PINNED - Lithium battery conversion/info

[ex-Gooserider]

Thanks, I will be putting that download to use once I've finished the pack testing... At least what my friend walked me through did solve it for the graph problem, but it sounds generally useful.... (chown, chgrp and chatr are so much simpler, though I mostly just use my file manager...)

I need to go through some of my connections again, as I had my discharge test interrupted when I bumped the cable and got an error message... However I was able to restart the test, and between the two have done a full discharge from full to 2.9V using the PL8.... Looks like I got 24.2Ah on the first part, and 68.7 on the second, for a total of 92.9AH - not bad for a nominal 90Ah pack...

I can see how it really falls off the cliff starting around 3.1V or so... I am now doing a recharge to see how it does for how much I put back - I know that should be more than I took out, but about what should I expect?

ex-Gooserider

[ex-Gooserider]

Well just finished the recharge to full - put in 94,191mAh in 6.6 hours - Graph didn't show much variation in the cells, especially once it peaked... Judging from this first test, it looks like the long sit at full charge didn't do a lot of harm... I did notice that it reached full charge (the knee in the curve) at about 5 hours, and then spent the next 1.6 or so hours balancing - is this OK or should I tweak something in the preset? (It said to terminate at 240mV)

A couple of graph questions -

1. Is there any program that can look at the .CP8 files that the CCS software saves OTHER than the CCS?

2. What is the best way to get the sort of photos of graphs that people are posting?

Another different topic, I have 4 cells left over, any suggestions about particularly good uses for them?

ex-Gooserider

[Burgerman]

They look like they will be OK after a few cycles. Test again after use, discharge down to 2.5V and then as they sit afterwards they will bounce back to 2.7+V.

Charge to 3.65V after a lomg store as it will fully saturate and even them up. Then the gap between the 3.65, and the 2.5V will give you a FULL capacity test. Headways are good quelity, giving better than the nominal rated value when new.

And unlike lead decades of lifespan. Best not to store full though!

Other software? No idea.

Screenshots?
2 ways.
I just press the PrtScr button. That copies the screen contect to the clipoard.
Then in any photo editing software like photoshop or whatever you prefer just past it. Many ways to do that.

And theres a thing in windows fur dummies. Called the SNIPPING TOOL. Its on your main menu. Add a shortcut to the start menu, he tadk bar, the desktop of somewhere easy. It does the snipping bit for you. I dont use it as keyboard shortcuts and copy past cont-v and ctrl-c etc is faster. Along with photoshop for edits and saving.

MY menu, yours will be on the main list not here...

[Burgerman]

4 cells? Make a small ADDON battery, with an ebay cc/cv boost board that is set to say 3 or 4A and 26.0V that will HELP or top up the lead battery during the day as you roll. Add an XLR plug. Set a cutoff that stops the thing when it drops to a safe voltage, or just fit a 2 dollar cell log with alarm.

[ex-Gooserider]

Well I did another discharge to 2.9V and recharged, and got the following two graphs, one of voltage and one of internal resistance...

The discharge had the cells tracking VERY closely... The charge did as well except right at the start.

I'm concerned about the one cell that is so much higher than the rest... Should I be?

Cell charge graph

Cell resistance graph

ex-Gooserider

[Burgerman]

They all look fine.
Internal resistance is not accurate. Dont worry. It IS accurate on a hobby lipo, charging on 3 inch long wires with super low impedance cells...

[ex-Gooserider]

OK, thanks for that... I wasn't sure about that one cell that was so much different from the others. The other 7 were reasonably close, so I didn't know if that oddball cell was a sign of some sort of problem....

ex-Gooserider

[ex-Gooserider]

I'm having a problem w/ my battery tester that I posted about a few messages back - same view as a reminder...

It is a cheap Ebay battery tester, that I think a lot of us have used in the past... It is supposed to cycle through showing the pack voltage and then each cell, with a settable alarm for any cell that goes to low...

I cut the shrink wrap plastic cover off it and hacked the connector to fit the battery charge connector, with the idea of putting it in a connector shell and thus having a nice small checker for my pack.... I wired the 9 pins of the tester to the 9 balance wire pins in the connector, which seems pretty obviously the way it should be wired....

However I get an alarm every time I plug it in... I get the correct pack voltage, and cells 1-6 are in the expected 3.x V range, but cell 7 shows 10.4V and cell 8 shows ZERO.... I have spent considerable time verifying that I made the connections correctly, no shorts, etc.... (both visually and with a meter) Everything looks fine...

As mentioned, the pack does the right thing with the PL-8, so I know the pack is wired right.

So I thought I had possibly gotten a defective unit... I got these from Ebay back when I bought the cells, and it was one of those offers for 5 testers for one price... So I have a bunch and did a quick and dirty job of making up a second tester w/ one of my unused plugs and just soldering to the legs of the tester...

It does the same thing!

Any idea what I might be doing wrong?

ex-Gooserider

[Burgerman]

No. I have a few, they all work perfectly. Not super accurate but good enough. I dont know what you are doing...


Should be wired, neg, on wire 1, then wire 2 onto pin 3, 3 to 4 etc until cell 8+ is on wire 9
What you gona need there is a multimeter!

Maybe you have some pins wired wrong on both halves so that the pl8 sees it correctly.

[ex-Gooserider]

No. I have a few, they all work perfectly. Not super accurate but good enough. I dont know what you are doing...


Should be wired, neg, on wire 1, then wire 2 onto pin 3, 3 to 4 etc until cell 8+ is on wire 9
What you gona need there is a multimeter!

Maybe you have some pins wired wrong on both halves so that the pl8 sees it correctly.

I've checked both visually and with a meter from the pack to the PL-8 and each cable - all show no problems... I also did a voltage test, and each shows the wiring is correct....

The pack is wired w/ the pack negative on pin 1,
+ of cell 1 (and neg of cell 2) on pin 2,
+ of cell 2 (and neg of cell 3) on pin 3
etc until pack plus (cell 8 +) is on pin 9

I am wiring the 9 pins of the checker the same way... This doesn't match what you are describing but I don't see how that would match the tester pin out...

ex-Gooserider

[ex-Gooserider]

I wired everything according to the FMA wiring mode per the PL8 manual, and have the PL8 set to use FMA mode, but it appears that if the pack is 8S, then there is no difference between the FMA and XH/EH modes...

I don't know what the checker is expecting, but since it's looking at an 8S pack, it shouldn't matter...

ex-Gooserider

[ex-Gooserider]

Also I just did a test of disconnecting the 5-8 pack since it was easy to do, and the checker works fine on cells 1-4 - shows pack voltage of 13.6 and each cell around 3.3v as expected... It will be a bit more of a pain but I am thinking it might be worth trying the 5-8 pack by itself....

ex-Gooserider

[ex-Gooserider]

I just did that, by removing the wires to the tester for cells 1-4, and moving the ones for 5-8 over to the first 5 pins of the tester - it worked as expected - 13.3V total, 3.3x per cell... So it seems to be something strange with the tester itself, or the proper wiring is not what it looks like it ought to be...

ex-Gooserider

[Burgerman]

Is one of them crimped and not making contact?

[ex-Gooserider]

Is one of them crimped and not making contact?

The pack wires are crimped except for the soldered connections to the DB charger connector, using proper crimpers, in accordance w/ mfg specs.... Also if one wasn't making contact, the charger wouldn't be working right either...

My wiring for both the original tester and the test setup is soldered....

ex-Gooserider

[shirley_hkg]

Scammed..
This can only do 7S, though looks indifferent.

A $20 Active Balance BMS with Bluetooth for monitoring is not unworthy . Check everything on your phone. Cool.

Can be re-use in future.

[ex-Gooserider]

Thanks Shirley... I will look into trying to find a similar unit that can do 8S, as I like the form... I am NOT interested in doing a BMS - no matter how fancy I doubt it would work on my flip-phone...

ex-Gooserider

[ex-Gooserider]

Seems it isn't even as good as Shirley claimed... I did a quick reconnect back to the original cells 1-4 configuration, and then added the wires for cells 5-7, leaving 8 disconnected, so acting like 7S. Got a pack voltage of 30V, normal 3.3+ on cells 1-6, and cell 7 read 10.4 volts (but I didn't get an alarm!) I took the wire off cell 7, making it a 6S tester, and it worked properly.... So definitely defective units...

I'm going to go ahead and try the other three since I have them, but don't expect much.

As an idle thought, how safe am I in just using the tester as a 6S unit, and not looking at cells 7 & 8 working on the assumption that if 1-6 are OK then the other two presumably are as well?

ex-Gooserider

[Burgerman]

Considering that I used to use the pretty good tester that works well, below, and now use absolutely nothing at all for years then I wouldnt bother!

Maybe for a week, to get the idea. Then your joystick will tell you all he clues you need.

[shirley_hkg]

You've done a capacity test that shows the lowest pack volt you shouldn't pass.

A voltmetre is good enough.

That thing itsn't good. It beeps under load where it's still far from empty.

[Burgerman]

Its not meant to test cells under load though. Thats a resistance test!

All cell logs should be used when not rolling. Not meant to leave plugged it.

Although with a hobby LiPo that was the intended use, that doesent actually matter as the silly LiPo batts dont drop volts as you load them up significantly. Because 130C etc... A 4Ah one will start a car!

[ex-Gooserider]

Yup all of them are junk... Work as 6S testers just fine, not as 7 or 8S... Looks like it must have been a bad lot or something, as all do exactly the same thing.

ex-Gooserider

[ex-Gooserider]

I 'm not testing under load - I can't right now as the pack isn't in the chair... These units do have a 'programming' button to set the alarm voltage, and I'm thinking it would be best to set it at 3.2 as my discharge test seems to show the voltage 'falling off the cliff' between 3.1 and 3.2, with not a lot of Ah output after that... I want to make sure it tells me when I need to charge BEFORE I get to the 'RIGHT NOW' point...

ex-Gooserider

[Burgerman]

Thats not so easy.

Very very flat discharge curve that varies more between cells and by temperature than it does by state of charge means doing this by voltage is never accurate.

Thats another reason that its best to fit a big enough pack that its all irrelivant.

[ex-Gooserider]

Just tried an experiment that may sort of let me make use of the crappy monitors... I tried wiring my test rig up as a 4S pack, using every other pin... I.e
Pin 1 - pack ground (cell 1 negative)
Pin 2 - Cell TWO positive (cell 3 negative)
Pin 3 - Cell FOUR positive (cell 5 negative)
Pin 4 - Cell SIX positive (cell 7 negative)
Pin 5 - Pack Positive (cell 8 positive)

The result is that I am in effect testing a 4S pack made up of ~6.xV cells as it is connecting to each pair of series cells....

I haven't tried playing with the alarm to see if I can get it to beep at useful point (which I don't see as really being useful...) but it DOES give me pack the correct pack total voltage and the correct voltage across each pair of cells... (~6.7V for a full pack) and I figure it is pretty unlikely that one cell in the pair would drop low enough to be a problem while the other stayed high enough to keep the total reasonable...

Does this seem reasonable as a temporary measure until I can get a better tester (if I bother...)

ex-Gooserider

[Burgerman]

Is there a decent BMS (1 to 2A balance HIGHLY configurable 200A) that has PC software and wireless or BT connection. Because I want to build a solar battery. And because I may fit one to a chair because the PL8 isnt made now and I want to see how good or bad these things still are. I may still have 5 PL8s, and so will still fit a proper charge/balance system but I want a BMS to play with.

The only half decent ones seem to be the JK ones but no PC software and I hate phones...

[shirley_hkg]

youtu.be/GNxn2SakirQ


He has played with JK bms for quite some time.
He has solved most of the connectivity issues of this bms.

[Burgerman]

But no Windows app...
And on a chair its huge, lots of wires, and 1 inch thick. So in place of 230Ah cells can only get 1 inch shorter 160Ah cells in battery box.
So ruins the range as well as longevity and safety...

[shirley_hkg]

I use the small one.

App on phone.

[Burgerman]

But it still means small 160Ah battery... And a mllion extra wires. OK for solar though. And no PC software! Phones are crap.