RC-Monster Forums - How To: Make a Y Balancer Harness

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How To: Make a Y Balancer Harness

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:

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:

http://scriptasylum.com/rc_speed/images/balancer_Y.jpg
Cut each of the 2s adaptor cables in half. Carefully pull the metal clip and wire out of the large 7 position connector.
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.
Solder the proper color thin gauge extension wires to the pack-side connector wires. Make sure to keep track of which wire is which!
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.
Heatshrink all solder connections.
Insert the metal clip/wires into one of the 7 position connectors in the order as shown in the picture below:

http://scriptasylum.com/forumpics/MA_2s2s_1.gif
Make a main charge lead Y harness as shown in the picture below:

http://scriptasylum.com/forumpics/MA_2s2s_2.gif
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.

http://scriptasylum.com/forumpics/MA_2s2s_3.gif

Hope this was clear enough...

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

Another great post for a sticky - Just following the wiring but assuming no harm in connecting red on second pack to the middle balancer to.

I'm assuming that the black deans inter connector is effectively making the link however I thought balancers could get funny if the wiring length / type was different - i.e. read different voltages.

Hyperion I know said to keep all balancer taps the same length.

I've been wondering if this will be possible using the cellpro 4s so I could balance charge 2 2s packs at the same time. It's a balancing charger, and charges each cell independently through the taps. I thought of using a Y type adapter with 2 cellpro balance pigtails, but I'm not sure if it's going to work or not.

Nice post, btw!

J.

@Arct1k: Thanks! No, there is no harm in retaining the red wire that is removed in the second pack IF the balancer leads and main leads are hooked correctly. If that wire was present and the user accidentally swapped the balancer leads and not the main leads, something WILL fry because you are shorting out the entire pack. Removing the red wire is a safety precaution for the masses. My personal adaptors leave the wire in there but I make sure that things are hooked right. Yes, the large bridge wire connects the two packs.

Yeah, you should try to make sure the wires were the same length/type, but the balancer discharge current is so small that there is little chance for voltage drop to occur. Even the main charge current isn't high enough to cause problems on 12-14Ga wire. It's another story if you were trying to charge at 50A+ though.

@83gt: Yes, it would work, but since you are charging through the balancer leads only, you would need the following wiring diagram instead:

http://scriptasylum.com/rc_speed/ima...s2s_nomain.gif
Just remember that the balancer leads/connectors are not designed for high charge currents, so keep the charge rate at 2A or less. Currents higher than that will cause voltage drop on those smaller connections and the charger/balancer will get erroneous readings.

the 4s cellpro charges at up to 3A, never had a problem with it in the slightest. It's probably the single best charger for LiPo that I've owned, if only it would charge at higher than 3A. I have the cellpro 10s 10A charger on my list of needed items. :D.

J.

Yeah, the charger can go higher than 2A, but you may experience voltage inaccuracy because of the small balancer connector/wires. Just something to watch...

Hey i have two Neu Power 5000mah car packs here. You might know they come with kokam taps on them but i needed to make an adapter and the only way to do that was to put hyperion taps on. I ordered the hyperion taps from max amps 2x 2s female, 2x 2s male and 1x 4s female. Now at the moment i am having one problem but i think that will turn into two once i solve this one.

How do i attach the balancing wires coming out of my pack to the hyperion tap?

Once i solve that problem i think the next will be the adapter to balance both packs as 1 4s pack.

How would i attach the 2 male hyperion taps to the 4s female tap to make that possible?

Thanks, Trever

If you want to use Hyperion taps to make the adaptor, you'll have to replace the Kokam connectors with Hyperion connectors on the packs. Just replace one balancer wire at a time (to prevent shorting), and you should be fine. I don't know how this will affect your warranty though since you are modifying the packs.

Alternatively, you could make your adaptor with male Kokam taps on one end (the pack-end), and use a Hyperion connector on the other end (balancer end). This would require no pack modification.

The principle is exactly the same no matter what connector you use. I can't think of any adaptor that cannot be made, it just takes a little time. Just make sure you have the wires in the right order and you'll be fine...

Im looking to make a top for a set of packs that have align taps. Is this method the same. Assuming that i remove a ground from the tap wires?

The methods are the same provided each cell has two wires and the junctions of each cell pair shares a common wire. Leaving the ground off is only for safety when using the main Y adaptor. If you plan to balance and charge through the balance connector only (not using main leads at all), you actually need to use ALL the balancer wires, like this.

I have replaced the taps on the packs becasue i couldent find female taps to match the stock ones. I have one red wire and two black coming out of the pack and into the now hyperion tap. I cant get the balancer (eos610i) to recognize the cells correctly? Dont know what to do. I think i have the wires in the wrong order.

Also i want to make an adapter to charge and balance both packs as one. I dont know how to do this either. I have the 2 female hyperion taps and the 1 male 4s hyperion tap. how do i connect them? What colors go where? And in what order? Also i will be using the main charger wires to do the actual charging. Thanks, Trever

Don't forget that the stock Hyperion balancer plugs are wired a bit oddly. For example, for a 2s pack, the balance connector has 5 wire positions, but only three are used. The wire order is red (most positive terminal), black (the tap between the two cells), and black (the most negative terminal). The red and black are right next to each other, while the last black is two connector positions away. See the diagram below for a more graphic example.

http://scriptasylum.com/rc_speed/ima...2s2s_wmain.gif

You can verify wire order by taking a voltmeter and placing the negative probe on the far (lone) black wire. Then, with the positive probe, measuring the next black wire will read ~3.7v. The red wire will read ~7.4v. This is the correct order. If you do not have those readings, the order is incorrect.

Also, look at your connectors. Wherever a connector position contains a wire, there has to be a wire coming out the other connector in the same spot.

Maybe a clear picture of your setup would help...

I know I am going to sound like a noob, but it looks like this is wired in series. That doubles the voltage right? I have an Ice and a LBA10 (w/ JST taps) and would like to charge 2 3s 3500mah packs. Is it possible to charge them both but do it in parallel so I can keep my voltage down for the ICE, and at the same time use the balancer?

Yes, these diagrams are for charging in series, which is the same voltage as how they are run in the vehicle. Charging in parallel is possible, but not recommended. Differences between end-of-run pack voltages can vary depending on the setup. So, if you parallel connect two packs with slightly different voltages, there will be current flow as the higher voltage pack will "charge" the lower voltage pack in the attempt to equalize. This will cause sparking, and if the voltage difference is too great, can exceed the recommended charge current rating.

Pack voltage difference becomes more of an issue with packs greater than 2s. To get a total pack difference of say, 0.5v, between two 2s packs, each cell would have to be off by ~0.13v. But, for two 3s packs, that same 0.13v difference on each cell would create a 0.8v difference, which could cause problems when connected together in parallel.

If using an Hv ESC, the voltage between two 2s packs will be different because one pack runs the BEC, so it will be drained further.

I'm not saying each pack will be different, but they could be.

The only way I'd parallel charge is 1) if the packs were always hooked in parallel when run and charged since they were new, or 2) balance offline (not hooked to a charger) in series first. Once all cells are balanced, then hook them in parallel to charge. Kind of a PITA IMO.

If your charger is not capable of 6s charge, the above method (2) would be the only way to charge two 3s packs without getting another charger.

Brian,
Happy birthday. I just want to say I always pay close attention to your posts as they have the most comprehensive knowledge I have seen yet. Always informative and willing to help. I gotta give it up to one of the forums most beneficial members.
That balancing bit was exactly what I was looking for.
Thanks