Battery ADD on pack - First Attempt -

[expresso]

It's in your sequence, if you straighten the connection path.

Oh yes - i see it - whow took me long enough - haha - but still what difference would it be if i were to use wire number 05 on the first pack of cells where i have it labled 0 ?

i am just asking - i am not going to do that - but just to know - a wire is a wire - you name it what ever you like - so numbers mean nothing - - but theres a reason i am sure or is there not ? and its just easier to start at 0 and go in order

or start at 1 where 0 would be - and then the end wire would be 10 and not 9 --

i guess the question is - the numbering is for us to keep track or other reasons i am not getting yet ?

[Burgerman]

If you go LOOK at the page I keep linking to it tells you and shows you all this.

- + - + - + - +

Gives us a:
3.2v + 3.2v + 3.2v + 3.2v battery = 12.8V total.

So 0v at the neg left negative end. Then, every + cell connection to the right gives us, for cell one, 3.2v, cell 2 is 6.4V, & 9.6v, and 12.8v as we count along the four cells plus side. So the order matters. The balancer want to see the voltage of each cell.

[flagman1776]

Your smart charger or your BMS/dumb charger (both do the same job) needs to monitor & control each cell parrallel group to see which cells need additional charging & which do not. Thats what balancing is.
So it needs to have a wire at each group plus & minus. In a multi group series, the balance wires do double service for adjacent packs. Basically there's a computer hooked to these leads... which takes voltage readings of each cell group. It can't read the correct voltages if the wires are not where they are supposed to be. It will cause errors if the wires are not put on in the correct order.

[expresso]

If you go LOOK at the page I keep linking to it tells you and shows you all this.

- + - + - + - +

Gives us a:
3.2v + 3.2v + 3.2v + 3.2v battery = 12.8V total.

So 0v at the neg left negative end. Then, every + cell connection to the right gives us, for cell one, 3.2v, cell 2 is 6.4V, & 9.6v, and 12.8v as we count along the four cells plus side. So the order matters. The balancer want to see the voltage of each cell.

Ok so its the balancer that is expecting to see a certain volt from a certain wire - the first Cell at 3.2V - the first wire on the balancer end is expecting that and so that wire needs to be on the first Cell pack -

so its hard wired on the balancer end to work this way - the next wire on the balancer end is expecting to see the next value of 6.4v etc etc, and moves down the line - if i am understanding correctly -

if i were to connect the 2 wire which the balancer is expecting 6.4V and its on the wrong cell pack which is 9.6v lets say - its out of wack and what happens - ? the charger gives off an error and stops - if using a hobby charger - if with the BMS - what would it do - just not balance it correctly ?

[expresso]

Your smart charger or your BMS/dumb charger (both do the same job) needs to monitor & control each cell parrallel group to see which cells need additional charging & which do not. Thats what balancing is.
So it needs to have a wire at each group plus & minus. In a multi group series, the balance wires do double service for adjacent packs. Basically there's a computer hooked to these leads... which takes voltage readings of each cell group. It can't read the correct voltages if the wires are not where they are supposed to be. It will cause errors if the wires are not put on in the correct order.

i see - when using a hobby charger - it will charge up to the rate you tell it too - normally - and then go into balance mode and work it out based on the Cells - how bad they are off balance or not - the charger balance plug thats hard wired in the charger - you would plug in your balance wires -

that plug thats hardwired in the charger is what determines the order of the wiring -- the charger is expecting to see 3.2v on the first wire 0 and 6.4 on the next group etc, - so the wires have to be in those locations for the charger to work and balance correctly -

so its hardwired to work this way - i knew there was a reason or else it wont have to be specific -

i wont do anything else till i hear back from either Shirley - and or Scollard - which i believe he understands this BMS and how to connect it - - if i hear back today - i will continue it later tonight -

thanks

[Burgerman]

I suspect you just skip the first 0V Negative one, all the rest are the same.

[expresso]

its slowly getting there - i am starting to understand a little bit at a time how it all comes together - the only way it charges the whole pack as one 24V or 26V etc, - is from the two charge wires POS and NEG - Red and black -

then when the pack reaches a set charge Volt - the balance wires kick in and each wire has a job to do depending on which group of cells its connected too - each wire would be balance each group up to different volts -

when done correctly - it should in theory be fully charged and fully balance - the BMS is what the hobby charger would be - i know BM - the hobby charger will do it better - faster - correctly - more control over the process - watching it - adjusting as needed - etc, - visuals are great - that i agree for sure - i like to know what is happening - and if they dont work correctly - not seeing what is happening is then a guessing game - and me being that i dont have the skill level as everyone else here - i wouldnt even know where to start to troubleshoot -

with the hobby charger - i would be able to see it and maybe figure it out or post a screen shot here - ok - learning as i go slowly - - i got all winter - just to say - i learned more in the past month when i decided to do this - than the few years i been reading on and off about it here - i wasnt really expecting to even try this a few years ago or even a few months ago - but its always been on the back of my mind and each summer when i ride - it surfaces again and i re visit the options

finally i got past that line and actually doing it - took some time but i crossed over now

[expresso]

I suspect you just skip the first 0V Negative one, all the rest are the same.

yes i think so - if i remember i believe i read that before from shirley or scollard or both - - but if thats the case and it has to be - since only 8 wires - then how does those Cells which are skipped get balanced ? or would the full charging somehow the BMS brings them up balanced only on that first Neg. which is skipped -

well see i guess -

[Burgerman]

but if thats the case and it has to be - since only 8 wires - then how does those Cells which are skipped get balanced ?

Your head will explode but heres how it ACTUALLY works...
The battery (all of it) is charged only by the ends, the big non balance wires just like your lead battery is.
The actual CELLs that get too high, only do that at the top of the charge. The BMS "pulls" them down. It sucks power from the highest cell and wastes it as heat. It only needs the middle 7 wires to do this. Since the ends (neg and pos) are connected anyway.

Those charge wires are the other 2 balance wires as well.

[expresso]

i got that - and still have my head

if it only needs the middle 7 wires - why do most all BMS etc, balance cables have 9 wires - those extra wires work to balance the ends POS and NEG even to a closer degree -

[Burgerman]

Because a hobby charger need an ACCURATE cell voltage reading to 0.001mV. Hence separate wires. Because the voltage measured on the END wires, is correct only when not charging. When it is charging, the voltage on the BMS end of the wire is slightly different because the wire has some resistance.

[expresso]

Ok - makes it very precise - BMS can have a little flex but the hobby charger needs to be and is more accurate - needing the extra wires to bring it closer to as accurate as it can be -

on my small pack - it wont be as noticeable but if doing a whole chair or the larger the pack - the more precise you want to charge and balance for best results -

[Burgerman]

Theres more to it than precision. It means that the BMS can actually spend much of the day UNBALANCING the pack in error because some incorrectly balance at normal working voltage all of the time. Then they have to spend all next day trying to get it back in balance at the top charged voltage...

Most hobby chargers balance only at the top at 3.6V. Or are adjustable, and so you choose at what point. 3.4V works best on a slow charge. 3.5v best if charging faster.

But basically yes.

[expresso]

I know Scollard - mentioned before the balance wire dosnt matter where i connect them along the buss bars - so i will do it all on one side of the pack so dont have to remove later if i add another roll later on -

just so i understand - the 4 hole buss bars - will have two cells that are Pos and two that are Neg - i would have to alternate the balance wires as i go down the pack ?

what i am trying to say is - lets say it starts off Neg. - then pack i would attach to the Pos side of the 4 hole buss bars ? then the next 4 hole buss bars - i use the Neg side of it ? would that matter - i mean they are still all connected anyway

so one balance wire ring on the Neg. first - or if that one is skipped - then i move to the next in line which is on the bottom with the 4 hole buss - i would need to put the ring connector wire on the Pos side of that 4 hole buss -

then move up to 3 and put the wire on the Neg side of that 4 hole buss -- along down the pack - is that correct - i am not doing anything yet - just asking because if you have the 4 hole buss - two screws on the Neg and 2 on the Pos side - but all connected -

i may be missing something and wondering what it is - unless i am correct - Odds against me there

[Scollard]

Expresso, No, the square bus bar is all the same no matter where you connect the balance wire. One balance wire per bus bar exactly as you labeled. The negative terminal does not need a balance wire because it's built in to the negative battery wire.

The way a BMS works and the way a hobby charger works is basically the same, just the hobby charger is smarter and more powerful. Both the BMS and hobby charger are looking at the voltage across 2 balance wires. They are expecting to see 3.3V between balance wire combination 0-1, 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8. If you add up the number of balance wires you need then you see there are 9. Shirley's BMS has wire 0 built into the neg battery wire, so you just have to add 8 wires. To answer your question about what happens if you hook up the balance wire to the wrong spot, the BMS or hobby charger will get the incorrect reading between the 2 balance wires and depending on how you wired it, could short out, blow up your BMS or charger or in the case of the hobby charger, shut down realizing there was a problem.

The way the balance wires work is they provide a drain on the cells if, when charging the pack, an individual cell begins to exceed the recommended charge voltage. The hobby charger does this in a much more efficient way than a BMS. It can put a much larger load on the individual cell to pull down the voltage while still maintaining a decent charge rate on the other cells. A BMS has only a tiny draw to put on the balance wires and as a result it will have to toggle the charging voltage on and off to maintain proper voltages in all cells. That is the basics.

[expresso]

Ok - i am back on track now -

Scollard - do i proceed now to attach the balance wires - BMS - ?

can you tell me the correct way to be sure i am going to do it right -


Zero on the buss bar - is the Neg. Black wire from the BMS - - then i use the balance wires numbered 01 to 08 following the numbers on the bars i marked already and the last one - Pos is 8 - that gets both the balance wire and the Red Pos from the BMS -

Should i do it later this way and get back with a picture ?

leaving the balance wires NOT connected to the BMS at this point or Connect everything - wires to the pack and balance end to the BMS end - and then post back with pic -

[Scollard]

Ok - i am back on track now -

Scollard - do i proceed now to attach the balance wires - BMS - ?

can you tell me the correct way to be sure i am going to do it right -


Zero on the buss bar - is the Neg. Black wire from the BMS - - then i use the balance wires numbered 01 to 08 following the numbers on the bars i marked already and the last one - Pos is 8 - that gets both the balance wire and the Red Pos from the BMS -

Should i do it later this way and get back with a picture ?

leaving the balance wires NOT connected to the BMS at this point or Connect everything - wires to the pack and balance end to the BMS end - and then post back with pic -

Yes, go ahead and place the balance wires but do not plug them into the BMS. Post Pictures when you are done. Remember you will short out the battery if a tool bridges between any 2 bus bars,

[expresso]

yes got it -- i will be very careful - - not sure how i will hold this BMS on the pack when done - just wrap it with clear film wrap like saran wrap from the kitchen type - or stick it on the side of the pack - or on top -

you want me to just connect the balance wires - small ones - or everything the charge wires also - and just not connect the balance wires to the BMS - All wires - but not the balance in the BMS end ?


which is the best way when i am done to hold it in place safely - will do this later on this evening and post the pic back -

thanks -

[Scollard]

yes got it -- i will be very careful - - not sure how i will hold this BMS on the pack when done - just wrap it with clear film wrap like saran wrap from the kitchen type - or stick it on the side of the pack - or on top -

you want me to just connect the balance wires - small ones - or everything the charge wires also - and just not connect the balance wires to the BMS - All wires - but not the balance in the BMS end ?


which is the best way when i am done to hold it in place safely - will do this later on this evening and post the pic back -

thanks -

Charge wires also. Don't connect the white Balance plug to the BMS just yet.

[Burgerman]

Remember that for long life, lithium likes to be stored about 60% full.
So after charging you will want to discharge it by about 8Ah until ready to test it.

[expresso]

Ok - All done with the Balance wires only - NO BMS -

how would i discharge it for storage once its all done - i wont be using this for a while - i still have to make a cable to go to my chair and find something to put this in -
some sort of plastic container that fits in the backpack

if i just left it alone - it would discharge on its own slowly -

to hold the BMS on the pack - the best place would be on one side taped down ?

[flagman1776]

Looks good & well marked. If it wasn't clearly marked, we'd have to guess if it was done right.

[Scollard]

Ok - All done with the Balance wires only - NO BMS -

how would i discharge it for storage once its all done - i wont be using this for a while - i still have to make a cable to go to my chair and find something to put this in -
some sort of plastic container that fits in the backpack

if i just left it alone - it would discharge on its own slowly -

to hold the BMS on the pack - the best place would be on one side taped down ?

You are looking good. You should start thinking about tightening each screw with the loctite and adding the plastic caps as you go. I think I would tape the BMS to the side of the battery. You want to make sure you can still see the lights on the BMS once it is attached. Since you do not have a hobby charger you can't take any charge out of the pack easily.

[shirley_hkg]

Everything looks good, and you are almost there.

Go and connect the 2 power lines , B- and B+ , of the BMS to the battery ends correspondingly now , and take photos again.


One thing that worries me is that you haven't insulate the BMS yet. Do not let it touch any part of battery, not even side of cells. Temporary measure would be put it in a siploc .

[expresso]

Looks good & well marked. If it wasn't clearly marked, we'd have to guess if it was done right.

yes Shirley did a nice job in marking it etc, - so that helped for sure

[expresso]

Everything looks good, and you are almost there.

Go and connect the 2 power lines , B- and B+ , of the BMS to the battery ends correspondingly now , and take photos again.


One thing that worries me is that you haven't insulate the BMS yet. Do not let it touch any part of battery, not even side of cells. Temporary measure would be put it in a siploc .

Ok - i kinda felt that i had to cover that BMS with something - but wasnt sure it was a must do - its still in the box so it didnt touch the pack at all yet - what would i use to insulate it - i can put it in a ziplock bag - but do i leave it in the bag and then tape it to the side of the pack with the lights facing out so i can see if i wanted -

[Scollard]

Ok - i kinda felt that i had to cover that BMS with something - but wasnt sure it was a must do - its still in the box so it didnt touch the pack at all yet - what would i use to insulate it - i can put it in a ziplock bag - but do i leave it in the bag and then tape it to the side of the pack with the lights facing out so i can see if i wanted -

Just search Rubber Sheet on Amazon and get yourself some to wrap the BMS and Battery.

[shirley_hkg]

I will put one or two sheets of cardboard between BMS and cells as insulation .

[expresso]

Ok - All done with the Balance wires only - NO BMS -

how would i discharge it for storage once its all done - i wont be using this for a while - i still have to make a cable to go to my chair and find something to put this in -
some sort of plastic container that fits in the backpack

if i just left it alone - it would discharge on its own slowly -

to hold the BMS on the pack - the best place would be on one side taped down ?

You are looking good. You should start thinking about tightening each screw with the loctite and adding the plastic caps as you go. I think I would tape the BMS to the side of the battery. You want to make sure you can still see the lights on the BMS once it is attached. Since you do not have a hobby charger you can't take any charge out of the pack easily.

I didnt get the plastic caps in yet - suppose to arrive middle of next week - but who knows now with the storm coming tomorrow and not sure if it was shipped out yet - Ebay - i have to wait to do the caps -

can i saran wrap the BMS and then stick it in a Ziplock bag - and tape it to the side of the pack that way ? i will then just remove each screw - remove the all the washers - , add the locktite and screw it down - i am also waiting on the T wrench to screw it down correctly - not to over tighten it - so i guess i will finish this next week once i get the Wrench preset to 5Nm - -

another question now that i am almost done - i will check how this fits in my bag - - if i notice i have room for another roll - would it be wise to do that now before i finish this - or just finish it and add it later - ?

i would have to order another 8 and wait again for delivery then - - at that point - i was thinking of getting the rest of the Cells for the full pack at the same time - what do you think ?

if i left if for later on to add another roll - how hard or difficult would it be to get that extra 8 working and charged balanced again ?

[expresso]

Ok

hows this ?

http://www.amazon.com/gp/product/B000QD ... _mrai_2_dp

http://www.amazon.com/gp/product/B0074I ... l_huc_item


let me know if any of these are good - so i can place an order - i wish i new i just placed an order yesterday -

is there anything you can think of that i may need to cover this or wrap the whole thing etc, - i like to place an order for everything else i may need to get this finished and covered protected safely -

i guess i have to wait now to get all the items before i finish it up ? No use connecting the BMS now till i can wrap it safely