PL 8 - Q and A section - How to Set up - Use etc,

[Burgerman]

Not until theres some proper windows software. Without that it all but useless to me. I already know theres a few tighter voltage limits and timers etc that we cant change that will trip us up. So even then, doubtful. Its been further safety nazi'd.

[Scooterman]

A Quickie to help clear up some doubt...

Balance current limit value (100-1000mA). Is this the balance current limit PER CELL?

So when charging with say an 8S pack and we set...

CC 20A
CV 3.6V
BV 3.5V
BC 1000mA

When one cell takes off and hits 3.5V, current between 0mA - 1000mA flows out of the cell, down it's balance wire into the PL8 where it is recombined with the CC (to maintain a CC of 20A).

Then the 20A CC flows back through all 8 cells again. This also happens (or not) to the other 7 cells depending on their voltage.

The CCS shows the bypass current as a percentage.

Is the percentage value, the % of the bypass current value? So if CCS is showing cell 3 bypassing 77%. This means 777mA is flowing out of the cell, down it's balance wire, and back into the PL8.

[Scooterman]

LIPOs?

looking at the PL8 user presets, the termination current varies around C/10 and C/20. The latter value for storage.

Whereas we use a starting TC value of C/500 for LIFE.

So why do we terminate lipos at a higher current?

PS: BM I ordered a cheap 2200mAh 3S lipo to play with.

[shirley_hkg]

We usually set Balance Start V at 3.5, so balance starts here and till the end .

Charge is still going with full throttle .

When voltage keep rising and reaches Charge Voltage eg. 3.58V , PL8 will keep no cell beyond this by manipulating the charge current . It leaves the CC stage and enters CV stage now .

Absorption period may vary . It depends .
CV timeout or Terminal current will end the charge , whichever comes first .

[Scooterman]

Thank you Shirley that's really helpful. Especially you explaining at what point the switch from CC to CV occurs. I never thought of that.

'learing all the time'

[shirley_hkg]

LIPOs?

looking at the PL8 user presets, the termination current varies around C/10 and C/20. The latter value for storage.

Whereas we use a starting TC value of C/500 for LIFE.

So why do we terminate lipos at a higher current?

PS: BM I ordered a cheap 2200mAh 3S lipo to play with.

Chemistry of Lipo is much more vigorous with very low internal resistance . Charge reaches every part of the cell very easily , so long absorption period is not necessary .

[Scooterman]

Got it, thank you

[Scooterman]

Initially at least, I'm planning to recharge my lifepo4 cells based on mileage.

I was going to calculate typical Ah consumption per mile. Then use that value to know when to recharge.

BUT the PL8 measures voltage to 3 decimal places. And although the discharge voltage curve of lithium is very flat, it still falls gradually. If you plug in the PL8 and press monitor, can the cell voltages give you a reasonably accurate way of telling how discharged the cells are?

[Scooterman]

Charge is still going with full throttle .

When voltage keep rising and reaches Charge Voltage eg. 3.58V , PL8 will keep no cell beyond this by manipulating the charge current . It leaves the CC stage and enters CV stage now

IF instead of using the PL8 you used a simple 3.6V 20A DC power supply and no BMS.

Would the cells be pushed to a higher voltage than the charger output voltage i.e. higher than 3.6V.

Could the voltage of the cells rise to 3.7, 3.8, 3.9, 4.0, 4.1 volts etc, until the first cells fails and causes a short or open circuits?

If so, is it due to the cell chemistry that cell voltage can go higher than the CV without throttling back the CC?

[Scooterman]

I guess a BMS is okay for small cells because the resistor can dump enough current/power without need to switch off the CC from the whole pack?

Or do BMS's always switch off the CC when one or more of the dump resistors kick in?

'Just trying to learn....'

[Scooterman]

And balanced cells only become unbalanced due to discharge, either discharge in use, and/or self-discharge.

How well balanced cells remain in balance during discharge is down to quality/age of cells. When they get near the bottom they all have slightly different states of charge. Then when CC is applied they all rises together (unbalanced) until we start balancing them at 3.5V for lifepo4.

Right I think I've got it.

(Sorry sometimes me putting my thoughts into words helps me understnad).

[Burgerman]

>>>IF instead of using the PL8 you used a simple 3.6V 20A DC power supply and no BMS.

You mean a 28.80V supply? (3.6 x 8?) as 3.6V will do nothing at all. The battery voltage is already about 25v. Because you have no access to each individual cell.

>>>Would the cells be pushed to a higher voltage than the charger output voltage i.e. higher than 3.6V.

So you would charge at 28.80V and IF ALL CELLS ARE EXACLY BALANCED then all cells will reach 3.6V at exactly the same time. But thats never happened yet!

>>>Could the voltage of the cells rise to 3.7, 3.8, 3.9, 4.0, 4.1 volts etc, until the first cells fails and causes a short or open circuits?

Yes. It does that to 3.8V even with the BMS working! And it hurts the cells. Its because TOTAL voltage at CV is 3.6V x 8cells. Thats 28.80V.
So if 4 cells are just 0.1V low, then the rest have to be at 3.70V. Reality is that they will all be at different more extreme voltages.

>>>If so, is it due to the cell chemistry that cell voltage can go higher than the CV without throttling back the CC?

Yes. In order to stop the fullest cell, from exceeding the choosen safe 3.600V the PL8 Balance charger or BMS tries to "pull down" the volts with a small current. But the charger overwhelms it as its much more powerful. So it has to be throttled back to remain below 3.6V for the highest cell before 28.8V CV is achieved.

[Scooterman]

Oh I see thankyou. Yes and I should have said 28.8v charger output and not 3.2v. I was muddling an individual cell with 8 cells.
But I do understand thank you

(3.7 x 4) + (3.5 x 4) = 28.8

[terry2]

Got my PL8 hooked up to my PC and the firmware is up to date.
I made a XLR to PL8 lead.

I loaded the PL8 software and then went to File\Import Fuel table to pre-set 1
I picked BMs Lead GEL MK XLR PLUG SAFE W Chr.PS8 it loaded.

If I press start on the PL8 the buzzer goes wild. What do I do?

Told you all I never had a clue

EDIT=So I have to tell it what power supply I am using...

[Burgerman]

1st of all you need the laptop connected. Dont look at or press anything on the charger... You can, later, but no need.

Load the XLR preset in position 1.
UPLOAD to the charger. Button says UPDATE.
Then check all the supply, firmware, options tabs and be sure correct settings and options choosen.

Then go to cells tab.
Be sure it says ready at the top.
CHOOSE the correct XLR profile from that drop down box.
Press the charge button on screen.

It should charge now. If not, and any errors will be shown. For eg no battery, or reverse polarity means you wired it wrong.

[shirley_hkg]

Look for error message on PL8's display .

[terry2]

1st of all you need the laptop connected. Dont look at or press anything on the charger... You can, later, but no need.

Load the XLR preset in position 1.
UPLOAD to the charger. Button says UPDATE.
Then check all the supply, firmware, options tabs and be sure correct settings and options choosen.

Then go to cells tab.
Be sure it says ready at the top.
CHOOSE the correct XLR profile from that drop down box.
Press the charge button on screen.

It should charge now. If not, and any errors will be shown. For eg no battery, or reverse polarity means you wired it wrong.

I went to File\Open preset to 1
I got no update?
I can see in the preset tab at the top "Gel MK XLR PLUG SAFE"

I went to the cells tab and no drop down menu. But it does say "No Data from PowerLab 8" at the top
And in the firmware tab Halfway down it says "Installed PowerLab 8 Firmware is unknown"
But on the PL8 supply window it says V3.3. Do I need to factory reset the PL8?

Now looking at the PL8 software it says at the top "No Data from PowerLab 8"

It's on the right Com port 3 and it says in green Com 3 open.

[Scooterman]

Chemistry of Lipo is much more vigorous with very low internal resistance . Charge reaches every part of the cell very easily

Ah that’s why lipos have a higher c-rate

[steves1977uk]

I went to File\Open preset to 1
I got no update?
I can see in the preset tab at the top "Gel MK XLR PLUG SAFE"

I went to the cells tab and no drop down menu. But it does say "No Data from PowerLab 8" at the top
And in the firmware tab Halfway down it says "Installed PowerLab 8 Firmware is unknown"
But on the PL8 supply window it says V3.3. Do I need to factory reset the PL8?

Now looking at the PL8 software it says at the top "No Data from PowerLab 8"

It's on the right Com port 3 and it says in green Com 3 open.

The PL8 has to be switched on while you're using the CCS software to operate/update it. Also is the FUIM3 connected properly?

Steve

[terry2]

The PL8 has to be switched on while you're using the CCS software to operate/update it. Also is the FUIM3 connected properly?

Steve

Thanks.

It's on and the software says at the bottom left Comm Auto..And in Green writing just to the right it says COM3 OPEN.

Windows 7 say Com 3 is a serial port. I have tried USB 2\3 ports. So it knows it's there.

[terry2]

I went to File\Open preset to 1
I got no update?
I can see in the preset tab at the top "Gel MK XLR PLUG SAFE"

I went to the cells tab and no drop down menu. But it does say "No Data from PowerLab 8" at the top
And in the firmware tab Halfway down it says "Installed PowerLab 8 Firmware is unknown"
But on the PL8 supply window it says V3.3. Do I need to factory reset the PL8?

Now looking at the PL8 software it says at the top "No Data from PowerLab 8"

It's on the right Com port 3 and it says in green Com 3 open.

The PL8 has to be switched on while you're using the CCS software to operate/update it. Also is the FUIM3 connected properly?

Steve

You was right
I had the 3 pin FUIM3the wrong way round
Now it says at the top "waiting to start"
Thanks for the help.

[steves1977uk]

There should be a red LED lit on the FUIM3 board when the PL8 is connected, do you see it?

Edit: You've solved it!

Steve

[Scooterman]

You was right
I had the 3 pin FUIM3the wrong way round
Now it says at the top "waiting to start"
Thanks for the help.

I did that when i first connected it. The stupid plug is reversible and the fum13 socket +/- markings on the PL8 are so small

Chemistry of Lipo is much more vigorous with very low internal resistance . Charge reaches every part of the cell very easily , so long absorption period is not necessary .

Ah, that's why lipos have a much higher C-Rate

[Gnomatic]

I had the 3 pin FUIM3the wrong way round

That got me too when I first started using a PL8.

[Burgerman]

If you are brave, BlueTooth... No wires, works about 30 feet away in the next room. So you can just plug it in, and wait till you go to bed with your laptop to charge and monitor it remotely. They should be made that way its just easier! Only got 1 done so far as i am stuck on bed. Been charging all my chairs, and hobby stuff on the bench, kitchen, and even the mower in the garage. While in bed. Just get my carer to connect the power supply/pl8 to the wall, and plug in the anderson or the lithium charge connector.

Theres 2 of us now. Snaker isnt brave. He has his connected externally so a bunch of wires. Sooner or later he will fit it inside and be done! Theres a thread here somewhere. Found it viewtopic.php?f=2&t=8496

[Scooterman]

LIPO
Hi, I got a cheap lipo 2200mah 3S to play with. It is much better than the 600mah lifepo4 cells I bought.

This is the graph from using the PL8 generic lipo faster charge preset.

Lipo 2200mAh 3S Generic Faster Charge -1 Cycle.zip

(92.34 KiB) Downloaded 179 times

Two things I noticed...

1) CHARGING: The cells almost stayed entirely balanced during charge with out the need to bypass any current. In fact I only saw a low percentage bypass flick on and off very occasionally. Is that because as Shirley mentioned, lipo absorbs the charge current so greedily that the cell voltage doesn't rise at the same rate as it rises for higher resistance lifepo4 chemistry?

2) DISCHARGING: I expected the discharge voltage curve to remain flatter? Although some graphs I see on the web appear to be flatter than others. Is that due to the discharge rate being 2amps I.E. almost C/1? If I reduced the discharge rate I guess I'd get a flatter DV curve?

LEAD
I have a pair of 28mAh sonnenshein gels that I want to connect in series on the bench and cycle to test their usable capacity down to about 50% DOD?
I will be using 4mm pvc flex as the charging cable.

BM - I am going to use on of your lead gel series presets. And I was going to set CC to C/3, and DC also to C/3 which will make both about 9amps is that okay?

And how low should I go voltage wise? I was going to set DV to 1.8 volts. Or should I go down to 1.65 volts?

[shirley_hkg]

You can adjust the current any time , via buttons on PL8, without stopping the process .

[Scooterman]

You can adjust the current any time , via buttons on PL8, without stopping the process .

I didn't know that thank you

[Burgerman]

Lipo and lithium ion is not like Life, it doesent have a flat discharge curve. So is easy to charge, and fuel works, etc. One thing. Dont take below 3.5V or it will soon die. Lipos dont like low voltages. They are low resistance too. So charge to 4.200V and they stay there. No long CV needed. And they will exploe or burn if ypou charge higher than that so be careful, dont charge them unattended.

[Scooterman]

Lipo and lithium ion is not like Life, it doesent have a flat discharge curve. So is easy to charge, and fuel works, etc. One thing. Dont take below 3.5V or it will soon die. Lipos dont like low voltages. They are low resistance too. So charge to 4.200V and they stay there. No long CV needed. And they will exploe or burn if ypou charge higher than that so be careful, dont charge them unattended.

By re-looking at the graph I see what you mean. There's no point letting the cell voltage fall off the cliff lower than about 3.65V looking at the graph, you don't gain anything and as you say it only shortens life of battery. I won't let that happen again