Sid Battery Balancers.

 There may be a better way to check or a specific email to use. 

YES Sean in the latest video say he will use  CRM  in the near future  and  will  eleminate  problem with customer orders . 

Insurance agent  and doctors use CRM to keep track of customer  needs .      

34 minutes ago, AquaticsLive said:

What is the best way to ask about an order of balancers.  I ordered 4 more on Jan 8th, may have fallen through the cracks.  I sent a message from the site, but I figure I may be better off asking here.  There may be a better way to check or a specific email to use. 

Not sure what happened.  Will get this straightened out.

Thanks Man

Balancers have been working great.  I just pulled the cover off my battery bank and was pleasantly surprised that when the the battery was topped off they all blinked in balance mode so nice to have something you don't need to monitor all the time.

Glad to hear.  FWIW, if the "serial comm" tabs on the balancers are strung together, you can pull a "status string" off the entire bank...if you're the kind that wants an "all-in-1-place" type of screen.

I haven't had any issues with the previous-gen balancers on any of the LFP batteries I've been using--save for the stupid mouse that wee'd all over a couple balancers, corroded parts off the board and resulted in one balancer draining a cell to near zero...

...yeah, I did manage to step on that mouse.  That didn't fix the batteries though.

Lol well that makes for a funny story.  Dam mice, I have the same problem at my cabin in the UP of Michigan they get into everything.

Dam mice, I have the same problem 

I  feed a couple alley cats  scrap food  and the cat  stay and eat the rats ( they are huge )  and  the cats  get fat fast  .  

I have been thinking

A better balancer would simply have a cap being quickly switched between cells

Same concept as the voltage pump on the USB to rs232 chip (forgot the part number)

Basically each cell would have 2 FETs connect it to the cap and current flows from higher cells into the cap and from the cap into lower cells

This could be done with a fairly low speed switching system using resistors to switch the FET off and a simple stepper circuit or with active drivers higher frequency can be used

The losses are minimal as it moves the charge around instead of shunting it

Of course there's much better methods of balancing a Lithium pack 😉.

I just picked the simplest method.

I did look at "moving power" methods instead of "wasting power"--but all of the "power moving" methods I'm aware of very quickly run into logistical issues.  Yes, I'm aware that there are a number of "power moving" BMS units out there--and many which seem to work very well for a number of people.  Thing is, an "ideal" BMS connected to an "ideal" battery--would do absolutely nothing (and for that matter, an "ideal" BMS would be none at all).  In other words, a BMS design could have significant major shortcomings--but "work perfectly" for someone simply because it has no work to do.

In short, "power moving" BMS units have either one of two main issues:

• If they can move power to any cell, they can only "balance" one (or depending on the design perhaps 2) cells out of the entire bank.  I believe the Chargery BMS utilizes this method.
  • not a problem if the battery bank is very good and just needs a bit of "adjustment."
  • but if you have an older pack with more than 1 or 2 cells that constantly need help (and especially on LiFePo4 packs)--it fails miserably. 
    • did not work with Sean's Li-Ion battery pack
• Simpler non-branded Chinese BMS boards with balance (switched capacitor or inductor methodologies) can "balance" each cell--BUT they HAVE to dump said power into the next cell upstream.  (Or the previous cell downstream, depending on the design.)  I haven't seen any that can selectively determine where to put the power--and if they could, a 16S bank would kinda require a 16 * 16 "dump gating" matrix.  Kinda big there...
  • if they're dumping from a full cell into another full cell, that balance unit has to also run at full power just to prevent its cell from getting further overfilled.  This quickly results with a line to the end of the string--and once you get there, where do you put the power that's been "ferried down the line"?
• The most common Chinese BMS boards (Daly, etc.) are the total loss method--utilizing an optoisolator with a resistor as a cell dump.  Maximum power is usually 30mA (0.03A), which is fine for small batteries in good condition.  They simply can't keep up with large off-grid battery systems that may be made out of older mismatched cells.

The capacitor shifting method is bidirectional at each step and so each cell is balanced by a measured amount either way with the previous cell in the step

Cells can be stepped in any order as it's a stored charge stepper so last cell balances the first in continues loop

in other words, this type of BMS design is the first one I listed, only capable of "adjusting" a single cell at a time.

Most of the Chinese BMS "active BMS" boards with capacitors are the second type of BMS design I listed.

A single cell at a time yes but switching can be as fast as the fets can handle

In effect it creates a mirrored voltage on each step

If all the cells match no current flows but the cap charge is effected by each cell as it passes

Think of it filling a little cup of energy from the higher batteries and spilling some of it into the lower ones

If you have .9 .9 .9 .8 .7

The cap will charge to .9 at the first cell and dump some energy into cell 4 and 5

The energy will be measured by the capacitance and voltage difference

As the cells balance the current drops to just the drive current for the fets

It will always move energy from the higher voltage cells to the lower ones

It never needs a specific voltage to balance as it's actively averaging the voltages

Admittedly, that's a lot like using a thimble to empty a water tanker.  You need considerably more than 0.2v difference if you plan to get a significant amount of power transfer with a cap...

Making matters worse, that tiny single-unit power transfer amount effectively gets divided by the number of cells.  Again, if you have more than one cell needing significant attention, this simply doesn't work on large-scale battery systems.

Imagine a cell overflowing (by 0.1v), and you take a thimbleful of water out of it every 16 seconds.  Problem is that the remaining 15 seconds, it's completely untouched and back to overflowing.

Well, the problem is that it will always be a 1/16th duty cycle (if there are 16 cells in the pack, for example).  And unfortunately the duty cycle is what matters, not the speed of switching.

Again, as I said before, this type of system (i.e. Chargery BMS) may work very well for quite a few people.  But an ideal BMS is no BMS--and if there's no work to do on the battery bank, even a miniscule 30mA shunt balance (Daly) may appear "to work" for quite some time...perhaps even the life of the pack.

addendum: not just a thimble (or maybe even a teacup, depending on the size of the cap)--but a 4/5ths full thimble or teacup at that.  Not going to move much water...