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Old Mar 11, 2012, 06:36 PM
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Parallel charging question

Parallel charging 6 x 1S 550mAh using a 6 x JST harness like this

Charger is Thunder AC6 like this one

The charger will not allow adjustment of cell count, or to specify 1S6P; all I can set is the charge rate.

Using the AC6 charger, what is the best setting to use to charge these batteries to 4.20v each AND then set them to 3.85v for storage?
-mike
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Old Mar 11, 2012, 07:40 PM
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Originally Posted by octanejunkie View Post
The charger will not allow adjustment of cell count, or to specify 1S6P; all I can set is the charge rate.
Check the manual again. You can absolutely set the cell count. Simply set for single cell (3.7V) lipoly, adjust charge current to your desire, plug in your charge harness and batteries, and initiate charge.

Optimal charge rate is dependent on the quality of your lipolys. Not knowing your exact cells, default charge rate would be 1C. 6 x 550mAh would be 3.3A charge rate.

Mark
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Old Mar 12, 2012, 03:40 AM
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One Warning...Cell count for charger is 1S if batteries are in Parallel and 6S if they are in series.

Both methods would require some sort of adapter....

sts41
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Old Mar 12, 2012, 06:16 AM
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Originally Posted by octanejunkie View Post
Using the AC6 charger, what is the best setting to use to charge these batteries to 4.20v each AND then set them to 3.85v for storage? -mike
LIPO CHARGE
1 Cell Lipo / 3.3A for parallel charging.
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Old Mar 12, 2012, 08:43 AM
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Originally Posted by freechip View Post
LIPO CHARGE
1 Cell Lipo / 3.3A for parallel charging.
First responder mrforsyth said the same thing...


Quote:
Originally Posted by mrforsyth View Post
Check the manual again. You can absolutely set the cell count. Simply set for single cell (3.7V) lipoly, adjust charge current to your desire, plug in your charge harness and batteries, and initiate charge.

Optimal charge rate is dependent on the quality of your lipolys. Not knowing your exact cells, default charge rate would be 1C. 6 x 550mAh would be 3.3A charge rate.

Mark
I know I can change the charge rate, didn't realize I could safely go to 3.30A

I guess 6 x 1S 550mAh cells = 3300mAh 6S6P; however the all the charger can sense is the capacity, cell count is still 1S

I tried the charge setting at 2.4A rate w 6 1S 550mAh batteries in parallel and this was my experience:
1) ran a charge cycle, batteries charged from 3.85v each to between 3.93v and 4.01v in 35 minutes. That doesn't seem "complete" to me, ran the cycle again.

2) second pass at the same rate took all 6 batteries to between 4.07v to 4.12v each in around another 30 mins. Getting closer to full voltage and decided to run the cycle again.

3) after the third pass all my batteries ended up between 4.23v and 4.27v after about 15 minutes!!!
Yikes


Quote:
Originally Posted by sts41 View Post
One Warning...Cell count for charger is 1S if batteries are in Parallel and 6S if they are in series.

Both methods would require some sort of adapter....

sts41
I can't successfully change the cell count unless charging in series, charger warns "voltage too low" when attempting to charge 6 x 1A batteries in series using a parallel adapter. The charger's programming anticipates the total voltage by cell count - for example; 2S = 7.4v, 3S = 11.1v - I can't "trick" it into a 6S6P 3.7V charge though it does make me confirm cell count occasionally, even when charging a single battery.

I made a "balanced" charging harness which allows me to balance 3 x 1S JSF batteries at the same time, which works well, but I can't go safely up to 3.30A charge rate - or can I?

I have since refined this harness, and went to 16GA on the main charge leads.


Overall I am a little disappointed with the AC6 charger, overall it does work but as far as programmability (it is "computerized" after all) it leaves much to be desired, even at $44.

I'm not sure why or how the AC6 is not capable of charging accurately, or at least not overcharging like it did in my experience above. Actually most of it's parameters are hard set and the user options are slim. The preset voltages for max charge and storage/discharge are also not end user defined, hard set at, 3.80v, which I cannot find how to change; that sucks.

Worst of all, compared to my standalone voltmeter, the actually the charger seems to be off by around 0.05v - I guess I can live with that if it is consistent and I understand that voltage in batteries will settle after resting after a charge or discharge cycle.

Thanks for the replies so far gentlemen,

Any thoughts?
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Old Mar 12, 2012, 08:54 AM
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You are getting confused about parallel charging.
Quote:
I guess 6 x 1S 550mAh cells = 3300mAh 6S6P; however the all the charger can sense is the capacity, cell count is still 1S
Charger has it right, you don't.

six 1s 550 lipo in parallel is not 6s6p 3300mah

Parallel charging increases MAH rating ONLY
Series charging increases voltage only.

Six 1s 550mah parallel = 1s 3300mah pack
Six 1s 550mah series = 6s 550mah pack

I see similar result when charging my 1S 500 mah pack for my small stuff and that it because there is no balancing done for 1S and so the charger relies on voltage only to stop the charge.

You are mixing packs that may have different amount of use one them and some may not be fully charged when others reach 4.2v and so the charger stops charging and some packs drop back down faster then the others.

The above pic looks like a SERIES harness to me. If that is what are you going to charge with now then you need to select 3S and .5 or .6 A to series charge.
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Old Mar 12, 2012, 08:54 AM
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It may be that your charger simply knows better than you do. 6 x 1S batteries IN PARALLEL is NOT 6S6P and if you tried to charge them as that you'd have smoke and flames.

If anything it's 1S6P i.e. 6 x 550mAh cells IN PARALLEL is equivalent to a 1S 3300mAh battery. And the charger CANNOT sense the capacity, that's why you MUST set the current yourself.

We can't see how your "balanced charging harness" is wired but it looks like that may be a series connection. In that case your 3 x 550mAh cells will look like a 3S 550mAh pack and the charger should therefore be set to 3S and 550mA (or probably 0.5A).

Steve
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Old Mar 12, 2012, 09:29 AM
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Originally Posted by octanejunkie View Post
I can't successfully change the cell count unless charging in series, charger warns "voltage too low" when attempting to charge 6 x 1A batteries in series using a parallel adapter.
It's a good thing that the charger had some safety checks to prevent you from attempting to charge a bunch of lipos to 25V per cell!

You don't charge in series with a parallel adapter.

I would suggest you spend some time understanding one of the parallel charging threads in this forum because if you keep trying, you might find away to trick the charger into helping you start a lipo fire.
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Old Mar 12, 2012, 11:45 AM
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I'm so glad I posted this, the 6S6P was a typo - I thought better of it after typing it but was too lazy to go back and edit it.

I do understand the basic differences between series and parallel circuits, and how these apply to this hobby, but I cannot understand how a 1S 3.7v charge on a 6x parallel harness at 2.4A resulted in all batteries charged to 4.26v (average).

I also don't understand how I can get a storage voltage of 3.85v out of my charger when the storage mode is hard coded to 3.80v - short of babysitting the process - I'd love to learn how to automatically accomplish this with the AC6.

While I agree there is much more I still need to learn about managing batteries, it does seem that the AC6 charger is limited on what it can do - or perhaps I am expecting too much for the price I paid.

Thanks for the replies so far!
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Old Mar 12, 2012, 11:50 AM
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My AC6 stores at 3.85V not sure what you are saying...

As to what to expect from it, its a 50W charger and works very well .
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Old Mar 12, 2012, 12:12 PM
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My AC6 stores at 3.85V not sure what you are saying...
When in LiPo storage mode, with 1S 3.7v selected, the charger shows what I interpret as it's target charge voltage in the upper right corner of the screen as 3.80v - it does however seem to leave the battery closer to 3.85v, but never exactly

If I am doing/setting something wrong I would love to learn what that is and change it...
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Old Mar 12, 2012, 12:16 PM
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It's not clear to me how you are measuring things. Charger? DVM? cell checker? While charging, after charging? If the charger - via the main ports or balance ports?

Each can give somewhat different results. ie: if you have the main and balance ports connected - it is not at all unusual for the voltage in the main display to be higher than 4.2V per cell while the charger is seeing less than 4.2V per cell on the balance connector. You can press the inc/+ button to see the voltage at the balance connector. (I have seen this on many chargers but I don't have one like yours.)

You do appear to be charging at less than 1C so it should take awhile.

Frankly I wouldn't worry about 3.8 vs 3.85. Anything from 3.7 to 4 is considered OK for storage. I normally don't storage charge since I time my flights to end a bit above 3.7V.
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Old Mar 12, 2012, 12:31 PM
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Originally Posted by octanejunkie View Post
When in LiPo storage mode, with 1S 3.7v selected, the charger shows what I interpret as it's target charge voltage in the upper right corner of the screen as 3.80v - it does however seem to leave the battery closer to 3.85v, but never exactly

If I am doing/setting something wrong I would love to learn what that is and change it...
Don't think you are doing anything wrong but that from 3.80 to 3.85V you should worry about it.
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Old Mar 12, 2012, 01:28 PM
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Originally Posted by Dave H. View Post
It's not clear to me how you are measuring things. Charger? DVM? cell checker? While charging, after charging? If the charger - via the main ports or balance ports?

Each can give somewhat different results. ie: if you have the main and balance ports connected - it is not at all unusual for the voltage in the main display to be higher than 4.2V per cell while the charger is seeing less than 4.2V per cell on the balance connector. You can press the inc/+ button to see the voltage at the balance connector. (I have seen this on many chargers but I don't have one like yours.)

You do appear to be charging at less than 1C so it should take awhile.

Frankly I wouldn't worry about 3.8 vs 3.85. Anything from 3.7 to 4 is considered OK for storage. I normally don't storage charge since I time my flights to end a bit above 3.7V.
I am measuring voltage post-charge using a device like this, as well as referring to the charger screen during and after charge; however the charger and volt-meter never concur with one and other - which is mildly alarming

I am charging at less than 1C only because I am challenged to determine the 1C rate of my various batteries - still getting my head around the math involved - but to be safe, while series charging, I am charging 550mAh lipos at 1A or less, and 160mAh at 0.5A or less = trying to get the fastest possible safe charge.
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Old Mar 12, 2012, 01:41 PM
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While most of todays lipo will safely handle more then 1C charge rate, the rate needed to charge is not hard to figure out.

1000mah lipo at 1C is 1A, anything under a 1000mah is of course .xxxA. With the AC6 the charging rate increments are of course in .1A or 100mah. Charing 550mah you can very safely select .6A or 600mah as the rate for charing.

Series charging increases VOLTAGE which on the AC6 represents cell count
Parallel charging increases MAH rating which on the AC6 is the AMP rate for the charging process.

For Series charging 1s lipo there is not too much to it BUT series charging packs of 2s or more BECOMES very interesting and CARE must be made when connecting packs. More so if you made you're own harness.

Parallel charging is much safer and popular.

But fully understand what you experienced when parallel charged with the AC6 your 1s packs. I get the same results and this is because my packs do not have the same use on them.

What I do is parallel charge my packs and then just before flying I top them off one by one. I have come to know how to work with the charger I got sort of speak..
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Last edited by freechip; Mar 12, 2012 at 03:46 PM.
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