Recently picked up a "Blinky" balancing device for my new Common Sense 3 cell lipos that have a matching plug and are recommended for use with the Blinky. I have a few dymond 3 cell lipos that don't have balancing plugs and would like to add a matching plug to them as well. While I am handy with a soldering iron and have built my own nimh packs, I have yet to work on a 3 cell lipo. Can anybody point me to a link that shows the proper wiring diagram to add a balancing plug to a 3 cell lipo. At the plug end of it I can figure out the proper pin placement based on the Blinky's setup. Just not exactly sure what needs to be done inside the wrap to properly wire the 3 cells and don't want to open one of my Common Sense cells to figure it out.

I have some etecs i would like to do that to...so if you find out...let me know if you would.

Thanks..

brian

Took the wrap off one of the Dymonds to take a look. The way I understand it the tabs on lipos are aluminum and thus hard to solder to, not to mention the increased risk of heat doing damage to the cell. Anyway, what I found was that all three cells were soldered to a circuit board that covers on end of the pack. In other words, the three cells are soldered to the underside of a small circuit board that completely covers the end of the pack. On top of this board are traces with solder that "wire" (no wire on the board...just solder and traces) all three cells in series. Easy enough so far and looks like I won't have to deal with the aluminum solder tabs on the lipos. I'll just solder the necessary four wires to the solder and/or traces on top of this board to wire a balancing plug to them. Or, at least...I would guess these traces and/or solder on top of this board aren't aluminum as well? Anyway, my main sticking point at this time is figuring out what the four wires will go to. The pin outlet on the Blinky balancer aren't all that clear, using words like "from negative to most positive wires". What I need to know is where the four wires need soldered to a 3 cell series pack and why. From there I can figure out what pins on Blinky these wires should be going to. I would have assumed that a 3 cell pack would have 6 wires on it's balancing plug (one negative and positive from each cell) in order to see each cell in parallel for balancing. That one has me scratching my head.

Actually, you only need 4 wires to balance a 3-cell pack. Why?

The pack is in series.

I recently converted all my Dymond LiPos to work with my Thunder Power TP-205 balancer. The TP-205 includes a handy wiring diagram, but the principle is the same.

So pick a side. I started at the negative post of cell 1, which happened to be the black wire on the TP leads. That makes it easy: black matches black.

Then on the NEGATIVE post for the center cell (cell 2), I put the second lead. Remember the negative post for cell 2 is the same, electrically, as the positive post for cell 1. Look at the top of the circuit board for your Dymond LiPo and you'll see it.

Then on the POSITIVE post for the center cell, attach the third lead. This is the same as the negative post for cell 3. I have two years worth of Dymond LiPos, and they are actually wired differently (one cell is backwards in the 2005 LiPos, and all face the same direction in the 2006 version). Just pick a post that's easy to get to.

Then finally, on the same tab as the red wire, attach your last lead.

So reading the four pins is pretty easy for your balancer:
Pin 1 - 2 : Cell 1
Pin 2 - 3 : Cell 2
Pin 3 - 4 : Cell 4

What those map to on the Blinky? I don't know, you can probably do a search on the forums to figure it out. But once you realize that every pin except for the start and end pins in the series packs do double-duty as both a positive and a negative lead, it's cake. No need for six pins on a 3S pack!

To wrap up the job, I re-taped the top of the LiPo, and added some foam to the other end, wrapping in electrical tape. The non-lead end seems to be the end that hits the ground first on a crash, so that's where a touch of foam gets applied

In other news, though, when I added the balance plugs I found that 2 of my 5 Dymond 3S LiPos were woefully out of balance. One I was aware of, because a cell had pillowed the previous year, but the other I wasn't aware of. Unfortunately, it only lasted 3 more flights before that out-of-balance cell died, despite the balancer. If I ever buy Dymond LiPos again, the first thing I'm doing is adding a balance connector!

Yep, wrote out a simple diagram of a 3 cell pack on paper last night and the solution became simple and clear. The Blinky "instructions" also have a pin outlet chart to go by and match things up. Negative of first cell to the farthest negative pin on Blinky, Positive of last cell to the first pin on Blinky. The two middle wires do act as a negative or positive lead, depending on which cell Blinky is testing. They go to the 4V or 8V pin outlets on Blinky respectively, depending on which lead is which on the battery. Anybody looking to figure this out can look at the Blinky directions and it'll become clear. If you still are confused then follow the criteria Blinky lists and use a volt meter to determine which is the 4V+ and which is the 8V+. It depends on which sequence of cells Blinky uses in order on the pin outlet (from negative to positive or positive to negative in series as listed on the pin chart). I believe Blinky lists it as starting on the negative side (furthest negative pin). In other words, the main negative battery plug wire is the cell that's negative's trace should go to the furthest negative on Blinky. The trace connection between this cell's positive and the negative of the next cell is the 4v+ terminal that would go to that pin on Blinky. The trace between this cell's positive and the negative of the last cell is the 8V pin wire. And, then the positive lead of the last wire (which also is the main battery plug's positive wire) would go to the furthest away positive pin of the four on Blinky.

Glad to hear somebody else used Dymond batteries. I'm pretty happy with mine that I bought last year, having put them through all kinds abuse. One even spent a night in a tree after the low voltage cutoff was hit in flight. Managed to recover it by slowly charging it a few minutes on Nimh charger to get it's voltage high enough for my lipo charger to recognize and charge. This is VERY dangerous so don't do it without knowing what you are doing and wearing the property safety gear in a fire/explosion proof open area. Did you have any trouble soldering to those traces/solder? I'm hoping I don't have to track down some special aluminum solder if it is.

Converted both Dymonds over to the 4 pin Blinky plug last night and it was easy as pie. You can find 4 pin Molex plug (or cut down a Molex with more pins) in many junk devices such as computer parts. I don't know if it matters but I kept all four wires the same length as I've read Blinky is so sensitive that any variation between each wire could cause it to be slightly off balance (which shouldn't matter anyway as it will get things real close regardless). Anyway, removed the shrink wrap from the Diamond packs and found a small circuit board on one end that all three cells are soldered to on it's underside. On top of this board are traces and solder which makes it much easier to solder your wires to. Didn't need any special aluminum solder or anything. The furthest negative pin to one side of Blinky is the main negative. Solder this wire from the Molex to the negative pole on the pack (the same trace that the main negative battery wire is soldered to). The next pin on Blinky goes between this cell's positive lead and the negative lead of the next cell (which are soldered together as "one" since the pack is in series). Doesn't matter if you solder it to the positive or negative between them. Just find an easy spot clear of shorts. The third pin on Blinky will go to this second cell's positive lead (or the negative of the last cell...doesn't matter again because these are also wired together in the pack). The fourth and final pin on Blinky is the positive and will to the positive lead of the last cell (the trace that the main positive battery wire is soldered to). Blinky of course has more pins on it's board but these are used for packs with more cells. Just start with the furthest negative side of Blinky and your 4 pin Molex should go on right there with it's next three pins in order with no gaps. In other words, the positive last pin of the molex does NOT go all the way to the other side of Blinky where the board is marked positive. Just pins 1, 2, 3, and 4 are used for a 3 cell series pack.

Be very careful while soldering. I used some flux to help the solder grab the wires off the Molex cable and the proper surface areas on the board. I'm experienced at soldering yet even I can make mistakes...and did. I dropped a blob of solder between two traces on the board and instantly ran outside with the pack and pitched it in my garden. I waited ten minutes and then approached it wearing goggles and gloves. Luckily the area where the solder had dropped was a small redundant trace line that wasn't needed and was thin enough to melt the trace away and stop the short before the cells went nuclear on me.

After I was done with the solder work I hitched up Blinky to make sure all was well. I then covered the entire circuit board and wires with shoe goo (a thick rubbery glue) to prevent the wires from moving or a short should a wire break free. After this dried I wrapped the pack three or four times with clear packing tape, being sure to leave the top and bottom sides of the pack open as the original shrink wrap did to allow the cells to receive are flow. I would have prefered using battery heat shrink wrap but didn't have any of the proper size. One cool benefit to using the shoe goo and clear packing tape is I can see right through them to the wires and circuit board should a problem arise.

To balance the packs I plugged them into Blinky first. All three lights should come on for about five seconds to indicate that all three cells are above the safest lowest battery voltage for lipos. After that Blinky will go into balancing mode. If a light comes on it indicates that cell is of higher voltage than the other cells and is draining it to match them. This may go on for several minutes or more until Blinky gets all 3 to match (it brings down the other 2 cells to match the voltage of the lowest cell). When this process started to slow or stop I then left Blinky plugged into the pack and then charged the pack with my Celectra lipo charger. As the charger does it's thing Blinky will again get more active as it constantly controls the voltage level of all 3 cells during the charge. Once the charge is complete Blinky should be showing no lights or maybe the occasional one as it tweaks the cells even more. So long as you aren't seeing lights coming on frequently (almost all the time) the pack is pretty well balanced and ready for flight. If the lights are on frequently but keep switching between all three cells then it also means the pack is near balance. If, however, the same one or two lights keep coming on at a pretty good pace it's getting that one (or two) cells down to the lower voltage of the third cell. For the most part the leds should be off more than a few minutes at a time if the pack is well balanced.

Took all three packs out for a flight yesterday and they performed well with no problems. Really glad I took the time to buy Blinky and convert my other two packs to the Common Sense/AstroFlight Blinky balancer.

I just got my Blinky and two 4 pin wiring harnesses from Commonsenserc.com to convert two Cellpro (Kokam) 3 cells over from the Cellpro 5 pin plug. I was surprised to find the extra wire on the Cellpro packs is NOT soldered to anything! I guess that is just so you have to buy a special Kokam balancer. The Blinky instructions tell you to move the red wire to the fourth position on 5 pin packs. Guess which wire wasn't being used by the Cellpro pack? Yup. The fourth wire. I cut one wire at a time from the 5 pin plug and soldered it to the 4 wire harness, skipping the fourth unused wire. Blinky is right now balancing my packs.

I also soldered a harness to a pack that didn't have any balancing leads. I was a little apprehensive but used safe procedures and took my time and it came out great. It is now balanced.

Hi five-string,
The Cellpro packs all use a 5 wire plug to accomodate up to a 4 cell pack into only one plug on their Cellpro 4S balance charger, rather than separate connectors for 2, 3 and 4 cells packs.
Pete

I see. I guess that makes sense for those who use Cellpro exclusively. I wish the industry would get around to standardizing these plugs, but I have standardized my own stock successfully.[sm=thumbup.gif]