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

[Gnomatic]

I picked up one of these, as using cheap helping hands like BM posted is an exercise in frustration.



100X better than cheap helping hands, but no magnifying glass. I don't see as well as I used to and need a solution.

My cells are all topped off now and will be in storage for 1-2 months. So I have time to practice soldering. My Hakko solder station is on the way along with a box of cheap Dsub connectors to practice on.

Going to meed a solution for a magnifying glass though ...

[Burgerman]

EBay, headband or glasses attachment with flip down 2 or 3 dioptre lenses. Don't forget you need a light as it makes things much, much easier!

[Burgerman]

And 6 packs of this to make a large ball of easy to shape tacky blutack !!!
Under 10 pounds delivered and lasts forever. http://www.ebay.co.uk/itm/201332604475

Eyes? https://www.amazon.co.uk/Carson-1-5x-Po ... +magnifier

DONT get the stronger ones if you already have a +dioptre prescription because it is too much! Otherwise other than looking a bit fragile these are completely invaluable!

Age... If you get the 4 dioptre ones, and you already use reading glasses, you can look for microbes... But need to be about 1 inch way.

[expresso]

thanks - i think the Blu Tack may work out best for me - i can keep it low on the table and stick the connector on it - - easy to move around - etc, - have to give that a try -

where i do my soldering is on my computer desk - which i have one of these http://www.fullspectrumsolutions.com/bl ... 18_ctg.htm

this thing lights up my whole bedroom - and gives very good light -

i also use another small lamp with mangnifier on it and a led light built in - goose neck etc, - sometimes that gets in my way if i have to lower it too low to the item - and always have to use those 3x or more reading glasses etc,

with those on - get very close and you see it all - very blurry unless you are inches from the connector -

the ones BM mentioned sound good and i seen them online - or in a magazine - you can adjust them and has a light on the sides of the frame i believe -


https://www.amazon.com/D-SUB-DB25-Femal ... +connector

used these to practice - it took a second order to finally get it right

[Burgerman]

Eyes? https://www.amazon.co.uk/Carson-1-5x-Po ... +magnifier

DONT get the stronger ones if you already have a +dioptre prescription because it is too much! Otherwise other than looking a bit fragile these are completely invaluable!

[Gnomatic]

Never needed glasses, vision used to be 20/20. But I'm in my 40's now. To read small text now I have to hold it far away. At the very least I could use some reading glasses. Haven't had an eye exam in eons.

What about something like this?

https://smile.amazon.com/gp/product/B00 ... UTF8&psc=1

[Burgerman]

Looks very cheap. Hopefully you don't get what you pay for! In your case just some +2 to +3 dioptre reading glasses from cheap china may be best. Ebay.

[expresso]

i went to Rite Aid - or any pharmacy and just took a pair they had - wasnt any cheaper - but it works -

[shirley_hkg]

First run of PL8 .

[Burgerman]

I wouldnt worry about internal resistance reading because its so very hard to measure and you have long cables. But check for loose bolts etc.

[steves1977uk]

Isn't it odd that it's always Cell 8 that has the higher IR, the highest I've seen on mine is 2.5mohm and usually it sits around 1.3-1.8mohm. All the others are 0.7-0.9mohm.

My latest graphs...

Steve

[Burgerman]

It has to do with the way the length of the long power cables get added to the resistance of the last cell. If you were to use 6 inch long cables and charge hobby lipos, it works perfectly.

Shirley, the first couple of charges will show a lot of imbalance. The next few will show less and less until they show none. Set termination to 1000th of battery capacity for the first charge, so all cells are soaked at 3.6V for a long time. Then reduce to 320th. And set discharge to not balance... Because that will unbalance this chemistry. You can only balance LiFePO4 once over 3.5V unless you charge at a very low rate at which point you can use 3.5V balance start. But it causes problems at higher charge rates.

[shirley_hkg]

We always put more ampere in than we can spend in a trip . 9P@15Ah ,to swap out the G24. Not necessarily go after perfect balance .

Say , I SHOW only one preset and opted for for quick start , it still has to go through 4/5 screens till we can actually start charging .

Missed anything ?

[Burgerman]

Not tried it but you can change the displayed screen or remove them in the PC software. Screens tab. Show or hide each.

[Gnomatic]

And 6 packs of this to make a large ball of easy to shape tacky blutack !!!
Under 10 pounds delivered and lasts forever. http://www.ebay.co.uk/itm/201332604475

Blu Tak doesn't dry out over time?

[Burgerman]

No. It gets a bit less tacky if you keep re-sticking it to walls and stuff over and over. But mines been collected over years from various sources. Still good.

Soldering connectors for eg. Stick 3 lumps to the bench. Stick connector on one. Cable on the other two like a train. Adjust so the tinned ends line up exactly with your tinned connector. Now you have both hands free to juggle iron and solder and flux and glasses and tongue ...

Learned the blutack trick from an old master!

Definition of expert: Someone that has made every mistake.
Definition of a master: Someone that has made every mistake twice.

[shirley_hkg]

How long does it take to reach 25 amp with SOFT START ?

[Burgerman]

Not long! Cant be fast, many people use generators on flying fields. They don't like sudden loads...

[shirley_hkg]

It said 5mA per second if my memery is correct .

Can 't find the SOFT START . Anyone knows where it hides .

[Burgerman]

Theres no specific setting, it just ramps up.

[shirley_hkg]

Can 't remember where I found the SOFT START . Anyone knows where it hides .

[Burgerman]

There isnt one. It just does so anyway.

[Burgerman]

For anyone interested in DISCHARGING and graphing batteries much more rapidly with the PL8v2

As it stands the charger can already discharge at up to 10A or 100Watts whichever comes first. So thats often adequate for a slow 20 hour discharge on a lead battery. But if we wanted to discharge lithium packs for storage, or to test capacity etc, we really want to do this faster. The PL8v2 can discharge INTO A LOAD at up to 40Amps. But its intended for small hobby packs and into big lead batteries on a flying site. You cant do that with a power supply.

However their is a workaround. Buy one of these. Its small, and gets hot! So connect it and run a cable to where it can sit away from where you are.
http://www.ebay.co.uk/itm/12V-24V-1000W ... 2425256282?

It needs to be able to be plugged in - in parallel - with your power supply and your charger. Feed the charger its 24V. Choose discharge, and set the charger to discharge into a battery. Set the regeneration voltage on the supply tab to say 26V or anything slightly ABOVE your power supply. And then plug in the load. Your power supply will heat it up... Now press DISCHARGE and the charger will lift the volts above the power supply leaving it unloaded. So now your load is the http://www.ebay.co.uk/itm/12V-24V-1000W ... 2425256282? and the supply is doing nothing. You can discharge at up to 1000 watts or more this way. Thats 40A at 25V on your chairs batteries. You can do the same with 12V or whatever.

One proviso. Some power supplies do not like to see a voltage higher than their output. If thats yours, fit a large solar blocking diode in series with the power supply for protection.

[steves1977uk]

Question BM, is it better to use the 125kHz Converter Frequency when charging above 10A on a full pack? Or is it just used when charging single cells?

Steve

[Burgerman]

Doesent much matter. Its about Amps rather than volts. But if its a setting that will stress components, or be wasteful, it will give an error and tell you how or what to set it to. Lower frequencias are more efficient, but need bigger better components at high currents. So in order to save some energy, it uses lower frequencies at lower currents.

[expresso]

I ended up with a reduced power supply limit on the PL 8 - i hit the wrong buttons on the front of the unit - i never used those buttons - always used the PC -
i must have set it this way by mistake -

how can i get it back to the way it was before i touched it ? no reduced power supply limit etc, - the preset is set to 15A for this one and charging at 12A -

my mistake - when the charge is done - how can i get the PL 8 back to the way it was ?

thanks

[Burgerman]

Change the settings on PC or reload preset

[expresso]

Change the settings on PC or reload preset

will see if it happens next time - in the supply settings on the PC - i checked off DC supply and updated - if thats it

for some reason in the supply settings tab - battery supply was checked off as enabled - i unchecked it and checked DC power enabled and updated it

next time i use it - i find out if that was it - i never used the PL 8 alone - and hopefully never have to - i dont like it that way - i like the PC way best -

[Andrey]

Found 2 different options about PL8 presets and just to be sure I want to make a summary.

1. this one: viewtopic.php?p=84510#p84510
2. looks too old, but... : viewtopic.php?p=72491#p72491

These two options has very different Balancing and Termination properties.
What preset better to use?

And some questions:
1. Is it better to charge to 3.60V or 3.55V?
2. Manual termination at 1/300th (or 1/500th) of C, right?
3. Balance start at 3.50 or "at C.V. only"?

Thanks.

[Burgerman]

If you charge a small LiFePO4 pack (less than say 12Ah, at a low rate, you can use a balance that starts at 3.3 or 3.4V. It doesn't cause problems but it is needed.
If its bigger than this, its best to start just before CV. So that the voltage does not overshoot. That means 3.500V.***

So charging to say 3.500V per cell (very slow, takes many hours to end) means you would set to balance at CV. or 3.5V as theres no difference. This probably needs a 1/800 to 100th/C termination to end up at 100% full/and completely balanced.
Charging to 3.550V as I do overnight, is still kind to the cells, and increases charge speed some, but still takes quite a while if you are to end up truly 100% full and balanced. Use maybe 500th/C termination value.
Charging to 3.600V is faster, as it needs only about 300th/C termination, still a little kind to the cells because the manufacturer specifies 3.65 +/- 0.05V.
Charging at 3.650V as specified by most manufacturers is a long way above normal working voltage. It doesn't harm them as such but wont give as many cycles long term. A 200thC is usually adequate to end up fully balanced and charged.

It all depends on:
How long you have available.
How well balanced or new the pack is.
And how fast you need to be.

You can charge to 3.700V and terminate at 1A or 100thC if you want. It will mean that it wont be as well balanced, and probably adequately good. But it will be faster! And wont live as long...

Set balance accuracy to 4mv or greater on a large pack, as its hard to hit the tight 2mv default. And we are talking about 1000ths of a volt here! And set time limits to long... And dont use fuel gauge... And charge at a low rate like 18 to 20 percent of capacity if time allows. If no time set max power!

Its all a compromise. The reason the manufacturers say 3.65V plus/minus 0.05V is because most cells die from being out of balance, and so one or another goes too high or too low. And charging to 3.7V doesn't hurt them quickly. But its over voltage. In that it doesn't add charge past 100% it just gets wasted as heat in full cells. So it pulls up low cells naturally to the same state. So affords a natural self balance mechanism across a series pack. It aids the useless BMS systems in keeping a battery pack balanced over time at the cost of some service life. The best way to get less warranty returns. This is why you see a cell with a 2000 cycle life. But a pack made from those cells, with a 1000 cycle life expectancy. With the PL8 we can do better.

***Starting balance earlier like 3.3 or 3.4V means that the 1A balance circuit kicks in too soon. During charge the lowest voltage cells may NOT be the lowest state of charge. Its down to wiring and cell resistance variation etc. So attempting to balance causes IMBALANCE instead that then needs about n hour to sort out at CV...