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Old Jan 02, 2009, 05:30 PM
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Quote:
Originally Posted by Atom1025
If you got a minute can you snap a pic of the bottom of the board Curious how you set it up. Thanks

Adam
Sorry Adam, but the rear of the stripboard is pretty boring and useless - as for safety and security I layered a coat of 2 part epoxy across the whole surface and then covered it in thin foam sheeting. Basically though, a few INSULATED wires are soldered across the relevant copper strips to form a common negative, and again, the relevant cell order pins are bridged across the strips too. Here is a schematic as well as pictures which I hope will make it clear.
The board is simple stripboard, available from Rapid / RS / etc ( in the UK anyway ) HTH.
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Old Jan 02, 2009, 05:35 PM
ProgressiveRC
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Wow, after over 90 days and 5,000+ views...what a strange turn this thread has taken based on the comments of a single user.

It seems to me in reviewing this discussion that in the face of overwhelming evidence that parallel charging is routinely performed (without incident) under a wide range of circumstances, there has been no physical, theoretical, or anecdotal evidence presented to support the claim that it is unsafe. Charge on. Rant off.

- David
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Old Jan 02, 2009, 05:37 PM
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Quote:
Originally Posted by write2dgray
Timbo,

My understanding is that the iCharger 1010B+ (pictured above) requires the main charge leads to be connected for any charge. Are you able to work around this in some way for lower rate charges to charge only through the balance coonection?

And yes, a pic of the bottom would be nice to understand how you traced that out . Very nice parallel board.

- David
Yes David, the 106 and 1010B do indeed charge through the main leads, and my posting was unclear - I apologize. What I meant was that it is only necessary to connect any 1 x battery to the main output, and then the others get "fed" via the common pack full potential pos and neg connections of the balancer plugs. Obviously, the balance leads connected to the individual cells are only really used for bleeding the excess voltage away from the high cells, and this is relatively low current. Hope this is clear.
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Old Jan 02, 2009, 05:40 PM
ProgressiveRC
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Seattle, WA
Joined Dec 2006
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Quote:
Originally Posted by badger-b
Sorry Adam, but the rear of the stripboard is pretty boring and useless - as for safety and security I layered a coat of 2 part epoxy across the whole surface and then covered it in thin foam sheeting. Basically though, a few INSULATED wires are soldered across the relevant copper strips to form a common negative, and again, the relevant cell order pins are bridged across the strips too. Here is a schematic as well as pictures which I hope will make it clear.
The board is simple stripboard, available from Rapid / RS / etc ( in the UK anyway ) HTH.
Great Tim, that makes sense. So, you bridged from the negative pin on the 4S over to the negative (right most) pin on the 2S, 3S, and 5S using short wires and similar for the remaining pins on the 2S, 3S, and 5S connections.
Quote:
Originally Posted by badger-b
Yes David, the 106 and 1010B do indeed charge through the main leads, and my posting was unclear - I apologize. What I meant was that it is only necessary to connect any 1 x battery to the main output, and then the others get "fed" via the common pack full potential pos and neg connections of the balancer plugs. Obviously, the balance leads connected to the individual cells are only really used for bleeding the excess voltage away from the high cells, and this is relatively low current. Hope this is clear.
Crystal. Thanks for taking the time to explain.
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Old Jan 02, 2009, 05:44 PM
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Yep, you got it,
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Old Jan 02, 2009, 07:01 PM
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Quote:
Originally Posted by write2dgray
It seems to me in reviewing this discussion that in the face of overwhelming evidence that parallel charging is routinely performed (without incident) under a wide range of circumstances, there has been no physical, theoretical, or anecdotal evidence presented to support the claim that it is unsafe.
The theoretical problem is quite obvious: when you connect two packs in parallel, only the internal impedance limits the rate at which one charges the other. Add onto that everything that could potentially go wrong with damaged or miswired packs.

You have only ANECDOTAL evidence that the resulting rate appeared safe in the circumstances where it was measured.

Since you are not the cell manufacturer, you are in absolutely no position to make guarantees that the mutual charge rate will always be safe, and it is the height of irresponsibility to be making recommendations for this technique with no sound basis to have confidence in its safety.

Based on the available information, the only morally justifiable recommendation is a recommendation not to do it
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Old Jan 02, 2009, 07:39 PM
Southern Pride
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Haralson County GA. USA
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Link I provide in post #128 just happens to be by a person who has designed many LiPoly chargers and balancers for names such as Orbit. I guess he is not qualified either.


Much of the parallel charging / discharging testing was conducted by Fred Marks of FMA Direct (non retired) and Charlie Wang (Mr. Thunder Power ) as well as engineers at Kokam but I guess they also lack the proper credentials.


Charles
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Old Jan 03, 2009, 02:40 PM
Proud to eat Kraut ;-)
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Hi!

I reported cstratton for obnoxious trolling, and moved him to my ignore list.

Please do not feed the trolls, and do the same.

Atom, Badger, thanks for your postings!

I'll put a link to them in my initial posting.

Cheers,

Julez
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Old Jan 03, 2009, 02:57 PM
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Quote:
Originally Posted by everydayflyer
Much of the parallel charging / discharging testing was conducted by Fred Marks of FMA Direct (non retired) and Charlie Wang (Mr. Thunder Power ) as well as engineers at Kokam but I guess they also lack the proper credentials.
Of those mentioned only Kokam (as a cell manufacturer) would be in a position to say anything definitive, and only for their cells. Have they published
anything in the way of application notes? There does not seem to be any real engineering-level content on their US website.

Remember also that user assembly adds a whole additional layer of risks - the problem is not only mismatch between parallel cells (which would be minimized if they've always been soldered together), but also the failure modes introduced by extra, user-assembled wiring. Again - assembling serial packs is perfectly possible, but AMA still prohibits due to the danger of getting it wrong.

What happens, for example, when someone momentarily looses focus and parallels a 2 cell pack with a 3??

Have you guys stopped to consider that you could be blamed if someone has an accident while following your recommendations? If you think about that for a minute, you will realize that you don't want to be on the record as arguing that it is safe.
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Old Jan 03, 2009, 03:29 PM
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Quote:
Originally Posted by Julez
Please do not feed the trolls, and do the same.
Duly noted. Ignore list activate.

Mark
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Old Jan 03, 2009, 05:52 PM
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He's on my ignore list too ! keep up the good work Julez and others
Incidentally, your "system" at the start of your thread, suggest that you only charge up to 2A if not connecting all main charge leads..... I have actually gone to 5A with no ill effects - the wires on the balance leads, and the stripboard copper strips seeming to cope perfectly well. Any comments ?
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Old Jan 04, 2009, 04:09 PM
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This might work well, but I see two potential problems:
First, due to the high resistance of the balance cabling, the pack with the main lead connected may see more than it's share of current initially.
Second, the charging process may take longer than usual, as the voltage drop of the balance cabling adds to the voltage level of the pack(s), making the charger prematurely reducing the charge current.

I charge via the balancing cables only if I have lots of time for overnight charges, like my 3 A123 packs charging at 500mA or so.
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Old Jan 04, 2009, 04:16 PM
Southern Pride
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Haralson County GA. USA
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I first saw this problem years ago with the Hyperion LBA 6 balancer. My solution was add heavy charging leads which cured the problem for single pack charging / balancing.

Back on topic
Sometimes a photo / drawing helps

http://www.rcgroups.com/forums/showp...6&postcount=64

Charles
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Old Jan 04, 2009, 11:26 PM
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Thanks guys! I was inspired to make a charging solution for my mCX and here it is.
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Old Jan 05, 2009, 12:45 PM
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Perfect!

Now let's hope noone asks how you balance your 1s packs
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