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HelicopterMain Discussion › Parallel Lipo Charging- Safety & Best Charger Recommendations
02-19-2014 09:57 PM  3 years agoPost 1
Flyrc67

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IL

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I have been doing some research on parallel charging Lipos and still have a few concerns on safety Issues. I understand the basic safety issues of not mixing chemistries, number of cells as well as matching battery capacities. But, I am still unclear as to weather there are still any other safety issues with parallel charging vs individual cell charging. Can someone help me better understand if there are other issues/risks to be concerned with in parallel charging.

Also, what would be your best charger recommendations for parallel charging between Hyperion, iCharger and Powerlab. In my case I will be using up to 6 cells max.

Thanks for your help.

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02-19-2014 10:04 PM  3 years agoPost 2
JKos

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Redondo Beach, CA

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The biggest safety issue with parallel charging is that none of the current chargers monitor the voltage of each and every cell but rather groups of cells. The charger cannot possibly know of a poor or broken connection to any single or multiple cells within in a group.

If you have four 6S packs in parallel, the charger is monitoring seven voltages (one for each 'S' and the total pack voltage). Only one cell of each group has to be connected to the balancer and the charger will think everything is going great.

In the extreme, one could plug only one pack into the balancer and then connect the other parallel packs only to the main output. The charger will go on charging.

Thus, the user nor the charger has any idea that one or more cells may actually be getting overcharged.

- John

RR rules!

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02-19-2014 11:12 PM  3 years agoPost 3
Dave Willis

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Sevierville, TN USA

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I alternate between Parallel and Single Pack Charging so I can keep a closer watch on the cells and how far the Packs have been discharged.

Dave

Futaba AMA 6679 IRCHA 675 VHA 11

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02-19-2014 11:29 PM  3 years agoPost 4
Craigdieslemac

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Valdosta, Ga USA

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Rarely do I ever parrallel charge more than 2 batteries at once. I have my batteries paired and they are only used with each other. Before each charge, I check both batteries by plugging them in and looking at the state of charge for each cell and tab over to IR. All of my batteries are really close of not at the exact same state of charge when fully charged and pretty close when discharged.

Aut viam inveniam aut faciam

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02-20-2014 01:11 AM  3 years agoPost 5
utahslim

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phoenix

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After flying, all my batteries are pretty much at the same level of discharge, so I just parallel charge them back up to 3.85V, which is storage level, when I get home. Then, before the next flying session, I parallel charge them up to full. Works great and I've been doing this method for years without a single problem. I use an iCharger 306B and parallel charge boards from ProgressiveRC. Excellent gear.

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02-20-2014 02:34 AM  3 years agoPost 6
Jerry K

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Houston Area

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Not to hijack the thread but maybe someone has the answer. What are the rules about using different size packs on the same airframe in parrallel such as 1 4S 3300 and 14S 1000? and then with charging them in the same arangment.

I am not trying this so please do not flame me. There is a reason for the question. It seems to me that both packs would discharge at the same rate but internal restance may prevent that.

Any thoughts?

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02-20-2014 03:48 AM  3 years agoPost 7
Cra-Z-1

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Washington,UT-USA

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Also, what would be your best charger recommendations for parallel charging between Hyperion, iCharger and Powerlab. In my case I will be using up to 6 cells max.
I just upgraded from an Icharger 206B to a 308 duo and absolutely love it. There is also a big brother to the 308; the 4010 Duo. I'm using a maximum of 6 cells right now, but the charger will handle up to 8. If you want to parallel charge your 6S together on one channel using a parallel board, it works great. I plan to charge 2 6S split packs (one 12S on each channel) with a parallel board on each.

The nice thing about a dual channel charger, is that IF you don't feel comfortable charging split packs in parallel, then you can charge each 6S pack on a seperate channel simultaneously.

Ban the Ban.

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02-20-2014 06:01 AM  3 years agoPost 8
FireNWater

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Collierville, TN

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Not to hijack the thread but maybe someone has the answer. What are the rules about using different size packs on the same airframe in parrallel such as 1 4S 3300 and 14S 1000? and then with charging them in the same arangment.
.
I'm going to assume that an extra space got in between your 1 and 4 above and you're referring to two 14S packs, one of 3300 Mah cells, and the other with 1000 Mah cells. If you try to parallel charge packs of different cell counts (total voltage), your board will blow up.
.
You can parallel charge two packs of EQUAL CELL COUNT and DIFFERENT CAPACITY just fine. Ohm's Law will precisely divide the current between them based on their capacity. In other words, if you're parallel charging at 4.3 Amps, 3.3 Amps will go to the 3300 Mah pack, and 1.0 Amp will go to the 1000 Mah pack. Both packs will finish charging at exactly the same time.
.
As for worrying about one cell in parallel packs being "not connected". If you are using a high quality charger like a PowerLab 8, it will detect that cell being "not like the others" and drop to "Safety Charge" mode. When that happens, you take both packs off and plug them in individually to troubleshoot which pack has the bad cell (or connection).
.
Using your example above, during parallel charging, the charger sees 14 cells with a capacity of 4300 Mah. During charging, all 14 cells will accept the charge at the same rate and their voltages will climb towards 4.2V within milliVolts of each other with minor trimming ("bypass" on the PL8). So say if cell #8 on the 3300 pack somehow came disconnected, that cell will not charge at the same rate at the other 13 cells since the charge only "sees" 1000 Mah in the #8 slot. The charger will detect that anomaly since Cell #8's voltage will rise above the other 13 cells and drop the whole operation into "Safety Charge" mode.
.
Your pack is not going to blow up or anything since at all times the max voltage of a cell during charging is limited to 4.2V, and the charger will detect the bad cell WAY before 4.2V, probably somewhere around 50% charge.
.
I find that most people who fear parallel charging either have never done it, or have a very poor understanding of the underlying physics of the process. I regularly charge 8 large packs in parallel at 40 amps and have never seen any of the "problems" some guys claim plague parallel charging.
.

Buy Cheap, Buy Twice . . .

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02-20-2014 11:33 AM  3 years agoPost 9
Jerry K

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Houston Area

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I am sorry for the mistake but even with it you answered my question. the example was 1x 4S 3300 and 1x 4S 1000.

Thanks

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02-20-2014 11:50 AM  3 years agoPost 10
Ace Dude

rrProfessor

USA

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As for worrying about one cell in parallel packs being "not connected". If you are using a high quality charger like a PowerLab 8, it will detect that cell being "not like the others" and drop to "Safety Charge" mode. When that happens, you take both packs off and plug them in individually to troubleshoot which pack has the bad cell (or connection).
That's not completely fool poof. The charger only has the ability to measure each individual cell voltage, it does not have the ability to ensure each cell in each pack in parallel is connected.

  

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02-20-2014 03:55 PM  3 years agoPost 11
Flyrc67

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IL

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Some very good insight into the parallel charging process in all of these responses. Thanks very much for taking the time to respond.

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