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

[expresso]

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i watched it get to 29.2V on the PL8 - on the graph you can see it reached a high of 3.657v - before it stopped
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I'll regard this as a good sign.

Yes Shirley - your the BMS expert i know - always been using them - it looks to be doing that and its not that bad if it keeps it the highest Cell at 3.657v when it hits 29.2v and then goes green -

i should have left it on and watch it more - but i didnt so my fault there - Time will tell once i use it all summer long - long rides etc,

i be the test subject

[expresso]

No. A cell went above about 3.75V and the BMS then did what I keep telling you they do! It DISCONNECTED the battery. Its the only way the BMS has to prevent the first full cell from exceeding the safety limit it has set. The CHARGER saw that as someone unplugging the battery for an instant. So off... And no they are not balaned.

This is what I keep telling you, it is NOT connected directly to the battery. And neither is the main power to the chair.

The PL8 error may be a bad cell connection or dirty connectors. Switch cleaner spray and check batt terminal connectors are clean/tight,.

BM i dont see where a Cell went above 3.657v on the graph - that was the highest one and it went green - i made a mistake to stop it then and unplug etc, - will leave it next time to see what happens -

When i say connected directly to the battery - i dont mean its directly to the battery without the BMS in the middle - its misunderstood

the battery box is sealed - has one SB120 connector outside of the box - when i say connected directly to the battery - thats what i mean - directly to that SB120 connector - of course inside the box is the BMS which that SB120 on the outside is connected to the BMS inside - then BMS to the rest of the pack -

i never meant to say its by passing the BMS and going directly to the pack - i didnt explain myself correctly - i assumed we all know by now that the BMS is always in the middle of the pack and charge port.. At least i think that way

could have been the wine also -

[Burgerman]

FINAL attempt!

BM i dont see where a Cell went above 3.657v on the graph - that was the highest one and it went green - i made a mistake to stop it then and unplug etc, - will leave it next time to see what happens -

There ARE no cells on the graph. Only the TOTAL voltage of all 8 cells. When it tells you a cell is 3.657V that is only the total voltage (which it can see) divided by 8.

Which means that the cells may all be at DIFFERENT voltages. And if half are below 3.657 then the rest are above it...
If the pack is out of balance its perfectly possible to have 7 cells at 3.5 volts and one at about 4.5...

The BMS can see the cell voltages though. And it DISCONNECTED the charger when it saw a cell go 3.75V Plus. While the rest may be anywhere from 3.35 up. Thats why the charger stopped. As far as it was concerned someone had unplugged it. The BMS did that, it cut off the charger like an off switch.

[expresso]

ah ok - i see - yes your right - that 3.657V is a cell group of 8 Cells - the BMS only knows the total cell count - NOT every single cell etc,

so yes thats true - any rest of the 7 Cells in that one Group can be all over the place - - and the AVG comes out to 3.657v and there fore the BMS kicks in -

i am recharging it again now - with the pl8 - i did a short 8 mile ride today - turned out to be too cold - i though it was better but sun went away and it got cold -

doing one pack at a time - next up 80ah pack and will see if the connections are good on the graphs - if not - then that has to be redone with cable wires instead of buss bars. if its good i leave it -

so much fun with a BMS pack

[expresso]

Ok this is the PL8 - i used to charge the BMS bounder

what do you think ?

[Burgerman]

The BMS has done the same thing to the PL8 that it did to the stock dumb charger.

It has seen a cell exceed the inbuilt 3.75v limit and has disconnected the charger from the chair. The PL8 then ended. So very short CV stage, and it basically stopped charging as soon as the highest ofthe unbalanced cells hit its inbuilt safety limit. So the low cells stay undercharged. No balancing occurs.

Restart the charge, and set charge amps to a low .9A (900mA). And watch what it does. It SHOULD be able to balance the cells without chopping off the charger, so it will continue to charge and balance for a while. And should give some kind of CV.

Post the Volt and A graphs.

[expresso]

i will do that tomorrow - i have to change the charge rate to lets say 1A instead of 10A ?

well i get an overvoltage error now on the pl8 when going to charge my 80ah pack - Cell 4 and 5 - is having a issue - first i got bad cell count and now this code 28

i check the pack volt and it shows 26.7V with volt meter - i hope its just the connectors - and not the actual Cells that are bad

what do you think ?

[expresso]

could it be that its a tight built pack so the cells are very close and dosnt take long CV to balance them ?

i know its a long shot and what are the Odds of that - but only thing i can think of -

[Burgerman]

Its whay you would see with:

a. dirty or bad connection on a cell balance wire/connector
b. dirty or bad connection on one of the heavier cell joining wires or a loose bolt...
c. a VERY high impedance cell. But thats unlikely because you have one high and one low on discharge. So it will not be that.

So its most likely a loose bolt or you crimped a balance wire ring terminal? Or something.... Or the bolt bottomed in the hole and is actually not clamping the ring terminals.

[Burgerman]

i will do that tomorrow - i have to change the charge rate to lets say 1A instead of 10A ?

No I said 900mA for a reason! That BMS has a max of 1A drain. It will likely never reach that. So 900mA means that the BMS should be able to use its balance system, continuously and never have to cut off the charger. So it should keep on going till the cells are balanced, and stay at CV longer so that the pack is fully charged.

[expresso]

i will take it out tomorrow and remove the connectors - screws - etc, - check Cell 4 and 5 - to see there voltages - if all good

i will make wire cables to replace the buss bars i am using -

balance wires - yes - i did crimp and have always crimped - those are the only wires i crimp - always worked well - i use the proper crimper for them - 3M ring terminals

i can check them also - not sure how i would though - if they looked good - as they always do - how would i check them ?

https://www.ebay.com/itm/22-18-AWG-10-S ... 1990097224

with the proper crimper - i can give them a tug and see if they seem loose ? so far - i may have done a dozen of those balance cables using the same procedure - all still working - i tried a different charge cable SubD etc, on the charger end in case it was the charge cable - but didnt do anything -

when i check the pack volt on the SubD cable from the battery end - shows 26.7v - thats a good sign - its Cell 4 and 5 - hopefully its the connection there -

i may have to use longer screws if i use wire cable for the connections - since i swapped them out to use the headway screws - for better contact - and now i may have to go back to the longer ones in order to reach

[Burgerman]

My money is on the stupid bus bars. Dont tell me they are also copper?

Those things are useless. Copper oxydises fast. As you watch. And gets worse later. Bus bars are also impossible to get flat, no proper contact, and they come loose with the movement bew=tween cells due to vibration, heat/cold etc. That will be your problem. And it will cause the issues that you describe as well as leaving a cell or two unbalanced. I mentioned all this several times but nobody listens!

Same with bolts. You want FLAT washers ONLY. 2 or 3 if the bolt is too long. Be SURE the bolts are not tight because they bottomed out and are not clamping the cell/terminals. Again I keep saying this and nobody listens! Those stupid spring washers do not work!

Crimps? You cant really test them. But they will oxydise and develop bad connections. Solder them!!!

On the PL8 and all other connectors use deoxit. Plug in out a few times. CHECK connectors for loose wires or factory crimps faults on the pl8 connectors etc.

[expresso]

I didnt use any spring washers - or lock washers etc, - only flat washer if i recall - or maybe i didnt use them ? could be - i will find out later today when i take it off the chair on the bench to remove them all - -

yes the buss bars are copper - bare of course and they were thin - so i doubled up on them - - everything worked fine up till Sunday - i also had the PSU issue then - swapped out the PSU - shipped back to seller for replacement -

i used locktite on the headway screws - i may have to use the longer screws i received since i will make the cable wires to replace buss bars - and will use extra flat washers on the ones that are needed -

and locktite them again when all done -

Balance wires - well i will see - never had issues before with the balance wires using the 3M ring terminals crimped - heatshrinked etc,

i can redo that also while i am at it - i will decide when i take it apart - i just hope the Cells themselves are OK - the rest i can fix

makes me think about my very first full pack now - its been fine going on 4 summer this summer - but i have used those copper ring terminals on the cable wiring - maybe one day i may take it out and redo those ends also - this is the 105ah headway - and 45ah headway packs i am using on the 646 - i keep an eye on it during recharging as i start using it -

i restarted the charge on the bounder BMS Chair at 1A charge rate - - lets see where that takes us

[expresso]

Ok Charge finished on the BMS bounder with the 1A charge rate - CV went a bit longer this time but not long enough - Term. is set at 65mAh

what do you think of this BM ?

whats the next step - should i try a 29.2V on the preset from its current 3.550 - change it to 3.6v ? and then 3.65V ?

[expresso]

i restarted the charge with a lower Charge Rate 900mAh - lowered the Term. rate to 30mAh instead of 65 -

and it didnt help - actually it started to raise again at the end - - never reached down to 30mAh and instead going up i stopped the charge and put the preset back to 10A charge rate - - 65mAh term. and 3.6V - instead of 3.550V - or should i put it back to 3.550V or the same as there charger at 29.2V ?

looks like this is the best it can get with a BMS installed - or may improve in time as i use it more often - recharging daily etc,

[Burgerman]

i restarted the charge with a lower Charge Rate 900mAh - lowered the Term. rate to 30mAh instead of 65 -

Finally!

and it didnt help - actually it started to raise again at the end - - never reached down to 30mAh and instead going up i stopped the charge and put the preset back to 10A charge rate

BECAUSE IT WAS NOW BALANCING!!!
It WASTES power when balancing, as heat. The BMS is actually now working. Thats why it was rising.
You should have left it alone to finally balance the battery. Its quite likely that its never even done this before. It cant do it at 1A because the charger gets disconnected as it can only sink 1A. You had it right, but then turned it off... It may take 30 mins, or 10 days to balance. But the current will eventually start to fall again to a low level. Set back to 65mA termination. And leave it running!

[expresso]

I see - - Ok let me start over -

what settings should i be use ? it only started to raise again when i lowered the Term. rate to 30mAh - trying to reach it and then started to raise again - i had it go to 3.6V

Start over now - the preset do i leave it at 10A charge rate - 3.6V and term. at 30mAh ? or 900mah Charge - 3.6V and 30mah term. - ?

when it was at 65mah - it ended and charger stopped - when i went to 30mAh is when it didnt end and was starting to raise - which your saying i should have left it there to see if goes down again ? and charge ends on its own ?

- 80ah pack - i removed all the connections - checked all my Cells - all seem fine at 3.3v - so thats a good sign - now i have to make 6 cables wires to replace the buss bars - it turns out i did use lockwashers on most of them - only a few i didnt because the screws were too short then and i used locktite on those

but Cell 4 and 5 which was flaky - had the locktite so makes me think maybe i put too much ? or the buss bars on those cells on the other end were doing it ? i will have to get new screws longer - using the headways mayber are too short also - at 8mm long - i will purchase 10mm long M6 x 1.00 x 10mm long - since the ring terminals are thicker -

balance wires - they all seem fine to me - i may just reuse them and check the pack when all done just to see - if still not good - then i can cut off the ends of the balance wires and add new rings on there. have to order some screws and a fuse anyway -

[expresso]

i restarted the charge with a lower Charge Rate 900mAh - lowered the Term. rate to 30mAh instead of 65 -

Finally!

and it didnt help - actually it started to raise again at the end - - never reached down to 30mAh and instead going up i stopped the charge and put the preset back to 10A charge rate

BECAUSE IT WAS NOW BALANCING!!!
It WASTES power when balancing, as heat. The BMS is actually now working. Thats why it was rising.
You should have left it alone to finally balance the battery. Its quite likely that its never even done this before. It cant do it at 1A because the charger gets disconnected as it can only sink 1A. You had it right, but then turned it off... It may take 30 mins, or 10 days to balance. But the current will eventually start to fall again to a low level. Set back to 65mA termination. And leave it running!

900mah rate - term 65 and charge 3.6V ? then restart ?

this didnt happen though till i changed it down to 30mah - the raising back up -

[expresso]

i restarted the charge with a lower Charge Rate 900mAh - lowered the Term. rate to 30mAh instead of 65 -

Finally!

and it didnt help - actually it started to raise again at the end - - never reached down to 30mAh and instead going up i stopped the charge and put the preset back to 10A charge rate

BECAUSE IT WAS NOW BALANCING!!!
It WASTES power when balancing, as heat. The BMS is actually now working. Thats why it was rising.
You should have left it alone to finally balance the battery. Its quite likely that its never even done this before. It cant do it at 1A because the charger gets disconnected as it can only sink 1A. You had it right, but then turned it off... It may take 30 mins, or 10 days to balance. But the current will eventually start to fall again to a low level. Set back to 65mA termination. And leave it running!

i could not know that it was balancing as you say - i recall remembering that if it started to raise - then term is too low - etc, so i stopped it -

i restarted it now - 3.6V 900mah charge rate and 65 term. i left it alone - i check it later and let you know - i seen it started to raise also

[Burgerman]

Termination should really be around 150mA. But leave for now and see what it does. When set low like that it should allow plenty time to balance. But once its done that it should be set to 3.550V per cell, and to 150mA termination. And a 4 hour CV time limit.

The problem is that if you increase charge rate to above 900mA then the BMS cannot hold down the high cells. So it cuts off or DISCONNECTS the charger totally. And everything ends... Marvelous these BMS! So you need a charger that does not turn off straight away but waits till the BMS reconnects so charge can continue. Thats what is SUPPOSED to happen. Yours appears to not be doing this. So in the end, the battery would get further and further out of balance and so your range would decrease. Why? Because the lowest cell will hit that 2.5V limit while the majority of cells are still half full... So the BMS then cuts off all power to stop that low cell from being destroyed.

[expresso]

Ok after this is done - i am not watching it - but its still going - not sure where its at now - not sitting in front of it - i will change the preset after to 10A charge rate - 3.550v and 150mAh Term.

what can i tell you - this is how its working - others that have this chair etc, just use there charger and not worry about it - they seem to be fine - or at least i dont hear about anything Neg. - but they dont know better so whos to say - i check it later and report back -

OR Can it be that they are balanced enough - if the pack was built well with close matching Cells etc, ? since i have been using the chair and recharging etc, - they may not need much balancing at this moment ? or there supplied charger is a match to there BMS - maybe they need to working together to get the best charge out of it ?

[Burgerman]

Ok after this is done - i am not watching it - but its still going - not sure where its at now - not sitting in front of it - i will change the preset after to 10A charge rate - 3.550v and 150mAh Term.

10A? It will cut off the charger as soon as it ends CC stage. No balance, and 95% charged.

what can i tell you - this is how its working

If that charger turn off, after CC stage alone its *not* working as intended.

others that have this chair etc, just use there charger and not worry about it - they seem to be fine - or at least i dont hear about anything Neg. - but they dont know better so whos to say - i check it later and report back -

Maybe others dont stop after CC stage alone. I am still not convinced yours does. You should wait a long time see if it begins charging again. If not, then it is not doing as intended.

OR Can it be that they are balanced enough - if the pack was built well with close matching Cells etc, ? since i have been using the chair and recharging etc, - they may not need much balancing at this moment ?

Even if balance was perfect and it wont be, there is still no CV STAGE! It just cuts power. So it will be about 90 to 95% charged, not balanced.

or there supplied charger is a match to there BMS - maybe they need to working together to get the best charge out of it ?

You monitored that. CV non existent so no balance and incomplete charge. The BMS expects a constant voltage. It can then turn back on once its dropped the high cells to a lower voltage and continue. Thats just how charging and BMS work. But that charger had stopped. As things stand it appears that you have no CV stage at all and thats where balancing happens. It is chopping off the charger as soon as it sees a high cell. It might work for a long time that way. But its wrong regardless. Theres no Battery "magic" happening.

[expresso]

ok - what i can do next time i take a long ride - after i get my 80ah pack fixed and back on the chair - i can use there charger again and just monitor it with the pl8 - but this time - leave it alone after the green light - let it sit there for hours just to see if it starts up again and continues or not etc,

then - another ride - i can try the PL 8 again - the preset is for 10A charging - NOT now - but normally its 10A - thats what i mean - once this is all done - and i use it again and recharge - it will be at 10A charge rate on the pl8 - is that not correct ?

there own charger is an 10A charger - any slower would take too long - even 10A is slow for a large pack

[expresso]

OK pl8 stopped beeped etc, - the graphs dont look much better actually -

so i guess thats that - i will monitor it next time and charge with there charger to see what it does - and i will leave it on

[Burgerman]

Those are EXACTLY what I expected. It spent 1.5 hours balancing hence the current. Then when balance completed the current fell away, and the charger stopped. Now its balanced. And full.

It also shows that the balance current is only about 100 to 150mA and the rest is the termination charging current. And around 1/3rdAh out of balance. Which isnt bad but its better to know. Now its done.

I would use the stock charger mostly. And now and again use this profile at 900mA and at 3.550V and set a 4 hour CV imit. Save and rename as BOUNDER BALANCE.

[expresso]

Good news then. I will do that. Stock setup bms and charger combo. Isn't too bad after all. Thanks

[shirley_hkg]

You haven't had enough expresso !

Your BMS balance @200mA, so termination should be 200mA + target value .

[expresso]

Ok so 150mA term ? Glad to know at least it's not that bad just had one espresso wine And take a break. Enjoy my new tube amp

[Burgerman]

Can you hear the music through that wooly sounding thing?

[Scooterman]

Now I've put the old AGMs in the Salsa, I thought I'd try using the PL8 to charge them via XLR. To be on the safe side I set the CC to 8A, and the TC to C/1000. I'd only used the chair that day to pop up the co-op so the batteries weren't very deep DoD.

But I switched the PL8 off after 4hrs because the current had plateaued and never looked like it would ever drop to 75mA.

Is it because the batteries are old and had a lot of use?

After unplugging from PL8 I plugged the chair in a mobility charger to 'float'

If I was to charge the chair again with the PL8 should I up the TC to C/100, i.e. 750mA?

NB: But I will probably carry on charging with mobility charger long term as I charge the chair in the lounge of an evening and the PSU and PL8 fans are noisier than the mob charger.