Recurring Charge - November 2006 LiPoly Balancing Whys and Hows

A look at litium battery balancing - why and how, including a review of the ElectriFly Equinox balancer.



Charging News

Sid Kauffman has again updated his clever LiPoDapter (as seen in the December 2005 Recurring Charge). He’s now added a mode for charging the brand new A123 cells. These cells have a different (and lower) voltage when fully charged than lithium-polymer types we’ve become accustomed to using. His device can be used to safely charge A123s when driven by any capable nickel charger, or even an existing lithium-polymer charger like the Astro Flight 109. For more info take a look at Sid’s LiPoDapter page.

Also recently released is a long-anticipated lithium charger from Tejera Microsystems called the Xtrema. It has an interesting feature set that is different from other chargers out there. One of these is the ability to explicitly set the end voltage that supports partial charges for storage as well as proper charging of those A123 cells. Another is a wide range of multi-function meter functions, so it’s sort of a charger and power analyzer in one box. They’ve also just released a software update specifically for this battery type. More info is HERE. I also see that Hobby Lobby, one of the Ezone’s main sponsors, is now carrying the Xtrema.

Also, just released in the last few days is a variant of the FMA Direct Cellpro 4s charger, which apperas to have software redone for the A123 cells. More info on this one is HERE.

The reason for balancing devices:

Each cell, individually, needs to be kept between about 3.2V on the low end and 4.2V on the upper end. (NOTE: these are approximate values that vary from battery to battery, especially on the lower end. What's important to realize is that these are the approximate points above/below which some sort of damage can occur.)

Regardless the type of cells you are using, to be safe, it is best to periodically check the voltages of the individual cells. This is best done when the packs are charged or nearly charged. If, when checked, the packs are out of balance, you need to do whatever is necessary to bring them to the point where they match closely (within a couple of hundredths of a volt, hopefully).

Thanks for chosing to read the Recurring Charge! This time the focus is on lithium battery balancing and various ways to do it, with a detailed look at the ElectriFly Equinox balancer.

Balancing your LiPolys – why??

Well, as we all know by now (or should, if we’re using them), lithium batteries are much less forgiving than nickel types when they’re operated outside of a certain voltage range. Also, when they ARE operated outside that range, bad things happen. If you’re lucky, all you do is shorten the life of the battery. But either ruining the battery itself or even those much-discussed fires are possible results of going outside each cell’s voltage limits.

But we don’t, except for our Aero Aces and other very small models (and in our cellular phones), use these cells individually. Instead we typically use them in series of anywhere from two to four, or even ten or twelve cells. So, unless the cells in the battery are perfectly matched for voltage and capacity when the battery is built and they stay that way, as long as we both charge and discharge them as a whole battery (and not individually), there is a danger that sooner or later individual cells will be driven outside their safe voltage range even if the pack, as a whole, stays within it.

It has been my experience in about three years of lithium-polymer battery use that quality packs, when used well within their rated limits (especially for discharge rates), will start out balanced and tend to stay that way. From that one could conclude that I don’t really need to worry about pack balance and that I don’t need any devices that are designed to help me balance my packs.

But things are changing now. First of all, cells are available which can deliver much higher currents, both in absolute terms and in terms of multiples of their rated capacity (so-called “C” ratings). Packs made from these cells seem to tend to drift further out of balance while being used within these higher stated limits than the older lower-current types. Second, there are less-expensive cells and packs available now, and these also seem to be a bit less consistent or vary more in capacity from cell to cell within a given battery pack. Both of these situations can set up the conditions for individual cells being driven to too high a voltage when a pack is charged with an ordinary series charger.

Regardless the type of cells you are using, to be safe, it is best to periodically check the voltages of the individual cells. This is best done when the packs are charged or nearly charged. If, when checked, the packs are out of balance, you need to do whatever is necessary to bring them to the point where they match closely (within a couple of hundredths of a volt, hopefully).

Balancer Types

Enter balancers: devices that are intended to be connected to a pack (via the pack’s balance connector – more on that at the end of the column) to remedy or prevent an out-of-balance condition. They do this by either bringing the higher voltage cells down to the same voltage as the lowest one in the pack after it is charged, or by attempting to prevent any individual cell from going over the upper limit while the battery pack is being charged, or some combination of those two actions.

”Post-Processor” Balancers

The simplest balancer acts to bring the higher-voltage cells in the pack down to the voltage of the lowest one. It does this by measuring the voltage of each cell then slowly discharging the high cell or cells through resistors until the voltages are all within the unit’s tolerance of the lowest one. A good balancer will get the cells to within 0.005V of each other (which is closer than most of us have tools to measure). You can think of this sort of balancer as sort of a “post-processor” for charging since you typically use it by plugging it into the pack’s balance connector after charging the battery to equalize the cells’ voltages.

This type of balancer can also be used while the battery is being charged, but since it’s not between the battery and the charger, it can’t actually prevent a cell’s voltage from going too high if the charger is putting energy in faster than the resistors on board the balancer can dissipate it. That said, charging with a post-processor type balancer still is an effective way to keep your batteries balanced.

Perhaps the best example of this type is the Astro Flight “Blinky”. You connect it to the battery’s balance connector and it immediately tells you how many cells it “sees” by lighting up one LED for each cell. Then it proceeds to first bring each cell down below 4.25V (if any are that high), followed by bringing all the cells to the level of the lowest one.

The Blinky is as simple to use as such a device can be. As long as you have a compatible balance connector on your battery, all you have to do is plug the Blinky in and it does the rest. There are no controls, and all functions are indicated by the LEDs on its small board. The Blinky’s manual describes not only basic operation but also its ability to tell you if a battery has been discharged too much (and what to do then) and includes hookup diagrams for a wide variety of different brands of batteries. More about different balance plugs below.

The Blinky is set up to plug into a balance connector with 0.1inch/2.5mm pin spacing, and with no skipped pins in the plug. The balance plugs used by Apogee, CommonSense RC, the new ElectriFly Power Series from Great Planes and quite a few others are directly compatible. PolyQuest, Hyperion, and others that are “PolyQuest compatible” have the correct spacing, but skip pins, so you need an adapter or you need to reconfigure the balance plugs on the battery in order to use the Blinky.

Astro Flight also has a simple little adapter for 2.0mm spacing balance connectors such as those used by Thunderpower and the FMA CellPro line. As with PolyQuest, you’ll need to reconfigure the balance plug on 2s and 3s batteries with the Cellpro balance connector to not have any skipped pins to use the Blinky on them.

Of course, since the way this type of balancer works is to drain one or more cells of your battery to get the voltages to match, you’re always starting off with a bit less than a full charge on your next flight – but the difference in flight time is negligible, really, unless things were really out of balance when you put the balancer on the pack.

Inline Balancers

The other common balancer type is designed to be used while charging the battery and is hooked up between the battery and the charger. These also work by shunting some of the incoming energy into resistors in order to keep the cells in the pack very near to one another in voltage as the charge progresses (just like the post-processor types) but they have the added ability to prevent serious overcharge of any one cell by disconnecting the pack from the charger altogether if any cell’s voltage goes too high. This sort of balancer can also be attached to a charged pack without a charger and used as a post-processor type if you like.

Since this type of balancer also works by draining the higher-voltage cells (even while the charger is running), if it hasn’t managed to bring the pack all the way into balance by the time the charger shuts off, then when the battery IS balanced it will be a little less than fully charged. This is a bit less likely than with the post-processor type balancer, but can still happen.

A good example of an inline balancer is the Great Planes ElectriFly Equinox. This is a balancer for two to five cell packs that can be used either inline (what they term “interface mode”) or as a post-processor (what they term “quick-balance mode”). I think the Equinox has a better user interface compared to similar balancers on the market today because it clearly indicates which mode it is in and it doesn’t take off running as soon as you plug in the battery to be balanced. Instead it waits for you to tell it what you want it to do. Let’s take a closer look at the Equinox.

ElectriFly Equinox balancer

Closeup of Equinox with a quarter for size reference.
Closeup of Equinox with a quarter for size reference.
Type:Inline or Standalone Lithium Polymer Balancer
Cell Count:two to five (harnesses supplied for two and three cells batteries)
Maximum charge current (interface mode):3A with standard harnesses, 6A with optional "high power" harnesses
Discharge Current:120 mA maximum
Charge termination:4.3V on any cell in pack
Discharge termination:3.0V per cell in interface mode
Other features:Reverse polarity protection on both input and output
Separate indication of mode (dedicated LEDs)
Manufacturer:Great Planes ElectriFly
Available From:Your local hobby shop or
Tower Hobbies

Physical aspects

The Equinox is in a compact and rugged-feeling plastic case, with a six-inch long input lead ending in a pair of gold-plated banana plugs, as well as a 7.5A automotive-style blade fuse on the left end, and the eight-pin socket for the output harness on the right end. Included with the balancer are output harnesses for 2s and 3s batteries, and a six-page instruction manual (which is also available on line here).

The manual does a good job explaining the various modes of operation, error indications, and has some handy flowcharts. These charts illustrate both operating modes and error indications succinctly. It also contains all the usual warnings and cautions about lithium battery usage.

The user interface consists of eight LEDs and a single pushbutton. Five of the LEDs, on the right center of the face, are yellow. These indicate the number of cells connected when you first plug a battery to be balanced into the unit by lighting steadily for a couple of seconds. They also indicate, when balancing is underway, which cells are being discharged by the balancer at any given moment. (Note that the first batch of Equinoxes had red and green LEDs instead of the yellow ones for cell indication.)

Two more LEDs on the upper left of the face indicate which mode the balancer is in. If it’s in interface mode, the upper, red LED will flash. If it’s in quick-balance mode, the lower, green, LED will flash. The last LED is labeled “Error” and is located just to the left of the pushbutton at the bottom center of the label. This one will flash a code if any one cell goes above 4.3V, below 2.0V or if there is a connection issue.

The button is used to select the operating mode, to abort the current operation and to recall error indications.

Inside is a clean and well-made circuit board with no little patches or jumpers indicating needs for circuit redesigns.


In either mode the Equinox connects to your battery pack’s balance connector by a specific harness for the number of cells in the battery pack you are charging. Harnesses are supplied for 2- and 3-cell batteries, and a set of harnesses for 4- and 5-cell batteries are available separately (for example here). These harnesses are rated for up to 3A, which is about as high as any battery’s balance plugs are good for as well. There is also a set of ”high power” leads available that plug into both the balance connector and the main output connector of your drive battery, allowing charge currents up to 6A. These high power harnesses, by the way, have Deans Ultra connectors for the main battery connections, which is handy if you happen to use that type of connector on your battery output leads.

The balance connector on the supplied harnesses is a 2.5mm/0.1 inch pin spacing plug – a different sized one for each cell count – that is compatible with the ElectriFly Power Series batteries and a number of other packs coming from China these days. If this is not the balance connector on your battery, you’ll need to either make an adapter or modify the output harness. Another alternative, especially if you have batteries with the PolyQuest/Hyperion type balance connector, is to get the appropriate output harness for the Hyperion LBA-6 balancer from one of the Ezone’s sponsors such as For example this is one for 3s batteries. They also have output harnesses ending in bare wires so that you can create your own adapter. Here are the Equinox and LBA-6 3s harnesses for comparison.

As I mentioned, to use the Equinox in interface mode you connect it to your charger via a pair of gold banana plugs. This suits a large number of chargers including just about all the ElectriFly units such as the various Triton family members and the PolyCharge4. If the charger you are using does not have banana jack outputs (for example the Astro Flight 109) then you’ll either need to change the plugs on the balancer or make up a suitable adapter. I’ve made a couple of short jumpers with a banana jack on one end and an Anderson Powerpole on the other for this purpose.

Using the Equinox

For standalone balancing (“quick-balance mode”), connect the battery to be charged to the appropriate harness and plug that into the right end of the Equinox. The number of yellow LEDs corresponding to the number of cells in your battery will light for a couple of seconds, then go out. The balancer is now in “idle mode”, awaiting your command. If the number of cells indicated is correct, press the button once to start balancing. The Error LED will light briefly indicating power is on, and then green “quick-balance” LED will begin to flash. Also the yellow LEDs corresponding to the cells actually being drained will be lit or flickering. Once the pack is brought into balance, the cell LEDs will flash five times, indicating the balance is complete and then the unit will shut down. Briefly pressing the button once at this point will recall the finish indication, or an error indication if one occurred. Once it’s finished, disconnect the battery.

For inline balancing (“interface mode”), plug the input banana jacks into the output of your charger, and connect the battery to be balance charged to the output end as before. You’ll get the same indication of cell count as mentioned above. If that is correct, then press the button twice to get into interface mode. The speed of the two presses is a little fussy – think double-clicking your mouse button and you’ll get it right. The battery will now be electrically connected to your charger and you can start the charger (if it doesn’t do so automatically) the same as you would without the Equinox in line. The red “Interface Mode” LED will also be flashing.

Your charger should not really be “aware” of the balancer at all and proceed normally. I have run my Equinox on chargers including the PolyCharge4 (December 2005 Recurring Charge), the Astro Flight 109 (with an odd adapter on the output side) and the E-Flite Celectra (June 2006 Recurring Charge), all with no noticeable effect on the charger’s operation other than a little prolonging of the constant-voltage portion of the charge. This is because some of the energy the charger is putting out for the battery is being bled off by the balancer as it acts to keep the cells in balance. How much this prolongs the constant voltage portion of the charge depends on how far out of balance the cells are at that point and therefore how much energy gets bled from the higher voltage cell or cells as they all come together. (By the way, if you charge a battery through the discharge leads while a standalone balancer is attached to the balance leads and is active, you’ll see the same effect.)

I have found that the Equinox will usually run for a few minutes (one or more cell LEDs still flickering) after the charger has declared it is finished. Then, just as in quick-balance mode, when the cells are in balance, all the LEDs for all the cells in the battery will flash five times and the unit will shut itself down. As before, you can recall that indication with a push of the button.

Be aware that the battery is electrically connected to the banana plugs whenever the balancer is in interface mode, so if for some reason they are not plugged into a charger they CAN short. I’m sure the unequal length of the input leads is intended to make this more difficult.

From either mode you can abort the current operation by pressing and holding the button for at least three seconds. This returns the Equinox to idle mode.

In Operation

OK – so enough explanations – how does it work? Well, in short, just like it should. You’ve probably gotten the picture pretty well from the descriptions above.

My best measuring tools can read to 0.01V and in both quick-balance and interface modes, when the Equinox says it is finished, the cells in the packs I have checked have all been within the limits of my measuring equipment – no more than 0.01V indicated between cells. I will admit that I have not tried using the Equinox to balance as a battery is being discharged, simply because I can’t see any reason why one would do it this way. LiPoly batteries tend to be the most out of balance when discharged and even if they are far apart then, they tend towards being balanced when recharged. A tool like the Equinox simply assures that they get all the way back to balance.

At no point in operation does the Equinox get more than just a little bit warm – but then with only 120mA at no more than 4.2V going through each “channel” there’s not much power being dissipated. A 3s battery with two cells being bled down at the maximum rate would be less than 1W going into heat.

Other than needing to get the knack of “double-clicking” the mode button just right to get it into interface mode, operation is simple and fairly intuitive.

It is also well protected against user mistakes. Because some vendors (such as Ezone sponsor CommonSense RC) use the same JST XH balance connector the supplied harnesses are set up to use, but with the opposite polarity, one can inadvertently plug a battery into the balance side of the Equinox backward (more on this below). In this situation it just sits there – no LEDs light, no fuse blows. Plugging a battery in the right way afterward wakes it right up.

The fuse protects it from reversed polarity on the banana plug input charger connections – as soon as the charger starts to put any current in, the fuse blows immediately. Yes, I tested this. Replacing it with another 7.5A ATO type fuse and getting the banana plugs in the right jacks and all returns to normal.

Incorrect cell counts connected are signaled by the LED labeled “Error” flashing for 10 brief flashes, followed by five groups of three flashes (the code for “connection error”) followed by the unit shutting down. The individual cell LEDs do not light under these circumstances at all.

The other two error codes in the manual are single flashes for a battery with a cell voltage over 4.3V and double flashes for a battery with at least one cell below 2V. I didn’t sacrifice any of my batteries to test these two indications.

An artificial test of balancing with the Equinox

To test some of the extremes of the balancer’s abilities, I discharged cell one of a 3s 1250 pack about by 250 mAh and a cell three by 450 mAh or so. This yielded cell voltages of 3.99, 4.16, and 3.86V respectively. I then plugged the Equinox in to port one of my PolyCharge4 that was set for a 1C charge, plugged the battery in, and put the balancer in interface mode. It immediately started bleeding down cells one and two as the charge progressed.

When the PolyCharge4 announced it was finished the overall pack voltage was 12.42V. Taking measurements of each cell shortly after this – with the balancer still active, yielded cell voltages of 4.07, 4.22 and 4.07V. The cell two LED on the Equinox was still on steadily at this point – indicating it was still bleeding the center cell at maximum effort. The cell one LED was, at that point, flashing about twice per second, indicating it was still pulling that cell down ever so slightly. Finally, after about two hours the cell voltages were 4.03, 4.02 and 4.03. After this it took a little over 200 mAh to bring the battery back to full charge.

What this demonstrated to me was that the maximum bleed rate of the Equinox was able to prevent what was essentially a fully charged cell from going more than a few hundredths of a volt above 4.2 while the pack as a whole was being charged at 1C even though there was a 0.3V difference between the highest and lowest cells when the charge was started. At the point the charger signaled it was finished the maximum imbalance was cut in half and the two outer cells, originally 0.14V apart, were equal. But it then took quite awhile to get the pack balanced all the way.

If this level of imbalance (0.3V) had been with the pack as a whole pretty much discharged rather than my artificial setup of discharging two of the three cells in the pack, the Equinox would probably have got the pack in balance by the time the charge was declared done.

Now with a less-conservative-about-the-end-state charger than the PolyCharge4 it MAY have gotten that center cell to the 4.3V cutoff threshold of the Equinox – at which point it would have disconnected the battery from the charger and worked to bring that cell back down to meet the others. Then the charge could be restarted with the pack in balance to bring the whole pack to a full charge.

The bottom line

As with other Great Planes ElectriFly charging products I’ve looked at in the last couple of years, this one does exactly what they say it will do with no surprises. As always, it’s hard to argue with that. If you’re looking to add balancing capabilities to your existing charging setup, the Equinox is a good choice.

Balance & charging all in one unit

There are now options that put using an inline balancer and a charger together all in one unit. One of these is the FMA Direct Cellpro 4s charger. I’ll have much more to say about it in a future column. Right now I will say that I liked my review sample so much that I bought a second one as soon as the second production batch was available (and before the recent price cut). I use my Cellpros more than any other charger I have right now. It is simple to use and it gives plenty of information on what it’s doing. And since the charger itself is monitoring each cell, when it's finished you have a fully charged and balanced pack.

OK – But what about cell protection during discharging?

There are also devices that are designed to prevent over-discharging any one cell in your battery by monitoring each cell while you fly. These install in your airplane and plug in between your speed controller and receiver, as well as into the balance plug on the battery. When the first cell falls to the “cutoff” value they reduce the throttle setting, much like a speed control’s own low-voltage cutoff (if set to “soft”) would do. There are a couple of commercial devices that do this, with more to come. There is also at least one do it yourself solution out there as well. Of the available devices, the one I like the best is the Dimension Engineering CellShield.

Here are three discharge protection modules.

I’ll have more to say about discharge protection modules in general in an upcoming Controlling Interest column. The CellShield has both a settable cutoff point and the smarts to cope with different balance plug arrangements without resorting to adapters (other than for pin spacing – the Astro Flight Blinky to TP adapter works for this).

Which leads to:

Balance plug madness!!

It seems that every battery pack builder uses a different plug for their balance connector. It isn’t quite as bad as all that, but if you have more than one brand of battery and you want to use a balancer from another maker, buying or making adapters is just about inevitable. This situation does make the use of balancers, balance chargers and LiPoly batteries more complex than it needs to be, though.

There are two approaches to balance connections. The first is individual connectors for each cell, as was pioneered by Tanic (“Tanic Taps”) back when most battery makers didn’t even give you any way to measure individual cell voltages. The second, and now much more prevalent, is a single plug that connects to each cell (or, in the case of large packs, each parallel set of cells) in the pack. For a single balance plug you have to have at least one more connection than the number of cells – a 2s pack needs at least three pins, a 3s needs at least four, and so on. From what I have seen, there are two basic families of these one-per-battery connectors: those with a pin spacing of 2mm and those with a pin spacing of 0.1 inch (2.5mm). Within those two groups there is quite a number of variations, though.

Some pack builders, such as PolyQuest and Hyperion (2.5mm), and the FMA Cellpro (2mm) line, use the same five-pin plug for two, three and four cell packs. They just vary the number of pins they use, while always connecting the pack negative and pack positive to the outer pins. For 3s packs one of the inner pins is skipped, and for 2s two of the inner pins are skipped.

Other pack builders use a different sized plug for each cell count, and use all the pins within the plug in each size. Some examples are Apogee (2.5mm) and Thunderpower (2mm) and the new ElectriFly Power Series (2.5mm). CommonSense RC also uses this approach, and the same balance plug as the ElectriFly Power Series, but wired with the opposite polarity!!

It would take me quite awhile to try and explain all the variations that I know of in words, so instead I’m going to point you to some information online with diagrams illustrating the various approaches. One good resource is the manual for the Astro Flight Blinky. Another is the instruction sheet for the FMA Cellpro node connector. A third reference is the fourth page of the manual for the Hyperion LBA-6 balancer – which has diagrams showing how the PolyQuest/Hyperion node connectors are wired. There is also extensive information posted here in the Batteries and Chargers forum on RC Groups including ways to make adapters to make various combinations work together.

Here are some of the balance lead adapters I've either made or acquired to deal with the mixture of batteries I have on hand.

From top to bottom they are:

  • Equinox (or LBA-6) to 3s Cellpro
  • PolyQuest 3s to CommonSense RC 3s (plugged into the 3s harness from an LBA-6)
  • PolyQuest 3s to Tanic 3s, where the JST is for the center cell, and the Deans plugs into the output lead
  • 3s harness for PQ/Hyperion that came with the LBA-6. Will also work in the Equinox
  • 3s CommonSense RC to ElectriFly Power Series - this is a polarity reversing extension
  • 3s CommonSense RC to Cellpro charge adapter (left) and Astro Blinky to Thunderpower adapter (right)
  • 3s Tanic adapter for Cellpro charging. Same idea as the PQ above - the JST for the center cell
  • FMA Direct's Cellpro charge adapter for ThunderPower and PolyQuest - with sockets for 2s, 3s and 4s batteries

Because things are so chaotic in the LiPoly battery market right now when it comes to balance connectors, whenever you are looking to connect one maker’s battery with another’s balancer or charger or discharge protection module, BE CAREFUL and be sure you understand how things are wired before plugging anything together.

Next time I think I’ll take a good long look at the FMA Direct Cellpro 4s charger and perhaps more.

Feel free to drop a note (or add a comment in the thread below).

Last edited by AMCross; Nov 21, 2006 at 08:33 AM..
Thread Tools
Nov 29, 2006, 04:24 PM
Registered User
As usual Bernard, you done good..!

Look forward to your next article on the FMA Cellpro 4S charger, and ANYTHING about A123 cells, they are the flavour of the month!

Nov 29, 2006, 10:19 PM
NYC's Finest
me too im planing on buying that cellpro charger, its the best charger i have read about because i have seen lots of good reviews, and like he said what up with a123 cells^ im still going to use li-poly batterys tho
Nov 30, 2006, 01:47 AM
Registered User
BEC's Avatar

I don't have any A123 cells yet....but I guess I'd better see about 'em. Not sure when that's going to happen (unless someone sends me some ).

Right now the A123-capable version of the Cellpro is what I'd suggest to people looking to buy new, and a LiPoDapter with an existing charger for others. But, as I say, that's based on zero experience with the cells themselves.
Nov 30, 2006, 01:50 PM
Registered User
Dr Kiwi's Avatar
Cheapskate question: can I adapt a Polyquest 3s PCM Guard (5-pin) and use it to balance a 3s TP 2100 ProLite pack (4-pin). Is this a matter of just getting the correct adapter, or are the "electronics" incompatible with Thunderpower packs. I have an adequate Apache charger so I don't need a $60 CellPro, and isn't a TP balancer (alone) about $50? - I'd like to re-use my PQ balancer (having decided their packs weren't too good, I got rid of those).

Cheers, Phil
Last edited by Dr Kiwi; Nov 30, 2006 at 02:15 PM.
Nov 30, 2006, 03:31 PM
Registered User
BEC's Avatar

The honest answer to that question is "I don't know" since I don't have one. However, a PCM Guard is NOT a balancer. It is only a charge overvoltage protection device. Details here:

The fact that the PQ device has five pins and the TP pack has four means that you have the an adapter to make as you suspect - but I imagine that as long as you get the right cells connected to the right spots on the PCM Guard it will do what it is supposed to do for your TP pack (which is, on charge, to prevent any one cell from going over 4.35V).

With the appropriate adapter(s) you can use the Equinox either standalone or in "interface mode" with your Apache charger to actually get balancing action for less than the price of the Cellpro. I realize as I type this that I probably didn't even mention the price of the Equinox (or the Blinky) in the column. Speaking of the Blinky - it, plus the TP adapter, will also balance your packs. I haven't run an Apache charger on a battery with a Blinky on the balance lead at the same time so I don't know how well they would get along, but I can't see any fundamental reason why it won't work.
Nov 30, 2006, 03:45 PM
Registered User
Dr Kiwi's Avatar
So, Bernard, to get my thick head around this: I just need an "Astro Blinky" with that "Blinky to TP adapter" you have a photo of. Then I should be able to connect this set-up in-line between my Apache and my 3s TP2100 to charge and balance all at the same time?

Let me re-read and re-think this: You article indicates that the Blinky is a post-charge device, but the Equinox is designed to be in-line while charging - should I go the Equinox route then.

What is the difference (cost) between the Equinox and the Blinky - is there an "Equinox to TP adapter" available?
Last edited by Dr Kiwi; Nov 30, 2006 at 03:55 PM.
Nov 30, 2006, 04:16 PM
margaret.roberts's Avatar


The blinky connects to balance lead and charger to power leads .

I use the blinky 1-6 cell balancers on 340mah 3s-6400mah 4s batts whilst charging and on big batts they are so light you can leave them connected for flying, they also have a nice led brightness visible in sunlight and measure the initial cell voltage with visual indication when plugging in ie. if below 3.2v that cell led will not light, best to charge at 1/10th c until voltage above 3.2v if so.

I buy mine from user id. real157 Richard Edmonston in Florida on ebay for $24.99 USA made and he sells great 20-30c batts as well, and a $19.99 balancer that is almost identical without low volt display and less bright leds which is also very good and i have a couple of those that i also use. Search- astro blinky- on ebay if not a member. I live in UK and delivery is 3-5 days to my address if paying using paypal.

PS. his 700mah-8000mah batts really are great.

I use the 700mah 3s with axi 2204/54 in shockies i fly outrageously and hardly warm heat, i also use them with axi 2208/34 in larger foamys and barely warm same flying style full power available to the last milliamp, pure class Hecells which most others just re-label.
Last edited by margaret.roberts; Nov 30, 2006 at 04:57 PM.
Dec 01, 2006, 10:20 PM
More props are better than One
TaSaJaRa's Avatar
Originally Posted by drtmind01
me too im planing on buying that cellpro charger, its the best charger i have read about because i have seen lots of good reviews, and like he said what up with a123 cells^ im still going to use li-poly batterys tho
I bought the larger size Balancer that looks just like the ElectriFly Equinox balancer.
The Hyperion LBA10 that does 6s packs. It will balance the A123's just as the I think
the ElectriFly Equinox will. I use 4s1p of A123's in my TL 50 wing. They work GREAT.
They are less than half the cost of what I was using to do 60+ amps cont. before.
I was using 3s2p TP 2100 15c's. The A123's are .5oz lighter than the TP 3s2p was.
Just I get a shorter flight time being the A123's are 2300mAH where the TP was 4200mAh.
But I can charge them at a much higher rate like 3c charge rate. But i don't charge over
4 amp to save battery life. I use the Xtrema Charger/Watt meter to charge my A123's.
It does great.

Later, Craig
Dec 01, 2006, 11:10 PM
Registered User
Thanks, awesome article!

I'm a li-po newb and am looking into buying some in the near future, so this article really helped me out.
Dec 02, 2006, 09:12 AM
Southern Pride
everydayflyer's Avatar
BEC nicely done. I added a Link to my Balancers / Adaptors Post to your write up.

Dec 05, 2006, 12:41 AM
Registered User
BEC's Avatar
Thanks, Charles. I try.

IntoTheAir - glad to help. That's why I do this sort of thing. And I know this is so doggone confusing right now......I've been doing electric airplanes for over 25 years and now is the golden age - but never has there been so much to have to learn and keep straight as there is now.
Dec 07, 2006, 02:14 PM
Registered User
Thanks for a good paper. It covers a lot of useful ground.

However, one thing it doesn't talk about is making your own adapters. Who's sokets do you use? I have a crimper, (very expensive!!) but what size wire do you use. the socket pins work best with 24 awg or thinner. Is this heavy enough for the current. I prefer to use stranded wire because of the application but this makes it a little more dificult to crimp on the pins

Have you any thoughts on this subject?
Dec 07, 2006, 02:27 PM
Registered User
Very well written and informative,

Dec 07, 2006, 02:31 PM
Registered User
Probedude's Avatar
Originally Posted by Geff
Thanks for a good paper. It covers a lot of useful ground.

However, one thing it doesn't talk about is making your own adapters. Who's sokets do you use? I have a crimper, (very expensive!!) but what size wire do you use. the socket pins work best with 24 awg or thinner. Is this heavy enough for the current. I prefer to use stranded wire because of the application but this makes it a little more dificult to crimp on the pins

Have you any thoughts on this subject?
Somewhere I have a thread describing the various makers for the connectors.

Here you go

The JST PA units that the Cellpro uses, the datasheet for the vendor says the 3A rating is with 22ga wire. That PA connector crimp is pretty darn small so if you buy a roll of 22ga wire, use that for all your packs and connectors. The PolyQuest connector is larger - no problems there.

Regarding wire construction, stranded is of course needed for flexibility and resistance to breaking, but even for stranded wire there are different types. I see 22ga wire with 7/30 construction (7 strands of 30ga wire), 19/34 (19 strands of 34ga wire) and even 168/44. Price goes up steeply with strand count.

Funny timing of this post - I just converted 4 of my Apogee packs to JST XH. Apogee tap wire is nice as far as strand count goes - almost like the 168/44 however the not so nice thing is the silicone insulation - it's thick and nicks easily. The stock Apogee tap connector is really poor too - the pins are not held in well.

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