Battery BMS question: Headway and 18650 exchangability

[dutchlincoln]

Hello,
I own a electric moped scooter, which i upgraded a bit. Kelly controller, 8Kw hubmotor, and so on.
I drove a few days with a Headway package of 24S2P, making 76.8 volts.

Now, i have a real bunch of 18650 cells, brandnew, from makita packs.
Yesterday, i made a large pack of it, making 24S14P. This should result into approx. the same: 77 volts at 22.5Ah.

Now, with the headway, i ran for approx. 35 miles, but with the 18650 package i get about 10 max before controller shuts down.

I put the same charger on them, with the same BMS from the headway's, and within an hour it says its full, charger stops. I can run about 5 miles with it.

I made the packe in sets of 5S14P.
I had 4 packs already made, and yesterday i made the last 4S14P.
This last pack wasn't fully charged by me.
I saw that this pack was run down to zero volts when the moped scooter stopped (trying to get life in it now..)

Again: cells are brand new...

What can this be, what did i do wrong, and how can i possibly solve this?
I really need a good quality package...

Any help higly appreciated.

 

[dnmun]

those cells are not lifepo4. they use a different chemistry.

they need to be charged to 4.2V./cell. the BMS will only balance them to 3.65V so they are mostly uncharged.

your 24S headways should charge up to over 88V to balance. not 76.

 

[dutchlincoln]

hi,

I didn't measure the voltage to be haunest, i just took the data sheet, that states 3.65V/cell
The link i used: http://stores.headway-headquarters.com/-strse-1/lifepo4-Headway-batteries%2C-Electric/Detail.bok?category=BATTERIES

Any supplier 18650: http://www.megabatteries.com/item_details2.asp?id=15584
I had an other, but just can't find the website now that quickly.

Am i wrong, or are the spec's thesame?
Also, the battery pack of Makita states to be 18 volts. When i devide that to 5S, i come at 3.6V/cell...

I thouht LiPo was 4.2 volts....
And which cells are you referring to to be 4.2V? The headway's, or the 18650's?

 

[dnmun]

the konions are not lipo. but they charge to 4.2V/cell. go read the stuff doc did with them. your 'headway' BMS is for balancing lifepo4.

 

[dutchlincoln]

ok, clear.
I'll read doc's info.

Still: i could charge them with the LiFepo4 charger of the headway's?
Just have to narrow down the series i guess to approx. 20S ?

Do i need a BMS with the Konion's? I can set everything in the controller as for max. amps and voltages. Not sure wether they need to be balanced charged.

 

[docnjoj]

I use Konions from Fatpacks 36 volts and about 12 ah. Mine stay in balance at 41.5 volts and have for years without any BMS. You do need to use a cut-off charge system. I use the original 4 amp Bosch charger that came with one of the fatpacks. I parallel 6 of them. I believe they use 10S2P so I have 120 cells. The once were discharged to 0 volts accidently when left connected over several days to the idle controller but came back perfectly fine. Konions in my estimation are still the best cells out ther. If only we could get them new!
otherDoc
Edit: Definitely start with the cells balance charged! Mine were charged to 4.15 and still are.

 

[dutchlincoln]

Hi,
Due to a project at work i have many many brandnew-never used packs at home
So new: yes they are.
All you state that these are at least as good as the headway's?


My intention is to disassemble them all again, and one by one create a pack from them.
Still looking for a good way to charge and balance them before i make a pack from them...
Or, is it possible to do so after the pack is build? (as i currently have..)

The last 4S pack i had too loosen the cells as they are combined in a pack on a different way. It's a new way, with an other PCB as well, i made some pics of them to show.

The 4S pack is on my lab power supply, but won't come up. It gives 3 amps max. current, but can't get any voltage in them yet...
i'll try a bigger psu tomorrow...

 

[999zip999]

Dmumn's Right on the headways 88v. @ 3.65v.. Go 21s on the konion's cell for 88v.@ 4.190v But better have other people chime in on this. And no BMS on the konion's just put so me balace wires on to monitor. It's good to put them in a long parelle string and charge but must of same voltage first. Then let sit. Or just use two seperate packs. But that is plugging away.

 

[dutchlincoln]

No need for 88v. Thats in fact too high for my 72V kelly controller. (90V max.)
I think 20S@4.2V is more than enough...
Gives me the opportunity to make more Ah's as well..
With the Headway's i already limited the speed at 75KM/h. That's enough. (legal speed is 45KM/h). Without limit it did 110KM/h... (approx. 70Mph)

8) 8)

 

[999zip999]

Go buy a Rc balance charger and balance wires.

 

[dutchlincoln]

ey...

I have 2 of these!
they're not that fancy (6 amps), but it may do the job!

Thanks for the tip!

 

[dnmun]

you do not need balance wires to charge the konions. you start the build by balancing all the cells to one voltage by shorting them all together so they start at the same voltage.

you have to do this whenever you build a new pack.

then you can charge them all up together while they are connected together with a single cell charger or you can then build the pack from them and bulk charge them to the 4.2V level.

so you would not need the BMS for charging the konions. they are essentially self balancing because the resistance climbs rapidly over 4.2V.

the headway cells have to be charged up to 3.65V to be fully charged, so i use more than the 87.6V but not much. about 89V+.

the 'headway' BMS can balance the pack with only the 87.6V but i think it better to add a little extra to force the pack to balance faster. with other BMSs like the signalab you have to add a little extra especially when there are several pouches in parallel.

but your problem was just that the konions are not fully charged. you should be able to build the pack with them now if you balanced them with the BMS already.

 

[dutchlincoln]

Hi,
At first, thanks for all the info and support, really appreciate it.

I can't get any voltage in the 4S14P pack...
Even my fat lab supply gives smoke in powering them
I'm afraid there's nothing more than to take it apart and try less parallel cells to charge...

The RC charger won't cut it either, as it says battery too low...

Any oter options?

Thanks.

 

[999zip999]

The balance wires are great for checking and maybe balancing

 

[999zip999]

Try 1p

 

[dnmun]

Hi,
At first, thanks for all the info and support, really appreciate it.

I can't get any voltage in the 4S14P pack...
Even my fat lab supply gives smoke in powering them
I'm afraid there's nothing more than to take it apart and try less parallel cells to charge...

The RC charger won't cut it either, as it says battery too low...

Any oter options?

Thanks.

i thought you had a 24S pack. now it is 4S? are these the konions you are talking about? do you have current meter so you can see how much current the charger puts out? did you damage it so it won't push current?

 

[dutchlincoln]

Hi,
At first, thanks for all the info and support, really appreciate it.

I can't get any voltage in the 4S14P pack...
Even my fat lab supply gives smoke in powering them
I'm afraid there's nothing more than to take it apart and try less parallel cells to charge...

The RC charger won't cut it either, as it says battery too low...

Any oter options?

Thanks.

i thought you had a 24S pack. now it is 4S? are these the konions you are talking about? do you have current meter so you can see how much current the charger puts out? did you damage it so it won't push current?

Yes, in total it is 24S.
as i stated, i use the Makita packs in it's original form, where they are 5S. I had 3 of these 5S packs that i used before, and made me a new 5S pack with it, and had to separate the latest version of the Makita packs due different build, and configured the last cells to 4S.
So in total: 24S.
14 p all naturally.

Hope this clears things up, sorry.
These are the konions indeed.