Quick Question re PL8 IR screen

[PorscheBoy]

Guys, been meaning to ask for a while;

When you are parallel charging multiple packs and you cycle through the PL8 screens, one of the screens shows the IR of the pack cells.

Now whilst I understand when charging say one 6S you get 6 IR readings, one for each cell, but when you are charging say 6 x 6S packs (therefore 36 cells) what is the IR screen indicating as it still shows 6 readings; is it the average of all of each numbered cells e.g. all no' 1 cells added together and divided by 6? or what?

What is the meaning of the universe....

Cheers

[Rob Barnes]

Its showing you an average I believe of what the IR's are, the same as it shows you the voltage etc. However if you plug it into your laptop you can see all of this in real time too as your charging.

[PorscheBoy]

Its showing you an average I believe of what the IR's are, the same as it shows you the voltage etc. However if you plug it into your laptop you can see all of this in real time too as your charging.

Cheers Rob,

I'll have a look next time as I seem to be getting a high IR on one cell indication on the PL8 screen (Couldn't be arsed to plug the lappy in... )

[Mike Sanders]

What is the meaning of the universe....

42.....

[PorscheBoy]

42.....

Only according to the mice!

[Andy from Sandy]

What it is showing is not an average as such but as in your example 6 cells in parallel per IR reading.

I don't have time for a worked example but you can google resistors in parallel.

[PorscheBoy]

What it is showing is not an average as such but as in your example 6 cells in parallel per IR reading.

I don't have time for a worked example but you can google resistors in parallel.

Err thanks?

[PorscheBoy]

It's all clear to me now (BTW not my numbers below, just for explanation)....

So all I need to know is what is each of the same numbered cells e.g. cell 1 across the 6 packs IR, then substitute into the formula (R1 through R6) and I'll get what the PL8 is already telling me... Super!

At least I have been educated, "every day in every way I am getting better and better"


R₁ = 12 Ω
R₂ = 18 Ω
R₃ = 6 Ω
1/R_T = 1/R₁ + 1/R₂ + 1/R₃
1/R_T = 1/12 + 1/18 + 1/6
1/R_T = 3/36 + 2/36 + 6/36
1/R_T = 11/36
R_T = 36 / 11
R_T = 3.27 Ω
The total resistance is 3.27 Ω.

[Andy from Sandy]

As you can see from your example the total resistance is very low compared to your highest value. I would conclude from that alone that the displayed IR during parallel charging is going to be somewhat meaningless. You will need to check each pack individually for the right reading.

[robgt]

If one of the IR readings is quite a lot higher than the other 5, and it happens to be cell(s) 6 that are displaying the high number, you will probably need to change the balance board "type" in the charger setup. One type is FMA node wiring and the the other is JST-XH node wiring. If set incorrectly, the cell 6 reading will display much higher than all other 5, and the charge will not be accurate on that cell either, which is no good for balanced LiPo packs.

I hope that helps.
Cheers,
Rob

[PorscheBoy]

If one of the IR readings is quite a lot higher than the other 5, and it happens to be cell(s) 6 that are displaying the high number, you will probably need to change the balance board "type" in the charger setup. One type is FMA node wiring and the the other is JST-XH node wiring. If set incorrectly, the cell 6 reading will display much higher than all other 5, and the charge will not be accurate on that cell either, which is no good for balanced LiPo packs.

I hope that helps.
Cheers,
Rob

Thanks Rob, I have looked at that setting before and my PL8 will only work with one setting, it turns into a rabid budgie tweeting alarm if I change that setting

[cjcj1949]

It might be a problem on your parallel board. Check out each position with the same battery and see if you get the same result. It could be nothing, or a lipo on its way out or a wire hanging on by a thread.