why i call Li fussy

Thanks to everyone for all the links. It's been a good ride and some good information was made available. Till next time!

After watching the link provided in the thread--there was another video with folks from Battle Born. They said that their recommended charging rate is 0.5 c. You can charge faster, but it will shorten the life span of the battery.

The 100 amp-hour battery uses 120 cylindrical cells. The number is 26650. voltage 3.2 and amperage 3.4

120 x 3.4 / 4 = 102 amp-hours.

Whack-a-mole…

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Might be time to close this one.

With such a dependable stream of mental gobbledegook, I stand by my previous - lol !!

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That CANBAT blurb from wegosolar is confusing about the BMS disconnecting at low temp, and how the heater works . The actual manual says:

" LiFePO4 batteries can safely charge
between 32°F to 113°F (0°C to 45°C). Canbat Low Temperature series (LT)
can be recharged between -31°F to 113°F (-35°C to 45°C). The LT series has a built-in heating system which activates when the temperature reaches the
freezing point. It works by warming up the lithium cells to above freezing
and only then the BMS would allow in the charging current."

The manual says the battery can be discharged down as low as -20C, so what is the state of play between -35C and -20C? No 12v to the rig? But it says the heater comes on (or did it say that? maybe means it activates charging when it gets up to freezing from a lower temp) at 0C, so where did the heater get its power doing that? (You are not charging at the time-- unless you are! :( )

It is a muddle with this brand's "info". Need another brand to check how it works.

I will predict that upon the next LFP thread these detailed explanations will all have been in vain - Calling it a form of ‘thread Alzheimer’s’ (Groundhog day 9.0) eems to be appropriate…

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Best to stay above 5C for charging. This value can be changed on some BMS to avoid any issues. The slow charge is about pointless IMO. Better to just avoid it.

FWC, thanks for the detailed explanation.

BTW, I did not invent the 0-5C "issue", that came from the Trillium charging specs to use reduced charging below 5C. The Relion heater lets charging begin at 5C. Seems to indicate that there is something going on there.

Para 6.6 here:
https://www.trojanbattery.com/pdf/Trillium_UsersGuide.pdf

Also, wrt the other question, note this from the same para 6.6--

"If the charger will not run until it detects battery voltage, be sure that Group 24 or Group 27 batteries are turned
on. If the charger provides charge without detecting battery voltage, and the battery is shut off, the battery will
turn on automatically as soon as the charger starts."

The charger that needs to see battery voltage first, is not quite the same thing as an inverter/charger needing 12v to operate its charger, but it does make you wonder (unless you know the details, which I sure don't)

It certainly seems to me (and probably others) that there is a whole lot of picking going on. To paraphrase, the question is never 'how does this work?' but 'looks like it won't work between 0 - 5c', 'looks like it won't work with an inverter/charger'. Then there is the 'it would be impossible to heat the battery because I made up some numbers', 'let me come up with some sort of crazy scenario where that might not work' etc. The whole point of this thread seems to be to pick at something without any real understanding or experience with how it works.

As to the 'BMS disconnects the cells', as you suggest, the writer of that really does not understand how their solid state BMS works. The battery will continue to allow the battery to discharge below 0C so clearly it cannot have 'disconnected the cells'.

As I think I have explained several times before, the BMS acts like a programmable ideal diode. For most of the time, when the temperature/voltage/current is within spec it is in bidirectional mode and will let current flow in either direction (ie it looks like a wire). When it is in charge cut off mode, either because the temperature is too low, or the voltage is too high etc, it will only allow current to flow out of the battery. When it is in discharge cutoff mode, because the battery is depleted, it will only allow current to flow into the battery. It will never be in both charge and discharge cut off mode.

A heated battery at low temperature is in charge cut off mode - it won't allow current into the battery, but turns on a heater upstream of the BMS 'diode' so that current can flow to the heater. To the charger it looks like any other LiFePO4 battery.

I am happy to explain how this stuff works and clear up some of the many misconceptions, but it would be nice if this wasn't always an argument.

Per FWC: “ For some reason there seems to be a great effort to pick this apart without really understanding how it works. The funny thing is, the sky is not falling and there are people actually out there using these.

If you are actually interested in how LiFePO4 batteries work, buy one and play around with it. Or even better, build your own.” …BINGO!!

Maybe the forum operator should charge per number of bit wasting keystrokes…

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