One upside of getting older is that you need to worry less and less about how long things are going to last. When I was younger and I was building a retaining wall or replacing underground plumbing, I would worry whether it would last the next 50 years. Now I only need things to last at most 20-30 years.
Just last year I was shopping around for batteries for my parents’ (who just turned 80) backup system and I was looking at the warranties on some of the batteries and then it hit me: Do I really need to pay extra for the battery with a 10 year warranty? Grim, but strangely also liberating.
My long-term plan … when the existing system needs to be replaced, me and ouma will get our last system and it will outlast us both with years to spare.
My parents, the same thing i.e. 83yo, they are on solar.
LS tonight. Prior to the 8 am one, no watts going into the bank at all, even Victron zero, yet the balancer is balancing (as per the pic), the cells ever so softly being balanced down to 3.45v from ±3.54v.
Topped up the lagging cells with the EV-Peak a wee bit.
Then the next LS hit, afterward recharged again at +3.5kw, little while later Victron dropped the charge beautifully to zero, and I topped the lagging cells a teeny bit again to 3.450v. The system is set to 3.45v now.
Leaving it for the rest of the night as is, cells won’t “run away” anymore.
Will see with tomorrow’s LS and recharges, how close the 18 cells are now with no intervention from my side.
The Delta goal is 0.004v as before.
This has been a loooong haul to add 3 more cells.
Delta is down to 0.008v already …
Could not have done this in parallel with LS as it is.
A big shutout for a damn good idea … @Louisvdw driver, when a cell hits 3.500v, the driver switches off the charger on the inverter.
Just waiting for that confirmation, as I may have found that out accidentally.
Guys, let me tell you, that is one very cool idea to have on any and all BMS’es. Stop charging dead before a cell goes bossies.
Am seriously thinking of activating Louis driver again just for that feature.
… just need to figure out how to switch off the driver throttling the bank when SOC goes over 90% slowing the charging down … a non-Linux oke here see, who breaks things.
Don’t need that as it wastes valuable sunlight on a balanced bank. Looi hom.
The context is a highly out-of-balance pack and a tiny balancer, and a flawed BMS.
The BMS does not register to charge at a low level which is a BMS flaw.
A setting is disabled to overcome the BMS flaw.
He concludes from this that balancing is better than no balancing.
He goes on to say balancing should happen all the time, charging, not charging and discharging.
There is only evidence that balancing should happen even when not charging ( because, ironically, it is still charging at a low level).
That is 2 + 2 = 7 territory.
No evidence is led to support the conclusion that balancing should occur whilst discharging.
I don’t even think that the setting he changed affects that ability, but this is not explored in the video. That is a step too far and not a safe conclusion to make from the evidence presented here.
Here is a clip where the problems with balancing during discharging are exposed, which also shows that a top-balanced pack returns to its top-balanced condition ( without balancing) after being discharged.
Andy, one day it is left, a few months later it is right.
In another vid later he also said not to keep an active balancer connected all the time if memory serves.
The vid I’m still looking for, where he discovers the balancing on discharging helped with a passive balancer … shifting the charge to another cell vs just generating more heat on one cell.
@Phil.g00 the more I think on this the more I think when one speaks of balancing when discharging on a “BADLY” balanced bank, that it can be advantageous using a “PASSIVE” balancer.
Passive generates heat inside the BMS on a cell that is higher than the rest … discharging it “faster” when balancing when discharging.
When charging the same cell gets the same heat loss when it jumps ahead.
It is “focussed” if you want, not so?
Shifting the charge between cells with an Active Balancer on Discharge. now THAT will cause chaos as in your race track example.
Of course that means that once the thing is balanced (or once it is no longer badly unbalanced), you should switch to only balancing while charging, as the holy scriptures require.
But I totally agree. Passive balancing when discharging, unless for a purpose, wastes energy and serves no purpose whatsoever.
Latest Setup (same as before):
Have no interface active between the bank and Cerbo.
Balancing starts at 3.45v … the least amount of energy wasted.
Victron brings it all back smoothly every time on time as expected, even when big loads go off with the bank on 100% SOC!
Just shows me yet again, cells need to be batch-matched (same resistance) … all of them or else.
This brings me to another observation:
Sitting on the sidelines I ponder on the fact lately that no manufacturer had LS level 4+ in mind when they set down their 10-year-one-cycle-a-day warranty with balancers that do mV.
It also makes sense after I did this thing here, that it is not a bad idea to set one’s bank on Keep Charged, with LS, for a few days/week, so that the balancer can properly Top-Balance the cells again at its leisure.
Something I got back from 4x4 forum … setting my batts to Optimized WITH battery Life, works great for Cpt and a cold front or two hanging over the city for days.
Set it to that, and “walked away”.
Used all the solar, some battery here and there, and some Eskom here and there, but after 2/3 days, my bank reached 100% again with 0.004v Delta.
Ag dis 'n nou 'n lekker gevoel. (sug)
Now to see how that works with LS level +4 and cold fronts …
So I tested that. Bank was solid, then I enabled balancing charging and discharging again.
Other cells popped up having trouble staying in balance.
Conclusion:
If a bank needs serious TLC, and you can monitor it, then do it, balance up and down. It does help.
But do not do it on a balanced bank.
Ps. Could have left it for weeks to see where the “new” unbalanced cells head, but then I thought: You’ve tampered enough now. It is balanced again, enjoy the 18 cells.
When summer is back properly … I just have to run the bank to 2.9v … just must.
I’m bored.
In 7de Laan vernacular … “dit is so banaal as alles werk.”
Oom Oubaas and his sayings … Hilda and her recipes with “met so bietjie skop” … her wanting to “hiekel kombersies” for geysers was when I last watched.
