PowerLab 8 V2 - Cell voltage monitoring issue - RC Groups
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Dec 25, 2016, 09:37 PM
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PowerLab 8 V2 - Cell voltage monitoring issue


Hello,

I bought a powerlab 8 v2 with MPA parallel board 3 months ago and have been using it without any issue since then. Yesterday, I was checking my 6S lipos using Fluke 115 multimeter for cell voltages and started charging them to put them in storage (charging single pack at a time). During charging, I started to monitor each cell voltage and noticed all cell voltages were identical. I stopped the charging and check the cell voltages again using the multimeter and they were certainly not at equal voltage. When I tried the pack using my hyperion charger, it showed the different cell voltages during charging.
Now, I am questioning if the powerlab charger is detecting the cell voltages correctly. I do not feel safe using the charger anymore.
Have anyone seen something like this?
Any comments and suggestions would be appreciated.

Thank you.

Heon
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Dec 30, 2016, 04:30 AM
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ggcrandall1's Avatar
Quote:
Originally Posted by haha0606
Hello,

I bought a powerlab 8 v2 with MPA parallel board 3 months ago and have been using it without any issue since then. Yesterday, I was checking my 6S lipos using Fluke 115 multimeter for cell voltages and started charging them to put them in storage (charging single pack at a time). During charging, I started to monitor each cell voltage and noticed all cell voltages were identical. I stopped the charging and check the cell voltages again using the multimeter and they were certainly not at equal voltage.

If you were charging in balance mode they would show identical on the charger. But when you stopped the charge the cells could have drifted a bit. You need to report the exact cell voltages.


When I tried the pack using my hyperion charger, it showed the different cell voltages during charging.

Was the Hyperion in balance mode?

Now, I am questioning if the powerlab charger is detecting the cell voltages correctly. I do not feel safe using the charger anymore.
Have anyone seen something like this?
Any comments and suggestions would be appreciated.

Thank you.

Heon
When you post questions like this you must report all the data. Real numbers, charger settings, etc. Also you say putting your batteries in storage, were the batteries charging or discharging?

Glen
Jan 01, 2017, 05:30 PM
Registered User
also, a lot of chargers do not balance when storage charging
Jan 01, 2017, 07:28 PM
Registered User
Quote:
Originally Posted by haha0606
Hello,

I bought a powerlab 8 v2 with MPA parallel board 3 months ago and have been using it without any issue since then. Yesterday, I was checking my 6S lipos using Fluke 115 multimeter for cell voltages and started charging them to put them in storage (charging single pack at a time). During charging, I started to monitor each cell voltage and noticed all cell voltages were identical. I stopped the charging and check the cell voltages again using the multimeter and they were certainly not at equal voltage. When I tried the pack using my hyperion charger, it showed the different cell voltages during charging.
Now, I am questioning if the powerlab charger is detecting the cell voltages correctly. I do not feel safe using the charger anymore.
Have anyone seen something like this?
Any comments and suggestions would be appreciated.

Thank you.

Heon
The big question is - how far off are the cell voltage readings ? ... less than 10mv is insignificant, morw than 50mv would mean it probably needs to be recalibrated.
Also note that the readings will be averaged over time, so the displayed values will always be slightly different from any instantaneuos readings you may take.
Jan 01, 2017, 10:44 PM
Registered User
Try charging your batteries without the MPA and see if they balance.
The polyfuses on "safe" boards can partially trip and throw off the reading of cells.
Discussed here:
https://www.rcgroups.com/forums/show...serious/page10
Jan 02, 2017, 07:00 AM
Registered User
What he is noticing is what I found years ago. That the charger always shows the cell voltages as the same, regardless of actual cell voltage unless they are miles out. And if they change on the charger 'all' cells change at the same time. Its not real, its averaged, feel good, looks neat, but its not a reflection of reality.

And yes I know there's 4 voltage levels... The one at the charger end while charging, and the one taken in the breaks (while still charging), and the one at the battery end while charging (and during the rapid breaks). You need high frequency meter with peak reading, or trend capture, say a fluke 289 as I use or similar to monitor all these at once, or a calibrated oscilloscope. Either way, the DISPLAYED cell voltage is more 'feel-good' so they all look the same than accurate. But its close enough.
Jan 11, 2017, 02:01 PM
Registered User
Quote:
Originally Posted by JohnWilliamson
What he is noticing is what I found years ago. That the charger always shows the cell voltages as the same, regardless of actual cell voltage unless they are miles out. And if they change on the charger 'all' cells change at the same time. Its not real, its averaged, feel good, looks neat, but its not a reflection of reality.
Just to add - I've had this confirmed by FMA/Revolectrix. Apparently they were getting complaints that the cell voltage values were changing too quickly ("flickering"), and so they added an averaging function when the cell voltages are within a set threshold of each other.
Jan 11, 2017, 08:57 PM
Registered User
one persons complaint is another persons feature