Balance adapter 3x 2s - 6s? - RC-Monster Forums

nativepaul · **Balance adapter 3x 2s - 6s? -** 08.31.2007, 04:39 PM

Does anyone know how I would go about wiring up an adapter to charge and balance 3x 2s packs as a 6s pack?
The balancer is an LBA10 and the packs use polyquest taps, I have 3 tap plugs for the packs and a 6s plug for the LBA10 but I am unsure how to wire them together.

BrianG · 06:53 PM

How about this?

Oops, never mind. I originally read it as 2 x s3 packs.

It is possible, but you REALLY REALLY REALLY have to make sure you have it wired right!

nativepaul · 08.31.2007, 06:34 PM

Brian, do you have one of those diagrams for 3x 2s packs rather than 2x 3s packs?

BrianG · 08.31.2007, 06:57 PM

I didn't, but I just whipped one up specifically for you.

The green circles are to show where you should zip tie the balancer leads to the main harness leads. The red wires with the gray ends show where those wires should either be removed from the connector, or put some heatshrink on them.

Hope it's not too confusing, but all I could come up with in a few minutes...

lincpimp · 08.31.2007, 10:54 PM

Brian, maybe I have the method a balancer work wrong. On a 2s pack the tap has three wires, one from the main pos, one from the main neg and another wire where the two cells are join, the series connection. Since the balancer has to read and compare voltage it would have to treat the red wire as the positive for the first cell and the middle wire as the negative for the first cell. Now for the 2nd cell the middle wire is read as the pos and the main neg wire read as the neg for the 2nd cell. If that is incorrect does the balancer read the first cell voltage of the red and middle black and then read the tolal voltage using the red and main black and subtract the voltage from the first cell reading to determine balance? Not sure if that makes any sense. I always ceck balance manually with a voltmeter by Checking the individual cells thru the balance connector by isolating the cells.

BrianG · 09.01.2007, 12:28 AM

I read that twice and still couldn't follow it.

Basically, the main charging leads electrically ties the red wire of the middle pack to the rightmost black wire of the first pack, so the red balancer wire isn't needed. This is the "safe" hookup. If the user accidentally mixes up the balancer leads and main leads, nothing bad happens - it just won't balance.

You can tie the balancer red wire of the middle pack to the rightmost balancer black wire fine. That would probably look right to most people. However, if someone mixes up the balancer plug and the main leads, a short would happen and vaporize something. Removing the common balancer wire between each pack just adds a little safety.

True, a voltmeter on each cell could be used to make sure all the cells are equal, but what do you do if one cell is a little high? You'd have to load that cell down individually. Not to mention that this voltage check should be done often, particularly during the CV phase of the charge.

lincpimp · 09.01.2007, 01:36 AM

Yeah, I need to do a drawing, not that I would post it as most peoples kids would do better than I!lol!

I am still not sure how the balancer reads the individual cells voltage in order to match them. I am sure that is is a simple circuit, but having trouble visualizing it.

Not sure how to explain this but how does the balancer know the voltage of the 3rd cell(1st one in the 2nd pack) as it appears that not using the red wire on the 2nd pack would eliminate the ability to measure across the pos and neg of that cell, the purple circle in the attached pic.

BrianG · 09.01.2007, 01:55 AM

Quote:

Originally Posted by lincpimp

I am still not sure how the balancer reads the individual cells voltage in order to match them. I am sure that is is a simple circuit, but having trouble visualizing it..

Most balancers I've seen aren't using isolated inputs for each cell, so I imagine they simply measure each wire referenced to ground. For example, to get cell 3 on a 4s pack, it probably subtracts the voltage on cells 1 and 2 from the voltage on cell 3 to ground. There really isn't much to a balancer. Most of the resistors on it are used to apply a load to any high cells. All of the measurement and logic must be done via a PIC or something.

Quote:

Originally Posted by lincpimp

Not sure how to explain this but how does the balancer know the voltage of the 3rd cell(1st one in the 2nd pack) as it appears that not using the red wire on the 2nd pack would eliminate the ability to measure across the pos and neg of that cell, the purple circle in the attached pic.

I know exactly what you mean, but let's see if I can explain it.

A pack's main black wire is electrically the same point as the most negative balancer wire.

A pack's main red wire is electrically the same point as the red balancer wire.

I think we can both agree on those two points, right?

When you use a Y cable jumper on the main power leads, you are effectively tying the most negative cell on pack1 to the most positive cell on pack2.

lincpimp · 09.01.2007, 02:03 PM

BrianG "Most balancers I've seen aren't using isolated inputs for each cell, so I imagine they simply measure each wire referenced to ground. For example, to get cell 3 on a 4s pack, it probably subtracts the voltage on cells 1 and 2 from the voltage on cell 3 to ground. There really isn't much to a balancer. Most of the resistors on it are used to apply a load to any high cells. All of the measurement and logic must be done via a PIC or something."

Ok, this makes sense. I was not sure if it measured individually or did somesort of subtraction. By leaving out the pos wires of the 2nd and 3rd pack I was having trouble inagining the circuit being complete to measure the cells seperately. However if the balancer subtracts tem to determine the voltage differences your wiring diagram makes sense. Thanks, now I can charge and balance my 2s 5000 packs as if they were a 4s pack, which is how I will use them. I just want to have all 4 cells balanced to each other.

nativepaul · 09.01.2007, 02:17 PM

Thanks very much for taking the time to knock that up for me Brian, it is as I suspected from your 2x 3s diagram, just remove the red wire and plug the blacks into the next slots but I wanted to be sure.

I use bullet connectors so I will be plugging the cells directly into each other to series them rather than using a main power harness and ziptieing them to the balancer harness, electrically this seems to be the same can you see any problems doing it this way (assuming I mark the balance plugs so they go into the right pack)?

nativepaul · 09.02.2007, 09:39 AM

Thanks again Brian, I made up the adapter this morning and just tested it out, it worked fine and after 5-10 mins my 3 new 2s packs where balanced together.

I also tried to balance my buggy's 4s flightpower 4350 pack for the first time, but the balancer switched itself off right after I plugged it in, after about 50 runs in the buggy and charging on my cheap Apache 2500 at 2.5Amps no balancing was needed at all, Flightpower rock!

Unfortunately my 1210/LBA10 combo didn't come with the dataport cable that it was supposed to Does anyone know the wiring layout of this? it looks like it uses standard Futaba servo plugs at both ends, is that right? I hope to get charging with my new combo before I receive the dataport cable in the post which will probably be weds or thurs if they get my E-Mail on Monday.

BrianG · 09.02.2007, 01:33 PM

lincpimp: No problem. I have a couple of these adaptors (2s+2s) that I use myself so I know they work.

nativepaul: Glad to hear you got it all squared away. The way I made the wiring diagram protects the cells if you happen to plug them into the wrong part of the balance Y adaptor, the worst that will happen is that the bakancer won't recognize the pack right.

As to the wiring of the data port, I imagine it uses a typically wired servo type cable, but not sure.