PINNED - Lithium battery conversion/info

[Burgerman]

Dont know. You wrote many words, but no idea what you are describing.

You reassembled the pack.
You fully charged and tested those 7 cells. You now have 7 good ones. And all connections are also tight.
And then you fully charged the pack.???

Correct?
And now discharging? The screenshot?

If so you didnt do some of the above correctly...

Or you didnt charge it yet??? Or is that chart just monitoring?

Not enough info. You MUST charge and balance the pack before discharge.

[expresso]

OH -

I put it all back together and then connected to the PL 8 - and monitor - - that screen shot was a monitor before i did anything at all -

now i am discharging it - i may have a chance that it will fix itself - ?


all screws were checked - all of them - i used new screws on the cells i removed them from - replaced the bad cell - to best of what i know - i believe i did it correct -

i did not charge it fully before i started the discharge - i thought i had to discharge it first -- then fully charge balance it - then discharge it again and repeat a few times ?

its a hour in the discharge - should i stop it - charge and then start discharge again or just leave it now ?

[Burgerman]

OH -

I put it all back together and then connected to the PL 8 - and monitor - - that screen shot was a monitor before i did anything at all -

now i am discharging it - i may have a chance that it will fix itself - ?

Stop discharging it will accomplish nothing useful yet!
Charge fully. When it stops, do it again half a dozen times so we know its properly balanced. (or as I said in a previous post that you ignored) set termination to a LOW level so the cells balance properly. Read back!
Set termination to 500th or 1000th C and for 3.65V for this one charge to correctly balance everything. 1000th C means 105mA on a 105Ah pack. Set anything between 200mA and 100mA. THIS charge ONLY! (150mA good choice)

It will hold all your cells FULL for long enough to ensure that the whole pack is fully balanced.

Then and only then, monitor it. And if that looks OK, then do a discharge test. You will likely find that swapping that one cell means its fixed!

[expresso]

Ok i changed the charge to 3.650V - term. 150mAh - and started the charge - for this charge only - then change it back to 3.6V charge and Term. was 200mAh - or leave it this way for the first 4 or 5 recharges before putting it back to the way it was ?

sorry i misunderstood the steps

[expresso]

first charge - now will set it back to 3.6V and 200mah term.

[expresso]

ok after 6 charges - the graphs looks OK for the 2nd charge up to the 6th - then i monitor it - and i dont think its holding up -

i will start to discharge it till i go to bed - then start again in the morn. and do a recharge - then a monitor again - but i dont think its going to fix it -

looks like i have to take it apart and replace all 7 Cells to be on the safe side - ?

[shirley_hkg]

Found one similar , 100Ah rated 2C , tested @98.5Ah .

@ £25.00

[shirley_hkg]

Found this too , and think you'd give it serious thought .

Look at the super low internal resistance , and tested capacity .

I'm quite confident that you can fit 16 of them in it , and that's 150Ah .

Should be good stuff . 0.36mOHM @ 2.65V That's really good , itsn 't it ?

@£17.00

[Burgerman]

1st one ok, but prefer the 125Ah one.
2nd one too tall...

[Burgerman]

Expresso, charge all, remove connections on all 7, replace the cell that falls lower... You dont need replace any that are ok.

What maybe happened is that one bad cell allowed all those to go lower in charge in that one group last summer.

[shirley_hkg]

1st one ok, but prefer the 125Ah one.
2nd one too tall...

Suppose you lay them flat , 16 cells , you need space :

L 135 + 135 + 29*3
W 215 + 29
H 29 * 6

Of course , you do need extra few mm on each size for bolts and insulation too .

[Burgerman]

Will work it out on paper and measure. But they must be new, not used or old stock. No point building an old battery...

I have 340 x 260 x 190 high. I cant figure out how you are fitting 16?

(L) 260mm x (W) 170mm x (H) 190mm each.

[expresso]

Expresso, charge all, remove connections on all 7, replace the cell that falls lower... You dont need replace any that are ok.

What maybe happened is that one bad cell allowed all those to go lower in charge in that one group last summer.

i already charged them all - all 7 were checked -- i did find one or two a bit lower than the rest - but all showed 3.4v when i check with meter

the bad one showed 1.8V now after a few days sitting out of the pack - the one that i couldnt charge at all - it first showed 2.4V

i am still going to discharge all day today and maybe tomorrow - i want to see how the graph shows whan i take out about 30ah and more - if any line falls out of the rest -

if i have to take the whole thing apart - and take a chance with one or two other cells - i might as well change all 7 and then i know for sure -
turns out i have the Cells sitting here - was going to use for the ADD ON - 45ah pack - - if after this discharge and recharge and monitor - if its still not good -
then i will replace them - using the new Cells i have - and i can either make a 30ah pack instead of the 45ah that was going to do - but i may need more orange blocks anyway - if i take the large pack apart - i may break them in the process - so i may have to place an order for those orange blocks

is EVassemable still the best place to get these items and Cells or is there a new better site to check out ? summer is close and i dont want to waste it checked cells now - i have a good month left to get this going - once june hits - i want to be riding - cant afford taking chances - and i have the cells here anyway - i can use the old cells to make that 12V pack i wanted for my PTA thing - so maybe wont be wasted - maybe a slim chance this will work out when i am done discharge and recharge -

since i am going to order new orange blocks etc, - maybe i just get another 8 or 10 Cells and still make the 45ah pack with a few cells extra left over ?

i have to decide in the next fews days when i finish this - i was not expecting this to happen this soon - not even a year in use - now i am worried - Ten years in use - not sure if i will make that mark -

thanks to Quickie - shes been helping me with this - couldnt have done it this fast without her helping me -

is they are any chance - any balance wires are bad or any wiring at all ? they all seem good to me - just curious - if i have to take it apart - wonder if i should make a few new wires - i have new lugs i like better - but dont want extra work for nothing - only if you think theres a chance it can be a wire - either balance or what ever etc, ?

[expresso]

here are all the graphs for the 7 cells in the pack now - some of them - just hit 14ah returned - some barely hit 14ah - and a few better ones closer to 15ah returned which that cell was one of my spares which i used to replace that one bad cell i found -

they dont seem TOO BAD all of them - but i guess its showing on the graphs -

[expresso]

next 3

[expresso]

last one

theres are in the pack now - discharging the pack -

[Gnomatic]

Found this too , and think you'd give it serious thought .

Look at the super low internal resistance , and tested capacity .

I'm quite confident that you can fit 16 of them in it , and that's 150Ah .

Should be good stuff . 0.36mOHM @ 2.65V That's really good , itsn 't it ?

@£17.00

I can fit 16 of these. My box is 346mm L x 260mm W x 240mm H. Would work in either my backup chair or main chair.

For the price, 16 of those is less than a pair of MK.

Shirley do you know anything on the history of these? Are they new, used, new old stock?

[Burgerman]

Supposed to be old stock. But how old, and how do you know how they were stored? Or used...

[Burgerman]

i have to decide in the next fews days when i finish this - i was not expecting this to happen this soon - not even a year in use - now i am worried -

You worry too much. Theres a reason. Not sure what since I am not there. But the other groups are fine. And all my three packs are fine. And one is 6 years old already. Shirley too has old packs.

You may have run it a bit low, and that one group went low first before the rest as one always does. Thats why you need to monitor with the cell meter from Shirley if you plan on running to say 90% of the range. So you can monitor what it does on a cell group basis. I use one to check and watch if its getting towards the 35 to 40 mile mark. Because suddenly one group reaches empty and drops fast.

Charge all 7 cells. Then disconnect them. Leave for a few days. See if any have lost voltage more than the rest.

[expresso]

i checked this morn. before i started to discharge again - monitor just to see - was fine - i will discharge much much lower first to see how it does - before a recharge and then monitor for a hour after that - to see if it falls out of line and how much - maybe it may just even out after this -

i will make the Cell monitor after i get this resolved - but it still shows a group avg. - and i remember the group Volt was about 3.1V after the 40 mile run which put back 95ah when i recharged - according to PL 8 when i got home to recharge

theres no way to know each cell with the cell monitor either - i see after i recharge again - what the next step i should try or do - if they look bad - i can replace all 7 - and instead of making a 45Ah pack - it can be 30ah pack - and i can use that ADD ON with the chair all the time so 105ah plus 30ah - should ease the load when going down low - ?

i would hate to waste time taking it apart those 7 cells again if i am just going to monitor then for a week ? i have to place an order for those orange blocks and 4 hole connectors to have in case i need to replace them all - not sure if i should get a few extra cells now or not - i dont understand why we can buy these cells here in the states - only from China it seems

if the graphs show somewhat OK - maybe its safe to use this way for the summer and then take apart next winter ? Can this be contained to only Group 1 going bad ? or will it continue to the rest of the groups - i would think group 1 would have to all go bad down low enough to start on the next group ?

[Burgerman]

i will make the Cell monitor after i get this resolved - but it still shows a group avg. - and i remember the group Volt was about 3.1V after the 40 mile run which put back 95ah when i recharged - according to PL 8 when i got home to recharge

Thats off load. Will be less as you accelerate or turn.

theres no way to know each cell with the cell monitor either -

Yes there is. ALL 7 are bolted together so are the same exact voltage as each other. You only need the volts for each group.

i see after i recharge again - what the next step i should try or do - if they look bad - i can replace all 7 - and instead of making a 45Ah pack - it can be 30ah pack - and i can use that ADD ON with the chair all the time so 105ah plus 30ah - should ease the load when going down low - ?

You could. Or you could find which one is still faulty. By charging and waiting...

[expresso]

from those graphs i posted - those are the 7 cells in the group right now - i can see at least 3 which are below the rest - OK you suggest i monitor this after i do a good discharge recharge - and if its not good - remove the 7 again -

charge each cell again - and leave it alone for a Week - check the volts after and replace any that fall under 3.4v ? - i feel if i have to replace 3 Cells - i might as well replace the rest and start off hopefully with 7 good ones ?

i have the extra cells sitting here for over 2 months - i can recharge 7 to see how much they lost in that time and try to use 7 of them which are close enough to each other - i dont mind another week of trying - but if i want to get going in June - i need to get going now will take weeks to get something from china if order in the next day or two -

the Cell monitor will have to be on my list to make and use now -- will find it later - i felt the pack volt was fine after the 40 miles - from PL 8 info - Cell groups fine also - so i figured i was OK

[Gnomatic]

Supposed to be old stock. But how old, and how do you know how they were stored? Or used...

At that price ..... cheaper than a set of MK's. If they turn out to be crap, no biggie. If they work as advertised, then its a win!

[Burgerman]

Theres many on ebay, or alibaba site cheap... But its hard to know why.

[Andrey]

Are you building a new pack?
Did you test all cells and charge before assembly? Because you would have found a bad cell before this point?
Are you sure its not a long thin CHARGE cable issue?

If not then you either have a bad connection like a bolt that you have missed and that is not tight, or a bad cell, or something.

A bad cell or bad connection / loose bolt will show in a full discharge test, as group 8 will discharge and drop off earlier than all the others. So do a discharge test. Set to 2.9V, and balance off. It will take a long time. Or undo all the bolts and connectors on one end of the cells in group 8. And test those alone, and test with a volt meter for obvious failure.

And before any of that it possible but unlikely that the charger itself is out of calibration. So if you have a GOOD volt meter with 3 or 4 digits after the decimal place, you can measure all 8 groups individually as it is discharging to be sure that what you see on screen is real. Must be good to measure a couple of mV. The figure you see will be different to the actual numbers on the charger because the charger charges and discharges in a high frequency pulse with breaks. And it measures unloaded voltage where you will be measuring the average. So ignore the difference between charger and volt meter.

Yes its safe to use. Has it just started to happen or is it a new pack? Does the voltage of group 8 fall faster than the rest after charge, if you choose to monitor?

I built this pack in September 2016, all cells was tested, charged, discharged (same amount of Ah), settled for few weeks and charged again. Combined in groups to have same amount of self-discharge before assembled in pack.
I can't be sure that the issue isn't because of cable (it is not thin, 12AWG silicone cable from hobbyking) but I worry about soldering for example, I did my best, but I had no experience before.

I did monitor test just after charge (first 45 minutes I did nothing, then I started to move chair). On group8 voltage drops more under loading.

[Burgerman]

Only by a few mV.

Drive it for a day, then choose monitor. And lets see how it looks with half a charge.

[shirley_hkg]

Found this too , and think you'd give it serious thought .

@£17.00

I can fit 16 of these. My box is 346mm L x 260mm W x 240mm H. Would work in either my backup chair or main chair.

For the price, 16 of those is less than a pair of MK.

Shirley do you know anything on the history of these? Are they new, used, new old stock?

Will ask seller about its quality and history .


It's made by ATL , that has good reviews on their products as I remembered .

[shirley_hkg]

For the price, 16 of those is less than a pair of MK.

16 of these cells do cost less than just ONE MK G24 gel battery here .

They ask £600 a pair .

[Gnomatic]

Found this too , and think you'd give it serious thought .

@£17.00

I can fit 16 of these. My box is 346mm L x 260mm W x 240mm H. Would work in either my backup chair or main chair.

For the price, 16 of those is less than a pair of MK.

Shirley do you know anything on the history of these? Are they new, used, new old stock?

Will ask seller about its quality and history .


It's made by ATL , that has good reviews on their products as I remembered .

Thanks. Consider me interested.

[Burgerman]

Same here, if I can fit them... Still dont see how. If they are healthy and as new. Or its a lot of work for nothing...