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

[expresso]

yes pictures please - looking forward to this one

[shirley_hkg]

Because 16x 90Ah cells leaves a gap... And room for 8 smaller cells as well.

Nothing can hide from you ! ! !

i have a hard time figuring how 16 90ah cells fit - i love to see some pictures when done - i have an empty battery tray that 2 MK 24 sit in perfect - from the 646 chair - but i dont think i can even fit 90ah cells in there at 36mm x 173mm size - i look forward to seeing how it fits - maybe i am missing something here -

My chair is US version INVACARE ARROW .
You definitely has run with it.

[expresso]

yes i seen the chairs here also - i look forward to see how creative you will be - that would be an amazing feat -

[Scooterman]

BM - You might be interested in this it, relates to what you were saying (above). The guy did some bench testing and I found the article interesting.

https://www.powerstream.com/lithium-pho ... oltage.htm

This is the page the above links from https://www.powerstream.com/LLLF.htm

[Burgerman]

Third, there isn't much difference in capacity when charged at 3.4V or 4.2 volts. Maybe 3% maximum. So surprisingly you can charge one of these cells at 3.4V and get almost the same capacity as charging at the recommended 3.65V.

Well 3.45V. But yes quite true.
The reason that the manufacturers say 3.65V is more to do with getting a full charge where the charger is a crap BMS and / or god knows what supplying the power. So they dont know how long it will sit at this voltage. If its 30 secs you get more of a charge at 3.65v. If its longer you get some small amount of self balancing to help the useless BMS. They get less back in the short term. And the cells age fast... But they dont care about that. So 3.550better. But it needs a longer CV or they dont get full.

[shirley_hkg]

And PL8 starts balancing @3.5V better, doesn't it ?.

[Scooterman]

Shirley what settings did you use for bench testing your cells in 8S?

I was thinking of these figures for 1 cycle...

Charge: 3.6V 18A
Balance: 3.5V
Terminate: C/500 so 180mA
Discharge: 3.0V 9A

But if you or BM suggest different I'll go with you guys, I'm still learning afterall

NB: I chose 18A and 9A as they divide nice as C/5 and C/10

PS: For testing I only have thin cables which would only cope up to 30A max.

[Burgerman]

Sounds about right.

[Burgerman]

If you charge at 3.500V CV (or less), you must set the balance to balance only at CV.
Thats means JUST set balance entire charge? to OFF.

[Scooterman]

Sounds about right.

for the reassurance

If you charge at 3.500V CV (or less), you must set the balance to balance only at CV.
Thats means JUST set balance entire charge? to OFF.

I remember you saying this when I was playing around in ignorance with the nasty little lifepo4s .

[shirley_hkg]

First charge is gonna be VERY unbalanced .
Set charge volt @3.50V, or fuller cells would be kept at high volt for prolonged period, waiting the weak ones to catch up.

Prepare to balance a cell or two , if they were way behind .

[Scooterman]

First charge is gonna be VERY unbalanced .
Set charge volt @3.50V, or fuller cells would be kept at high volt for prolonged period, waiting the weak ones to catch up.

Prepare to balance a cell or two , if they were way behind .

Oh, okay Shirley thanks. And from what BM said earlier, I’ll set balance to off.

[Scooterman]

PS have you any idea how long to cycle an 8S pack?

I suppose I could do the maths but don’t know what SOC the cells are at the moment, although the LF90 spec sheet might say?

[Scooterman]

BM - When we charge at say 3.6v and balance at 3.5v, do we start balance at 3.5v to reduce the overall charge time?

Or is it because if we to balance at CV 3.6v we’re a bit too near the cells top range?

But we can charge/balance at 3.5v CV because we’ve got a safety margin?

Just trying to learn....

[shirley_hkg]

Prepare to balance a cell or two MANUALLY , if they were way behind .

Oh, okay Shirley thanks. And from what BM said earlier, I’ll set balance to off.

No !

You have it balanced @3.50V first . Then increase it to 3.6V , termination current 50mA, till they are full .

Now you can discharge to 3.0V

They came with 30% SOC .

[Scooterman]

Ooh okay Shirley thanks for correcting me, it could have been a disaster

I post some screenshots of the parameters before switching on. But it won’t be until later today or tomorrow morning as I need to re-stock up on grub and

[Burgerman]

Oh, okay Shirley thanks. And from what BM said earlier, I’ll set balance to off.

Thats not what I said...

[Scooterman]

Oh, okay Shirley thanks. And from what BM said earlier, I’ll set balance to off.

Thats not what I said...

No, you didn't did you...
Just keeping you on your toes

I just checked the CCS and have set 'balance entire charge' to NO. The dialogue boxes are great on the CCS cos it says BEC to NO means cells only balance at CV and do not balance at CC. Setting BEC to ON shortens overall charge time. But I'm just testing cells at the moment.

BM - Here's your lifepo4 presets I tweaked

LF90s 90Ah 8 SERIES.zip

(871 Bytes) Downloaded 189 times

Learning all the time.

[Scooterman]

I just re-read Shirley's post, and will reduce TC to 50mA when I charge them tomorrow. It's set at 180mA in the preset I attached

[Scooterman]

Prepare to balance a cell or two MANUALLY , if they were way behind .

What do mean by this Shirley? How can I manually balance a cell or two if they're well behind the others?

[Scooterman]

General PL8 question about using the PL8 without the CCS.

When it faults out it says PRESS RESET

But how do you reset it manually? Holding down either the ENTER or BACK buttons doesn't reset it. The only way I've found of resetting it is disconnecting it from the PS.

[Burgerman]

No idea I use the laptop...

Read the manual.

[Scooterman]

No idea I use the laptop...

Read the manual.

That's fair enough. I have read the manual several times (I printed off a copy). But it doesn't say. It doesn't matter, I was just a in case there was something obvious I was missing.

're the manual in general, there's lots of drawings and diagrams about how to connect cells and packs, but not much text. I wish there was more detail about charger options and the CCS, etc. Although the CCS software has some good pop up explanations.

[shirley_hkg]

Prepare to balance a cell or two MANUALLY , if they were way behind .

What do mean by this Shirley? How can I manually balance a cell or two if they're well behind the others?

We don't want keeping cells at high volt for too long, while waiting the empty cell catching up. Sometimes, we have to stop charging in series, but to charge the un-full cells one by one. Just in case.

BM works the other way round. He lines up all cells in ONE BIG CELL. Then charges them till 3.6V in one go first, and re-arrange them in 8S .

The cells I got differ in 1Ah or 2 in most , so yours will all reach 3.5V in an hour or 2 . Don't panic .

[shirley_hkg]

PL8 is fun .

I'm balancing some newly bought 25h cells ; below 3.5v.
Charge volt set at 3.475V .

Will bring it up at 3.6V afterwards.

[Scooterman]

Thank you Shirley I really appreciate that

I'm really looking forward to giving them their first charge this morning, I've got all the temporary links made, I just gotta fit them. Can't wait

I wanted to do it yesterday but I had the washing (laundry) and food shopping to do #drudgery But that's all done now

Although for the food shop I did use my cycle trailer I adapted to fit my scooter, it's brill

[Burgerman]

New hobby. Playing with the PL8. Once you learn it, and use it 99% of the time from a PC, its a bit addictive. The only time I ever use mine without laptop is at the flying feild if my laptop battery is dead...

I'm really looking forward to giving them their first charge this morning, I've got all the temporary links made, I just gotta fit them. Can't wait

[Scooterman]

PL8 is fun .

I'm balancing some newly bought 25h cells ; below 3.5v.
Charge volt set at 3.475V .

Will bring it up at 3.6V afterwards.

The graphing software is brill!

I used to PL8 to recharge my leads for the first time yesterday. I wanted to try and work out the Ah per mile for the scooter. t came to about 2.5Ah per mile with a trailer full of food shopping on the return trip.

[Burgerman]

It will be a little better than you thought. Because with lead you put back a fair bit more than you used.

They waste power towards the end of charge. As the voltage aproaches AROUND 13v, they gas internally (split water to oxy/hydrogen = takes energy) and they then recombine it (wastes a bit more energy)... So the less Ah you use, the more gets wasted on recharge. And it can be a fair bit. Like 25% on a top up.

With lithium its about 3 to 5% over a full charge wasted as heat/resistance alone.

[shirley_hkg]

PL8 is fun .

I'm balancing some newly bought 25h cells ; below 3.5v.
Charge volt set at 3.475V .

Will bring it up at 3.6V afterwards.

Then, they all reach 3.6V in seconds .