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Old Jan 17, 2010, 06:42 PM
Major Electron Addiction
USA, NC, Wilmington
Joined Aug 2006
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I am currently using an Ioata DLS 90 with a 2000 watt Honda generator. This allows me to to run three Cellpro 10s chargers simultaneously while charging three 6s 5000mah packs. I have observed all three 10S chargers pulling 24 amps each from the power supply and charging the packs @ 10 to 11 amps.

I have the jumper installed in the Iota power supply which enables it to provide 14 volts under load.

What kind of increase in charge rate could I reasonably expect with this new charger, given the above info?

I am not interested in moving to a 24 volt power supply. If I could see a significant increase in charge rate, then I will start making upgrade plans.

As always, my thanks to the beta testers for their assistance with the forum members, and to FMA for their continued efforts to meet the needs of our hobby.
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Old Jan 17, 2010, 07:11 PM
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USA, GA, Marietta
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rodsmith123,

If my math is correct you are putting about 250 watts into each of the three packs. That's about 750 watts total.

At 14 volts input the PL8 will put out about 500 watts. So you could only charge two of your packs with a single PL8 charger.

If you are talking about multiple PL8's then you could double the the charge rate on those packs.

Glen
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Old Jan 17, 2010, 07:13 PM
CPII HD & PL8 beta tester
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Aubrey, Texas
Joined May 2009
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Quote:
Originally Posted by rodsmith123 View Post
I am currently using an Ioata DLS 90 with a 2000 watt Honda generator. This allows me to to run three Cellpro 10s chargers simultaneously while charging three 6s 5000mah packs. I have observed all three 10S chargers pulling 24 amps each from the power supply and charging the packs @ 10 to 11 amps.

I have the jumper installed in the Iota power supply which enables it to provide 14 volts under load.

What kind of increase in charge rate could I reasonably expect with this new charger, given the above info?

I am not interested in moving to a 24 volt power supply. If I could see a significant increase in charge rate, then I will start making upgrade plans.

As always, my thanks to the beta testers for their assistance with the forum members, and to FMA for their continued efforts to meet the needs of our hobby.

Supply Voltage = 14
Supply Current = 70A
PowerLab Input Current = 50A (max limit)
No. Cells = 6
Full Charged Cell Voltage = 4.2
PowerLab Efficiency (Worse Case) = 85%
Answer: PowerLab Max Output Current = 23.6A

Jack
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Old Jan 17, 2010, 07:17 PM
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Quote:
Originally Posted by ggcrandall1 View Post
Parallel charging on the PowerLab 8 is safe as you must parallel the balance taps as well as the main charge leads. Therefore there will never be a single cell that can be over charged. The other beta testers and I have seen this in practice.

However I am not here to convince you about parallel charging. If you do not think it is safe then by all means don't.

As to FMA giving a guarantee that it is a safe procedure I expect they don't. But then I don't expect that any other manufacturer does either.

Glen
What about undercharging of cells thereby causing accelerated pack aging ?

The Powerlab looks like a nice single channel / single pack charger for a very limited audience. I do applaud FMA for continuing to advance there product line, but it would be nice to see them focus some of there effort on the mainstream user verses the niche user.

Safety is a concern with all types of charging whether you would like to believe so or not. The images displaying multiple batteries being parallel charged does imply that it is safe to do with this charger...so YES it does appear that you are trying to convince somebody of its efficacy.

It would be nice to hear the official FMA position on this subject.

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Old Jan 17, 2010, 07:47 PM
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Seattle
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Quote:
Originally Posted by ggcrandall1 View Post
Well there is the option to parallel chargers. So it's possible to split a 12s into two 6s packs (probably already are) and charge them together.

Also parallel charging should not be a concern. The beta team has been doing this regularly with this charger and others.

Glen
As Charles would say, see my post on this a couple pages back.
http://www.rcgroups.com/forums/showp...2&postcount=87

Questions in my post on this topic have not been addressed.
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Old Jan 17, 2010, 07:50 PM
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Quote:
Originally Posted by Ultraviolet View Post
What about undercharging of cells thereby causing accelerated pack aging ?

The Powerlab looks like a nice single channel / single pack charger for a very limited audience. I do applaud FMA for continuing to advance there product line, but it would be nice to see them focus some of there effort on the mainstream user verses the niche user.

Safety is a concern with all types of charging whether you would like to believe so or not. The images displaying multiple batteries being parallel charged does imply that it is safe to do with this charger...so YES it does appear that you are trying to convince somebody of its efficacy.

It would be nice to hear the official FMA position on this subject.

Hi:

I can totally appreciate your concerns about the safety of parallel charging. Fact is, there are a lot of things that can go wrong. We will not deny this. In fact, for developmental purposes, we have established a table which spells out all of the potential safety hazards associated with parallel charging. That is exactly why we are in development on a companion product to the PowerLab 8 which we mentioned up front in the first post. For lack of a better name, at this time we're calling this the "Smart Parallel Adapter", or SPA. For a fraction of the cost of a second PL8 charger, the SPA promises to address most if not all of the inherint safety issues of parallel charging. The beta team is fully aware of the SPA, but they have not yet gotten them in their hands. Beta testers are fully aware of certain risks associated with testing. It is their choice to accept these risks during the course of testing to take full advantage of the available power of the new unit. However, SAFETY is a fundamental concern for FMA in all of our charging solutions and will not be over-looked. In due time, the beta team will be able to demonstrate the SPA in action. In essence, packs of same cell count (2s-6s) and same capacity may be connected to the SPA. When connections are final, the user presses a button. The device tests the 2 packs to make sure safe conditions exist. Then it energizes a series of switches to interconnect the packs in parallel. This is done before the charger is started.

So, you asked for the official FMA position on this subject and this is it. Parallel charging via the SPA is intended to effectively double the capacity of the PowerLab 8 in terms of how many cells/packs it can charge and it will ensure the safety of parallel charging. FYI, our main thrust for this device is to be able to support the many aircraft configurations utilizing 2 packs from 2s-6s wired in series during operation. In addition, we plan to make a version of the SPA that is also backward compatible with the existing Cellpro 10s charger.

Sincerely,


Tim Marks
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Old Jan 17, 2010, 08:36 PM
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Delton,Mi
Joined Jun 2009
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Quote:
Originally Posted by SteveM732 View Post
I wish the Multi4 had come with a discharge too. Though in my case I'd have taken a paltry 100mA just so I could get packs down to storage voltage.

If you look at the progress that FMA has made from the 4S to the 10S, and from the 10S to the Multi4, and now from the Multi4 to the PL8 then I think it is safe to say that whatever they have up their sleeves next will be even better. They've only ever added features and not taken any away that I am aware of. Maybe some day they'll revisit the 4 cell market and make something you can use.
Maybe some day they will out with the Powerlab 4
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Old Jan 17, 2010, 08:53 PM
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Tim, Thanks for the response. Just so you know, all my chargers are Cellpro's.
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Old Jan 17, 2010, 09:17 PM
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Melbourne, Australia
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Quote:
Originally Posted by Ultraviolet
What about undercharging of cells thereby causing accelerated pack aging ?
Can you explain what you mean here ? Can you explain the mechanism by which parallel charging leads to undercharging of cells ? And given that charging LiPo cells to below 4.20V can greatly extend their cycle life, in what way does the problem you describe accelerate pack aging ?
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Old Jan 17, 2010, 09:43 PM
Southern Pride
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Haralson County GA. USA
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Oh good yet another evils of parallel charging debate. Yes there are potential problems just like there are with series charging and even charging single cells for that matter.

Some such as this post here

http://www.rcgroups.com/forums/showp...2&postcount=87

are convinced that if all the cells are not at the same voltage that the higher voltage ones will charge the lower voltage ones way to fast. Sorry but this has been proven to be untrue over and over and over again.

Some are concerned that if a cell in parallel with others fails it will damage the others. This is a real possibility but packs(cells) being charged in parallel and then used in series do not spend that much of their life connected in parallel. In the past (years ago) having a 11.1V 3000 mAh pack it was common for this to be 9 cells each 1,000 configured as a 3S3P, there were no large capacity cell available. These cell lived like this and yes sometimes a cell failed and took other cells with it as in pulled their voltage down. This was in fact no worse than having a single cell in a 3S 3000 mAh battery fail as they continue to do to this very day.

Those who are super concerned could always use a cell checker to check cell voltage of each battery before connecting them in parallel. You can also connect only one of the to be paralleled batteries to the balancing leads(port) check those cells voltages ,swap to the other battery and do the same then if you are happy reconnect the first one and press go.

IMO no matter how you look at it it is far safer to charge 2 ,4. or even 6 same cell count Lipolys in parallel then it is to charge them in series.

I once read a post on another User's group that stated that every LiPoly he had ever charged in parallel failed very soon.

That may very well be entirely true but I feel that there were other issues. I have charged LiPolys in parallel for well over 5 years. I use to charge 3S 1320 5 at a time in parallel all of the time back when myself and son flew mostly flat plate Foamies.


Charles
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Last edited by everydayflyer; Jan 17, 2010 at 09:48 PM.
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Old Jan 17, 2010, 11:48 PM
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Seattle
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Quote:
Originally Posted by everydayflyer View Post
Some such as this post here

http://www.rcgroups.com/forums/showp...2&postcount=87

are convinced that if all the cells are not at the same voltage that the higher voltage ones will charge the lower voltage ones way to fast.
Please do not paraphrase my comments. If you need clarifcation just ask. The actual text was:

With the current process for parallel charging, that single low cell would be charged in an uncontrolled manner by the other pack.

What I'm describing here is not that the weak cell is "charged to fast" as you put it. But its being charged in an uncontrolled (and unmonitored) way. There is no charging circuit with safety protocols in between the power source and the low cell. There is no automatic voltage checking of the cell to detect a failing condition. If the pack were to be plugged into a Cellpro 10s or 4s (not parallel), the safetly protocols would alert the operater and stop the charge. No such protection exists when the bad cell is directly connected to a power source with a higher voltage.

Since when did it become safe to connect a lipo directly to an unregulated, unmonitored power source?

Quote:
Originally Posted by everydayflyer View Post
Those who are super concerned could always use a cell checker to check cell voltage of each battery before connecting them in parallel. You can also connect only one of the to be paralleled batteries to the balancing leads(port) check those cells voltages ,swap to the other battery and do the same then if you are happy reconnect the first one and press go.
This is overcomplicating a simple process and adding the potential for human error. Today, with my current Cellpro products, these extra safety steps are not required. They are taken care of by the charger.

Quote:
Originally Posted by everydayflyer View Post
IMO no matter how you look at it it is far safer to charge 2 ,4. or even 6 same cell count Lipolys in parallel then it is to charge them in series.
Perhaps if you are using a popular non-FMA product that allows the user to incorrectly connect node wires and charge leads, frying your node wires, and adapter boards. Then yes, perhaps series is less safe for owners of those chargers. Thankfully the safety features in the Cellpro 10s prevent this simple and common mistake. Thanks Tim!
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Old Jan 17, 2010, 11:51 PM
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United States, IL, Schaumburg
Joined Dec 2007
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Thanks Jack and Glen. It sounds like starting a charge sequence on the PL 8 will be a little more involved than the 10s.

Considering the advanced features it will have however, I would expect it.

Thanks again.


Dave


Quote:
Originally Posted by Jack Doherty View Post
My Cellpro 10s always starts charging showing a screen that says:

"CHARGING Press
MODE for Info."

If it's not already, it would be great if the PL 8 would start the charge showing the main charging screen automatically. Just a little annoyance to have to hit MODE every time.


Dave

The PL8 can start a charge two ways.
1. If "Hold ENTER for Fast Start" is not checked the following screens appear

Set Charge Rate?
>x.xxA

Set Discharge Rate?
>x.xxA

(CLIP)

Hope this helps
Jack Doherty
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Old Jan 18, 2010, 01:11 AM
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Quote:
Originally Posted by Gregor99 View Post
What I'm describing here is not that the weak cell is "charged to fast" as you put it. But its being charged in an uncontrolled (and unmonitored) way. There is no charging circuit with safety protocols in between the power source and the low cell. There is no automatic voltage checking of the cell to detect a failing condition. If the pack were to be plugged into a Cellpro 10s or 4s (not parallel), the safetly protocols would alert the operater and stop the charge. No such protection exists when the bad cell is directly connected to a power source with a higher voltage.
How is this any different than a single pack that has cells wired in parallel to increase capacity?
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Old Jan 18, 2010, 02:36 AM
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Seattle
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Quote:
Originally Posted by kcobra View Post
How is this any different than a single pack that has cells wired in parallel to increase capacity?
I don't run my packs in parallel and hope I never have to. At least with LiPos. But as to your question, packs wired in parallel in a model are done so after they are safely charged, and balanced. When the packs leave the charger, the operator knows the state of all cells, which includes voltage matching.

When you pull packs off a model, there's no way to know the voltage of each cell without first taking voltage readings. I know some will say that's trivial. But its one more manual step that is not required with the current Cellpro chargers. But even then, a simple voltage test is not as thorough as the safety mechanisms employed in the Cellpro chargers. I could be wrong, but I believe those safety mechanisms will not work properly when you have multiple cells on the same node channel.
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Old Jan 18, 2010, 04:32 AM
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Haralson County GA. USA
Joined Oct 2004
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My parallel charging experience.

Take a cell charged to 3.7 volts and one charged to 3.9 volts connect them in parallel and nothing bad will happen.

Some LiPolys are constucted with cells in parallel that are hard wired in parallel then perhaps you should do some research.

3S2p 4000 means a nonimal 11.1V 4000 mAh capacity battery which is constructed from 6 cells each one being 3.7V nonimal and 2,000 mAh capacity.

There is not a single cell in the battery which does not have another cell in parallel with it 24/7.


Charging in parallel debate is not really a PL8 question . issue IMO. Like Tim stated if you are uncomfortable with charging in parallel then by all means do not do so.

I have always stated it is your money spend it as you please,they are your LiPolys treat them as you please.

I have charged LiPolys in parallel for five years and shall continue to do so as do hundreds of others.

Up in the Batteries nand Chargers Forum there is a Thread decicated to parallel charging and it is a very active thread with many supporters.


Charles
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