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

[Scooterman]

11Ah not 11 amps

[Burgerman]

Shirley asked me to move this here...
Why PL8, and not other hobby chargers...

I will give just ONE example of some important changes I got sorted over a 2 year period.
Behind the scenes, the charger looks at the highest and lowest cell voltage as you charge. Previously, if it ever saw a 150mV gap, it stopped charging and then started a "safety charge" at just .5A. That was originally intended to stop burning down houses with LiPo chemistry. They retained this with oher chemistries.

So after a few argument/discussions the gap between the highest and lowest cells "allowed" was increased to 250mV to try and stop that happening. Which was better but not actually quite enough. Its possible on an unbalanced pack to exceed this. And so by by also modding the presets I am now able to increase that further still to 350mV. And to set it to not start checking untill a higher voltage threshhold. So now this never interferes and prevents the PL8 from properly charging and balancing an unbalanced large LiFePO4 pack.

Why? Because the improved 250mV gap they now allowed, doesent work on LiFePO4 packs that are large as they may exceed this gap and trigger a slow .5 amp charge and take over 3 weeks to charge... And they shoot up from 3.3 to official 3.65 volts at the charge end fast. Thats a 350mV gap. So their increased 250 is not enough. But on a badly balanced pack, thats quite possibly a 3.2V low cell... So I increased the voltage that it begins to check to above our usual charge voltage... Because theres no safety issue on this chemistry and so now this "feature" does nothing!

Remember this was one fix of many. Like the charge voltage where balance begins. It was fixed at a too low voltage, UNBALANCING our large packs for hours as they charged, only to have to rebalance later on for another few hours.

There were another half a dozen similar changes for lithium, and a few for lead that prevents issues and lets us charge properly. All now sorted if you use firmware 3.33 and my modded presets.

Anyone using a different charger, like the new ones with the built in bump controller thingy, or any other manufacturer will run into all the same issues and be starting from the begining all over again... So every time people say what about x charger I despair! Knowing that behind the scenes lives a phone book of computer code that was written by a programmer that does not understand batteries waiting to catch them out with as yet unknown problems and lack of important user settings.

[shirley_hkg]

YES ,
and this too.

And lead. Was originally the hyperion. They were keen to learn and I did a LOT of beta testing and talking to them. Very responsive company. But it turned out unreliable and the guy running the company's son had an accident and kind of went offline for a few years and they stopped making them at least for a bit. So I was looking for a replacement.

The PL8 existed but was so safety nazid down, and its settings were so restrictive that it was a nightmare. And it wouldnt allow many settings we needed, had a bunch of bugs or "features" in firmware that prevented charging Lead properly. And the same with LiFePO4.

So I spent a lot of time trying to get them to fix stuff and hundreds of emails. They didnt exactly work with me and it was more argument than a helpful response. In the end, they changed a bunch of things in a firmware update once they figured out I might be right, that allowed it to be used for lead/LiFe properly. And changed some presets. The problem is that they want to make 1000 excuses as to why their way is safer. But too restrictive. Because they are dealing with hobby idiots that are exploding LiPo batteries and burning down houses. And we found a way to mod the presets too, to allow a few wider settings than appears on the CCS software internally. 2 years of partly adverserial contact with their beta tester. So PL8 is now good! But it was hard work... So I bought 4.

[expresso]

BM - i am using the PL8 to monitor the Charge with a XLR Y cable - but it dosnt show the Cap in on the PL8 -

Can the PL8 do that ? or do i have to actually charge with the pl8 - this is on the Bounder with BMS - i wanted to check the Cap. in during recharge -

i am using the preset with BMS no Balance - but just monitor it - charging with the bounder charger - is there a way to see Cap in this way ?

Thanks

[Burgerman]

Capacity is Ah. The PL8 is monitoring only, so it watching volts. It has no way to know how many amps is flowing.

[expresso]

ok i see - so the last time i seen it - i must have used it to charge also - i didnt take a long enough trip today - maybe on a longer ride

i can recharge with the PL8 - should be safe ? just the once to see the Cap in ?

[Burgerman]

Yes. Via the charge port. As many times as you want!

[expresso]

yes i would only use the XLR charge port - it would be safe for the batteries ? BMS is in the middle so cant be worse ?

thanks - i can look at the time now to get an idea - if 4 hours - i can assume it put back about 40ah at 10A charge rate

[Burgerman]

No better than that thing it came with. And you can see whats going on. If it was me I would add the T connection to the cell taps as well and charge it properly.

Neither the PL8 or the charger it came with knows if its finished, or still out of balance though. So you may need to play with the termination current till it ends about an hour after CV. If in doubt, set a 1 or 2 hour CV time limit and set the termination really low. Like 100mA. To give the BMS some time to balance/work.

Also if its stored in winter, you can set a 8 hour CV time limit, to allow it time to rebalance after storage unbalances the cells.

[expresso]

i have to check the preset to see the details - its set to 65mAh term.. so its low enough to give BMS time to balance them
CV 8 hour time - i havnt touched this preset - its how you did it for me - if i need to change something ? let me know - or i use it this way

i am not going to touch inside the battery box - its new - and covered - i use it as it is till it no longer works for me - as long as i get my 40 mile range with the added extra 80ah -- and never get stuck or have the BMS cut off on me - i am not going to stress it -

will get the 100A fuse for the ADD ON because of what we talked about - its an extra safely feature in the event BMS cuts off for real on my long rides -

i can leave my other chairs alone with the 60A on the ADD ONs ? one chair is with lead - 646 is full lithium - - nothing has a BMS on my packs so i can just change out the ADD ON on the bounder with BMS to 100A fuse ?

[Burgerman]

All sounds good to me.

[expresso]

charge finished - i can say that - it does NOT go past 3.657v 29.2v - this is from the PL8 monitoring -

next time i will use the pl8 to charge and see the Cap in also - it does seem to end fast when reaching its set volt of 29.2v - balancing wise seems fast - but who knows if they are really fully balanced -

[expresso]

Ok now its my turn - i just got a BAD Cell count on the pl8 - when going to charge my 80ah ADD ON - Safety Code 20 -

i tried it a few times - - so what does this mean - ? bad cell connection ? i used the supplied copper buss connectors - they were thin and i doubled up on them - was fine till right now ?

do i have to take it apart and making cables to connect ? or anything else i can try on the PL8 end ?

[expresso]

Update - i turned the PL8 off and back on - seems to work now - but i noticed two cells where out of wack - from the rest of them

i did have my PSU go a bit wary today and changed it out - - i have two ideas - either i got a few Bad cells or the connections

which means i have to take it apart - make new cable wires to connect them and retest - or i am stuck if that dosnt fix it - - strange because it was perfect in use and recharging till today.

[Burgerman]

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,.

[expresso]

Wait BM - these are two things that happened - - or rather 3 today

first i went out and left my other chair charging - but during this time- my PSU went a bit wary - - something is loose on the connectors -

so thats one issue - resolved - changed PSU and returning it to be replaced - i had it a month -

2nd - i charged the bounder and just monitored it with the pl8 - i never seen the volts go past 3.657v on the PL 8 and the graphs shows that

that was the end of the charge cycle --

3rn - i went to charge my 80ah and got the error code - i tried a few times - checked my charge cable - then i powered off the PL8 and back on restarted it and its fine -

but it started on a safely charge first - before i stopped it - powered it off and back on - all fine as it was before - so it may be just fine my connections on the Pack itself - and just a fluke with the PL8 given the issue with the PSU also

i will leave it alone till i recharge again - next time i use it - and see - if i dont like the graphs or something seems out of wack - then i will take it apart and rewire with cables instead of the buss connectors i used which are bare copper

my only concern are the Cells - as long as they are good and its not a BAD Cell in the pack - i can deal with the connections - and bad PSU going back to the seller tomorrow for replacement - first one that failed on me - i have 3 others to work with -

i may just pick up another pl8 - just in case -

[Burgerman]

it does NOT go past 3.657v

TOTAL!!! Divided by 8.

Thatin reality may be 7 cells at 3.5V and one at about double this!!!

3.5 + 3.5 + 3.5 + 3.5 + 3.5 + 3.5 + 3.5 + ONE AT 4.7V makes 29.2V... You and the charger CANNOT KNOW. So when a cell hits about 3.75V the charger is DISCONNECTED by the BMS for a while (a mosfet turns off) while the crappy balancer pulls it THAT CELL down lower to a safe voltage. Then it reconnects. As long as the charger didnt think this was someone pulling out the charge plug, it would carry on later to try and balance the cells. Which may take hours.

The PL8 may allow that. The charger on your graph appears not to and has turned off.

[expresso]

yes i know - but thats nothing i can do about it - once charger is done - i stopped it - it dosnt float - if i leave it connected - it will restart if the pack volts goes below 27v - or else it does nothing -

so i stopped the monitoring and thats it - done - end of charge - NOW - i cant know if the pack is fully charged balanced wise - i just have to charge after every use - to try to keep them balance as best i can.

i will try the PL8 next recharge - to see -

i am more concerned about my 80ah ADD ON - the chair pack - not much concerned - its covered one way or another - or if or when its not - then i take it out and do it my Way - it be fine for a while

[Burgerman]

2nd - i charged the bounder and just monitored it with the pl8 - i never seen the volts go past 3.657v on the PL 8 and the graphs shows that

that was the end of the charge cycle --

NO! READ POST ABOVE SLOWLY.

The PL8 DOES NOT KNOW the cell voltage. It divides the TOTAL volts by 8 to give an idea. But in reality they are all different. Your BMS DISCONNECTED the charger as it is supposed to do, thats how they work. I have been telling you this for days. While it tries to sink some current internally to lower the voltage of the cell(s) that are above 3.600V. It cuts off charger completely at around 3.75V highest cell typically. Then watches the cell voltage drop, and then RECONNECTS the charger Rinse and repeat. The charge port is NOT connected to the battery. It is connected VIA a MOSFET that the BMS turns on and off.

So it turned off the charger because it disconnected the battery completely for a short period. The charger saw a low current... Of zero. And stopped. Or stayed on? Maybe only the BMS stopped. But that charge port is not connected direct to the battery. It gets switched on/off by the BMS.

[Burgerman]

The other pack, will just be dirty connectors or the balance wire conector on the PL8 or the terminals on the balance wires. Hopefully they are soldered and NOT crimped...

[expresso]

i get it what your saying about the BMS and Charge volts - it can only display the total for a group of 8 -

nothing is going to change that - if using a BMS this is how its going to work - like it or not - not going to worry about the BMS Chair pack

use it - charge it - use it - so on - till its not good anyway - one year - or 3 - i deal with it when it comes to that

my packs i am more concerned - and i think it was a fluke - it charged fine - but as always - if i notice anything - i check the connections - but i think its not that - just a fluke with the pl8 today and PSU etc,

[expresso]

each cell can and will have a different volt - added up it can show a good total volt and charger is done - at 29.2v - if they are all up and balanced fine - if not - charger will stop either way - it will only restart if pack volt is below 27v

charger can stop and restart based on the BMS - during the charge up to its set 29.2V - once it hits that - thats it - done - dosnt mean all the cells are fully balanced - i get that - thats why its important to recharge each use to lower the chances of out of balance cells by too much

thats the best you can expect with a BMS system -

[Burgerman]

They usually stay at CV ON/OFF for a long time as thats the only way to balance. As it it, its charging, and appears to stop as soon as it sees CV which means NO balancing is actually happening.

I suspect that the PL8 stopped monitoring when it saw the BMS cut off the charger which then turned off. Or the charger continued on, after the high cells were brought lower. ON/OFF for some time. Thats what is supposed to happen with a bms.

____________________

The BMS charge system is crap. By design. And you cannot tell whats actually going on with basic systems either.

The way it works is plain stupid!
Its a bit like trying to drill a hole. Some drills can be throttled at the trigger to allow you to start slowly, or to go very carefully at the end in a controlled fashion. Thats the PL8 DRILL...

A BMS controlled drill would be ONE fixed speed. Full power. Always on. No trigger. And the on off switch would be at the wall socket... To control its speed you keep switching it on and off. All the finess and control of a 1970s arc welder.

[shirley_hkg]

- if not - charger will stop either way - it will only restart if pack volt is below 27v

charger can stop and restart based on the BMS - during the charge up to its set 29.2V - once it hits that - thats it - done - -

Hope you're incorrect on this , or it will be a totally wrong setup , otherwise .

Do you know how long it takes for a 100ma BMS to drag a 100Ah pack down to 27V ? Hours and hours .
That means you will have one/two restarts at most for an entire night .

Charger has to restart, whenever BMS resumes charging .

[expresso]

BM - The Charger stops once the light is green - it does not float - according to the charger specs i found - i saved them somewhere -

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

i stopped the PL8 myself at this point - since there is nothing else thats going to happen - i understand whats happening and why the BMS does it this way - it may be bad and stupid etc, etc, BUT it dosnt matter - unless BMS get better at this and unless the industry changes how they make them - and they wont - they are working the cells to there MAX on both ends of the spectrum -

its a dumb charger like all the rest - CC CV and done - it may have a mechanism that works along with the BMS to turn on and off etc, or it may not have nothing and BMS is in control - which is what i believe -

Shirley - According to the Charger manual which i dont have at the moment - or i seen it on there website - you can leave it connected after it goes green but its not floating - it will start again if left connected at some point when it sees a pack volt of 27v or less -

when i said it will start again when it sees a pack volt of 27v or less - i dont mean this while its charging - i mean after a full charge is done - and if you left the chair alone for a long time with the charger connected - this is what i read about it -

like any other dumb charger with a float - this does not have a float - and yes it would take a very long time for a full 100ah pack to discharge down to 27v - i would think

i wouldnt do that - i have charged it every so often in the winter or when not in use much just to keep it somewhat balanced -

this is the charger -

[expresso]

http://www.epowerfirst.com/product.asp?fid=14&fid2=62


10S is the one -

actually it talks about a floating mode here - - but i recall reading it dosnt float - maybe i have my manuals on it - and i read it there - dont know -

i dont think it floats -

[expresso]

it may be Crap by design - its the best crap they are coming up with so - we have to take the crap - if you get a chair built with lithium or anything built with lithium - it will have a BMS -

i can take it apart remove it - or just make my own pack - but why do that now - its new - it was covered - just use it till it burns out and then redo it without -

alot of users would love to have a plug and play system like this - for many reasons - as long as it works and takes me where i want to go

[shirley_hkg]

-

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
-

I'll regard this as a good sign.

[Burgerman]

as long as it works and takes me where i want to go

And with no CV theres no balancing. So in the end it will likely get miles out of balance and you will stop for no expected reason... When one cell is only about half charged at 29.2V. Personally, I would want to know! Your choice.

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

Yes. Correct. It did CONSTANT CURRENT where the volts climbed. and then the BMS cut off the charger, and at that point, NO CV STAGE. So NO BALANCING possible!!! And no float. Thats wrong!!!

i stopped the PL8 myself at this point - since there is nothing else thats going to happen

Wrong. The charger was DISCONNECTED by the BMS temporarily while it dragged the high cell, that triggered it to disconnect down toa more sane level. It was NOT at 3.657V thats just a bit of maths, not a reading. That highest cell must be over 3.75V.

- i understand whats happening and why the BMS does it this way

No you dont!

- it may be bad and stupid etc, etc, BUT it dosnt matter - unless BMS get better at this and unless the industry changes how they make them - and they wont - they are working the cells to there MAX on both ends of the spectrum -

No if you are correct and the charger turned off than it is NOT doing as it is intended. But I suspect you are wrong and did not wait long enough, and the BMS will reconnect the charger once it has drained some from the high cell(S). If the charger HAS turned off, that is INCORRECT. It has not had ANY CV stage at all. And no balancing. So you will have a problem.

its a dumb charger like all the rest - CC CV and done - it may have a mechanism that works along with the BMS to turn on and off etc, or it may not have nothing and BMS is in control - which is what i believe -

BOTH! But its not working or you did not wait long enough.

[expresso]

BM - Ok its possible that i should have left it connected there charger - and waited to watch if it dropped down - according to the manual and spec sheet - when it goes green its done -

and I DID Stop the Charger Myself believing it was done at green - i stopped the pl8 monitoring and i stopped the chair charger - unplugged everything - thats it

i do understand how its working even though i may not be explaining myself correctly here - after all these years about the BMS - i get it

it may have reconnected and continued to charge if i left - maybe it was just pulling down a higher Cell when it reached 3.657v - and may have restarted if i left it alone long enough - or maybe not - i didnt do that - so i cant know for sure -

i will use the pl8 next to recharge - but i will when i have time to watch it longer - do it again same way and monitor again just to see if it drops CV and how far - how long etc, -

if this BMS stops the highest Cell at 3.657V - that wont be that bad as we think - its more than we may like - but its within its Max limits -

i know it will shorten its life etc etc but its not That Bad i dont think if in fact it dosnt allow any cell to exceed that volt. yes it may go up down and repeat that process for the other cells which may be out of balance - but this is what a BMS is designed to do - so its doing it as design -

Till it Fails me - i am not going to stress it - i keep an eye on it - and MY 80ah pack is what i am more concerned about to make sure thats Ok - life it short - just use it and go -