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Old Jan 28, 2012, 04:45 PM
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If you don't like to read, this post ain't for you.

Hi everyone,

so now it happened, I joined the club of PowerLab 8 owners after researching the web for way too long, looking for a decent, balancing LiPo charger. This forum not being the least of reasons. After reading dozens of pages I felt pretty hyped and almost desperately wanted one of these chargers. It sounded just too cool to let it go by.

Now that I've had it for a few weeks and done at least a couple of charging cycles - not having done more with the weather to blame - the rose-colored glasses are starting to wear off and I find myself wanting to know more about a few... peculiarities of the charger and software.

Before I start to get into details I want to say I read the manual cover to cover, skimming over only a few sections like the expansion mode which does not apply to me, and lots of pages in this and other threads. Yet I am aware that there is a great chance some of what I am going to address will have been asked before. Please bare with me, this forum is far too vast to not miss things.

1) When I start a charge in PB or NiMH mode, the charger will sit there for 40 seconds looking pretty, but seemingly not doing much of anything. In LiPo mode it's 20 seconds before the current gates are opened. Not only does my old charger start every chemistry right away. But I'm especially baffled by this because from the advertisement I got the impression that the PL series is doing everything it can to cut down on charge times. Yet it's seemingly wasting precious time before it even gets going.

2) This is something that I really can't put my head around and really annoys me. When the charge actually gets going, looking at the reported "current", it seems like the PL is taking about a minute to ramp up the current from zero to hero. At first I thought it's just cautious. But the reported "pack capacity" leads me to believe the current goes from naught to full right away, with the reported current being some uber-long average. And this I do not get. I want to see what my charger is doing, when it is doing it. Knowing (to the best of my deductive skills) that the reported numbers do not necessarily reflect reality unnerves me. Quite a bit.

3) Voltage detection of the charging circuit has me worried. For example when I disconnect a battery during monitoring, I can watch the reported voltage drop extremely slowly over the course of several minutes, with the charger apparently not even noticing that the battery is gone. Also after switching the PL on I can reliably enter LiPo monitoring, with some voltage being reported. Only a while after power on the PL will refuse to start monitoring, because no pack is connected. After reading about the surge protection circuitry, I could somewhat explain this behaviour to myself. However when I disconnected a NiMH pack during trickle charge (that was an accident actually, I thought the charge had ended. My old charger did not (and could not) trickle charge) the PL did not realize this, but instead started to increase the voltage in what I guess was an attempt to get the charging current back to where it should have been. Only after 6 minutes it finally got the hint that the battery was gone. Now I know that there is probably not much of an issue here, if the PL only goes wrong when no battery is present, since logically it cannot harm the battery if it is not there. However I am somewhat uneasy about this as I have the niggling thought it might get the voltage detection wrong eventually when a pack is connected, too. My old charger would recognize a disconnected pack the moment I pulled the plug, so that was my expectation for the PL, too, just to explain where I am coming from.

4) When a charge is in CC mode, the current fluctuates. I had set a 700mA charge with the current moving between 690mA and 710mA. Is this normal? I thought it would be possible to maintain the current in a much narrower window.

5) What is the purpose of "Conv. Frequency"? Besides not really getting much from the help text, I found only one preset where changing it would not result in an error. Maybe it should be removed altogether?

6) Charging a 12V AGM battery I noticed that the charger and CSS showed different values for mA and mAh, with the CSS consistently being about 10 mA higher than the charger.

7) With the default screens configured for the LiPo presets, when I switch from the screen with "CHEM----NAME----" (3rd) to "CHEM +0.00A 0000" (10th), on that screen the first row will be correct for a moment, but then start alternating between showing the correct values and the 2nd screen of the preset name. This does not happen when I switch away from the 3rd screen into the other direction (to the 4th) or get to the 10th screen from the 9th.

8) Can I charge LiIon batteries? Since it's also CC/CV I reckon I can use a LiPo preset and change the "Charge Voltage". Is that okay?

9) Is the serial port specification available somehow? I'm interested in accessing the live charging data, to write my own tools.

10) I want to support the request for a preset that allows setting a voltage with a maximum current limit. This would upgrade the PL to a regulated power supply with potential usage scenarios way beyond running in electrical engines.

11) When I set a preset to do 1 cycle and end with a charge, it goes Charge->Discharge->Charge, whereas I expected Discharge->Charge. Can I set it up that way somehow?

12) The interpolation for the graph drawing manages to miss interesting values and thus changing the look of a graph completely as time goes on. This phenomenon was mentioned in post 3518, too, and I attached a few images as well. You can see how the peak (which is strange in itself) appears and disappears. In the XML export I can see it is really there and I think it's significant enough to be in the graph all the time, too.

13) I have sent memory dumps of problems (in my book) and never heard back. Should I? I kinda expected to hear if the issue could be confirmed or not.

14) Is it possible to limit the charge by mAh?

15) The balance % shown is a percentage of what? 1A, charge current, min(1A, charge current) or something else?

16) It would be nice to see why a charge ended, i.e. fallback or timeout. Or if that is possible already without checking on the graph how much time passed between switching to CV and ending the charge, how?

17) I used internal discharge a few times, not producing a significant amount of power. After a while the fans enganged, blowing mildly warm air out. So far, so good. But they never switched back off until the discharge completed much later. It would be nice if they disengaged again once the temperature dropped enough.

18) It would be nice if modes that do not support balanced charging, like NiMH and Pb, did not ask about using banana jacks. Not much of a point in answering No.

19) During NiMH charge the the "Int. Res." tab shows 2 cells. Not a biggy, as it does not show values. But I would have expected a message along the lines of "Not available for this preset".

20) It would be really nice to see individual cell capacity. That way a weak cell would become obvious very quickly. Also it would be nice to get a graph of the balancing % per cell. Right now I can at best guesstimate from the cell voltage graph how much balancing happened, but it is more like reading tea leaves.

21) Using the "Generic Accurate Charge" preset, the PL showed "CHARGING 3S Set 1.5A 4.208V". 4.208V? Charge voltage was set to 4.200V, why the difference?

22) I enabled the display of cell voltage with three digits of precision. During the charge I noticed however that the third digit, representing mV, did not change in single increments, but only several mV at a time. About 6 I think. Is that normal? I thought voltage measurement was accurate to 78ÁV.

Now, if you get the impression that I dislike the PL, that is not the case. I am trying to understand why it does what it does and provide feedback to help make it better.

There, all done for now. I know it is long, but a serious charger deserves serious amounts of text.

Btw, the list is numbered simply for ease of reference in follow up posts, not to imply an order of importance.

Regards.
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Old Jan 28, 2012, 06:28 PM
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Wow, nice handle and lots of good questions. Let me take the low hanging fruit.

EDIT: Added answers for #2 #8 #9 and #17

1) When I start a charge in PB or NiMH mode, the charger will sit there for 40 seconds looking pretty, but seemingly not doing much of anything. But I'm especially baffled by this because from the advertisement I got the impression that the PL series is doing everything it can to cut down on charge times.

This is normal. The charger is working on matching the input and output voltages accurately and safely. I would not say the he major focus of the charger is speed. It is certainly a byproduct of the highest wattage charger on the market. But it terms of priorities, safety first, accruracy second then speed. In fact, there are some tuning options to make the PL8 operate even faster without compromsing safety, but with a slight reduction in accuracy.

2) This is something that I really can't put my head around and really annoys me. When the charge actually gets going, looking at the reported "current", it seems like the PL is taking about a minute to ramp up the current from zero to hero. At first I thought it's just cautious. But the reported "pack capacity" leads me to believe the current goes from naught to full right away, with the reported current being some uber-long average. And this I do not get. I want to see what my charger is doing, when it is doing it. Knowing (to the best of my deductive skills) that the reported numbers do not necessarily reflect reality unnerves me. Quite a bit.

Like the answer for #1 the charger is matching the input and output. Where are you seeing "Pack Capacity"? I'm not following the comment about the uber-long average. Please expand.

4) When a charge is in CC mode, the current fluctuates. I had set a 700mA charge with the current moving between 690mA and 710mA. Is this normal? I thought it would be possible to maintain the current in a much narrower window.

That sounds normal to me.

5) What is the purpose of "Conv. Frequency"? Besides not really getting much from the help text, I found only one preset where changing it would not result in an error. Maybe it should be removed altogether?

This adjust the frequency used by the DC-to-DC converter. The lower frequencies are more accurate for low current charging of small cells. The higher frequencies are more efficient for high loads used with the high power charging presets.

8) Can I charge LiIon batteries? Since it's also CC/CV I reckon I can use a LiPo preset and change the "Charge Voltage". Is that okay?

http://www.rcgroups.com/forums/showp...postcount=3179

Quote:
Originally Posted by everydayflyer View Post
LiIon made in the past 5 years or so charge to 4.2 per cell same as LiPolys and same Presets can be used. If it is marked as 3.6 Volts instead of 3.7 then you can use Preset #4 LiPoly Long Life which cjharges to 4.1 per cell or you can modify any of the LiPoly Prsets to charge to only 4.1 V per cell.

Most LiIon cells can not be charged greater than 1C and some need to be charged even lower. Best to do some web searching for the manufacture's specifications.
9) Is the serial port specification available somehow? I'm interested in accessing the live charging data, to write my own tools.

Take a look at this thread. http://www.rcgroups.com/forums/showthread.php?t=1335386

11) When I set a preset to do 1 cycle and end with a charge, it goes Charge->Discharge->Charge, whereas I expected Discharge->Charge. Can I set it up that way somehow?

You can set this in the CCS. Its in the presets, under the "discharge" tab, seventh item down.

14) Is it possible to limit the charge by mAh?
Not currently. More than this setting, I would like to see a discharge by mah.

15) The balance % shown is a percentage of what? 1A, charge current, min(1A, charge current) or something else?

Percentage of current being bypassed by the balancing circuit. Up to 1amp (99)

16) It would be nice to see why a charge ended, i.e. fallback or timeout. Or if that is possible already without checking on the graph how much time passed between switching to CV and ending the charge, how?

Not a common request. But using the PC software will show this.

17) I used internal discharge a few times, not producing a significant amount of power. After a while the fans enganged, blowing mildly warm air out. So far, so good. But they never switched back off until the discharge completed much later. It would be nice if they disengaged again once the temperature dropped enough.

The heat sink is internal and it is difficult to tell from the outside of the case how hot it is inside. Discharging is a hot operation and a little fan overrun is probably a good thing.

18) It would be nice if modes that do not support balanced charging, like NiMH and Pb, did not ask about using banana jacks. Not much of a point in answering No.

I would also like to see the question about bananas be enabled/disabled for each preset. That would address this as well.

20) It would be really nice to see individual cell capacity. That way a weak cell would become obvious very quickly. Also it would be nice to get a graph of the balancing % per cell. Right now I can at best guesstimate from the cell voltage graph how much balancing happened, but it is more like reading tea leaves.

Older versions (Cellpro10s) had a graph of balance bypass. I liked this and miss it. For cell degradation you can use the IR which is reported per cell. Also during a high current discharge with an external load, you can see the indvidual voltages dropping more quickly for the weaker cells.
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Old Jan 29, 2012, 06:19 AM
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At the moment I am using a L702b charger http://bit.ly/xj0uD5 as I thought this was the most feature rich charger around at the time. After reading about the PowerLab 8 I am very tempted. Can the PL feed Logview. I use Logview on the L702b as the graphs produced are very detailed and seem far more detailed and flexible than the PL graph function in the supplied software. I did notice that you can export data from a saved graph for import into another application such as a spreadsheet. What is the data interval thats recorded and can it be varied.
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Old Jan 29, 2012, 01:04 PM
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Can the PL feed Logview. I use Logview on the L702b as the graphs produced are very detailed and seem far more detailed and flexible than the PL graph function in the supplied software. I did notice that you can export data from a saved graph for import into another application such as a spreadsheet. What is the data interval thats recorded and can it be varied.
The logging intervals are configurable as follows:

1, 10 (default), 60, 120 seconds

The builtin graphs cover most scenarios. But occassionally there is some data I'd like to look at in a different way. For that, I export to txt which produces a tab delimited file. Then import into Excel. I've attached sample so you can see what the output looks like as well as test an import to Logview.

Also note that the Powerlab software can export to West Mountain radio format. You can use thier free graphing tools to view the charge data and do things like overlays.

Just out of curiosity, what graphs would you like to see that are not included in the CCS?
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Old Jan 29, 2012, 02:00 PM
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The logging intervals are configurable as follows:

1, 10 (default), 60, 120 seconds

The builtin graphs cover most scenarios. But occassionally there is some data I'd like to look at in a different way. For that, I export to txt which produces a tab delimited file. Then import into Excel. I've attached sample so you can see what the output looks like as well as test an import to Logview.

Also note that the Powerlab software can export to West Mountain radio format. You can use thier free graphing tools to view the charge data and do things like overlays.

Just out of curiosity, what graphs would you like to see that are not included in the CCS?
Thank's Gregor, I will have a look at the sample and see if it will load into Logview.

The graphs are quite comprehensive in the Powerlab software but I have got used to using Logview which, apart from a lot of German language, is very configurable. But apart from that I like the large screen graph whereas as far as I can gather the graphs on PL are in a small window loosing a lot of detail. Its not easy to check exactly what they look like on my machine till I buy the charger. But I do like how the software looks in general.
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Old Jan 29, 2012, 02:41 PM
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EC5 connector sets

Where are the EC5 connector sets found on the store?

Do you mean the International or USA store?

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Originally Posted by Tim Marks View Post
Hi:

I guess you're referring to the MPA? We have made EC5 connector sets available on the store. I'm just letting you know, if you wait for a model with a specific connector like PowerPole, you may wait indefinitely.

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Old Jan 29, 2012, 02:47 PM
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The graph window is re-sizable in the PL8 software (but the control window is not). The graph view also displays data point values at the cursor which is handy if you want to get a precise value without going to the data file itself.
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But apart from that I like the large screen graph whereas as far as I can gather the graphs on PL are in a small window loosing a lot of detail. Its not easy to check exactly what they look like on my machine till I buy the charger. But I do like how the software looks in general.
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Old Jan 29, 2012, 02:53 PM
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The graph window is re-sizable in the PL8 software (but the control window is not). The graph view also displays data point values at the cursor which is handy if you want to get a precise value without going to the data file itself.
Ahh thats brilliant. I didn't know that. I have downloaded the software but there is so much I cannot do like view the graph window until I actually get a charger to connect up. And the software tour on ProgressiveRC's website doesn't seem to work.
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Old Jan 29, 2012, 03:15 PM
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I have downloaded the software but there is so much I cannot do like view the graph window until I actually get a charger to connect up.
I've attached a sample charge log so you can see what the graphing looks like on your machine. In the CCS, select "File\Open Graph" path to the unzipped file. Use the "View" menu to select the different reports from the graph.

Also a feature I use alot is to view the logs "live" during the charge.
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Old Jan 29, 2012, 03:20 PM
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Originally Posted by Trill View Post
Where are the EC5 connector sets found on the store?

Do you mean the International or USA store?
Hi:

On REVO USA Store:

http://www.usastore.revolectrix.com/...EC5-Connectors

On REVO Intl Store:

http://www.store.revolectrix.com/Pro...5-Connectors_2

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Old Jan 29, 2012, 03:22 PM
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Ahh thats brilliant. I didn't know that. I have downloaded the software but there is so much I cannot do like view the graph window until I actually get a charger to connect up. And the software tour on ProgressiveRC's website doesn't seem to work.
Hi:

Thanks! I'll let David know. In the mean time, the CCS Tour is working fine on www.revolectrix.com

Go here:

http://www.revolectrix.com/CCS_Tour.htm


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Old Jan 29, 2012, 03:28 PM
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Thanks for your prompt reply!

Do the PL8s inbound to the USA store have the latest firmware updates? When can we expect our orders from the USA store to be shipped?

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Old Jan 29, 2012, 07:12 PM
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Originally Posted by Gregor99 View Post
Wow, nice handle and lots of good questions. Let me take the low hanging fruit.
Thanks, Gregor, I appreciate you taking the time to help me out.

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Originally Posted by Gregor99 View Post
1) When I start a charge in PB or NiMH mode, the charger will sit there for 40 seconds looking pretty, but seemingly not doing much of anything.

This is normal. The charger is working on matching the input and output voltages accurately and safely.
40 seconds to match voltages? I am not sure I am buying that. In LiPo mode it takes "only" 20 seconds (still very long, if you ask me), so it does seem to be possible faster. I admit that comparing LiPo and NiMH chemistries is a bit like apples and oranges, but still I would like to hear a more technical description of what happens during the that time. At the rates I am currently charging, those 40 seconds do not really make any difference. But for those at the cutting edge of what charge current packs allow, 40 seconds saved must seem like an eternity. No?

Quote:
Originally Posted by Gregor99 View Post
2) This is something that I really can't put my head around and really annoys me. When the charge actually gets going, looking at the reported "current", it seems like the PL is taking about a minute to ramp up the current from zero to hero. At first I thought it's just cautious. But the reported "pack capacity" leads me to believe the current goes from naught to full right away, with the reported current being some uber-long average. And this I do not get. I want to see what my charger is doing, when it is doing it. Knowing (to the best of my deductive skills) that the reported numbers do not necessarily reflect reality unnerves me. Quite a bit.

Like the answer for #1 the charger is matching the input and output. Where are you seeing "Pack Capacity"? I'm not following the comment about the uber-long average. Please expand.
Okay, sure. I am not always good at putting my thoughts into words, sorry for that. So, when a charge is on its way, there are, at least, three figures that give an insight into what is happening with the pack: Charge current, charge put into the pack (capacity IN) and supply current. And during that first minute, those values do not fit together. While the reported charge current ramps up quite slowly, the "Capacity IN" rate of change (delta mAh per second, if you want) is near constant. But if the current was really ramping up over time, the "Capacity IN" would have to grow faster accordingly. The supply current would also have to rise at about the same rate as the charge current, but instead makes one big jump. "Pack Capacity" is what I saw in the graph, just another name for the "Capacity IN". By uber-long average I meant that a mathematical mean over the charge currents of the last minute could explain the reported current, but in my opinion that is less than ideal.

Quote:
Originally Posted by Gregor99 View Post
4) When a charge is in CC mode, the current fluctuates. I had set a 700mA charge with the current moving between 690mA and 710mA. Is this normal? I thought it would be possible to maintain the current in a much narrower window.

That sounds normal to me.
Maybe it is. I was just used to the graphs of my old charger, where the current chart was perfectly flat during CC mode. But I am open to believe that it does not show the true current, but the value that it is trying to charge with. I am lacking the equipment to validate this myself.

Quote:
Originally Posted by Gregor99 View Post
5) What is the purpose of "Conv. Frequency"? Besides not really getting much from the help text, I found only one preset where changing it would not result in an error. Maybe it should be removed altogether?

This adjust the frequency used by the DC-to-DC converter. The lower frequencies are more accurate for low current charging of small cells. The higher frequencies are more efficient for high loads used with the high power charging presets.
Maybe I need to read up more on DC/DC converter technology, but this does not really tell me much. When is a charge low current and when is it high? But that aside, it is not possible to change the preset value anyway, because the CCS will show an error. So IMHO the setting makes little to no sense. Okay, it tells me with which frequency the charger works, but why do I care? I cannot change it anyway.

Quote:
Originally Posted by Gregor99 View Post
8) Can I charge LiIon batteries? Since it's also CC/CV I reckon I can use a LiPo preset and change the "Charge Voltage". Is that okay?

http://www.rcgroups.com/forums/showp...postcount=3179
Just what I wanted to hear, great!

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Originally Posted by Gregor99 View Post
9) Is the serial port specification available somehow? I'm interested in accessing the live charging data, to write my own tools.

Take a look at this thread. http://www.rcgroups.com/forums/showthread.php?t=1335386
Very cool project. I am especially intrigued that there was a chance to get support from the developers. I wonder what became of that.

Quote:
Originally Posted by Gregor99 View Post
11) When I set a preset to do 1 cycle and end with a charge, it goes Charge->Discharge->Charge, whereas I expected Discharge->Charge. Can I set it up that way somehow?

You can set this in the CCS. Its in the presets, under the "discharge" tab, seventh item down.
I had tried that and it does allow me to change between Charge->Discharge and Charge->Discharge->Charge. But I did not find a way to set Discharge->Charge.

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Originally Posted by Gregor99 View Post
14) Is it possible to limit the charge by mAh?
Not currently. More than this setting, I would like to see a discharge by mah.
What is your use case to discharge by mAh? For charge I would set it as another safety net to prevent over charging. Ie for a 2000mAh pack I might configure 2400mAh so in case everything else failed this will end the charge.

Quote:
Originally Posted by Gregor99 View Post
15) The balance % shown is a percentage of what? 1A, charge current, min(1A, charge current) or something else?

Percentage of current being bypassed by the balancing circuit. Up to 1amp (99)
Percentage of current, yes, but of which? Say I am charging with 500mA and balancing shows 50%, is it effectively balancing with 250mA (50% of 500) or 500mA (50% of 1A)?

Quote:
Originally Posted by Gregor99 View Post
16) It would be nice to see why a charge ended, i.e. fallback or timeout. Or if that is possible already without checking on the graph how much time passed between switching to CV and ending the charge, how?

Not a common request. But using the PC software will show this.
It does? Where? So far I had always checked the graph. If there is an easier way that I am overlooking, please tell.

Quote:
Originally Posted by Gregor99 View Post
17) I used internal discharge a few times, not producing a significant amount of power. After a while the fans enganged, blowing mildly warm air out. So far, so good. But they never switched back off until the discharge completed much later. It would be nice if they disengaged again once the temperature dropped enough.

The heat sink is internal and it is difficult to tell from the outside of the case how hot it is inside. Discharging is a hot operation and a little fan overrun is probably a good thing.
I agree that fan overrun is preferable to melting the charger. But if the discharge gets away without using the fan during the first five minutes, I think it does not need to run for the remaining fifteen. I mean the seems to be a temperature sensor built in, so why just trust it to engage the fans and not also to disengage them.

Quote:
Originally Posted by Gregor99 View Post
20) It would be really nice to see individual cell capacity. That way a weak cell would become obvious very quickly. Also it would be nice to get a graph of the balancing % per cell. Right now I can at best guesstimate from the cell voltage graph how much balancing happened, but it is more like reading tea leaves.

Older versions (Cellpro10s) had a graph of balance bypass. I liked this and miss it. For cell degradation you can use the IR which is reported per cell. Also during a high current discharge with an external load, you can see the indvidual voltages dropping more quickly for the weaker cells.
Cell degradation was just an example of what the number could be used for. But since you brought it up already, using the IR to determine cell health to me seems a bit like slamming a door shut to get an echo by which you can guess the size of the room. Another example why seeing cell capacity would be useful is when you have a model with, say, a 6S flight pack, where you connect additional equipment (eg. your night flight illumination) to some cells via the balancing lead. But even if there is no sensible reason, I like numbers.

Cheers
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Old Jan 29, 2012, 07:52 PM
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whew.got some novelists up in here.
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Old Jan 29, 2012, 08:39 PM
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Quote:
20) It would be really nice to see individual cell capacity. That way a weak cell would become obvious very quickly. Also it would be nice to get a graph of the balancing % per cell. Right now I can at best guesstimate from the cell voltage graph how much balancing happened, but it is more like reading tea leaves.
PL8 is not an 8 channel charger it is a single channel charger capable of charging up to 8 LiPoly cells in series. I fear the cost to build a 8 channel 40A per channel charger would price it way out of reach of most hobbiest.

Remember PL8 charges the cells in series and maintains balance by bleeding(discharging the higher vltage cells) so the others can catch up.

It is easy to spot the deminshed capacity cells as they are the ones being bleed / being balanced / charge pulled from them.

IMO, running lights , video cameras and such from part of the cells is never a good idea. Use a voltage regulator connected to full battery output voltage to supply aux. loads.or use a seperate battery for them.

If you really need / want to see indivual cell capacity then do a CCS discharge with cell voltages and you will have them. Well not exactly but relative capacity anyway.

Charles
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Last edited by everydayflyer; Jan 29, 2012 at 08:44 PM.
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