PINNED - Lithium battery conversion/info

[expresso]

http://www.ebay.com/itm/Bontrager-5Nm-P ... 1874799853


i got this one -

[expresso]

How fast i can discharge the pack with the PL 8 - ? i want to test it again - wont ride - just discharge it deep enough and recharge -

can i discharge at 10A or more a hour ?

[Gnomatic]

How fast i can discharge the pack with the PL 8 - ? i want to test it again - wont ride - just discharge it deep enough and recharge -

can i discharge at 10A or more a hour ?

Will discharge your pack at 25A.

http://www.ebay.com/itm/divert-dump-loa ... SwJ7RYUB9K

[Gnomatic]

http://www.ebay.com/itm/Bontrager-5Nm-Preset-Torque-Wrench-4mm-Hex-Allen-Fitting-8401-New/252676472548?_trksid=p2047675.c100011.m1850&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D40130%26meid%3Df2069c06f7ac43e881f3346a02533b4a%26pid%3D100011%26rk%3D1%26rkt%3D5%26sd%3D111874799853


i got this one -

Thanks. Since you didn't seem to overtighten your cells with a 5Nm wrench, I assume I won't either,

[expresso]

no idea what that is - i can use the PL 8 to discharge - just not sure what is the fasted i can set it on the PL 8 i just want to discharge about 80 ah

thats deep enough to recharge and see - will try 20A discharge if it allows me - get it done in 4 hours tomorrow - then recharge -

[expresso]

this may be a better graph now - maybe i wont need to remove it after all if it keeps getting better after a few more cycles ?

[shirley_hkg]

Do you still have access to these cells? If so, what would there price be in USD? If any info on the background of these, it'd be much appreciated.

Thanks!

Seller replied these were sold out , when I asked him about their IR .

Similiar NOS items are all over Taobao , and prices are not much differ from mine quoted above .

[Burgerman]

Expresso, what was the volts of the cells BEFORE you start to charge?

[expresso]

Expresso, what was the volts of the cells BEFORE you start to charge?

i will check that later tonight when i recharge - i am discharging it now with the PL 8 - tonight i will recharge it again - and check first - but i noticed it now even during discharge when it started etc, - Cell group 1 is a bit below the rest of the line -

its a few mAh i think - 3.148V - compared to 3.150 for the rest - its close and closes the gap within a minute - i post it back either later tonight after i charge or tomorrow - now that i think about it - the last time i did take the pack out was to add the breaker - and change the power wires - which i did have to remove the top Row - thats the only thing i can think of - if this dosnt fix its self after - i may have to remove it again and double check the top row -

bummer - but what can i do -

i may just redo the wiring for the top row maybe - if i dont find any loose screws on the top row - then i would be lost as to what to check or do next - i checked my charges i did for this year with the chair which i didnt use from last year

first charge seemed fine - second one i seen the change - now third yesterday - still a lazy group much much better than charge before - tonight would be the fourth charge after i discharge - we see - but i have a feeling i have to check it out of the chair - have to call tech to take it out for me

[Burgerman]

Its likely a loose screw, one of any of them... Or it might be nothing more than the resistance of your charge lead / harness. After a few miles if all voltages are pretty similar, say half discharged, then don't worry.

3.148V - compared to 3.150 just 2mv! Thats just a 500th of one volt! If they were 15 to 20mv apart I may worry a tiny bit.

[expresso]

Its likely a loose screw, one of any of them... Or it might be nothing more than the resistance of your charge lead / harness. After a few miles if all voltages are pretty similar, say half discharged, then don't worry.

3.148V - compared to 3.150 just 2mv! Thats just a 500th of one volt! If they were 15 to 20mv apart I may worry a tiny bit.

i will make sure to check it this time to see before i recharge - that was an example - it was close - and the gap closed with in a Min. to even - the only screws i removed was the top row when adding the breaker - when i take it out to check - not sure when now - i be happy if i find one loose there at least i would know and can just re locktite it and tighten it down better.

the problem with the top row is i cant use the wrench to tighten it - i have to use reg. loose allen key first - then use the wrench - because i cant make a full turn there - so its possible one of those screws could be it - and its only the top row in the front where i have to tighten it down this way - the rest was fine doing it with the wrench -

[Burgerman]

Check ALL. If you failed to solder any connections and relied on a crimp (spits! shakes head), that can also be a problem and unless done exceedingly well, and it usually is the problem...

[expresso]

Check ALL. If you failed to solder any connections and relied on a crimp (spits! shakes head), that can also be a problem and unless done exceedingly well, and it usually is the problem...

i did both crimp and solder - the pack was solid - all last year i have to remove it once before - then i had to remove it to add the breaker - i think that may have been it - if in fact i find a loose screw there -

i have to make a charge cable to test it now outside of the chair - if i find a loose one - i will fix it on the top row i bet -- - i hope - i can then test it first again discharge - and recharge to see the graphs - if its good - not need to remove the top row - or touch anything else -

if the graph still shows something - then i guess i have to remove it and double check - at which point i may even make new wires with the new heavy wall lugs i found - that would take more time - i see which is best way i guess -

i feel the bottom part is solid - 90ah - i never touched that - only removed top row to change the power cables on the ends 0 and 8 - and used heavy walled lugs - then i had to remove it again when i added the breaker - never used it since really till now -

i may be lucky if the tech can remove it for me tomorrow - he may be around in my building for someone else -

[expresso]

Discharge graph

then i monitored it for few min.

[expresso]

i recharged - this graph looks fine - maybe i have to use it more and cycle it a few times to get it back to normal

[Burgerman]

Yes maybe was a little out of balance due to storage.

Go a little further. And then check. Or take out say 65Ah.

[expresso]

i will try to run it down some today if i can - its not as sunny out today - i see if its too windy or not - its not that easy to get over 25 miles - i have to actually work i want to get it at least 20 miles and over today and see

i hope thats all it was - since my tech isnt coming here today as i expected yesterday -

[Gnomatic]

I assume its the Blue Loctite 242 that we're supposed to use assembling packs.

Any reason not to get this version over this one which is supposedly newer but costs almost twice as much?

BM I know you prefer not using the stock lock washers and instead just rely on the Loctite. Is there any disadvantage to using the stock lock washers, or ones like Goose mentioned, in addition to the Loctite? Or are the washers just plain unnecessary if Blue Loctite is used?

[expresso]

https://smile.amazon.com/Loctite-Heavy- ... ds=loctite

i used this one - -

[expresso]

30 mile run - to test it - monitor - shows its off

3.280 all the groups -

Cell group 1 - 3.275

recharging now and i noticed that Cell 1 group dropped a bit and back up after 35 min into the charge -

so it looks like i have to take it out and check it -

[expresso]

this is after 30 miles - i think its very minor if it dosnt change from this - but never the less - its on my mind and i have to check it - so i will remove it once i get the tech to do it for me - and recheck it - it has to be the top row - thats the only thing i touched -

if i dont see anything out of place on the top row - i will remove it and start over - every screw - plate - clean sand it and redo a few wires with new heavy wall lugs -

if i have to do all that - i will even add in a lock washer to be sure this time -

here are the results - what do you think BM ?

[expresso]

i removed the pack and everything is tight on the top row - but i did notice that on Cell 1 - too much glue - the others on the top row look fine - the Ends 0 and 8 are fine -

i will remove the screws on the top row - just leave the ends alone - on the front - - remove the rest on the top row - front and rear - and clean sand the lug a bit - etc,
clean the screws - and reinstall -

then test it on the bench - i will do a few discharges and recharges - if that shows up good - then i wont touch the rest of the pack and pack it up again to reinstall

this must have happened when i installed the breaker -

[Burgerman]

If all connections are tight you may have one cell not as good as the rest in group1. Less capacity. You have 2 spares... Difference is only very slight. May not be worth worrying about it yet. Make sure you dont leave your spare cells to go dead. Charge each one, remove about 1/3rd the capacity. (5Ah.)

[expresso]

Ok - i will just try the top row - the inner cells - in the front of the top row - will remove - clean up contact - put back - and do the same for the rear of the top row cells - i wont touch the 0 and 8 cell because those are clean in the front -

and retest it first on the bench for a few cycles - i have to believe if anything its one of those contacts - and Cell 1 does look like its too much overflow - me trying to be sure it wont come loose - may have over done it when i added the breaker -
i had to remove that top row - nothing else was touched - and everything worked fine all last summer - i havnt used the chair since last summer - so when i touched it for the breaker is when i did it - and i hope thats all it is

hopefully in a week i will know - will start on it later today - it cant be too bad if it stays this way - the numbers showed 3.280 for all of them except Cell 1 group 3.275 - once charge stared its even in a 30 secs

thanks

[Gnomatic]

expresso, not trying confuse, but group "Cell 1" as it appears on your PL8 graph is NOT your top row of eight cells. You have an 8S 7P pack. In other words, you have 8 groups of 7 cells wired in parallel. So group "Cell 1" as it appears on the PL8 graph has a total of 7 cells. What your top row does, is add a single extra cell to each of the eight parallel groups(Cell 1 - Cell 8 on the PL8 graph) in the main part of your pack below.

My point with this, *IF* you have a single cell that has aged a bit quicker in group "Cell 1" as appears in the graph, there is a 6/7 chance that the POSSIBLY going bad cell is in your main pack on the bottom.

You just need to trace your balance leads to the connector and figure out which of the 8 rows of cells has the balance lead connected to it that the PL8 reads as group "Cell 1." Kind of hard to make out from the pic below, but you should be able to figure it out by tracing the leads.

That will tell you which group of 7 the *potentially* going bad/quicker aging cell is in. As it stands, group "Cell 1" is not very far at all off from the rest. Just something to keep an eye on at this point in time.

[Burgerman]

Resist the temptation to touch your tongue on those terminals.

[Gnomatic]

Resist the temptation to touch your tongue on those terminals.

Its the only way to know for sure!

[expresso]

Oh you didnt confuse me - i been confused a lot time ago

the reason i tackled the top row was because its the only thing that has been touched since i done it - i am lost if i had to really find a BAD Cell if it comes to that -
i already did what i was planning and its discharging now - since its slow - i will stop it later tonight and restart the discharge tomorrow - - then i can recharge and check -

i will try to do this a few cycles to see if anything changes -

what i did find on the top row was - many had too much Locktite - and i found 3 screws which didnt have any - how i did that - dont know - those 3 screws where not connected to any wires - -

i removed one connector at a time - cleaned the screws - connector - lugs what ever it seemed to need and did both front and rear of the Top Row only -

if this dosnt fix it - then i either use it this way and watch it - if it dosnt get any worse - i leave it alone - or if it does - have to take it apart and start over -

i rather do that in the winter if thats the case - and i rather use new screws - which i dont have - would anyone know the size i need to purchase ?

maybe a link to the correct screw - i would just buy enough to replace them if i have to redo it - not trilled about the idea but what can i do

i have no idea what the PL 8 thinks Cell 1 group is - i dont want to think about that right now -

[expresso]

First discharge about 16ah - then monitor it for 20 mins - looks great - - then recharge - looks good - then monitor after the first recharge and its better
but still off by about 1 to 2 now instead of 5 before - it varies from 1 off and then goes to 2 off from the rest - then the rest all drop and its only 1 off again -

its better - will continue to repeat this process - during this week to see if it improves any - i was hoping this was it - -back to drawing board

[Burgerman]

As you charge or discharge theres a point around half charged where all the cells voltage changes. A step...

Its only at this step that you are seeing a problem. The step happens sooner or later on that group number 1. You wont see it unless you discharge further than say 50%.

Meaning it has a slightly lower capacity. That could be a cell, with a little less capacity or a bad connection on a connector, balance wire, or bolt. Usually a bolt...

Only on one of the 7 cells in group 1.

The only danger is that as you reach 40 to 45 miles that group no 1 may run out of power before the rest and go below 2 volts. Which causes damage. So your real question is does group 1 go out of power and voltage fall fast before the rest do? The reason that Shirley inc a cell monitor is so that you can see if that happens .