This 13S BMS

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jaunty

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Oregon
Greetings,

I just snagged up this BMS from china and I want to get some input. There are 14 leads.

1st off - I got this because it was dirt cheap($20 shipped). So naturally, I'm suspicious of it. But, I'll give it a chance to prove itself (for fun).

Anybody used this or seen this? It seemed rather small to me, but the ratings state 30A continuous and 60A peak.

Thoughts?
http://www.aliexpress.com/snapshot/6667188929.html?orderId=67259245884784

actual product





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Thanks for the reply Nobuo!
I was wondering about the B+ because most other threads i've found don't really mention it.

Cheers!
 
Just starting to mess with a BMS now that i have a lithium pack, so sorry if its a noob question. If you dont hook up to the B+ does it only balance during charging, and not discharging?
 

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BMS always execute the balancing during the last charging CV phase and also while charging is finished (restarting the charger when needed), when the first paralleled group of cells reach ~4.20V and during one hour or more depending on how unbalanced is the pack.

Because the balancing just discharge unbalanced higher charged cells (you can notice BMS balancing phase hit because it gets hot) BMS doesn't waste that energy while you are using the battery pack, it does it while charging.

BMS doesn't need the B+ on the PCB for anything related for balancing. All the "B+" connections are actually made through the balancing wires (where the balancing discharging is done). About the BMS board that mention jaunty, I know B+ is unnecessary. There are very different BMS boards, so maybe others could need B+ for anything essential. Just contact always manufacturer (not seller/reseller).

50% or more of BMS boards even doesn't have the B+ connection on the PCB.
 
So just so I'm clear on these,

the BMS does not do anything while the battery is discharging?

It only executes its methods towards the end of the charging method?

Are there are BMS for Ebikes that manage during discharge?

I am using older used cells so I'm trying to figure out how different my batteries are allowed to be during building.
 
the BMS monitors the current flowing through the BMS B- lead and if it exceeds the level that the battery can produce it will turn off the BMS. this protects against shorts on the output.

do not bring B+ onto the BMS pcb. it only goes to the charger and controller.

if your battery is built from scratch then all of the cells have to be balanced to each other before assembling the battery.

if you building a battery from unknown reused laptop cells then you have to test them to verify they can store charge and do not have internal shorts before you assemble them into a battery. they all have to be at identical voltage when assembled into the battery the first time. otherwise it is impossible to balance the pack.
 
dnmun said:
. they all have to be at identical voltage when assembled into the battery the first time. otherwise it is impossible to balance the pack.
Click to expand...

after one discharge this wont be the case, so whats the point of the BMS then?
 
After one discharge i mean,
I ride, and the cells slowly become unbalanced.
I plug it in, and the BMS does its magic to ensure the cells all reach 4.2 volts when charged.

When i initally build, what tolerance for series batteries should I have.

0.1V 0.01 V? 0.001 V ?

Thanks dnmun
 
So i can probably use this BMS for any number of cells in series? I see that the number of connections goes up higher, but they only provided me with the 13S harness.

I want to test it out with a single series set of cells just to verify that it functions correctly. Also to do some testing on how it performs balancing.
 
sometimes a BMS can be used with less serials than specified. for example a 13s BMS could be used with a 10s battery. It depends of the BMS circuit itself, ask manufacturer.

You can always pick two together pair of balancing wires and connect a single cell. While you charge the cell directly from your 1s 4.2V charger, when you will reach 4.20v or more, the BMS will automatically discharge the cell. You will notice the BMS gets slightly warm.

You can do this with the 14 wires, pair by pair to check the all 13 balancing circuits.

Maybe there could be a BMS that doesn't work discharging a 1s alone. But 99% should work
 
What I plan to do is get a few more ammeters and connect them to some unbalanced cells with the BMS wired in so I can see how the balancing is taking place. I will use my digital power supply.
 
you do not have to install an ammeter in the sense wires. you can measure the voltage drop across the shunt resistor and that will determine the current flowing through it by ohms law. if you do not understand you need to go study some simple stuff like ohms law.
 
dnmun said:
you do not have to install an ammeter in the sense wires. you can measure the voltage drop across the shunt resistor and that will determine the current flowing through it by ohms law. if you do not understand you need to go study some simple stuff like ohms law.
Click to expand...


you're a piece of work. Try replying without being condescending one of these days.

The voltage will be changing, therefore the current will be changing, that is why I will monitor the current directly. I have completed the electrical engineering courses. If you dont want to engage then get off my threads.
 
then you should understand and not have to be so insulting. did you get to ohms law yet? did they talk about kirchoff's rules for circuit equations yet? is this a college course but it should be end of semester already. so you should know this already.
 
:D :D
I know all that stuff, but know nothing about how the BMS operates and is constructed.
Have you done this? can I easily access shunt resistors on this BMS?
 
Nelson37 said:
Jaunty - DrkAngel has some extensive posts concerning re-cycled batteries, testing, and matching. Highly recommend these. Excellent reading.

Would also be interested in any findings concerning - Avg number of dead cells per original OEM pack, also frequency of dead cells at one end of the pack, also in any photos of original packs with and without problems relating to "end cells". Frequency of dead cells other than at end location also useful.

Too many people using re-cycled cells to say it can't be done, whether it is cost- or time-effective would depend on the individual situation.

Seems very feasible to me with some significant start-up work.
Click to expand...

Yes I have read his posts. many thanks goes to Drkangel!

For my cells, I'm going to buy a factory new version as a benchmark. You have some good questions there about which cell dies out in the original packs. I might be able to get some information there in the long run, since I've numbered each cell as they come out of the packs. I'm having a hard time finding "bad" cells. None have been self discharging yet and they've been at 4.2 for a few weeks. Once i get the new UR18650ZT i'll have an idea about actual capacity versus stated.

to find average number of dead cells per pack would be highly dependent on the type of pack and type of cell. I can say that my first lot of sanyo (from lenovo) had the UR18650FM cells and they typically only charge to 4.0-4.1 volts, but I haven't tested them all yet. A few have heated up while charging, whereas the orange UR18650ZT can easily reach 4.3V (only been through 30 cells so far) but I am impressed with this lot. The red sanyo I will probably find some other use for.
 
jaunty said:
dnmun said:
you do not have to install an ammeter in the sense wires. you can measure the voltage drop across the shunt resistor and that will determine the current flowing through it by ohms law. if you do not understand you need to go study some simple stuff like ohms law.
Click to expand...


you're a piece of work. Try replying without being condescending one of these days.
Click to expand...

I agree, Dnmun is a condescending piece of work, he has talked down to me before too, assuming I'm a moron, not knowing my background etc.
I'm sure he's heard it from others before.
He seems to be making friends everywhere on this board.
 
So i bought another one of these exact items on aliexpress, except this time they sent me a different unit. Its larger. So basically they just send you whatever they want to i guess. I'll post some pics and compare them later.
 
jaunty said:
So i bought another one of these exact items on aliexpress, except this time they sent me a different unit. Its larger. So basically they just send you whatever they want to i guess. I'll post some pics and compare them later.
Click to expand...

It happened me also with Greentime, once they sent me one with different quantity and type of fets, I'm pretty sure the current limit was slightly different, but I didn't do the right measuring. If you want to stick buying BMS on Aliexpress, I recommend to you this seller and their BMS borads:

http://www.aliexpress.com/store/all-wholesale-products/536657.html
 
Hi guys,

I have a similar 20S BMS from greentime. Attached the BMS wiring diagram.
Anyone knows which is the correct connection order? I don't want to damage the unit by connecting the wrong wires first.

Many thanks
Viktor

BMS_greentime.jpg
 
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