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Old Jun 01, 2006, 07:07 AM
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FMA CellPro Charger

Apparently will exceed 1C charge rate on any pack.

http://www.rcgroups.com/forums/showt...17#post5556040
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Old Jun 01, 2006, 08:14 AM
Southern Pride
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Well I read post 7 ,8 and 9 there and it sounds like FMA clearly states it charges automativly at 1C but if it is charging at 2C or 3C it is OK because we stated 1C just to keep usres from being to concerned and we (FMA) have trestred it charging cheap packs at high rates with no problems.

Kinda remindes me of another Thread on an automatic charger that also charges at greater than 1C .
It also most seems (reads) like that if you set the charge rate it must not be greater than 1C but if the super smaret charger sets the rate anywhere betwee 0.2C and 3C is just fine becuase the charger knows best.


From reading marketin hype it would seem that this is indeed the worlds greater LiPo charger.

Snip from

http://www.rcgroups.com/forums/showp...50&postcount=8

Quote:
Two packs of low cost cells, one 90 mAh and one 250 mAh were cycled at 10C charge and withstood that sufficiently well to give cycle life of 150 before capacity went below 80%

Charles
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Old Jun 01, 2006, 08:24 AM
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I never understood how the charger determines what amperage to charge with. Sounds to me like FMA may have opened up a real can of worms!! Brings back memories of the first "plug and play" computer thingies.

Doug
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Old Jun 01, 2006, 10:48 AM
BEC
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Or the much discussed Ripmax Quattro or Graupner LiPoly Charge 4, which also sets its current automatically and sometimes goes above 1C, especially with high discharge rate-capable batteries.

(Oh, upon closer reading of this thread I see Charles already pointed that out )
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Old Jun 01, 2006, 01:10 PM
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You got that right!

Quote:
Originally Posted by everydayflyer
this is indeed the worlds greater LiPo charger.


Charles
Charles: You got that right!

OVER 3O FEATURES OF CELLPRO 4S CHARGERS. Every feature validated by independent beta test.

1)Adjustable current from 0.25A to 3A in ľ amp increments. It can charge any size battery.
2)Auto Amp feature detects current of all sized packs. You can charge a 50mAh pack right after a 6400mAh pack without making any adjustments.
3)Can charge up to 24Ah packs in a single charge.
4)Low Voltage Restore repairs over discharged packs. Over discharge down to 0.5 volt per cell will be repaired to 98%.
5)Charges 1 to 4 cells individually just like a cell phone charger. That means it is impossible to start a fire.
6)Display is accurate to 10mV.
7)Cell Balance is accurate to 10mV. (That is 10/1000 of a volt!)
8)Shows Charge Amps and Amp Hours accurate to 1%.
9)Runs on 10 to 16 volt power supplies up to 5 amps.
10)Charges competitors batteries with the appropriate adapter. The will balance just like the Kokam cells.
11)Can charge thru the node connector without the Deans. This is convenient for top off charging in the aircraft.
12)Charge and control accuracy not degraded by charge lead length. Use up to six feet if you choose.
13)Can charge 1Ah and smaller packs at 3C for a 20 min to 95% charge. Full charge is 28 min!
14)Fuel gauge eliminates the guessing of battery capacity. It shows 0 to 100% and is accurate to 5%.
15)Fuel gauge instantly tells the state of the battery and allows quick 15 min fast charges in between flights.
16)All LiPos can be topped off without any danger of overcharge.
17)Can charge physically damaged packs without the danger of fire.
18)Cold weather charge mode protects batteries from over charge in the winter.
19)PC viewer software allows graphing of individual cell performance.
20)Can be directly tied with the West Mountain discharger for complete cell by cell analysis.
21)Input and output are reverse polarity protected.
22)Shows 21 different error codes to describe any problem.
23)Error codes can be reset with the press of a button.
24)Three screens show individual cell voltages, amps, amp hours, fuel gauge and charger operating mode.
25)Total plug and play without any user intervention.
26)Over temperature protection allows operation in any climate.
27)Charger runs at 90% efficiency, which means it generates very little heat.
28) The charger will handle continuous 3 amp current indefinitely up to 100 deg F ambient. Then there is a high temperature mode that drops the current down to 1.5 amps max. So, if someone tries to charge in the hot sun, the charger wonít be damaged from overheating.
29) The fuel gauge maintain 5% accuracy over the entire voltage range.
30) Charges one to four cells in series.
31) High performance microprocessor makes 14 safety checks per clock cycle even down to validating connector pin integrity.
32) Does all the above seamlessly and automatically. If you donít care and donít want to know, then all you need to know is that you can plug in a pack and leave the unit to do its job and never worry about fires, unbalanced cells, or swollen packs.
33) Nothing to "daisy-chain". All contained in one compact unit that you plug in the pack to and let it "do it's thing".
34) No "blinkin lights" that leave you wondering what is going on. Just read the LCD display and CellPro keeps you posted in plain alphanumeric. If your pack has a problem, it secures it and tells you what is up.
THIS CHARGER MAKES LI POs SAFER THAN THE MANY MILLIONS OF CELL PHONE & LAP TOP LI IONs IN THE FIELD.
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Old Jun 01, 2006, 01:19 PM
Southern Pride
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rest of the quote

Quote:
From reading marketin hype it would seem that this is indeed the worlds greater LiPo charger.
Never mind that is behaves contray to its Owner Manual and violates FMAs and other LiPoly vendors charge rate recomendations.

If Fred say it is so then who are we to question him?

I will stick with my Thunder Power chargers,Astro Flight 109 ,Tritons and Apachee s .They never charge faster than I tell them to.
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Old Jun 01, 2006, 01:23 PM
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I was gonna say that he kinda twisted your words around there charles...
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Old Jun 01, 2006, 01:26 PM
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Looks like Fred would make a good lawyer or politician!! Talk about taking out of context.

Doug
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Old Jun 01, 2006, 01:27 PM
Southern Pride
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Haralson County GA. USA
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Quote:
Originally Posted by pflumitch
I was gonna say that he kinda twisted your words around there charles...
Some say the Bible is the greatest book ever written. Ever notic how this world greatest book can be used to prove so many totally different points of view.

IMO snips of a post without a link back to the original are cheap shots.


Charles
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Old Jun 01, 2006, 01:43 PM
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Some talk about hype at this late stage in the game.

When their pet companies do the talking it is "instructive talk". When everybody else does it it is hype. Talk about the pot calling the kettle black.

BTW, I meant pot as in cooking utensil, not the other kind, the one that grows in fields and it is smoked by some.
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Old Jun 01, 2006, 02:16 PM
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If I may add a little different perspective...

I am not sure about Li-Poly, but Li-Ion cells are supposed to pass certain safety tests in order to qualify for international shipping. One of those tests is to charge at double the "recommended" rate, then let the cell rest and it should not show any signs of physical damage.

It could be that manufacturers are stating 1C charging because they are mindful of this testing. If they published a 3C charge rate they may have to show that the cell does not sustain any physical damage at 6C. From a manufacturers perspective, it is easier to stick with a 1C charge recommendation.

The performance effects of charging faster than 1C are still being worked out. I have not seen any graphs that indicate a performance loss at 20 cycles when fast charging is used with a pack.

I think the question we should be asking is "How do you fast charge a Li-Poly battery?"

Fred has indicated that they are using pulse charging. My Schulze charger uses pulse charging with Nickle chemistry, so I can relate to that. I recently set my Schulze on Auto charge with a 9S 1400 mAh NiCd pack. After a few minutes of analysis, I was surprised to see it charging away at 5 amps. The cells never got hot, and after a while it dropped the current down, but it did spend a fair amount of time at 5 amps. Consumer NiCd cells are also rated at 1C charging, but the Schulze analyzed the pack and decided to use around a 3.6C charge rate.

The Schulze charger determines the charge rate by measuring the internal resistance of the pack during the pulse charging. If it is possible to do the same thing with a Li-Poly pack, it would be possible to charge at a fast rate without heating (or damaging) the cells in the pack.

I have done the "bulk" charge on Li-Ion cells at up to 5C, but have noticed that with a constant current charging at 5C starts to heat the cells up. If you change to a pulse current, I think the whole game changes...

Another point to keep in mind is that the battery manufacturers are stating that the way to charge a pack is using a CC/CV charger and limiting the charge current to 1C. Once again I will point out that when you go to pulse charging, the criteria may change.

Tom
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Old Jun 01, 2006, 02:27 PM
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I posted similar observations on the Cell Pro auto charge current behavior here.
http://www.rcgroups.com/forums/showp...1&postcount=44

The limited data I've seen on charge rates > 1C seem to indicate that charge rates up to 3C result in a fairly minimal life cycle impact at least on packs in good condition. However I haven't seen nearly enough data to make me comfortable with it being the default "Auto" mode behavior and don't like the fact that the manual is misleading on this point. The Cell Pro also seems to clamp the cell voltage at about 4.23 V per cell and I'm not comfortable with it charging at over 1C to 4.23 V through the completion of the CC phase as I've seen it do.

I'd be a lot more comfortable with its behavior if it charged at >1C up to 4.10 V / cell and then started reducing the charge rate to no more than 1C at 4.20 V.

As I mentioned in my other post, it also apparently "fudges" the displayed cell voltages in an apparent attempt to show the voltage that would result if charging was terminated at that point rather than showing the actual cell voltage.

It seems to "work very hard" to ensure that packs come off the charger at 4.20 V. On a 3s1000 pack with the charge rate set to 1000 mA, I saw the charge rate drop to 6 mA just before it indicated charge completion. That's well below the 3-5% of charge rate I've seen advised for CV phase termination. I suspect most LiPo users want/expect their packs to come off a charger at 4.20 V /cell and FMA may have felt they had to meet that expectation. The four different balance chargers I've tried all seem to use a voltage clamp slightly over 4.20 V.

Personally I've seen enough data to convince me that final cell voltage is an important factor in cycle life and would prefer to tradeoff a little capacity for more cycles. Given that the Cell Pro has a "PC interface available" it would have been VERY nice if they used it to implement selectable "clamp voltage selection" (4.20 V or less) for advanced users.

I noticed that the Cell pro manual mentions a temperature sensor that reduces final cell voltage to 4.10 V at temps below 32 deg F. Since it's likely just a simple thermistor, I'm considering opening it up AT MY OWN RISK and voiding any warranty and wiring in a couple of switch selectable resistors to allow fooling it into using a 4.1 V clamp voltage and make me comfortable with charging above 1C. When it enters the CV phase, I can reduce the charge rate to 1C and allow it to pump in a bit more charge when desired.

I'd also be interested in any comments on this statement in the Cell Pro manual that hasn't seem to get much notice here.
"Tip: Because FMAís cell balancing technology monitors individual cells, you donít need
to cool a pack before charging it. Go from flying to charging to flying again without waiting.
FMA cell-balancing chargers are the only ones that can charge a pack immediately
after discharge without damaging the pack."

As I stated in my other post, I'm generally pleased with the Cell Pro and the Auto charge behavior is not a big deal to me personally as I don't mind setting the rate manually. The clamp voltage bugs me far more but it seems to be fairly common behavior in current offerings and it seems not to be any worse than many others and certainly not dangerously high.

Mike
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Old Jun 01, 2006, 02:44 PM
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Quote:
Originally Posted by SilverFoxCPF
If I may add a little different perspective...

I am not sure about Li-Poly, but Li-Ion cells are supposed to pass certain safety tests in order to qualify for international shipping. One of those tests is to charge at double the "recommended" rate, then let the cell rest and it should not show any signs of physical damage.

It could be that manufacturers are stating 1C charging because they are mindful of this testing. If they published a 3C charge rate they may have to show that the cell does not sustain any physical damage at 6C. From a manufacturers perspective, it is easier to stick with a 1C charge recommendation.

The performance effects of charging faster than 1C are still being worked out. I have not seen any graphs that indicate a performance loss at 20 cycles when fast charging is used with a pack.

I think the question we should be asking is "How do you fast charge a Li-Poly battery?"

Fred has indicated that they are using pulse charging. My Schulze charger uses pulse charging with Nickle chemistry, so I can relate to that. I recently set my Schulze on Auto charge with a 9S 1400 mAh NiCd pack. After a few minutes of analysis, I was surprised to see it charging away at 5 amps. The cells never got hot, and after a while it dropped the current down, but it did spend a fair amount of time at 5 amps. Consumer NiCd cells are also rated at 1C charging, but the Schulze analyzed the pack and decided to use around a 3.6C charge rate.

The Schulze charger determines the charge rate by measuring the internal resistance of the pack during the pulse charging. If it is possible to do the same thing with a Li-Poly pack, it would be possible to charge at a fast rate without heating (or damaging) the cells in the pack.

I have done the "bulk" charge on Li-Ion cells at up to 5C, but have noticed that with a constant current charging at 5C starts to heat the cells up. If you change to a pulse current, I think the whole game changes...

Another point to keep in mind is that the battery manufacturers are stating that the way to charge a pack is using a CC/CV charger and limiting the charge current to 1C. Once again I will point out that when you go to pulse charging, the criteria may change.

Tom
You have it right, Tom. As for the detractors, the most famous uttterance from the Bible may be paraphrased:

"Forgive them for they know not what they do (or say & write about)-------"

Never bought one, never tested it, have no idea what they are saying, but feel they have to attack as they feel a threat to their benefactor vendor.
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Old Jun 01, 2006, 03:07 PM
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I apologize as I can't find the reference, but wasn't one of the reasons for the 1C charge limit is because you are pushing voltage through multiple cells in a series? The reference stated that higher rates could be used if you were only charging one cell, rather than forcing a cell to "pass voltage" to the next cell in a series pack. Since this charger uses taps to charge, it would seem that the direct access of each cell permits raising the bar a little.

Just a thought...wish I could find that reference again, but I can't seem to find that magical groups of words for the search engine...

- Jim
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Old Jun 01, 2006, 03:15 PM
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Quote:
Originally Posted by X-Terminator
You have it right, Tom. As for the detractors, the most famous uttterance from the Bible may be paraphrased:

"Forgive them for they know not what they do (or say & write about)-------"

Never bought one, never tested it, have no idea what they are saying, but feel they have to attack as they feel a threat to their benefactor vendor.
Seems to go both ways with both detractors and supporters offering little factual basis for their comments. Thankfully those posts are easy to identify and ignore and they're are plently of folks here offering useful comments, observations, tests and references. Frankly I've been put off by seeing the Cell Pro feature list posted repetitively and Fred's "don't worry, trust us and no one else comments" but have tried hard to not have it affect my comments.

Given the current competition, I think the Cell Pro is a nice product and reasonably priced and have recommended it. That doesn't mean I think it's perfect or I like the Auto charge behavior. Then again, I'm probably not the typical main stream user it's aimed at.

Mike
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