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Parallel Charge Board

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Deleted member 3641

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I ordered a 2S-3S board without knowing much about them and now that I got it and try to use it, its got to go back.... I have XT30 packs.
image1(3).jpeg

Got this one on the way now to use with my B6 Charger.
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Am I correct in thinking that you add up the number of packs (amps per pack) to set the amperage output on the B6?
So charging 4 packs would be four times the amps I would use for a single pack?
 
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I ordered a 2S-3S board without knowing much about them and now that I got it and try to use it, its got to go back.... I have XT30 packs.
View attachment 4343

Got this one on the way now to use with my B6 Charger.
View attachment 4344

Am I correct in thinking that you add up the number of packs (amps per pack) to set the amperage output on the B6?
So charging 4 packs would be four times the amps I would use for a single pack?
Yeah, that’s how it’s done (e.g. 450 x 4 = 1800). I have done a rapid charge at 1.5 times the normal charge rate (e.g. 450mah x 1.5 = 675 mA and I sit there and watch it until it’s finished). You should sit there anyway when charging, but my quad room is next to the lounge room and i check every 10-15 mins. Batteries need to be of the same capacity though when parallel charging.
 
Actually they do not need to be he same capacity, only the cell count needs to be the same, many misunderstand this. I often charge 450, 650, 850, 1300, and 1550 mah 4s together at the same time. Usual rules apply though, as in I never leave a charging session, I babysit the whole time. If you guys need an explanation of why this is ok, let me know.
 
Actually they do not need to be he same capacity, only the cell count needs to be the same, many misunderstand this. I often charge 450, 650, 850, 1300, and 1550 mah 4s together at the same time. Usual rules apply though, as in I never leave a charging session, I babysit the whole time. If you guys need an explanation of why this is ok, let me know.
I was under the impression that they needed to be the same mAh. If that is the case, how does it deal with different charging amp rates per mAh capacity? What amp charging rate would you use at that point?
 
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Actually they do not need to be he same capacity, only the cell count needs to be the same, many misunderstand this. I often charge 450, 650, 850, 1300, and 1550 mah 4s together at the same time. Usual rules apply though, as in I never leave a charging session, I babysit the whole time. If you guys need an explanation of why this is ok, let me know.
Even as I was typing that last sentence, I knew you would be responding! Despite the fact I’ve read your very reasoned explanation regarding charging different capacity (same cell count) batteries, I still use two different chargers. I mostly run 850 and 1300 4S batteries and often take both the 3” and 5” quads out together and hence two chargers. Next time you post up your explanation, I’ll see if my head will let me print it out and nail it to the wall above my drone stuff....
 
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When we charge our batteries, you notice that as the voltage rises and gets nears the full charge level that the current backs off to a trickle as the charger then starts to discharge cells that are too high through the balance lead, so the low cell can catch up. Now think about putting one of each of the batteries I listed above on to charge at the same time, they are all lets say 4s, so no matter the mah, as the voltage rises on all of them, the charger will do the same thing since it is all really about the voltage level. In the instance I gave above the charge current would be 4.8 amps (450+650+850+1300+1550=4800 milliamps or 4.8 amps), and it is really as simple as that, each battery will get less amps as the voltage rises and the current backs off as it nears full charge. Remember, when parallel charging, all the number 1 cells in each battery are shorted together and they also charge together, and the same for cells 2-X.

Rules for parallel charging...

1) ALWAYS check each battery for NO MORE than about .2 volts difference in the entire pack between all batteries you will charge together, and consider if there is a cell that is more than about .1 different from all the other cells it will be paired/shorted with (again think of all the #1 cells among the packs, etc).

2) Always plug the mains lead in first so that the overall voltage can equalize between the batteries that are (already) connected, then plug in the balance plug second. If the voltage is .1 volt or less between, lets say all the number 1 cells, then this isn't quite as important since the current during equalization of all the shorted to each other cells will not be too great, but it is always a good rule of thumb for safety.

3) Good batteries that are charging at 1C will actually get colder as they charge instead of warmer, always grab each battery to test it for any heat a few times during the charge cycle. I like to check after the first few minutes, then again as it nears 4v per cell, and then again as it starts to lower the current as it gets to 4.2v per cell.

4) NEVER EVER leave your charging station while charging except to maybe hit the bathroom or get a drink, and check for cold batteries and any visible puffing/swelling before you walk away for that very short period.



There are 2 things to keep in mind when you parallel charge, one is that a bad battery can cause the charger to repeatedly overcharge and discharge all the other cells in the batteries as it tries to get the one weak cell up to voltage, and two, you will always get a little better balance on the battery charging them individually than you will when you charge in parallel, but it is minor and makes no difference at the field when you fly. In order to reduce the time it takes to charge, and to improve balance, I will often storage charge the batteries after a day of flying to 3.85 which also balances them at that voltage so that my charge is much faster and the balance function takes a lot less time when I go to charge to fly. Since storage level is pretty easy to achieve quickly, I will often storage charge them individually to get that better "pre" balance before they are parallel charged the next flight day.

I hope this makes some sense, I have probably missed some minor knowledge points, but these are the basics for safety.
 
When we charge our batteries, you notice that as the voltage rises and gets nears the full charge level that the current backs off to a trickle as the charger then starts to discharge cells that are too high through the balance lead, so the low cell can catch up. Now think about putting one of each of the batteries I listed above on to charge at the same time, they are all lets say 4s, so no matter the mah, as the voltage rises on all of them, the charger will do the same thing since it is all really about the voltage level. In the instance I gave above the charge current would be 4.8 amps (450+650+850+1300+1550=4800 milliamps or 4.8 amps), and it is really as simple as that, each battery will get less amps as the voltage rises and the current backs off as it nears full charge. Remember, when parallel charging, all the number 1 cells in each battery are shorted together and they also charge together, and the same for cells 2-X.

Rules for parallel charging...

1) ALWAYS check each battery for NO MORE than about .2 volts difference in the entire pack between all batteries you will charge together, and consider if there is a cell that is more than about .1 different from all the other cells it will be paired/shorted with (again think of all the #1 cells among the packs, etc).

2) Always plug the mains lead in first so that the overall voltage can equalize between the batteries that are (already) connected, then plug in the balance plug second. If the voltage is .1 volt or less between, lets say all the number 1 cells, then this isn't quite as important since the current during equalization of all the shorted to each other cells will not be too great, but it is always a good rule of thumb for safety.

3) Good batteries that are charging at 1C will actually get colder as they charge instead of warmer, always grab each battery to test it for any heat a few times during the charge cycle. I like to check after the first few minutes, then again as it nears 4v per cell, and then again as it starts to lower the current as it gets to 4.2v per cell.

4) NEVER EVER leave your charging station while charging except to maybe hit the bathroom or get a drink, and check for cold batteries and any visible puffing/swelling before you walk away for that very short period.



There are 2 things to keep in mind when you parallel charge, one is that a bad battery can cause the charger to repeatedly overcharge and discharge all the other cells in the batteries as it tries to get the one weak cell up to voltage, and two, you will always get a little better balance on the battery charging them individually than you will when you charge in parallel, but it is minor and makes no difference at the field when you fly. In order to reduce the time it takes to charge, and to improve balance, I will often storage charge the batteries after a day of flying to 3.85 which also balances them at that voltage so that my charge is much faster and the balance function takes a lot less time when I go to charge to fly. Since storage level is pretty easy to achieve quickly, I will often storage charge them individually to get that better "pre" balance before they are parallel charged the next flight day.

I hope this makes some sense, I have probably missed some minor knowledge points, but these are the basics for safety.
Agree 100% with your explanation, I've just always struggled with, as per your example, pumping 4.8A through all the batteries including the smaller capacity ones. Understand that the charging current will decrease as each of the batteries come up to full charge but it worried me in the past and I haven't done it since. May give it another go when next I'm home and sit there and stare it until the charging is finished.
 
Keep in mind that "all the current" isn't going through "all" the batteries, think of it like a fire hose feeding a bunch of smaller garden hoses through a manifold, the small hoses are not taking the full amount that the fire hose supplies, it is being divided down by the manifold just like the parallel board does.

Again, I hope my analogy makes sense.
 
Here is a decent diagram from the iCharger page (one of the best chargers in the industry I might add, wish I could afford one) and this should give you a good visual on how all the current being sourced by the charger is being divided by 4 in this example, and as the voltage rises in a given battery, it actually creates a "back pressure" that reduces the current into that battery and into the ones that have less of this higher voltage back pressure, like I said, it is really all about the voltage. Since all the battery mains neg and pos are all shorted together, they become a parallel circuit and therefore become a single "average" of all the voltages, and will also start charging from the highest voltage batteries into the batteries with the lower voltages.

1590720198747.png


This parallel circuit we have created with our parallel board is unlike our 4 in a series circuit (4s stand for 4 in series), which adds the voltages together to give us our 16.8 volt pack, and of course is the positive lead on one battery connected to the negative lead on the next. Voltage is always the most critical component since it is literally the "pressure" that causes current flow, no difference in voltage potential, no current will flow.

You could literally hang off a high tension power line and not feel a thing even with upwards of 14,000 volts on it, because there is no ground for all that potential.
 
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Another great knowledge point here, many people worry about the C rating, age etc of all the different batteries... ok so they are all 4s, and they are all LiPo chemistry, so same cell count and same "type", check and check...

1590720902559.png

And the biggest concern for attaching batteries with too great a difference in voltage is that it will burn the balance connection traces on the parallel board and not the actual balance lead wires on the battery, for this reason I always plug the fist battery into the last slot so that when all 4 cells register with the charger I know that at least in that moment the traces are all good all the way back to the charger since it is a single long trace back to the inlet connector. I will never forget the first time I plugged into the parallel board and saw a cell not registering and I had blown a trace, even at less than .2 volts difference in voltage, the balance traces on the board will not handle very much current, and I had to solder a piece of wire to repair it.
 
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Manufacturers say don’t mix capacities in a parallel charge board.

I agree because to the charger, the parallel board appears to be a single battery. The charger/board doesn’t charge the batteries individually. They all get the same current.

If you charge at 1C for the larger capacity batteries, the lower capacity batteries will be charging at a rate that is higher than their 1C rate and may be over charged.

You may be able to charge mixed capacity batteries at the 1C rate for the lower capacity batteries, but the lower capacity batteries will reach full charge before the larger batteries and the charger will shut.off before the larger capacity batteries reach full capacity..
 
Manufacturers say don’t mix capacities in a parallel charge board.

I agree because to the charger, the parallel board appears to be a single battery. The charger/board doesn’t charge the batteries individually. They all get the same current.

If you charge at 1C for the larger capacity batteries, the lower capacity batteries will be charging at a rate that is higher than their 1C rate and may be over charged.

You may be able to charge mixed capacity batteries at the 1C rate for the lower capacity batteries, but the lower capacity batteries will reach full charge before the larger batteries and the charger will shut.off before the larger capacity batteries reach full capacity..

I showed my references form the leader in RC hobby charging, iCharger, can you please show your references? And as I stated above, (with 40 years working on Central Office power for the telephone systems) the batteries do NOT get the same current.

1590881565948.png
Of course, parallel charging carries risks, and while some of the battery manufacturers would rather side on "caution", electrically it is sound with care.
 
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I showed my references form the leader in RC hobby charging, iCharger, can you please show your references? And as I stated above, (with 40 years working on Central Office power for the telephone systems) the batteries do NOT get the same current.

View attachment 4372
Of course, parallel charging carries risks, and while some of the battery manufacturers would rather side on "caution", electrically it is sound with care.

Sorry, I didn’t save the instructions that came with my parallel charge boards, but what I said is what I remember from reading the instructions. I also know that the boards have no intelligence, so all the batteries and their cells are just connected in parallel, which is why the charger sees the parallel board as one, big, higher capacity battery.

Here is a link to one website that supports what I said:


As you point out, the iCharger website contradicts this.


However, the iCharger is just another smart charger so it, connected to a parallel board, can’t vary the current to the individual cells in each group of cells - it sees the parallel board as one big battery and their site says as much. I’m not saying tbat smart chargers don’t vary the current/voltage to each group of parallelly connected cells during balance charging. I’m saying the group gets the same current, so a lower capacity cell in a group of higher capacity cells may receive more than its 1C current if you are charging at the 1C current of the higher capacity cells. This fact can be bad, especially if charging at higher than 1C. The iCharger website says this too but differently,. They say that “you can mix batteries of different capacities within reason,” but they don’t do a good job of defining what is reasonable.

Although you can mix capacities “within reason,“ there is, as you say, (higher) risk, which is probably why most other sources state not to do it. It seem like good advice, which I follow and I suggest that anyone that isn’t fully aware of how parallel charging works follow as well.

We may have to respectfully agree to disagree on this.
 
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@Earthman, I am happy to admit that parallel charging can be a risky game, the only thing about this whole conversation I disagree with is the notion that when parallel charging that all batteries "get the same current", this is simply not true. When it comes to charging it is all based off the voltage potential, and the real concern is that one or more of the batteries is weak/bad and the voltage doesn't rise in unison with the others. When the voltage on the battery rises it creates LESS of a difference in potential with the chargers voltage, and based on ohms law, less current will flow into the battery with a higher actual voltage. That is all I am saying here, so I am happy to respectfully disagree with someone who uses critical thinking in their argument. Kudos!
 
@Earthman, I am happy to admit that parallel charging can be a risky game, the only thing about this whole conversation I disagree with is the notion that when parallel charging that all batteries "get the same current", this is simply not true. When it comes to charging it is all based off the voltage potential, and the real concern is that one or more of the batteries is weak/bad and the voltage doesn't rise in unison with the others. When the voltage on the battery rises it creates LESS of a difference in potential with the chargers voltage, and based on ohms law, less current will flow into the battery with a higher actual voltage. That is all I am saying here, so I am happy to respectfully disagree with someone who uses critical thinking in their argument. Kudos!

I see what you are saying and agree with you. I misunderstood your point.

My statements and concerns about parallel charging and charge rate assumed the cells in parallel were at the same voltage but have different capacities.

For example, if you charged a 100-mah cell in parallel with a 1,000-mah cell at 1C for the larger capacity cell (1-amp), the lower capacity cell would be charging at 10C, which may cause problems as a result of the high charge rate.

If both cells were fully discharged, the smaller capacity cell would reach full charge in about 6-min at 10C (at which point current would stop flowing into the smaller cell but the damage may already be done), while the larger capacity cell would require about 60-min to reach full charge at 1C.

Anyway, I think we are on the same page.

Thanks!
 
Overall I agree, but I want to try explain why the small battery doesn't get 10C while charging. Look at it like 2 ballons, they can both withstand the same pressure (voltage), but one is a small balloon (100 mah) and the other is a much larger balloon (1000 mah)... proportionally both balloons would grow in size at a given rate until full pressure was achieved in both, so the correct "volume" gets into both at a proportional rate based on "pressure".

When I charge a 1000 mah and a 100 mah together, at 1.1 amps of current, the current the charger puts out is serially DIVIDED (becomes a parallel circuit) by the parallel charge board and it electrical connections, the current does not travel in a serial fashion at this point and the 1.1 amps does not go down both paths, it is split, but how is it split. When the smaller 100 mah battery gets its X number C rate of the 1.1 amp charge rate (what ever C it is in the very beginning) its voltage will rise in proportion to the mah capacity of that 100 mah battery ("theoretically" it will rise in voltage FASTER than the larger 1000 mah battery will). When that occurs (small battery is now higher voltage than the larger battery) it will create a "back pressure" that has nothing to do with the mah of the battery and is a matter of the voltage level and the difference in potential created and the amounts of proportional current associated. This phenomena just so happens to make a 100 mah get .1 amp, and the 1000mah to get 1 amp.

We agree 100% on at least one thing, there are a hundred reasons for people to err on the safe side when dealing with lipo's. An advanced charging practice isn't for everyone and should include constant monitoring.
 
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Overall I agree, but I want to try explain why the small battery doesn't get 10C while charging. Look at it like 2 ballons, they can both withstand the same pressure (voltage), but one is a small balloon (100 mah) and the other is a much larger balloon (1000 mah)... proportionally both balloons would grow in size at a given rate until full pressure was achieved in both, so the correct "volume" gets into both at a proportional rate based on "pressure".

When I charge a 1000 mah and a 100 mah together, at 1.1 amps of current, the current the charger puts out is serially DIVIDED (becomes a parallel circuit) by the parallel charge board and it electrical connections, the current does not travel in a serial fashion at this point and the 1.1 amps does not go down both paths, it is split, but how is it split. When the smaller 100 mah battery gets its X number C rate of the 1.1 amp charge rate (what ever C it is in the very beginning) its voltage will rise in proportion to the mah capacity of that 100 mah battery ("theoretically" it will rise in voltage FASTER than the larger 1000 mah battery will). When that occurs (small battery is now higher voltage than the larger battery) it will create a "back pressure" that has nothing to do with the mah of the battery and is a matter of the voltage level and the difference in potential created and the amounts of proportional current associated. This phenomena just so happens to make a 100 mah get .1 amp, and the 1000mah to get 1 amp.

We agree 100% on at least one thing, there are a hundred reasons for people to err on the safe side when dealing with lipo's. An advanced charging practice isn't for everyone and should include constant monitoring.

HighTech, thanks for the additional explanation.

I assume that you are saying that 1.1-amp maybe flowing into the parallel charge board, but that flow would be split between the two batteries in our example. So, if both batteries are at the same voltage, they would each see 0.55-amps until the lower capacity battery was full, at which point it would stop accepting charge, and then the higher capacity battery, which requires more time to charge, would receive the full 1.1-amps; i.e., the full, available flow. I understand and agree with this.

I still see the higher than expected charge rate (higher than 1C) that the smaller battery sees as a potential problem. Also, I have to wonder if it is safe to keep the smaller battery at the charge voltage longer than needed.

In any case, I think we’ve beat this to death as a thought experiment and should move it to the physical testing phase (just kidding, or let’s kick it over to Joshua Bardwell).

Thanks!
 

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