Initial Winston top balance

[YARGESOL]

Good Day! Planning to finalize installation soon. I ve got 1000ah Winston(still in the box). Apparently 3,2V each. What option Will be Correct for initial charge:1). Charge separatly each cell with a 4V 15A charger. 2). Connect to invertor(Quattro), ABMS and charge from the shore. 3). Same as 2nd,but with solar MPPT. 4). Run the motor+Balmar+MC614. The Last 3 option are for parallel 12V
Thanks

[PaulCrawhorn]

Shore power.

Charger that you can adjust termination at between 3.45V and 3.60V.

If using a PSU (no self-termination) or the charger that goes too high, then an adjustable HVC circuit that cuts if its input based on battery post voltage as above.

Put all the cells in parallel, checking they are within 0.1V of each other first.

Assuming your balancing kit (BMS) does top balancing, then bring them up together to 3.60V maximum, at a slow rate, say under 0.2C

Do NOT allow battery post voltage to ever get above 3.60V, even that is higher than you want to use for normal daily-use cycling.

Once there, let them sit in parallel to "self equalise" for at least 24 hours. Then atomize, let them sit isolated for at least another 24 hours.

Did any drop voltage more than the others? Identify your "weaker links" they will determine the performance limits of the bank as a whole.

[PaulCrawhorn]

Ideally you will then "break in" the cells, do 10-20 cycles between 3.45V and 3.0V at a low rate, say 0.2-0.3C in order to complete proper SEI formation.

If needed this step can be done at bank voltage hooked up in series.

[PaulCrawhorn]

After that, you would (also ideally) use a Constant Current dummy load and a precise timer to measure the discharge cycle at the automatic 3.0V cutoff

or maybe a coulomb counting wattmeter, but that is less accurate.

This is a Capacity test, setting your initial State of Health "commissioning" benchmark, used as a point if comparison to measure how fast your bank is wearing out as it is cycled.

Ideally each cell separately, record its measured Ah to two digits. Obviously you must in future benchmark testing recreate all the conditions to be identical, same testing gear, temperature, current rate, HVC / LVC, same gauge wiring, etc

[PaulCrawhorn]

In normal cycling mode, for longevity keep your charge rate below 0.4C, a bit higher is OK in warm weather, but go much slower when the cells get cold. If in freezing ambients, consider warming pads.

Also for longevity, terminate charging at 3.45-3.50V Bulk / CC only "charge to and stop" is fine, or minimal Absorb / CV stage

absolutely nothing to be gained by pushing in those last few mAh except unnecessary stress on the cells, reducing lifespan and pushing them out of balance.

[PaulCrawhorn]

It is important that you can easily monitor the per-cell/group voltages.

Your balancing gear (the BMS?) should let you adjust at least the start-balancing voltage and stop-balancing mV delta. The balancing current rate, higher the better, and capacitance or shunt based is better than resistive-bleeding style, but that last is cheaper, therefore much more common.

Do not re-balance in normal cycling usage, unless (until) you observe the cells are over 50mV apart within your normal cycling pack voltages.

As infrequently as possible, even annually is a sign of very healthy and well matched cells.

When the bank gets well worn, or suffers from an incident, infrastructure failure allows too high or too low voltage, then balancing may be more frequently required. But doing so more often than needed will just exacerbate the problem.

[PaulCrawhorn]

If all the other care factors are OK, then the next most important factors in extending longevity are:

Do not let the bank sit at Full when not needed for cycling. As much as practical, your use case or system design limitations may make that impractical. But certainly in "storage mode" keep the cells under 3.4Vpc, isolated from any circuitry and cooler the better.

And the last longevity factor is a major one; your average DoD should be as low as possible, certainly not going over 85-90%

ideally staying above 3.1Vpc except in emergencies. Talking about measuring "at rest" here. High C-rate loads may pull V to below even 3.0V that is OK for a short time, so long as they bounce back up once the load is cut.

An average of 3.2Vpc compared to 3.1V, or the latter compared to 3.0V can mean triple the cycle lifespan.

Again, if your use case requires otherwise, or you just don't care about getting maximum lifespan, not required mostly not relevant to safety.

[YARGESOL]

Thank You very much, Paul, for such a comprehensive instruction. Will follow
Vladimir

[s/v Jedi]

With four 1,000Ah cells you’re in for a process that will take a while…

If you connect the cells in parallel then 0.2C is still 800A which is a pretty stout charger.

I have Winston cells as well. First you need a multimeter that can accurately measure milliVolts. If you don’t have one, then order it now; I can confirm this cheap one being accurate: https://www.amazon.com/ANENG-Multime...8410753&sr=8-5

Now you want a bench top power supply 0-30V, 0-10A minimum. I got this one: https://mastechpowersupply.com/volte...-aviation.html
but on Amazon or eBay you can get a 10A model for less than $100.

Now document each cell using it’s serial number and mark them physically with a Sharpie like #1, #2 etc. Make a logbook (or spreadsheet) to log measurements.

Now measure each cell at mV accuracy, i.e. 3.403V and put that incl. the date in the logbook. Calculate the avg. and the difference between highest and lowest cell. My guess is that you will be within 10mV max. deviation.

If so then connect the cells in series and charge with the power supply set at 13.6V. When the current tapers to less than 5A, shut down the power supply and disconnect it from the batteries. Wait an hour and now measure, log and do the same math for all cells again.

Now connect all cells in parallel, set the (disconnected) power supply to 3.5V, switch it off, connect to the cells and switch it on again.

When the charge current goes below 20A (or 10A when you only have a 10A charger), stop charging. At this point, you are done. The document I link below has another step to 3.6V per cell but with your big cells, charge rate is so slow that the cells will be full at 3.5V.

Now let them rest and do the measurements and logbook again. It would be good when max. deviation is lower than when you started. Keep an eye on that number.

Now it is best to discharge the batteries to 70% or so. Using an inverter is the easiest way.

Here is “the bible” which also describes this method: https://marinehowto.com/lifepo4-batteries-on-boats/

I changed the first step at 3.4V to a series-connection step because this takes long and you shorten it 4x that way. If the cells are more than 40mV apart before you start, I would not do this but when your Winston’s are like mine, they already are balanced and probably sequential serial numbers so not much to worry about

[YARGESOL]

Thanks, Jedy, for practical advice. Will follow