Need some help with this one, a reference or some sort of comparison box around it for context. Otherwise it's too subjective.I would add mention that an active balancers primary advantage is the ability to move much more charge around than what a passive balancers "burn off" can accomplish.
I've done experiments with active balancers, and they do indeed increase the effective capacity by boosting the low cells, but unless its low (10A or less) discharge rate the active balancers can't keep up. The end result was only a 100wh increase if I remember correctly -not much. However what I was referring to is the highest capacity passive balancer tops out at 1A of "burn off" where active balancers start there. The highest capacity active balancer I know of is a 10A JK BMS, also branded as a Heltec.Need some help with this one, a reference or some sort of comparison box around it for context. Otherwise it's too subjective.
For example, in my non-EE brain it immediately confuses me because resistors are dirt cheap and getting more energy burned off is just a matter of letting more watts/s burn off? So, couldn't any passive system easily match any active system?
Since you addressed high temp cutoff, low temp cutoff could also be added. Any LiFePO4 battery deployed in an environment that could see temperatures close or below 32° F needs low temp cutoff.
<whoosh!>I've done experiments with active balancers...
As well you should!I have a violently strong objection to the memory effect portion.
Thanks for this feedback! I saw that in Will's interview with Battle Born, but couldn't see how to say it clearly and concisely while also providing guidance. The general adage of cutoff at 32° seemed simpler/less-confusing. Could you provide a link to the graphs/tables you mention? I'm thinking a reference to a more detailed follow-up would solve the dilemma.From the graphs and tables I've seen, a 32F/0C cutoff isn't sufficient.
Will mentioned using passive in combination with active, but as I didn't understand it I left it out. I don't suppose you have a general reference to a when you should use both so I can take the cowards way out and just put in the link?... I found a "Sweet Spot" by also using the Passive Balancer of the Chargery's.
Passive Balance ON for Charge & Storage, OFF during discharge. Start Passive @ 3.300, allowing for 20mv difference.
ON during Storage to discharge more when a runner cell hits HVD so the BMS will resume charging quicker once the cell settles and Hi Volts are transferred to Lo Volt cells by the Active Balancer.
I found that this in combo with the QNBBM, helps to control the divergence at both the Top & Bottom of the voltage Curve by hitting the "Runner Cells" allowing for a more even charge and higher intake of charge. IN general, throughout the Voltage Curve the cells diverge far less than without the Active Balancer as I can "see" the transfer from Hi to Lo cells. Average Difference during normal use 9-17mv. Passive really only helps for knocking down the runners allowing the other cells to gain more power before the BMS forces an HVD cut-off.
I'll have to go through these... it'll take a while... I believe the original paper quoted was from 2010 and @snoobler's was 2013. So, if new articles from 2018 are debunking the original science that's great news! As with Snoobler's I'll link it up in the other thread as I review the tech articles.Memory Effect (long debunked for LFP) - A hangover from NimHi, NiCad and other rechargeables.
PLUS Numerous Scholarly Articles since 2018 to current disproving memory effect. Use Google-Foo.Lifepo4 battery refers to a lithium-ion battery using lithium iron phosphate as a electrode material, which has high safety performance and cycle life.www.grepow.com
That's what I had always heard too, but since 2010 seems like they were wrong (it's different from the issue with old batteries). There are links in the wiki and a discussion here: https://diysolarforum.com/threads/lifepo4-wiki-entry.17874LFP doesn't have the type of memory effect that the old batteries have.
Thanks for this feedback! I saw that in Will's interview with Battle Born, but couldn't see how to say it clearly and concisely while also providing guidance. The general adage of cutoff at 32° seemed simpler/less-confusing. Could you provide a link to the graphs/tables you mention? I'm thinking a reference to a more detailed follow-up would solve the dilemma.
Sweet! No time now, but will swing back later and beef up the entry with your links! Thank you!!!...Simpler, but not always sufficient....
Definitely not! Anything that big no one would read. Ideally it's just the most important stuff with links to follow-ups, not restricted to BMS selection alone. But hey, your forums if you think it needs more or less let's do it! ;-)... are we trying to make a comprehensive document that definitively answers all possible questions...