V13 - "new generation" BMS

[Chriull]

Imho it's a pity that such information is "hidden" in some wheels mega topics:

@SquallLHeart - is there a setting so the wheel stops charging automatically at some certain voltage/percentage like possible with the ks22?

And one could respect the manufacturers recommendation for the used 18650 Samsung 35E in the 30s(4+4)p config and charge just to 30*4.05V=121.5V with balancing for full cycles!

[SquallLHeart]

No setting, the BMS was designed to stop charging when a cell reaches 4.185V as Marty and others have already mentioned. With an adjustable charger, that is really how most people currently control stopping a charge earlier.

Not familiar with a setting on the KS22 to stop charging earlier.. how does that work exactly?

[meepmeepmayer]

Here's the linked post as a quote:

18 hours ago, SquallLHeart said:

I covered it in a very short YouTube video.. but the information I was given is that the cell balancing will happen when 3 conditions are met..

(Regardless of the battery being at full or not.. because everyone keeps talking about needing the wheel at 100% battery for the batteries to balance.. and people started freaking out because charging stops when a cell reaches 4.185V)

conditions are.. as I've been told by InMotion:

• Battery cells are over 3.7V (so like.. 111V)
• The difference between cells exceeds 30mV
• The charger is plugged in

That means cell balancing on the V13 should be assured and everything is good Just charge to full (charger stops) and then keep the charger in for a bit regularly.

[Chriull]

1 hour ago, SquallLHeart said:

Not familiar with a setting on the KS22 to stop charging earlier.. how does that work exactly?

From what i read here the stop voltage/percentage can be set by the app.

There is also some control wire to the charger - but don't know what this is for in detail. Maybe just as some kind of anti spark protection with controlled voltage start stop?

A combination of both would be great - adjustable stop voltage with this guaranteed balancing!

No idea if this is done by the ks22 bms?

[SquallLHeart]

1 hour ago, meepmeepmayer said:

Here's the linked post as a quote:

That means cell balancing on the V13 should be assured and everything is good Just charge to full (charger stops) and then keep the charger in for a bit regularly.

as mentioned, you do not need to charge it to full to have it balance. doesn't hurt to leave it plugged in though.

[techyiam]

It is a great feature to have cell balancing before being fully charged. 

Unfortunately, no information is forth coming as to the best procedure to take in order to fully balance battery packs.

[Tawpie]

I guess I'm a skeptic... a youtube video says it has "active balancing", but that's as yet unverified. I wonder if EcoDrift is willing to sacrifice a battery to look carefully at the BMS to see if indeed it uses active balancing?

Not saying it ain't true, but active balancing isn't cheap. The LTC3300 is a 10A monolithic active balancer from Analog Devices that runs 12USD/piece from DigiKey (17USD if quantities aren't high) and can balance 6 cells. The V13 will need 40 of these babies, almost 500USD cost to the manufacturer. These parts are in 7mm square 48 pin LQFP packages, require a transformer + MOSFET pair per cell and likely AD's cell stack monitor(s) so 'lots' of board real estate is necessary. 240 transformers... even little bitty ones, will take a bit of space and money.

THANKFULLY you can see your individual cell voltages (I think) so you can tell if your pack ever gets unbalanced. Personally, as long as you can see what's going on and they started with matched high quality cells, I would just keep an eye on it and wouldn't be at all worried.

Datasheet (sample application diagram is at the top):

https://www.analog.com/en/products/ltc3300-2.html#product-overview

Edited January 20, 2023 by Tawpie

[Tawpie]

Analog's article on active balancing... not a ton of info and nothing new, but some pretty pictures!

https://www.analog.com/en/technical-articles/active-battery-cell-balancing.html

Texas Instruments has a nicer writeup with alternate techniques... AD's solution may be gold plated!

 

Edited January 20, 2023 by Tawpie

[SquallLHeart]

3 hours ago, Tawpie said:

I guess I'm a skeptic... a youtube video says it has "active balancing", but that's as yet unverified. I wonder if EcoDrift is willing to sacrifice a battery to look carefully at the BMS to see if indeed it uses active balancing

I believe I made the mistake by calling it that.. I edited the video description in hopes to clear it up...

afaik, active means it can balance during both charge and discharge cycles.. where in the case of the V13, I'm sure it needs to be plugged in and charging.

however, the main misunderstanding is it needs to be at 100%.. which it does not.

[Chriull]

3 hours ago, SquallLHeart said:

Afaik, active means it can balance during both charge and discharge cycles.. where in the case of the V13, I'm sure it needs to be plugged in and charging.

Active balancing means that charge from a fuller cell can be transferred to an emptier cell.

Passive balancing means that a fuller cell will be less charged and/or discharged to the level of the other cells.

Active balancing could be used during usage too, passive balancing makes sense while charging.

Using active balancing would be another big leap, although i'm not sure if it would be advantageous for EUCs.

3 hours ago, SquallLHeart said:

however, the main misunderstanding is it needs to be at 100%.. which it does not.

Inmotion could add a setting to charge to anywhere between for example 60-100%.

Together with the single cell monitoring and balancing during charge over 3.7V that should be all we need.