Using a Turnigy 6 to balance a LiFePo4 4S w/ reversed wires?

I have a Turnigy Accutel 6 I use to charge the RC lipos for my eMTB. I would like to balance charge y 4S LiFePo4 pack that I think has a BMS type wiring (as in picture). The Accutel is wired for RC packs, which has the opposite wiring (one pos/4 neg). I'm not even sure the voltage is additive/cumulative (1S, 2S, etc.) with each successive wire in the RC /Accutel balance lead.

Is there an adapter that will allow me to use this chargers balance port with the the LiFepo4 pack's lead, wired this way?

I gave it my best Googling, checked the manual, etc. couldn't find the answer.

Thanks

If you can't find a cable for it, just buy an extension cable with the right connectors on it, then cut it in half, and reverse the wires yourself, splicing them back together.


But I think you'd probably get better answers if you kept the whole problem and all it's questions in the first thread about it, so those already helping you would see your new questions and answer. Most people don't read the whole forum and so don't always see new threads for a problem with new questions, and assume a problem was fixed or given up on when the orignal thread doesn't get further info or questions posted to it.

Make whatever adapter you need, Jst balance cable extentions are handy and easy to work with, since they have the wires attached, and both female and male plugs. Cut in half, pick the end you need, start splicing. Easy.

Just wire them up the way your RC charger is. cell zero is your negative, all other wires are positive, cell 1-whatever the count is. So a 4s pack has 0,1,2,3, and 4. 5 pins.

FWIW, you know some of this, but others read who don't.

amberwolf said:

But I think you'd probably get better answers if you kept the whole problem and all it's questions in the first thread about it, so those already helping you would see your new questions and answer. Most people don't read the whole forum and so don't always see new threads for a problem with new questions, and assume a problem was fixed or given up on when the orignal thread doesn't get further info or questions posted to it.

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I will keep that in mind and post accordingly, thanks .

I do want to say I dont start new threads thoughtlessly, or purely for my benefit or to bump up to the top The way I've approached forums is that I'm thinking of other people (members or not) with the same problem, can search and find specific problems addressed, with the specific subject header flagged by search engines, as it's own standalone subject, rather than a solution buried in a long thread about about my personal project, often with no specific goal, which may or may not be broadly useful or interesting. Before I start a thread I do make sure to ask myself if someone else could possibly benefit from it, and post as many photos and diagrams as possible for illustration. I've found forums organized this way very helpful when searching by keyword. I write all that not to argue or as an excuse, solely to say I try not to just start new threads willy nilly, it is by design to try to contribute.

But that said, I am a junior member here and will of course conform to forum norms and the directives of ES senior members and admins. Thank you

dogman dan said:

Make whatever adapter you need, Jst balance cable extentions are handy and easy to work with, since they have the wires attached, and both female and male plugs. Cut in half, pick the end you need, start splicing. Easy.

Just wire them up the way your RC charger is. cell zero is your negative, all other wires are positive, cell 1-whatever the count is. So a 4s pack has 0,1,2,3, and 4. 5 pins.

FWIW, you know some of this, but others read who don't.

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I guess what im not sure about is:

So the balance port(s) pins going in to the charger are 1st pos, 2nd neg, 3rd neg, 4th neg, etc. like RC lipo packs. If I wire a plug that is 1st neg, 2nd pos, 3rd pos, etc., like my lifepo4 balance lead, wont the polarity be a problem? Or can the Accutel detect and switch polarity of incoming balance wires?

Or do you mean completely rewire/solder a new balance lead directly from the cells in the 1-pos, 2-neg, 3-neg, 4-neg 5-neg order? If so, that would work definitely, but it might not be worth the bother.

The other issue posibly is im assuming that the lipo voltages going up in wire order arent cumulative/additive (unlike lifepo4 lead, ie 1-neg all, 3.65v, 7.3v, 10.95v, 14.6v). I havent tested, but I think the lipo balance wires are just the straight voltage of each cell (1-pos all, 2-3.6v, 3-3.6v,4-3.6v, etc.)

Unless I completely dont understand the lipo balance wires and whats going through them. thx

I don't think I understand what you're describing, so I'll describe what I've always seen for all balance connectors.



All the cells are connected positive of one cell to the negative of the next more-positive cell.

So...call the most negative cell "1". The next most positive "2". If there are four cells, then the most positive of all is cell "4".

Meaning, the ground (negative) of teh whole pack is the negative of cell 1. The positive of the pack is the positive of cell 4.


So a balance lead would have five wires, and the "first" wire would be the pack negative (and cell 1's negative), and the fifth wire would be the pack positive (and cell 4's positive).

The second wire would be cell 1 positive, and cell 2's negative.

The third wire would be cell 2's positive, and cell 3's negative.

Etc.

Does that make sense?



If your actual balance connector is wired differently than that, it would be strange, because doing it any other way than that order (regardless of which end starts as "pin 1") means a higher potential between pins, more of a risk of dangerous shorts.

The actual connector might be different between them, or it might be keyed differently (reversed), but the wire order should always be the same.

I appreciate the reason for posting the separate thread--if anyone ever actually used the search instead of just starting new threads I'd say that would be very helpful.

Unfortunately, very few do.

To make info even easier to find you could add to the ES wiki, either updating existing articles or adding new ones.

But it's up to you how to post--I was just suggesting it because often someone helping another with a particular problem only sees the one thread, and without knowing there is another thread, they don't know why the first one (or several) was abandoned.... Or the new thread gives new information on the problem, that the original helper(s) could use to give a better answer (if they knew the info existed).

mjp8081 said:

I do want to say I dont start new threads thoughtlessly, or purely for my benefit or to bump up to the top The way I've approached forums is that I'm thinking of other people (members or not) with the same problem, can search and find specific problems addressed, with the specific subject header flagged by search engines, as it's own standalone subject, rather than a solution buried in a long thread about about my personal project, often with no specific goal, which may or may not be broadly useful or interesting. Before I start a thread I do make sure to ask myself if someone else could possibly benefit from it, and post as many photos and diagrams as possible for illustration. I've found forums organized this way very helpful when searching by keyword. I write all that not to argue or as an excuse, solely to say I try not to just start new threads willy nilly, it is by design to try to contribute.

But that said, I am a junior member here and will of course conform to forum norms and the directives of ES senior members and admins. Thank you

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This is how I see it. You are just counting cells from the positive side, but the convention is to count up from the negative side.

Take a 4s lipo pack. on the balance plug, one end is a negative wire, usually its black. All the others are positive wires. The black one is pin zero. then the next one down is cell one positive, and so on till the last red wire that is positive to cell 4.

But yes, most of those positive wires are also the negative wire of a cell, except for the cell 4 positive. This exception is why we call all those 4 wires a positive wire. ( cell one negative is cell zero, and of course the last red positive can't be the neg of another cell. )
I learned this by simply looking at how they label the pins on a cellog 8 Pin 0 is the one with the black wire. then the cells are labeled 1-8 on the cellog. The last cell is the positive end. The first cell is the negative end of the string. I suppose this became the convention because as you add cells in series, the voltage adds up. So it starts with one cell, and that positive terminal is cell one.


Lets say you wanted to check the voltage of cell 3. Starting with the black negative wire, count down the row. 0, then 1, 2, and 3 is your cell three positive wire. Where is the negative of cell 3? its pin number 2, its also the positive of cell 2.

Returning to your original question, if your lifepo4 balance plug is not wired so it plugs in to your charger with the negative matching the negative on the charger, you just need to make up an adapter, or change the plug to conform with the lipo convention jst plug.

Yikes--Ok first off all THANKS sincerely, for all the 'splaining, taking all the time to help me figure this out.

Now after reading all that twice, my little brain hurts and I still cant picture it. But here's a thousand words about my lead as I tested it, this is what I do know:





Now what I dont get is when youre talking about wires being positive or negative--they are either attached to the negative or to the positive side of the batteries--i dont know how they could be either. Short of rewiring all the balance leads to the cells, I still dont see how to get a completely reversed 0-pos/1-neg/2-neg/ etc lead out of this. But I will read the last replies a few more times, see if I can figure it out.

Also, by search engine I was speaking more about people using and coming in from like Google or DuckDuck, not really the internal ESdC search feature, but yeah I understand.

ok thanks dudes

oh, another question: I was shopping for BMSs at Bestech, and some are listed as max charge amps in a range, rather than a fixed number, like 5a-100a, rather than just 100a. Does that mean they will not charge with anything lower than 5amps? Or what?

http://www.batterybms.com/128v4spcmbmspcbforlifepo4batterypack/products-2543.html

mjp8081 said:

But here's a thousand words about my lead as I tested it, this is what I do know:

Click to expand...

The picture shows exactly what we're talking about, in the voltages you've measured.

Now what I dont get is when youre talking about wires being positive or negative--they are either attached to the negative or to the positive side of the batteries--i dont know how they could be either.

Click to expand...

Because the positive of the first battery is directly connected to the negative of the second, and the wire is connected to both of them because they are attached to each other.

So whether it is + or - depends on where you're measuring from.

Short of rewiring all the balance leads to the cells, I still dont see how to get a completely reversed 0-pos/1-neg/2-neg/ etc lead out of this.

Click to expand...

Your picture showing the measurements shows you already have the same wire ordering that every pack typically has. THere is no need to rewire anything, unless the connectors are different, in which case you can change those, or make an adapter from one kind oto the other.

OK, thanks, also I found this:

http://www.tjinguytech.com/charging-how-tos/balance-connectors


Sorry for all the ignorance on my part, I get it now. The first and last wires will be neg only and pos only, the ones in between are connected IN SERIES (duh)

I just need to find that type of connector-- looks the same, same size, but is slightly different and wont work

Also, any idea on what it means when the BMSs rated max charge rate being expressed as a range (5a-100a) rather than a simple 100a? I will resist starting a new thread on the subject, even though it is pretty unrelated to this thread. :wink:

Believe me, 9 years ago it was even more confusing to me. I have an agriculture degree, not EE.

No rewire to reverse it, just stop counting backwards.

I think you got it why now. When you connect in series, you connect one cell to the next, positive to negative. Then that wire connects there, so it could be thought of as both positive of cell one, and negative of cell two.

The convention is the negative of a string is called 0 or just negative, and then each wire after that is called a positive of a cell.

You might need to rewire to make the plug fit because its a different type, but I doubt it was put on backwards by the factory. ( is possible but not so likely)

BMS wiring can get confusing, since some have 5 tiny balance plug wires for 4 cells, and some have 4. Some bms use the batteries main wire for the negative, and then the balance plug wires are all positive. No cell 0 on the plug.

Your bms has wiring I'm unfamiliar with. Larger input and output wires vary, some use the same wires for charging and for discharging. Then there is usually a female plug where the smaller balance wire go. Yours seems to have 5 wires in and out, plus a balance plug.

If your pack has a bms, then you don't need to use the bms functions of your charger. You just need to use the two main wires, and select non balancing charge mode on the charger. If you run naked, then you can use the balance plug to use the RC chargers balancing function when you charge.

So good news, I connected it (in reverse order basically), it read and balance charged no problem--so WIN. However, the 4s60p pack will not charge over ~12.8v, while my other packs will go to 13.4v--the Accutel stops charging, says "reached capacity" at about 13.1v then drops after down to ~12.8v fairly quickly. I think if I check it in a few hours, it will drop more. I am bypassing the BMS btw.

Each series reads around S1--3.2v, S2--3.1v, S3--3.1v, S4--3.1v

Any ideas why the cells will not accept full charge?

When I first received the battery, it read 12.6v, I figured it was just undercharged, so I installed in parallel with the 13.2v battery, hoping they would balance out. Instead it went down to 10v or so and would not charge past there.

The company I bought from had me test it and said it was the BMS that needed replacing. So as I am waiting for my new one, I thought Id do this test with my Accutel to see if the cells would charge without the BMS so here I am now.

I will do a separate post about my dealings with this company LithPower. on Alibaba. These batteries were supposed to be "drop in replacements for lead acid deep cycle 12v batteries", no fuss. So many problems and hours later, I now know how to build my own from scratch.

And again, the BMS max charge rating expressed as range (5a-100a) on Bestech's site, any idea? A sales woman wrote me and said "5-100A, it mean the mini, continuous charging current is 5A, and max. continuous charging current is 100A", so I still dont know if that means current below 5a wont charge batteries.

Alrighty, thanks dudes.