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Old Aug 10, 2012, 10:00 AM
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New York
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pretty simple. when cells are connected in parallel they start balancing immediately whether a charger is connected or not. generally takes a matter of minutes for higher charge cells to bring up the lower ones. after a while the lower will be higher and the higher will end up lower. when connected to a charger it sees them as one cell and proceeds to bring them all up to full.

one big misunderstaning is that they all have to be same charge state or capacity. this is not true and, as i mentioned in the other thread, even less of an issue with our small lipos.
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Old Aug 10, 2012, 10:05 AM
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But the circuit is "open", so the confusion. Does this mean that electrons will flow from one cell to the other in such an open circuit?
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Old Aug 10, 2012, 10:28 AM
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the circuit is definitely not open. as long as there is wire between all the positive (red) and between all negative (black) the circuit is closed. if you are suggesting we should connect + to - in order to charge that is not a good idea:

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Old Aug 10, 2012, 10:43 AM
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Quote:
Originally Posted by cgpirre View Post
This has been bothering me for a while... How do they 'balance' if only the cables of the same color are connected to each other? Or do you plug in the banana connectors, and start the charging process 10 minutes later?
I'm not convinced of this 'auto balancing' that goes on, and if it worked as explained, it would be a bad idea to connect a full and a flat battery together, as the full one would immediately discharge at 12-15c into the flat one that only likes to be charged at 1c. Bang!

So...pass.

The closest I have seen to something useful is this http://www.ebay.co.uk/itm/180949028840 to charge Walkera batteries using a balance charger. Plug in multiple batteries and the charger will treat them as separate cells of a multi-celled battery - and not overcharge the full ones - and stop when they're all done.

I'm sure it could be modified to stick JST sockets on the end, or maybe someone sells something already, I just haven't found it.
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Old Aug 10, 2012, 10:52 AM
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Quote:
Originally Posted by Brandigan View Post
I'm not convinced of this 'auto balancing' that goes on, and if it worked as explained, it would be a bad idea to connect a full and a flat battery together, as the full one would immediately discharge at 12-15c into the flat one that only likes to be charged at 1c. Bang!

So...pass.

The closest I have seen to something useful is this http://www.ebay.co.uk/itm/180949028840 to charge Walkera batteries using a balance charger. Plug in multiple batteries and the charger will treat them as separate cells of a multi-celled battery - and not overcharge the full ones - and stop when they're all done.

I'm sure it could be modified to stick JST sockets on the end, or maybe someone sells something already, I just haven't found it.
I am using this for ages now to charge my batteries ... the ones for my walkeras, for the msr, for the mcpx and for the 120SR (in which case I use the charge harness for the msr batteries and some adapters that Horizon Hobby sells)
You can even use two of them and charge 6 batteries at a time as a 6S battery - by using one additional 6S to 2x3S adapter (about another 4$)

I do this because I like to SEE the readouts of the charge data.

(Unfortunately whenever I write that I use this, there is IMMEDIATELY one of the parallelcharging promoters who tells whoever asked that parallel charging is soooo much better and all the stuff about it is a modern myth (the questions and negative ideas some people harbor) and makes my post drown and be forgotten (not that I really care, I am just sad because it tends to zone out information that might actually feel useful to some readers ...

EDIT:
oh, and just to be clear, my "critique" at the "parallelcharging promoters" does NOT in any way refer to a specific person/member !!!
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Old Aug 10, 2012, 10:53 AM
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Quote:
Originally Posted by Brandigan View Post
I'm not convinced of this 'auto balancing' that goes on, and if it worked as explained, it would be a bad idea to connect a full and a flat battery together, as the full one would immediately discharge at 12-15c into the flat one that only likes to be charged at 1c. Bang!

So...pass.
since you believe that connecting 2 batteries together can have different voltages then not too surprising you subscribe to the "must be similar charge" theory.
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Old Aug 10, 2012, 10:56 AM
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Quote:
Originally Posted by erdnuckel2 View Post
(Unfortunately whenever I write that I use this, there is IMMEDIATELY one of the parallelcharging promoters who tells whoever asked that parallel charging is soooo much better and all the stuff about it is a modern myth (the questions and negative ideas some people harbor) and makes my post drown and be forgotten (not that I really care, I am just sad because it tends to zone out information that might actually feel useful to some readers ...

EDIT:
oh, and just to be clear, my "critique" at the "parallelcharging promoters" does NOT in any way refer to a specific person/member !!!
lol!
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Old Aug 10, 2012, 11:09 AM
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Maybe wikipedia will help ?

http://en.wikipedia.org/wiki/Series_...rcuits#Voltage


Parallel circuits

If two or more components are connected in parallel they have the same potential difference (voltage) across their ends. The potential differences across the components are the same in magnitude, and they also have identical polarities. The same voltage is applicable to all circuit components connected in parallel. The total current is the sum of the currents through the individual components, in accordance with Kirchhoff’s current law.
Voltage
In a parallel circuit the voltage is the same for all elements.


Quote:
Originally Posted by Julez View Post
I once connected a fully charged and a fully discharged pack (100% charge difference), and the current was about 2C initially. It became much less after 30s, and after 2 minutes, it was only a couple of hundred mA.
With a max of 50% charge difference, the current should be even lower.

Cheers,

Julian
Regardless of that ... why would you want to connect charged battery to empty one instead of flying it out.

p.s. Sorry for "parallel charging promoting" - this will be my last post ! I promise !
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Last edited by shafter; Aug 10, 2012 at 11:15 AM.
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Old Aug 10, 2012, 11:11 AM
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correct-a-mundo!
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Old Aug 10, 2012, 11:18 AM
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Originally Posted by dave1993 View Post
since you believe that connecting 2 batteries together can have different voltages then not too surprising you subscribe to the "must be similar charge" theory.
No, I believe that different batteries connected with different voltages will immediately try and equalise the voltage difference with potentially explosive results.

I also believe that with a proper, balanced charging harness, all the batteries only share the Black lead and the Red leads are separate and each cell is handled individually by the charger.
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Old Aug 10, 2012, 11:24 AM
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Quote:
Originally Posted by shafter View Post
Maybe wikipedia will help ?

http://en.wikipedia.org/wiki/Series_...rcuits#Voltage

Regardless of that ... why would you want to connect charged battery to empty one instead of flying it out.
That was an extreme example to illustrate the potential danger. You could easily have a selection of batteries with 1, 2 or 3 minutes flight still in them, but you don't want to 'fly them out' because it's not worth the effort, so you fly with a full one and put them in the 'to be charged later' pile.

Any difference between the batteries will immediately be equalised according to the link you supplied above (which doesn't apply to batteries, by the way, because they are supplying the voltage, but will attempt to make the voltages the same) and unless they are very close in voltage, the speed of equalisation could easily exceed the 1C they want to be charged at.

It's like putting 5A into one instead of 0.5A if that makes it any easier to understand.

OK, try this thought experiment.
One flat battery is connected to one full battery as described previously.
How quickly do they "equalise" to half charge?
If it takes 1 hour for one battery to be charged from flat to full, how many seconds to go from flat or full to half charged is too fast?
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Last edited by Brandigan; Aug 10, 2012 at 11:31 AM.
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Old Aug 10, 2012, 11:25 AM
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Sorry Dave, but I still don't get it...
So you're saying that if I were to connect 5 batteries to a JST charging harness, which just bundles all red together, and all black together, they would balance each other out, even though the 'charging' end is still open? Like in the attached picture.
How/why?
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Old Aug 10, 2012, 11:33 AM
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Quote:
Originally Posted by Brandigan;22409958

[I
Any[/I] difference between the batteries will immediately be equalised according to the link you supplied above (which doesn't apply to batteries, by the way, because they are supplying the voltage, but will attempt to make the voltages the same) and unless they are very close in voltage, the speed of equalisation could easily exceed the 1C they want to be charged at.

It's like putting 5A into one instead of 0.5A if that makes it any easier to understand.
Read Julez post i quoted in above, current flowing between empty and fully charged pack was only 2C !

If you want to charge using series harness and multiplied voltage (that's how bigger 2S-6S packs are built):

Beware of that: (source: https://sites.google.com/site/tjingu...erial-charging)

Quote:
All the packs you charge in series must be the same capacity. For example you could charge a 3s 2200mAh lipo, a 2s 2200mAh lipo and a 4s 2200 mAh lipo in series together, but you can not charge a 3s 2200mAh lipo in series with a 3s 3200mAh lipo.

All the packs to be charged in series together need to be very close to the same voltage per cell. If I had to put a number on it I would say within .05V per cell.

Serial charging is best suited for someone looking to charge flight packs made up of pairs of packs like 2x 3s 2200mAh packs used in a 500 sized heli.
It's just not the correct solution for our small 1S cells
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Old Aug 10, 2012, 11:44 AM
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Quote:
Originally Posted by shafter View Post
Read Julez post i quoted in above, current flowing between empty and fully charged pack was only 2C !

If you want to charge using series harness and multiplied voltage (that's how bigger 2S-6S packs are built):

Beware of that: (source: https://sites.google.com/site/tjingu...erial-charging)

It's just not the correct solution for our small 1S cells
That 2C cannot be correct unless it took 1/2 the time to equalise that it would have taken to charge at 1C.
So if a 1C charge takes 1 hour, a 2C discharge takes 1/2 hour. How is that even useful to wait for half an hour to equalise the batteries before you can start charging them?

The proper harness is exactly the solution to the problem with similar 1 cell batteries, as is explained in the quote.

Just don't mix a 500mAH with a 600mAH in the same charging harness because the charging current needs to be correct for all of them to be @1C.

I have 3s batteries where some of the cells are slower to charge than others as they've got older. So the charger quickly charges up the faster cells then the last one is a bit slower, but it stops charging the full ones. This is exactly the same as if you have a selection of single celled batteries of different ages but identical specs (600mAH, 500mAh etc), where they only share Black, and Red is individual for each battery in the harness.
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Last edited by Brandigan; Aug 10, 2012 at 12:39 PM.
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Old Aug 10, 2012, 11:52 AM
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New York
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Originally Posted by cgpirre View Post
Sorry Dave, but I still don't get it...
So you're saying that if I were to connect 5 batteries to a JST charging harness, which just bundles all red together, and all black together, they would balance each other out, even though the 'charging' end is still open? Like in the attached picture.
How/why?
i see where the confusion arises. youre looking at it like there is a difference between charger and cell when in fact for parallel there is no difference. some of the batteries becomes the charger. in other words high voltage cells are chargers and low voltage ones are "chargees". you always connect charger positive to battery positive. never the othe way around (i hope). so a parallel pack (+ to +, - to -) equializes because high voltage cells are the chargers for the low voltage ones.
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