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

[Burgerman]

They appear to be about 97% efficient. But it depends on charge and discharge cell temperature, and how much energy wasted on balance, and choosen cv termination current. But thats very good, quite close.

Remember that if say .5Ah to 1Ah is wasted on CV/Balance then thats a low percentage on a 90Ah discharge. But its about 3x more % on a 30Ah discharge. So its not linear. But it gives a good idea.

So you like your PL8?
A good tool if you take advantage of what it can do.

[Gnomatic]

20A discharge. What on earth did you use to discharge 85Ah into? Never mind, just realised it was 12V 4S...

So shirley used his chair to dump 85Ah from that 12v 4S pack @20A. I'm trying figure out how this was done. Was the chair used as the power supply for the PL8 and using regenerative discharge??? I'm curious .......

[Burgerman]

Theres a few ways to discharge via the PL8.

1. internally, resistive, just wasted energy as heat. I use this all the time. But its limited to 10A max and to 100W max. So while its good for discharging a low voltage pack, or cell, it takes a day to do a full 24V battery for e.g.

2. you plug the PL8 into a powerchair for eg as the power supply. Set it to battery and regenerative discharge in the supply tab. Now you can either charge, or discharge the battery you are working on at 40A regardless of volts. So I can discharge my helicopter pack at 40A back into my chair at the flying field. You can do the same, with a full powerchair pack. As long as the chairs battery or the battery you are dumping the discharged load into has MORE space than the battery you are discharging.

So you can run your 200Ah chair for a few days, till its about 2/3rds empty. Then you can use that to discharge a 100Ah battery into with room to spare, at 40A so its fast.

Or you can add a dummy load... This takes 20A at 12V and 40A at 24V. So you can plug this into your supply battery as you discharge with the PL8 so that you dont need to have a huge battery or an empty one...

[shirley_hkg]

So you like your PL8?
A good tool if you take advantage of what it can do.

It is good. Really good . Especially after your elaborated solicitation to unleash all its limitation it had.

Actually its more economical than having one BMS on EACH chair .

It'd be perfect if it came with AC power , so we could take it away from home .

[Burgerman]

http://www.wheelchairdriver.com/PL8v2-Presets/

[Scooterman]

Do we need to know about "Fuel"?

And how to generate a "Fuel Table"?

[Burgerman]

Fuel, doesn't work. Its a thing added for dummies and low impedance LiPos. Where it works.

[Scooterman]

And there are no dummies in this forum!

[shirley_hkg]

Soldering completed .

Note back view of Female to battery ,
in case you want to clone one yourself .

[Scooterman]

Soldering completed .

Note back view of Female to battery ,
in case you want to clone one yourself .

Nice one Shirley

Yes I will definitely have a go at cloning a second one. I'm looking forward to using my new so!dering iron. But I will have a practice with it before tackling the d-sub.I

"Practice makes perfect!"

[Scooterman]

When I was charging my 600mAh cells the max bypass current was 9%.

If the CC was set to 300mA, does that mean the max bypass current per cell was 27mA?

If for example a cell is 100Ah, can the PL8 bypass 9A or does it bypass a lower % current for larger cells?

If so what is the maximum bypass current per cell the PL8 can handle?

[Scooterman]

Also is the max bypass current set by the user charge preset, or does the PL8 set the optimum max rate automatically? I.E. Has the advanced used any control over the max bypass current rate?

[Scooterman]

I'm going to part answer my previous question, in that it must be less than 9% for large cells because the thin balance wires couldn't handle 9A+

[Burgerman]

Depends what the balance current was set to. I set yours low for small cells. It can be 1A. 1000MA. And then even so it is proportional. So the PL8 can use 5 to 100% as it requires, up to your choosen limit.

[Scooterman]

And when charge current drops down to about 3-5% of the cell Ah rating?

So for 100Ah cell, PL8 switches off when CC drops to between 3A-5A?

(I got the 3-5% figure from www. battery university)

[Scooterman]

Depends what the balance current was set to. I set yours low for small cells. It can be 1A. 1000MA. And then even so it is proportional. So the PL8 can use 5 to 100% as it requires, up to your choosen limit.

Ah so the balance current can be set by the user, I didn't realise that. Do you choose a value based on the cell mAh and other specs, the same applies to cell chemistry i.e the CV rate and CC rate depending on C-rate of cell? Might it be different for different brands of cells? Is it a learning experience, i.e. Over the years you learnt from experience what charge preset is likely to work best for the cells you want to charge.

I wish I had that knowledge

[Mechniki]

I wish I had that knowledge

Some of the knowledge would be good. I think I lack the confidence to start something I probably will not finish. And besides it's not just confidence, ability, limitations it's understanding. Even if I can picture in my mind what I want, can I achieve it, in reality probably not.

[Burgerman]

Ah so the balance current can be set by the user, I didn't realise that. Do you choose a value based on the cell mAh and other specs, the same applies to cell chemistry i.e the CV rate and CC rate depending on C-rate of cell? Might it be different for different brands of cells? Is it a learning experience, i.e. Over the years you learnt from experience what charge preset is likely to work best for the cells you want to charge.

I wish I had that knowledge

On small cells (with subsequently high impedance) the balance circuit pulling a high cell down to the correct voltage would be instant and not real. The cells resistance just allows the right numbers to be seen on screen and by the charger. But when released the voltage springs back. So you need less balance current, over a longer time to lower the ACTUAL cell state of charge, rather than just the voltage temporarily while its loaded by the balance current.

So on small cells, it needs to be set as a fraction of the cell capacity or charge rate. On anything bigger than 2 or 3Ah it needs to be set to 1000mA. As it then speeds things up.

[Mechniki]

I am assuming that the PL 8 is a PSU for a combustion engine conversion of alternator power to charge a chair? There's too many posts, I only gave up with Facebook 2 years ago (in reality Last June). I never read much there.

[Burgerman]

No...

Its an advanced charger that is programmable. It can charge from DC 10V to 30V, or with a power supply indoors, from AC, all chemistries, all battery types, inc balancing cells, and graphing charge, discharge, and monitoring. From a watch battery to a full sized EV car/bike. At 10mA up to 40A with time limits, ending currents, delta V termination, etc etc.

[Mechniki]

cool piece of kit to own then, they get seriously hot? Saw the post regarding the PL 8#2 catching fire and the fault wasn't identified. Something to which I didn't understand (don't own a PL 8). But maybe in a few months time.

[Mechniki]

Soldering completed .

Note back view of Female to battery ,
in case you want to clone one yourself .

Do the connections need soldering, isn't there a plug set?

[Burgerman]

I think you are a long way from making, fitting, ad using a lithium pack. Read the thread pinned at the top. Theres no plug and play.

[steves1977uk]

cool piece of kit to own then, they get seriously hot? Saw the post regarding the PL 8#2 catching fire and the fault wasn't identified. Something to which I didn't understand (don't own a PL 8). But maybe in a few months time.

Nope, unless you get a faulty one which expresso did, but he sent it back for a replacement. My first PL8 is 4+ years old and still works fine.

Steve

[Mechniki]

Thanks Steve

[Scooterman]

Nope, unless you get a faulty one which expresso did, but he sent it back for a replacement. My first PL8 is 4+ years old and still works fine.

Steve

Do we need a spare or can we wing it with just one?

[Burgerman]

I got 4. They may stop making them. And in spite of a lot of looking and returning I have yet to find anything that can match it. Or even come close.

[Scooterman]

Something to which I didn't understand (don't own a PL 8). But maybe in a few months time.

A battery is made of a number of low voltage cells linked together to give higher voltage

Not all the cells in a lithium battery pack charge evenly
Some cells charge faster than others

So cells need balancing during charging to prevent one of more cells being damaged and/or exploding. KAPOW!!!

PL8 charges lithium battery pack safely

As BM says, PL8 also charges other types of cell chemistries

[expresso]

I got 4. They may stop making them. And in spite of a lot of looking and returning I have yet to find anything that can match it. Or even come close.

would you know for sure if and when they stop making them - so we can purchase another in case ?

[Scooterman]

I got 4.

Thats okay then I can swap you one for my heinous tyres I’ve currently got for sale