid wire. The solid wire was chosen mostly for the fact that I already had some on file. Solid wire is capable of conducting more efficiently then stranded wire. As these cradles have a solid frame and don't really need to be shock rated, it's not a bad idea.

    18 gauge wire is rate for 3 amps conservatively, and due to the very short distance and low voltages it could easily handle more in this application.
    If you are looking to go up to a 10 or more amp charge I would consider using 14 gauge while also rigging it to bypass the stock battery holder contacts as seen here.



    Upgrading the positive contacts, I pushed a stripped section of the wire though the battery holders contact holes and bend the exposed section.



    I then pulled the wire back and made a quick solder weld to the contact.

    This is the part where you have to be careful as the heat for the weld has likely started the plastic melting regardless of how fast you were.



    A "tool" handy for this procedure is some "parts chiller" Basically a freezing action spray.
    Once I made the weld, while carefully holding everything in place, I took the chiller and sprayed it onto the spot where I had made the weld, solidifying the plastic before it could slip and ruin the holder. You would otherwise have to hold the wire in place until everything cooled down.
    If you don't have any boutique parts chiller, you can just use computer "air spray" tilting the can sideways so that the raw liquid sprays out. This is pretty much the same thing as parts chiller.

    The other option, if you wish to avoid soldering all together, is once you have the bent wire in place on the inside of the battery holder contact, so simply glue the wire in place on the outside of the holder. I have not tried this personally, but with the right glue and proper technique it could be a good idea.



    To make the negative contact you pretty much go through the same motions. The difference being that you would pinch the negative wire on the end of the spring like so. This would bypass the spring avoiding any dependency the circuit has on its quality or conductivity.



    Afterwords, as the spring offers some thermal isolation from the plastic, it is considerably easier to apply solder without the risk of meltdown.
    Once again, if you wish to avoid soldering, you can just pinch the wire onto the end of the spring without the need for solder.
    Mind you, the solderless methods are likely to work with solid wire only.



    Here we have the revised finished product. I like how the solid wire allowed me to shape it into a more uniform layout.

    As discussed in this thread, these particular methods using balance charging systems might be somewhat redundant.
    In the case of the 2x50mm cradle, a parallel system might be a better and less complicated way to go.
    On the other hand, I find balance charging method advantageous in the 4x65mm cradle when I wish to hit more then 2 cells with a high rate charge. As my particular charger is limited to about 4 amps due to the powersupply used, I would be unlikely to hit 4x26650 LiFe cells with a 1C charge using the parallel method.


    The Lux Luthor Magnet Method.





    Since the creation of this threat, Lux Luthor brought to my attention another great way in which to utilize the Balance Charging system.
    I've decided to try my hand at it.

    If you live in Canada, you are likely familiar with the Home Hardware. My local A&J Home Hardware on Bouchard street in Sudbury can be a modders paradise, as they will custom cut you wire or pipe, have a workbench where they help you rough fit projects, and have the stock consistency of a nation wide chain store.

    In their limited stationary supply section I was delighted to find they stock just the perfect kind of magnet we need for this project.
    As this is a nation wide chain, these magnets should be available, (if by special order) at any home hardware across Ontario, and even Canada I would imagine.
    This package cost $7.49cdn +tax.



    As you can see, I constructed a 4S harness using 6 magnets.
    Five for the BC connector (Balance Charge) and the common Negative;



    and one for the floating Positive:



    This idea is, you can snap on as many BC connector leads as you need to match your cell count.



    Seen here, I have snapped together 3 cells for the charge. The Blue 3s wire being the last in the chain, snapping the floating posative onto the end of that chain, and omitting the Green 4s lead.



    The insulated side of the battery seems a good place to snap the omitted lead magnet. It should stay out of trouble there.



    With the remaining Magnets, I soldered up some parallel jumpers so I can use that particular method of charging for a pair of cells.
    In this configuration, the omitted magnets are just all snapped together in their standby positions on the negative common side, while the BC connector is not plugged in.

    The tricky part of the rig is the soldering. Too much heat applied to the Magnet can strip it of its magnetization rendering it useless. I've known this for a while. It's common knowledge among competent guitar techs that the use of high output soldering guns has been known to demagnetize electric guitar pickups.

    Lux has mastered it, and has dropped tips among the forum. I myself have been soldering for over 16 years, and have the right equipment, so though reluctant to damage the magnets, I figured I could handle it.

    The trick is to be quick, avoiding to much iron time on the magnet. You pretty much have to know how to solder and have decent experience doing so.
    Refer to the "Butter on Toast" tip mentioned earlier in the thread. In this case, imagine using a blow torch to heat the bread just enough so that the butter melts into it, but without actually toasting it.

    The method is something to be seen. I have made this HD video to illustrate.



    If you can do the motions as seen here, you should be able to pull it off.

    What you are seeing is:
    A: I "tin" and preheat the wire for soldering,
    B: I tin and preheat the magnet surface ",
    C: I fuse the preheats and tinned parts together,
    D: I quickly spray some "chiller" on the magnet to remove all access heat.

    Tinning in the process of pre-fusing some solder onto the surfaces to be connected, as you would with contact cement glue, or even epoxy.
    It's pretty much a mandatory prerequisite to making a good solder joint.


    For tools:
    - I have a set of jaws or "helping hands" to hold everything,

    - A 35watt soldering iron. Note the medium flat tip used. Too sharp a tip might not spread the heat evenly. To wide may spread it too much making it hard to focus your
    heat and overheating the magnet. The right tip could make or break this joint, you should be good with a fine tip though. A 35-45 watt iron with a med flat tip is pretty much a swiss army knife of irons to those who can use them well. DO NOT, use a solder gun!

    - Some FINE standard Rosin Core solder. Nothing special but the size. Too thick could flood your joint making for a sloppy work.

    - Parts chiller. The chiller has been discussed already, look for the pic of the can.

    I was able to pull this off in one shot with no damaged magnets.
    If you are not confident doing this, I would practice on some random pieces of metal. Maybe try soldering to the edge of a penny as they are about the same mass as the magnets, just keep in mind, It will take about half the time to fuse to the magnet as it would to the penny. I would recommend soldering to the edge of the magnets as it will take longer for the heat to spread across then it would if you soldered to middle. For soldering the common negative, fuse the main lead and the BC lead together before welding to the magnet so that you only have one joint to make.

    Last but not least, mind the polarity. When you stack the magnet, they will only snap together one way, if you want your wires to be oriented a certain way, best to figure out how they will snap together before making the connections.

    ENJOY !
    Last edited by Conte; 01-27-2010 at 12:02 AM.

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    Flashaholic* Conte's Avatar
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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    Thread reposted due to accidental deletion.

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    *Flashaholic* kramer5150's Avatar
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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    I have a similar charger, and charge my individual 26650 & 18650 cells in parallel. It works great with CC/CV chargers like this one that terminate at 4.2. FWIW, I also use a Lenovo 15V laptop P/S and it works great.



    Last edited by kramer5150; 01-13-2010 at 11:31 PM.
    CLICK HERE for my flashlight reviews.
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    Flashaholic* Conte's Avatar
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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    Good reference Lux, The magnet method is pretty slick and defiantly as modular as you can get.

    The only aspect of that I'm a bit sketchy on, is, since the Pos and Neg leads are permanently soldered to the first and last S lead, how do you scale it down for less cells ? Without cutting a while new harness ?

    I you haven't already, (I didn't see it mentioned or illustrated in your thread), what I'd do, is get one more magnet, and solder JUST the pos leads to it. Then after you can scale the harness down, and sandwich the Pos magnet to whatever the Last S magnet is.

    It never occurred to me to use magnets to connect batteries until I met some of your posts. Now I use them to attach batteries for experimental purposes.

    I have a similar charger, and charge my individual 26650 & 18650 cells in parallel. It works great with CC/CV chargers like this one that terminate at 4.2. FWIW, I also use a Lenovo 15V laptop P/S and it works great.
    Ah, that's how the normal bank chargers work, eh ?
    I was never sure if I should trust that method. The normal bank chargers run a pretty low C-Rate. If I wanted to charge each cell at a High - C rate, I'd have to dial in a 2xC rate for two batteries in Parallel.
    What C Rate do you feel comfy hitting a parallel system with ?

    Seems you had the same idea in how to chop up a Battery Holder.

    You idea is a good supplement to this thread.

    PS: My Charger came with a cheap PSU that broke. Having a spare adapter for my laptop saved the day.

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    Flashaholic InHisName's Avatar
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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    I am just discovering these 'hobby' chargers. Can NiMH AAs be connected in same fashion and charged successfully with these type of chargers ? This seems like the only way to speed up charging one cell at a time and still do a decent job of it. I have a C9000 but on occasion I want to charge more than 4 at a time.

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    *Flashaholic* LuxLuthor's Avatar
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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    Quote Originally Posted by Conte View Post
    Good reference Lux, The magnet method is pretty slick and defiantly as modular as you can get.

    The only aspect of that I'm a bit sketchy on, is, since the Pos and Neg leads are permanently soldered to the first and last S lead, how do you scale it down for less cells ? Without cutting a while new harness ?
    Since you can use the 6 cell (7 balance wires) plug for any number of cells from 1 through 6, you could just use the 7 wire plug going to magnet wires to correlate with the number of cells.

    Like in your example photo below where you used the 4s plug, with 3 wires to charge your 2 cells, I would just use those same right most 3 wires going to the 3 magnets. Then I have the main power aligator clips going to another outside larger red/black wire for main charging power.



    Just imagine where you are showing the two empty plug slots, you had wires in those slots, but those extra 2 wires were not being connected to anything. That would be how I would treat those two wires with magnets soldered on them. If I wanted to charge 3 cells, then I would bring the 4th magnet wire into play; 4 cells, the 5th magnet wire. This photo in my thread shows all the wires being used.
    Last edited by LuxLuthor; 01-14-2010 at 01:00 AM.

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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    Quote Originally Posted by Conte View Post
    ..... I was never sure if I should trust that method. The normal bank chargers run a pretty low C-Rate. If I wanted to charge each cell at a High - C rate, I'd have to dial in a 2xC rate for two batteries in Parallel.

    What C Rate do you feel comfy hitting a parallel system with ?
    Charging Lithium cells (of the same type) in parallel works well. I charge 8x 16340 (650mAH capacity) at 5A (max. charging current of the charger) which is just a bit less than 8C.


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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    Hello Conte,

    Glad to see you were able to get this thread back up... after I accidently deleted it.

    At any rate, nice set up, and nice write up.

    Tom
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    Most batteries don't die - they are tortured to near death, then murdered...

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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    Hello Rmteo,

    While 5 amps is close to 8C for one 650 mAh cell, when you parallel them as you have it is actually just under 1C for the battery pack.

    Tom
    Behind every Great man there's always a woman rolling her eyes...

    Most batteries don't die - they are tortured to near death, then murdered...

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    Flashaholic* Black Rose's Avatar
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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    I don't have a hobby charger yet, but I think I am heading in that direction with the different Li-Ion cells I am getting.
    Quote Originally Posted by Conte View Post


    Would it be possible to get a photo of the back of that terminal strip?
    I'm on how it's connected to the back.

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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    Quote Originally Posted by Black Rose View Post
    Would it be possible to get a photo of the back of that terminal strip?
    I'm on how it's connected to the back.
    The balance leads go to each of the cell connection points in order, like this (order is important):
    Code:
    Charge + ==================
                              |
    Balance 3 ----------------+
                              |
                              -
                             | | Cell #2
                             | |
                             ---
                              |
    Balance 2 ----------------+
                              |
                              -
                             | | Cell #1
                             | |
                             ---
                              |
    Balance 1 ----------------+
                              |
    Charge - ==================
    (The main charging wires are not shown in the photo.)
    Last edited by Mr Happy; 01-16-2010 at 05:33 PM.

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    *Flashaholic* LuxLuthor's Avatar
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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    Quote Originally Posted by Black Rose View Post
    I don't have a hobby charger yet, but I think I am heading in that direction with the different Li-Ion cells I am getting.


    Would it be possible to get a photo of the back of that terminal strip?
    I'm on how it's connected to the back.
    It also appears to me that Conte is not using a 2 cell balance charging setup here. He has the two cells in parallel, essentially becoming a large mAh single cell. A single cell does not need a balancer plug at all, just the outer red/black main current leads.

    Balance charging as Mr Happy demonstrates assumes 2 or more cells are in series. If this was to be a balancing setup, the black and yellow wires would need to be reversed in the white plug. Then the yellow wire would need to be going in between the two cells. I am showing how it should look in Conte's example using my magnet leads.



    Why would you want to do balance charging instead of putting all cells in parallel (which can be done if you have no balance charging capability)? To save time charging. My above setup is charging cells up to 2300mAh which goes a lot faster than up to 4600mAh
    Last edited by LuxLuthor; 01-16-2010 at 04:49 PM.

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    Flashaholic* Conte's Avatar
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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    It also appears to me that Conte is not using a 2 cell balance charging setup here. He has the two cells in parallel, essentially becoming a large mAh single cell.
    . . . No, that's a series balance setup.

    Why would you want to do balance charging instead of putting all cells in parallel (which can be done if you have no balance charging capability)? To save time charging. My above setup is charging cells up to 2300mAh which goes a lot faster than up to 4600mAh
    Not to mention it also gives the charger control over each cell, enhancing charge quality.


    I could take a picture of the back of the terminal strip if you really want, but it wont' tell you much, a schematic is really the was to go.
    The picture I took of the manual is the schematic you want to use.

    Mr. Happy's schematic is good too. I just of drawn it upside down to match the perspective of my chargers balance plugs, as the wires are not actually labeled. That's just my charger tho, others could very well be the other way around.

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    *Flashaholic* LuxLuthor's Avatar
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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    As an instruction guide for newbies, it becomes confusing to not keep red as positive, black as negative. I'm not seeing in this view with the wires soldered to those terminals how you are using the same middle lug as "common negative," as you said below pix going from 1s to 2s.



    Here is the finished product. I used the centre lug as the common negative, and the adjacent lugs on either side for 1s and 2s connections, then labeled it as such.
    You can see by Black Rose's question, and my interpreting this as a 1s2p setup that it isn't making obvious sense as shown. I don't doubt that you have a way to hook it up properly, but it is confusing when you cannot follow each wire if someone wants to copy what you did--which I assume was your intention in making this thread.

    Two other opinions:

    • Charging identical cells in parallel will work out just fine with Lithium cells, so I'm not sure what you think you are gaining when you say you are enhancing the charge quality.


    • if you use those holders, they have high resistance (which accumulates in series) & the springs heat up, so it doesn't work well with higher amp charge rates. The 1 Amp you mentioned in your first post will be fine.

    The nice thing about using Lithium Manganese or Lithium Iron Oxide safe chemistry cells is that you can charge them at much higher rates. The RCC guys fast charge them in 10-15 mins, so you need low resistance contacts/wires for that.
    Again, thanks for your work in doing the thread and taking photos.

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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    Quote Originally Posted by Conte View Post
    ...Not to mention it also gives the charger control over each cell, enhancing charge quality.
    Balance charging is used with series connected battery packs that cannot be disassembled for charging such as this 3S1P rated at 2200mAH, 20-30C discharge rate:



    When you are discharging the pack at 60+A, you want to be sure the cells are balanced. Balance charging does not necessarily enhance charge quality.

  17. #17

    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    Cool idea, using a laptop PSU -- I've been planning to get a hobby charger "at some point" for a while now, and as I have a spare 90W power brick, that's one more piece taken care of.

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    Flashaholic* Conte's Avatar
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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    As an instruction guide for newbies, it becomes confusing to not keep red as positive, black as negative. I'm not seeing in this view with the wires soldered to those terminals how you are using the same middle lug as "common negative," as you said below pix going from 1s to 2s.
    Ah I see what you are saying. Ok, I'll update it with a better pic of hookup.
    I thought I had it covered with the pictures of the 4x65 cradle. The 2x50 cradle was mostly featured to show construction methods.

    Charging identical cells in parallel will work out just fine with Lithium cells, so I'm not sure what you think you are gaining when you say you are enhancing the charge quality.
    I used the term loosely. I hadn't before considered a parallel charge.
    I had been charging them in series before for the most part, and as mentioned, I noticed "the new LiFepo4 cells in particular can be sensitive, yielding different state of charge readings, fresh of the charger when charged together in series." Hence why, for my application, it enhances the quality of charge.

    I admit, the 2x50 cradle is somewhat redundant, and parallel charging might be a better option for 2 cells. I would of made it 4 cell but I only had 2 holder left of the 6 pack.

    Since my particular charger is limited to about 4a of current, parallel is not as feasible for me when charging more then 2 cells, which is what persuaded me to take this route.

    if you use those holders, they have high resistance (which accumulates in series) & the springs heat up, so it doesn't work well with higher amp charge rates. The 1 Amp you mentioned in your first post will be fine.
    I'm aware, I was disappointing when I get the holders in, and found them to have such flimsy leads. They are the the biggest weak link right now. I'm confident those springs could probably handle the 1C charge I generally tend to use but at the moment I can't seem to get the charger to push more then 1.5a thru the cradle. I set it to 2.3a, it's starts at 2, then drops to 1.5, then drops further averaging most of its charge at about 1.1a. I believe I felt warmth on the leads at 2a.

    I think the "smartness" of the charger is detecting a deficit in the plumbing it has to work with and is throttling down automatically to match it. I knew the leads were going to limit me, but it's just ridiculous. There is not gauge listed on the wire so I was unable to predict their load and resistance values.

    At this point, I do believe I will be upgrading the cradles with some higher gauge leads. Once I have completed this revision, I will add it to this thread as an upgrade option.

    I'm glad you appreciate it. I didn't really make this as a n00b how to guide like my other posts. More of an idea share among tech geeks, after all, unless the newbie can solder well, read a schematic, and has a basic understanding of electronics, this is already above their scope.

  19. #19
    Unenlightened
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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    I am a newb to CPF and am building a balancing setup for charging with my e-station BC6 charger.

    I am in need of 4 pairs of magnetic leads like those previously offered by LuxLuthor with the purchase of cells from him.

    How can I go about obtaining these ?

  20. #20
    *Flashaholic* LuxLuthor's Avatar
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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    All makes sense. Thanks for additional feedback! Always good to share ideas back and forth!

  21. #21
    Flashaholic* Conte's Avatar
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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    Revisions Made.

  22. #22
    Flashaholic*
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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    Quote Originally Posted by Wallace L View Post
    I am a newb to CPF and am building a balancing setup for charging with my e-station BC6 charger.

    I am in need of 4 pairs of magnetic leads like those previously offered by LuxLuthor with the purchase of cells from him.

    How can I go about obtaining these ?
    I'm in more or less that same boat, as I'm looking into putting together a hobby charger setup for probably up to 6 cells... I don't believe you can readily purchase magnetic leads. You can do it yourself if you are skilled with a soldering iron; I've read that you can ruin the magnetic ability of the magnets if you aren't fairly quick with your soldering.

    That's another reason why some go for the cradles; I know I can manage to make one like Conte's even with my rough soldering. The magnetic leads are still an attractive option though, it really doesn't get more flexible or compact!

    Quote Originally Posted by Conte View Post
    Revisions Made.
    Thanks for keeping this thread updated, it's a really great guide and has given me a bunch of ideas for my own eventual setup.


  23. #23
    Flashaholic* Conte's Avatar
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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    Lux Luthor Magnet Method added.

    What say you, Mr.Lux ?

  24. #24
    Flashaholic* Black Rose's Avatar
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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    Another magnet option for Canadians is Lee Valley tools (if you have one nearby).

    They have a good selection of rare earth magnets.

  25. #25
    Flashaholic*
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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    Magnets dont mess up the batteries?

  26. #26
    Flashaholic* Conte's Avatar
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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    No, hasn't seemed to have been a problem, and I think Lux has been doing it a long time.

  27. #27

    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    Amazing thread Conte - thank you for the time and detail you put into this. Definitely on my project list

  28. #28
    Enlightened benckie's Avatar
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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    here is revision 2 on the 2s balance charge lead set up for 18650's i had to cut the springs in the battery boxes as they are for none protected cells and I'm using protected cells so to get them to fit i had to remove the spring and reverse the polarity of the battery boxes (run the batteries the other way round) i have also made some singular ones for protected cells and use red heat shrink to cover the black wires and black heat shrink to cover the red wires so there is no confusion witch way the battery goes.

    here is a pic of the 2s balance charging set up





    here is a pic of the single 18650 ive been using.



    this is a 3s1p protected charge box i brought off fleabay its only good for unprotected cells, but has built in protection, over voltage under voltage plus a few other features.



    I'm waiting on some more bits to make 3s balance charging leads and a 6s balance charging lead for the 18650 batteries, ill post up some pictures of them once the bits get here, got to practice soldering magnets.

  29. #29
    Enlightened benckie's Avatar
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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    revision 3 for charging

    single



    2 cell balance charge



    3 cell balance charge



    just waiting on some more parts to make a 6 cell balance charging lead.
    Last edited by benckie; 08-06-2011 at 09:24 PM.

  30. #30
    Enlightened benckie's Avatar
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    Default Re: Tech Tricks: Homemade Balance Charging Cradles.

    this would have to be a great one

    http://www.hobbyking.com/hobbyking/s...acks_2_6S.html

    if you made your own balancing leads, you could charge from 12 to 36 li-ions at one time, or 6 x 2s up to 6 x 6s lipo,s you would need a charger with a 6s balance port and atlest 10 amp charge rate, or 20 amp charge like the icharger 208,s

    i use that parrallel charging board for my lipo,s for my rc truck, with a icharger 106b+ and a p350 power supply

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