PINNED - Lithium battery conversion/info

[Burgerman]

Yes maximise capacity!!!

3.480V actually charges to 100%, provided you choose a low termination current. But it takes much longer at CV to charge and balance to a lower termination current.

The reason that the manufacturer says 3.600 to 3.650 is because of the typical useless innacurate bms balance capability.

If charged above 3.500v for long, then the cell is slightly overcharged, higher than its natural full resting voltage. So it affords some level of natural balancing and loses the extra as heat. The overcharged ones are already full and cant get fuller, but the low ones get pulled up still. This helps the typical useless 100mA bms balance capability to keep the cells in balance in a typical ebike etc with a dumb charger. And so results in fewer cells getting returned as faulty... Its about minimising warranty claims.

If we use the PL8 set to 3.500V and with its 1A super accurate balance capability, and throttling down to 10mA (or enen stop/Reversed) to avoid any overcharge, and set to begin balance from 3.400v to 3.500v (not less!) depending on charge rate, with a LOW termination point we end up with a 100% charge without volts being very high. So super safe and better service life than the 2000 claimed at 3.65v.

Doing the same with a BMS will work too to a degree, as long as the charger has some setting to terminate at say 1/500thC or lower. But the BMS will still allow individual cells to go higher repeatedly... In any case the cells only burn AFTER the BMS has failed shorted or its mosfets fail, and the thing has caught fire or the wiring has. Then it sets light to the plastic/etc

Best bet, throw it away its not required!

[shirley_hkg]

I was irrelevant. The pack caught fire when idle , not while charging .

It shorted on the main wires.

A better placement of fuse seems a more logical solution to this case, than a PL8 , itsn't it ?

[Burgerman]

Plenty are caused by the stupid bms mosfets failing shorted. Or balance failing shorted. Even when sat. But usually on charge. Like the boeing dreamliner... That was caused by BMS but ended in a fire because it used lico laptop style cells...

[shirley_hkg]

BM, I have a question.

Regarding the main cable, is it necessary to split into 3 , 4 ends in order to bolt it to several cells ?

[Burgerman]

No. The straps or bus bars on the headways are 1mm x 16mm. Thats a 16sq mm area bus bar connector! But several thinner cables are more flexible, so it can be easier. I dont do that though. I have seperate charge cables. Seperate power take off cables. Both fused accordingly.

[shirley_hkg]

Can't resist the price tag. I wasn't holding back and result in 114 pieces …… for no intended usage yet.

Totally, we have bought over 300 these Taiwanese 40152 15Ah cells.

[Burgerman]

Who are we?

How old are they? And what will you do with them?

[shirley_hkg]

Who are we?

How old are they? And what will you do with them?

THEY are two of my wheelies, at their thirties.

They are going to do 9P8S ie 135 Ah.

Mine are going to sit around , till I figure out what to do with them.

Shopaholic.

[shirley_hkg]

It's been a nightmare … trying to make connectors out of copper strips , not brass , used in electrical installations.

They are soft, and are easily pulled onto the drill bits.

[Burgerman]

Use the headway ones. Or cables and ring terminals.

[LROBBINS]

I've had no trouble drilling freshly annealed copper strip, but mine is probably thicker to begin with and I progressively increase hole diameter. Alternatively, clamp the strips between two pieces of wood and drill through the sandwich. Of course, I only have to make 6 strips for the aux (power distribution) module of the CANbus controller, not the large number you need for these batteries.

[shirley_hkg]

Yes, looks like a mould seems inevitable.

[Scollard]

Best way to punch busbars is to rent or buy yourself a hand operated punch.

[Burgerman]

Or use alloy bars anda drill press. Aluminium alloy is good enough for millions of miles of the worlds power grid. It is easy to drill. And brass too.

[shirley_hkg]

BM, did you cast your vote yet ?

IN... or... OUT ?

[Burgerman]

Out.

[shirley_hkg]

[Burgerman]

Those are headway cells. Came out of the same factory.

[shirley_hkg]

How can you tell ?

Start assembly it into 24V block, so I can run it for a few cycles , and to see if it is good .

[Burgerman]

How can you tell?? Because other than the plastic wrapper they look identical.

Why wouldn't they be good? Are they old or mistreated??

[shirley_hkg]

Why wouldn't they be good? Are they old or mistreated??

Anxious to know that too .

Just ordered tailor-made 6-hole connecting bars. Will come in a week. .

[expresso]

I am thinking ahead a bit here - but i am curious - is there a way if i make a pack with two parts - 2 12 volt packs and connect together -

but is there a way i can make the balance wiring for the two pack to be modular ? for example - place both 12 volt packs in the chair - connect them to make 24 Volts - and then connect the balance wires also - ?

the reason for this would be so i can easily install and remove one 12 volt pack at a time - is that possible ?

the same way you connect the two 12 volt packs - can it be done with the balance wires also - where you just connect them after you install both packs in the chair - if i had to remove them - i can just disconnect them again and remove one 12 volt pack at a time -

[Burgerman]

That's what my green chair is.

[expresso]

so it can be done ?

how do i go about making the balance wires modular ? so that each battery pack 12Volt would be totally separate from the other one and once place in the chair - just connected together - balance wires also -

do you have pictures of how this can be done by any chance ?

[Burgerman]

My charge cable goes from the charger to a connector on the chair, as yours does. From there it splits into 2. Each has a connector that uses 5 balance wires... The large wires still go to each end of the battery. There is a connection between the two batteries as well, just like your lead ones.

See the pics on the green chairs thread and look at the battery pics.

[Burgerman]

viewtopic.php?f=2&t=5380&start=160

download/file.php?id=4301&mode=view This is two halves.

[expresso]

that looks huge - but i dont see how you have the balance wiring in two parts ? separate from each half -

i want to be able to make two 12 volt packs - totally separate from one another - place them in the chair and then connect the wiring to complete it - balance wires also -

i am also looking into tires for the pilot chair - if i can find someplace to make me a spacer to fit my motors - - i want to give that a try - tubeless rim tires - i can even cut my fendor on that chair if i have to -

i will start another section for this - to ask you some more questions - i am still unable to break my 30 mile record -

i will give it a try on monday - wake up early and try for 40 miles - it feels great - now i want to see if i can work on the pilot chair - the one with the front casters i am doing now - want to see if i can do the rear tires also - and maybe if all goes well change that to lithium also maybe - if i see that i can do two parts - modular with all the wiring - i may consider it for this coming winter project i want to get the tires on first and see how it feels - if i can find someone to make me the correct spacer for rims with tires etc, to work - and cost is Fair enough - i do it -

[Burgerman]

i want to be able to make two 12 volt packs - totally separate from one another - place them in the chair and then connect the wiring to complete it - balance wires also -

That is what mine is. 2x 12V packs. 120Ah.

Look at the large battery charge connector. Close to it, is 2x 4S balance connectors comming from the big subD connector.

[expresso]

oh yes i see that now - thats great - so far so good - - i am not commited just yet to this project - but i see how it can work in some way - not sure i am want to use the 12ah cells - the space i have to make it fit in is tight -

one group 24 is sideways and the other is the long way - with a big cross bar over the top - so i need to make two 12 volts packs that i can place in there one at a time and then connect them both - - i like how the 15ah cells worked out for me on the 105ah pack -

this would have to be different - and maybe come out to only 90ah pack - not sure how i would fit the extra row on top - it would have to be 4 cells on top of each 12 volt pack - to make it 105ah - but the space is tight and the cover leans down towards the rear of the case -

maybe those new 16ah cells - use those and make two 48ah packs - connected giving me 96ah - that i think for sure would fit just fine - would be a huge improvement over lead with the ADD ON - but i would also make another ADD ON - using the same 16ah cells - either 2 rows giving me an extra 32ah or 3 rows making 48ah on top of the 96ah - would be a little tippy with the extra weight in the rear - but thats fine with me - with this chair - i like it - i have fun with the wheelies -

i can then gift my 36ah pack to my friend with the BMS - - i am thinking ahead - just thinking for now - i want to work on those tires first since the ride is tooo hard for me now - if i can solve that and get a nice comfortable ride out of it - then i can do this in the winter and make this chair a real back up - since i cant go back to lead - i did 30 miles today and felt great - but i need a nice soft ride to do it - or else i feel broken at end of day with a hard ride -

[shirley_hkg]

The first half .