Battery IR PL8 ?

[expresso]

having a strange issue - IR on the cells

brief history - i been using 60ah Cells for an ADD ON for about 5 years now - One cell in the pack was always a bit behind - i decided to finally take it apart - and replace it with one spare cell i had - turns out it it didnt change much - so i checked the balance cables - the ring ends were bit beat up -

i replaced them all now - i removed all the wiring - i made new wiring to connect the cells - there was another bit of an accidental touching of the cable with pos and neg. bit of sparks and wire got very hot fast - my girl helping me - now i dont blame her - its my fault for not taking extra protection by covering the rest of them exposed studs

i only said it a dozen times to not let any touch etc, it was a simple thing but anyway - done -

so i decided to check each cell now - starting with the one that sparked - looking at the IR - around 32 - 34 at times etc, i figure its not good -

now doing another cell from the pack - about the same IR also - that wasnt bad before - i will do another one tomorrow and check it -

i got the tool to check the volts and IR from china - and when checking it with the tool - it not the same IR - its much lower under 2 - which is about what the PL8 showed when i had the pack made and charged it - with the full pack made - the PL8 showed the IR for Cell 2 to 7 under 2 IR - Cell 1 and 8 - around 2.8 IR

so how is it showing me around 32 IR when charging it single cell at a time ?

which do i believe - i figured the cello was bad but the others seem to show the same -- so maybe its not bad ?

i will do a few more till weekend when i plan to build it again as a whole pack and then check it - i am trying to use the ADD ONs if i can make more use of them before looking to buy another 8 - isnt worth getting a few extra when i found 8 Grade B - for under $300 - was told they are new grade B never used

its an ADD ON - not as important as a full chair pack -

what gives with this IR ?

thanks

[Burgerman]

having a strange issue - IR on the cells

brief history - i been using 60ah Cells for an ADD ON for about 5 years now - One cell in the pack was always a bit behind - i decided to finally take it apart - and replace it with one spare cell i had - turns out it it didnt change much - so i checked the balance cables - the ring ends were bit beat up -

What does "behind" mean? Lower capacity? Lower voltage at same Ah state of charge Lower ir higher resistance? Lower as in self discharge rates? And lower measured with what and how?

i replaced them all now - i removed all the wiring - i made new wiring to connect the cells - there was another bit of an accidental touching of the cable with pos and neg. bit of sparks and wire got very hot fast - my girl helping me - now i dont blame her - its my fault for not taking extra protection by covering the rest of them exposed studs

Cell interconnecting cables or cell balance cable???

so i decided to check each cell now - starting with the one that sparked - looking at the IR - around 32 - 34 at times etc, i figure its not good -
now doing another cell from the pack - about the same IR also - that wasnt bad before - i will do another one tomorrow and check it -

Doing?? What is doing? Check it with what?

i got the tool to check the volts and IR from china - and when checking it with the tool - it not the same IR - its much lower under 2 - which is about what the PL8 showed when i had the pack made and charged it - with the full pack made - the PL8 showed the IR for Cell 2 to 7 under 2 IR - Cell 1 and 8 - around 2.8 IR

I read that 4 times. No clue what you mean. And when you say under 2 are you talking about mOhms?
The CABLES will be around that or more. The cells must be measured DIRECTLY to get any kind of accurate reading. I too have one of those chinese internal resistance meters. They are pretty accurate if used properly. And if you inderstand what you are doing. You can use it to test your cables too. The cables may be higher than the cells.

so how is it showing me around 32 IR when charging it single cell at a time ?

What is IT?
Do you understand that wires have frequently got a higher internal resistance than the cells? And that a full or empty cell has a much higher resistance than one that isnt full or empty, like 3 to 6 times? And that the CONNECTIONS to the cell you are chargeing may show a bigger resistance than either the cell or the cables alone? Or that the PL8 cant read resistance accurately without balance taps? That device or the PL8 readings on resistance can be useful only if you understand that a tool is only as useful as the person using it.

which do i believe - i figured the cello was bad but the others seem to show the same -- so maybe its not bad ?

You believe what the tools are telling you. Just because you see different numbers doesent mean either is wrong. They are telling you different things. And for different reasons.

i will do a few more till weekend when i plan to build it again as a whole pack and then check it - i am trying to use the ADD ONs if i can make more use of them before looking to buy another 8 - isnt worth getting a few extra when i found 8 Grade B - for under $300 - was told they are new grade B never used

its an ADD ON - not as important as a full chair pack -

what gives with this IR ?

You must understand ohms law. And that the super low levels of internal resistance in the mOhm range are increadibly hard to measure. It is the sort of differences you see between a lump of wire 3 inches long compared to 12 inches long. The resistance for all intents is zero. You are measuring that!

[expresso]

with the pack all done - before i took it apart

with the PL 8 - the IR showed this

a little behind - meaning during charging the graph lines - all about even with this one Cell a bit behind lower than the rest - i call it being behind lower weaker what ever is the correct term.

i checked the balance cables - ring terminal on that one cell that was a bit behind wasnt great shape - i removed all the wiring and redid all the balance rings - i also redid the cables interconnecting the cells to each other - i didnt like them how there were done at first - but i left them and it did work fine -

i just decided since i had a spare cell - i replaced the cell that was a bit behind the rest - and it didnt change the outcome - just a tiny bit - so i decided to change all the rings and new interconnect cables

so i have 9 cells - i went to charge and discharge one at a time - and recharge to check the IR - and so far each one i did - 3rd one now - all show about same IR 32 mOhms - i assume its mOhms -

the thingy from china - same one that Shirley got - that one - its all set up already - i dont have to configure it - with that - it tells me the volts and IR of the cell - those numbers do not match at all with what the PL 8 is showing me at 32 mOhms

with the thingy - its below 2 mOhms -

why is that ?

[expresso]

you see the graph the white line cell 3 - a little behind the rest

thats what i went to try to fix - i figured i change the cell since i had one - but it didnt change much - actually that shot was with the cell replaced - the one before it was a bit more behind -

so i proceeded to do the wiring now - clean all the contacts replace the rings and new interconnects - i am not too trilled how i did them - i didnt have the correct Lug for the wire i used - so i see if it helps or is worse - if worse - i may have to buy the correct size for the wire

i did solder it - so hoping that makes up for the size difference -

i just decided to check each cell single - before i put it back this weekend - and then see if anything changed for better or worse or no change

and looked at the IR while i am recharging each one single - i was expecting to see a lower IR or close to what the graph shows above - when i seen 32 or 34 etc, i was confused-

[Burgerman]

the thingy from china - same one that Shirley got - that one - its all set up already - i dont have to configure it - with that - it tells me the volts and IR of the cell - those numbers do not match at all with what the PL 8 is showing me at 32 mOhms

with the thingy - its below 2 mOhms -

why is that ?

Because one is reading AC as in impedance, and ONLY the cell. And the other is reading resistance in dc, and is including the connections and the cables. Both are useful. Both are correct. both are tlling you different things.

[daveonwheels]

the more i read this thread the more i'm convinced espresso does not understand basic electronics. ohm's law is fundamental!!!!
and IR is hard to measure in a meaningful way

[expresso]

yes you are correct - i never said i did understand it - i dont know this stuff - i never done it before - i know enough to do what i need to do - and not all details etc, - reason why i ask here -

alot of you guys do know and understand it - i worry about the pack after i put it back together - recharge - discharge and recharge to see how the graphs behave

i bet and hope the IR then will be the same as the one i posted above - i was expecting similar numbers to show when doing single cell -

internal means inside - and Resistance means to me - when something is making it harder to pass thru i understand that - but dont know electronics and all the laws involved etc,

i surprised myself even doing what i do

[Burgerman]

Measure each ell with your new meter across its terminals when say 80% charged. And compare. All should be very similar. And almost the same as a short bit of cable. And almost the same as a short bit of cable... the difference between 1mOhm and 2mohm is huge! Half or twice as good. Less than the wires. The PL8 works in a similar way with 4 wires. So it can sense the battery voltage change under a known current. But long wires and several connections make it all less accurate. When charging 1 cell with no balance wres it is also measuring cable + cell resistance. So will be much higher reading. You can use your new toy to measure motor impedance, and cable impedance too. Try it.

Its a bit like all tools. A socket set or spanner is not much use if you dont know whats inside your engine. But eventually you learn by doing.

The battery loom on a stock chair is around 35mOhm. More than your cells. They should be if 200Ah, less than 1 each. In series = less than 8.

Readhere to see how internal resistance changes with state of charge. https://batteryuniversity.com/article/h ... erformance

[Burgerman]

And then look here.

This is a healthy A grade cell! Measured at a not full or empty state. Note voltage. direct with no connections or wires. Because they may be more than the battery own resistance. At full charge it may be 3 times that.

[expresso]

right - thats the tool i got now - and when i checked them single no wires etc, it showed a much lower IR - less then 2

i dont know if it was full or not so full when i checked them

with the PL';ploi8 8 single cell charging etc, i have maybe 2 1/2 feet of cable with alligator clips soldered - and during the whole charging stage - i looked at the IR tab and seen that the numbers way off - so i though the cell may be bad - but doing a 2nd and 3rd cell - all showing the same - i am not so worried now

i plan to put the pack back this weekend - and see how it works out as a pack - graphs -

i hope its better and dont have one cell lacking behind a bit - that would be perfect - if not - i hope its not worse than before at least

i never bothered before since its not a big deal - its an ADD ON - worked fine - just that one cell - which may not be the cell itself - could be the wiring - balance wire etc, -

i redid them - but not 100% with the interconnects - they be fine but i wouldnt use them on a Real in the chair pack - this was a quick thing i used what i had - didnt want to buy the ring terminals again - i may have to if this dosnt work out - i dont have enough to do it again -

anyway - i see on the weekend -

also - i did get those Blue rings for the balance wires - - and they do feel better the ring itself - thicker stronger than the 3M insulated with the glue that i been using all along - i will use those going forward as you suggested - solder just the tip and crimp it a bit to hold the wire in place - - i will try a few of them first with loose 22awg wire before actually making the real ones -

i have a ratchet crimper - that will only release when fully done - i have to see how it can use that - maybe try it on the larger setting so it wont smash it down too much and can release it to open - - i can try with the blue cover in place and without to see which works best -

[Burgerman]

with the PL';ploi8 8 single cell charging etc, i have maybe 2 1/2 feet of cable with alligator clips soldered - and during the whole charging stage - i looked at the IR tab and seen that the numbers way off - so i though the cell may be bad - but doing a 2nd and 3rd cell - all showing the same - i am not so worried now

Thats because the PL8 is measuring the cables, the push in banana plugs, the solder joints, and the croc connection to what? A bolted on connection? So it adds up all the resistances and displays that as the resistance it sees. All much higher than a good cell.

[expresso]

yes thats good to know - i was worried that the cell was bad -

since the rest are all showing the same when charging it this way - i am not concerned now - and can just charge them each and build it this weekend - and then see how it is fully done

checking them single with nothing connected - not sure what stage they were in - there were not empty for sure - maybe closer to the full stage - all showed a much lower IR - under 2 for sure - i recall more in the 1 and change

i see over the weekend how it works out -

[Burgerman]

At 2mOhm its not great. It depends what the new ones measured. And C rate. If it measured say 0.3mOhm as in those good cells above that mean its SIX TIMES better. Six times lower resistance, 6x less voltage drop under load. 6x less voltage rise under charge...

2mOhm x 8 cells meand 16mOhm total. A new MK is 4 to 4.5. A new odyssey much better for sport is 2.5mOh. So 5 in total.

If they start at .3 and go to .6 then thats bad news. Double the resistance.

[expresso]

i dont know what these were when i got them 5 years ago

they are 3C steady and 5C short burst - 60ah i am sure there were not new cells - i can say i get about 55ah out of them some a bit less at 53ah

the post above shows the pack IR tab from PL 8 if its not great - then its not great - but they work fine enough as an ADD ON - not going to stress this - as long as it shows a good graph when done - when they are no longer working or not enough for my needs - then i worry about getting another 8 -

i still have the 80ah ones i want to try to repair - over this winter and see how they hold up -

[expresso]

i do remember the specs when i got them

they were said to be under 2 mohm - that was 5 years ago - so i am not surprised too much - since learning more how they are selling these things - i dont think any of these cells i purchased were ever Brand new grade A - only the headways were -

now i know better to ask specific - and in doing so - i am getting answers like - yes brand new Grade B on some - i found some that state brand new Grade A also - then comes down to costs

moving forward i would shoot for Brand new grade A if i were doing a full Chair pack - with ADD on packs - not stressing that much - the cost isnt worth it for that purpose - i found Brand new cells Grade B - 60ah - good price - i would get them if i needed them now for an ADD ON - but i want to try to use what i have already first

this 60ah and 80ah if i can manage to fix it - re drill the holes - if i manage to save that pack - i can use either then - i am tempted to get another 8 cells - prices are good - but i have too many add ons then - i wait and see how these work out first

[expresso]

https://www.aliexpress.com/item/1005003 ... 2e0eovJpmt

these are the cells i have - i didnt get them from this seller - but the cell size etc, 60ah is the same - specs same as i remember

being an ADD ON - the 3C and 5C rate got me interested - so 5 years ago i knew less than i know now - and i still dont know much now so considering

i always had that one cell a bit behind the rest from the start - i just didnt bother with it since it was minor and just used it this way - i just got the itch now to just see if i changed the cell - if it resolved it - and it didnt so its not the cell

i got 5 years out of them - if they died today - i be fine and not upset about it

Now with a full in the chair pack - different story - i would want the best cells i can get and do a much better job with the wiring interconnects - i dont want to remove the packs once inside the chair - and so for - i didnt have to - just the small ADD Ons i am playing around with -

[Burgerman]

i always had that one cell a bit behind the rest from the start

Could be that the best capacity cell. Could be that its the highest self discharge cell. Or both. Could be from a different batch and so slight chemical changes that change voltages compared to the other cells. Could be higher resistance and so wasting more during discharge. Could be a disimilar metal somewhere causng a slightly different mv reading. The only way to know is touse measurin tools and by logic and reason. So that your methodology is correct.

Because "a bit behind" doesen tell you anything.

[expresso]

i took a guess that was the reason it was a bit behind - what do i know - first thing would have been - like you said -check each cell with tools -

i knew my cabling wasnt the greatest on those inter connects - but it didnt bother me then - it worked fine enough for my needs then - i stopped using it years ago - and had it on my indoor chair - now i have the smaller 36ah on my indoor chair and was going to use this 60ah on the bounder

unless i fix the 80ah - this is the reason i decided to take it apart change cell - now new wiring - i still dont like how the interconnects came out - but should do - or else have to redo them again - i dont want to buy more stuff for this pack - its the only one with different sizes of studs etc, if there were M6 - i have plenty of those laying around now


as long as it can get me by - enough for the day with the bounder - i be ok with it - -

i was going to lend it to my friend on his bounder so he can do more - with me together - i made him the cable to connect it etc, - but he never used it - dosnt ride as much as me - i was doing him a favor - i would have to install it and remove it to charge it each time - if he wanted - not to leave steady on his chair

hes not interested in doing anything - and now - no pl8 either so forget it all together -

[expresso]

https://www.aliexpress.com/item/1005003 ... 2e0eovJpmt


if i had to buy cells for ADD ON - i wouldnt think twice getting these - the price is great - says Brand new - but i am sure its Grade B - i still would take it -

if you had room inside the chair to fit 16 of them - and were on a budget - still cheaper than a pair of MK 24 - lowest i seen them so far

[shirley_hkg]

Measure at the cell's electrodes , if you want IR of the cell.

Tapping at other places will add resistance to the true value, say terminals/lugs, dirty contact surfaces. Further away from electrodes , higer the value.

If you used LOCTITE , do check the surfaces for its residual

[expresso]

i did use loctite - i had to clean all the Nuts - good - to reuse - cleaned the terminals - i am charging each cell up - this weekend will put back as a pack and see

i will check again using that tool

one thing about that tool - it uses a battery inside - are you suppose to charge that thing or have to change the battery when it dies etc,

how do you open it to change the battery ? the same tool you got from china

[Burgerman]

Charge it. Micro USB cable same as many devices use.

[expresso]

oh i didnt notice that

i have it in the box still - i should charge it then before use

[expresso]

i redid all the connectors interconnects and balance

i never labeled the cells - so when i took it apart - they got all mixed up - before i took it apart - cell 3 was the weaker one

now its cell 2 - which i am sure it was the same cell 3 as before

doing a full discharge its the weakest of the bunch - Cap is at 52ah - the rest may have been good for about 55ah

these were sold as 60ah cells 5 years ago - and it never had the full 60ah then - the cell 3 acted the same way from day one - when tested it was at about 55ah Cap.

now after 5 years of use - as an ADD ON - its more or less the same - maybe a bit less now but not by much -

i wont invest in anything else with this pack - it will be used as is till it dosnt give me enough range - then retire it to my indoor chair -

looking the IR - its the lowest of the bunch also -

will be moving on to the next pack - 80ah thats the one i want to redrill for M6 and check all of them - if i can manage to repair that pack - i be good for another 5 years between the two - still have a 45ah headway pack also - still going strong

a small abused 60ah pack still going 5 years later - and many more years to go in use - cant complain -

[Burgerman]

So theres not much wrong now?

Making all the loom properly fixed it then?

Does it not worry you that your bounder pack may have all the same issues but you cannot know.

[expresso]

no nothing is wrong but its the same way it was really - that one cell is still lacking behind the rest

its the first to discharge - its not too bad - and i used it this way always - i was hoping to fix that one cell that is behind a bit - to keep them all closer -

when i changed cells - it didnt do anything - so i ruled out the cell - then i changed all the rest of the wiring and balance ring ends -

i am not stressing this no more - it will stay this way and i will use it - i know better when its in use - if its enough to get me thru the day with the bounder

i hope to get the 80ah fixed - re drilling the holes - M6 repair kit - and if not worse case i have the 45ah headways - and those are GOOD -

150ah - total is good for the day - i am glad i did the wiring again anyway - the innterconnects - one broke - - the balance ring end on a few of them were a little mangled up -

in the end - this is a solid 50ah pack -

the bounder battery - who knows - can be just as screwed up or not - no way to know - have to just use it and pay attention - all i can do is watch the number on my JS on the bounder -

i got used to how it works and how long a number stills - etc, - yes i now it can change daily - not always the same - but its how i knew something was wrong before - with the ADD ON because of the numbers

if i see those numbers drop faster than i am used to and depends how far i went already - i know something is wrong or out of wack somewhere

it sits on 9 then 8 for a long while - i shouldnt have a 7 till i am on my way back from the long ride i take - if i get it on the way going - i may be a bit concerned - i will have to feel it out

best i can do - or add a larger ADD ON - like 100ah - to be sure - i found some cells - same size but 100ah - they say brand new - but i am sure its grade B for the cost - but thats ok for an ADD ON -

who knows what will happen with the bounder battery - if insurance will even pay to replace it - or i have to make my own -

all these low cost cells i see - hard to know if your really getting a brand new Grade A cell even if they say it is - watching youtube - so many of them all bullshit -

but cost wise - you have to consider them if its in your budget - i know now for sure - all cells i ever purchased were not Brand New Grade A - none of them except the headways -

i know better now - ask more detail questions - i want to get it in writing or emailed that its Brand new Grade A never used - QC label in tack - full Cap etc,

this way i have something to prove in case they are not when tested -

you have to wonder - you see many cells - all same size - different Caps some say 230ah - some say 240ah - some say 200ah - 176ah - yet all same cell size i

they are used cells rewrapped - and sold as ever they have in Cap. - thats why you see some cells say good for 2000 cycles - yet the same cell Brand New is 6000 cycles - it was used and already 20% if not more is gone - they relabel it as what ever Cap is there - and sell them as such

wont be a while till i need a full in the chair pack now - but its a tricky purchase - i would hate to buy the expensive ones and find out they are the same as the cheaper ones - then the fun starts to get your money back

[Burgerman]

But now you understand the importance of quality matched cells. perfect clean terminals and balance wiring and all soldered with similar metals like tinned brass terminals everywhere.

How to use your impedance meter.
Fuuly charge all your new cells. Or old ones.
Individually discharge each one by around 50 to 60 percent.
Measure each one at the same temperature the following day. Make a note of readings. They should all be both LOW and the same plus or minus 10%.

[expresso]

Yeah somewhat better understanding. Balance wires will use new blue rings. will do them as u suggested now.

Matched cells very important its finding them the hard parr. I have to believe the seller. The last batch I got in my new chair were not new the looked nice clean. But had 185ah. Not 200ah as stated they think we r stupid. They show the data when. Fully charged may show 200ah. Buts it's the discharge total u need to have 200ah. I got great deal with those. FREE in the end. I rather not have to deal with that again and get new grade a calls. Not bullshitting. It cost them this time.

[Burgerman]

I have to believe the seller.

No. YOU have all the tools to check impedance, capacity, self discharge rate in your flat.

[expresso]

yes i do but only once i get them here -

you have to still hope you find a good seller and trust them - so far - dosnt seem i have the luck with that - they all seem nice during pre sale - its after the sale thats the problem -

first thing i do once i get them - see how they look - no damage on the box on the cells etc,

QC label - should be there - but they either not there at all or scratched off -

so next thing - charge full - discharge full - if the Cap. dosnt match - now your problems start

from now on - i will also check IR with this tool - just to have a base line - i wont buy any more cells that are not laser welded studs on top at least M6 size - i notice some of those welded studs also are not large enough the base that your Rings lugs will sit on - its raised from the cell with a smaller round surface
they could have - should be a larger surface

some i found with a square surface which may have a better contact - but they have to be welded studs - from now on - not dealing with adding my own - even if Cells are brand new - dont want to deal with that - its too easy to strip them -

i would keep asking if the Cells are Brand new grade A never used - matched Cap and match IR - and will tell them i will test each and every cell - the looks and appearance also matter - they should look the same - and always will use my Credit Card for the purchases -

have to remember to ask for the data sheet for the Cell and maybe even weight them - to see if they match the data sheet - i would need a scale for that then - but its another thing to check - if the weight is totally off - could be something