How To: Make a Y Balancer Harness

[lincpimp]

Originally Posted by Arct1k

Don't know what that linc guy is on - That what I was saying...

Man, Do you just want to send me your posts to proofread before you throw them up on the forum? I can do that for a small fee, just to help out... Or is it too early for you?

[medusa'd maxx]

so if ive got this right and I use my balance charger to charge through both packs main leads siultaneously with the 2 2s taps converted to 1 2s tap I should be right (the packs are identical)
thanks for the input pls correct me if I'm wrong

"Lipo batteries make everthing better!"

PS i'll check your answer in the morning got to get up in5 1/2 hours

[Arct1k]

Yes.

[lincpimp]

Originally Posted by medusa'd maxx

so if ive got this right and I use my balance charger to charge through both packs main leads siultaneously with the 2 2s taps converted to 1 2s tap I should be right (the packs are identical)
thanks for the input pls correct me if I'm wrong

"Lipo batteries make everthing better!"

PS i'll check your answer in the morning got to get up in5 1/2 hours

Yep, that is correct.

[BrianG]

Maybe I should add a parallel charging/balancing diagram to my site...

Originally Posted by BrianG

I posted this over at the NitroKillers website and thought it might be useful here too. Anyway...

At the request from one of the MaxAmps Admin team, I am creating this thread to explain how to make balancer Y adaptors that will allow you to charge and/or balance two seperate lipo packs as one pack.

This how-to will cover making a 2s+2s adaptor, but the principles are the same for other arrangements like 3s+2s, 3s+3s, 4s+3s, etc. Diagrams for other various lipo pack configurations can be found here (scroll to the bottom). Also, I will assume you know which tools you will need and how to solder properly.


Lipo Pack Requirements:

Both lipo packs must meet the following guidelines. Failure to do so may result in difficulties in balancing and uneven cell performace characteristics.

• Each pack must have the same capacity. Don't mix two packs with different mAh ratings, such as a 2000mAh pack and a 3000mAh pack.
  
  
• Both packs should have always been used together.
  
  
• Both packs should be the same age.
  
  
• Both packs should have seen the same number of cycles. For example, do not use one pack that has seen 10 charge/discharge cycles with a pack with 20 charge/discharge cycles.
  
  
• Both packs should have seen the same type of use. Don't mix one pack that has been used on a low power system with one that has been used on a high power system.
  
  
• Both packs must have the same charge level. If you have brand-new packs, it is recommended to balance them together as one pack "off-line" before charging for the first time to make sure all cells start at the same level. "Off-line" means that only the balancer is hooked up with no connection to the charger.

Parts Needed:

• Balancer connectors: Two of these: http://www.maxamps.com/LBA10-2S-Balance-Harness.htm
  
  You will be using the large connector from one of these to hook to the LBA10 balancer, so no need to buy that seperately.
  
  
• Deans plugs: One female and two male plugs.
  
  
• Balancer wires: Use 20 gauge or 22 gauge wire. Try to find flexible wire to prevent breakage after repeated bends. A good choice would be a good length of decent gauge flexible servo wire. You'll need 3x the amount of black wire as red since a 4s balancer plug has 3 black wires and 1 red.
  
  
• Main charge lead wires: Use 14 gauge noodle wire or larger wire. These are perfect: http://www.maxamps.com/14AWG-RED.htm and http://www.maxamps.com/14AWG-BLACK.htm
  
  
• Heatshrink for the thin 20/22Ga wires. RadioShack carries a nice kit of different sizes: http://www.radioshack.com/product/in...ductId=2104090

Making the Adaptor:

1. Lay out both packs and the balancer unit to determine the exact lengths of wires you'll need. Figure in enough wire slack to allow easy placement in a lipo sack, or other fire-resistant container. Try to keep the total length under 2 feet though. Below is a picture of a completed adaptor I made. Note that the charge leads are NOT the same length as the balance leads. This is so the wires connect to the battery packs and my LBA without the stretching or bunching of wires:
   
   
   
   
2. Cut each of the 2s adaptor cables in half. Carefully pull the metal clip and wire out of the large 7 position connector.
   
   
3. On one of the pack-side connectors, remove the red wire. This is important! This prevents you from burning up a balancer wire if you accidentally hook up the balancer wires wrong. Use an xacto blade tip to gently and slightly lift the little plastic tab holding the metal clip into the connector, then slide the wire out.
   
   
4. Solder the proper color thin gauge extension wires to the pack-side connector wires. Make sure to keep track of which wire is which!
   
   
5. Solder one of the metal clip/wires (removed in step 2) to each end of the wire extensions (step 4) using the proper color wire. Now, you should have a pack-side connector on one end, some long wires, and wires with metal clips on the other end.
   
   
6. Heatshrink all solder connections.
   
   
7. Insert the metal clip/wires into one of the 7 position connectors in the order as shown in the picture below:
   
   
   
   
8. Make a main charge lead Y harness as shown in the picture below:
   
   
   
   
9. Tie-wrap each "leg" of the main charge lead to the correct "leg" of the balancer connector as shown in the picture below. And yes, it DOES make a difference. This ensures that the proper balancer connector is used when you hook up the main charge leads.
   
   

Hope this was clear enough...

The next time I make one of these, I'll snap some pictures of the actual balancer wiring steps.

Brian,

I have some questions regarding your schematic under "Lipo Wiring" @ http://scriptasylum.com/rc_speed/_lipo.html. The example I will use is the 5S2P lipo configuration. I want to know what is represented by the wiring where the positive and negative junctions of each pack seem to be bridged to another adjacent pack?

I also noticed that there is only one balance tap for this entire configuration. It seems to be independent of the number of packs that are put in parallel provided that each pack has the same number of cells since I changed the parameters just to makes sure for myself. This seems to contradict your instructions on how to make the Y harness.

Hope you can clarify this for me.

Brian,

I have some questions regarding your schematic under "Lipo Wiring" on your website. The example I'm using is a 5S2P lipo configuration. I want to know what is represented by the wiring where the positive and negative junctions of each pack seem to be bridged to another adjacent pack? In the attached photo it is circled in green if you can make it out lol.

I also noticed that there is only one balance tap for this entire configuration. It seems to be independent of the number of packs that are put in parallel provided that each pack has the same number of cells. I changed the cell parameters just to makes sure for myself. This seems to contradict your instructions on how to make a Y harness, where there are two balancing taps, one for each pack.

Hope you can clarify this for me.

[BrianG]

The part you circled in greed is simply the bridge connection between each paralleled cell. A 5s2p pack is simply made up of two paralleled cells, with five of those pairs in series. The picture shows what looks like bus bars for the sake of example, but lipo cells are generally not shaped like that so the tabs would just the tied together to make the connection. A123 cells though, would have bus bars similar to that because of their shape. It simply comes down to the cell's physical shape and layout.

Yes, there is only one balance tap no matter how many paralleled cells there are. This is because the contact points for each paralleled cell are electrically the same point, so only one set of tap points are needed for each paralleled set. That drawing is only used if one wants to make their own lipo pack; it shows the electrical connections even though it might not look like that in the real world. This happens all the time in the electronics world where a schematic diagram never looks like the physical layout. A schematic is handy for the designer/builder/troubleshooter. A layout diagram would show the true physical layout of the components, but it is difficult to troubleshoot/build a circuit using this type of diagram. The diagram you circled is really a combination of a schematic and a layout diagram, hence the slight misunderstanding.

Now, on the Y adaptor diagram, it assumes the individual packs were wired correctly, so from a connector standpoint, it does not matter if the packs are 2s1p or 2s200p. This diagram is to show how to wire a series charging/balancing harness when using two packs.

I hope all that made sense!

Hi Brian,

I am still confused about the whole bridge thing. If these cells were regular rectangular lipo cells (not A123), what would the bridge physically look like (the green thing I circled). Also, when you say "the contact points for each parallel cell are electrically the same point," if I have two packs in parallel, what does this look like as well? I just never seen or heard of these concepts before and this why I am asking.

Thanks for your help.

[BrianG]

With a regular rectangular lipo cell, a parallel pair would be made by simply putting the cells on top of each other so both + tabs are touching and both - tabs are touching. Then you just fold them together and solder.

If you have two seperate packs in parallel, you'd have two seperate balance plugs. There is no current drawing for that specifically.

Okay so going back to the 5s2p example, would all the + terminals of the first pack go on top of all the + terminals of of the second pack and the same with all the negative terminals and not just the + and - terminals at the ends of both packs, which make up the power/discharge leads?

[josh9mille]

Is this kinda the same thing? http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9910&Product_Name=2_x_3S_->_6S_Splitter_JST-XH__(5pcs/bag)

[simplechamp]

Yes, that is the same thing.

[josh9mille]

Originally Posted by simplechamp

Yes, that is the same thing.

I wish they made one for 2s batteries, or can you just plug 2s batteries into that?