48v lifepo4 battery voltage query

[fabieville]

If i set my mppt controller to charge my 48v lifepo4 battery to 54.6v and it stays at that voltage would this be considered as been charged to 100% or would it be seen as been charged to 90%?  seeing that i did not let the battery charge up to 58.4v. Most sites recommend charging to be 3.4v to 3.65v per cell which would be 54.4v to 58.4v. So i just want to know if stopping at 54.6v would be seen as been charged to 100% or 90%. I want to calibrate by battery discharge/charge monitor correctly.

My battery bank is 200AH. I want to charge only to 90% and discharge to 20% so i can get max cycles out of the battery as the more charges you do to 100% is the less cycles u get from it. Charging to 90% or 95% is what most websites recommend.

[mab]

I obvious answer is "it's up to you" i guess.

If it were me doing my own battery then I'd want to set 0 and 100% to the true values, then when i looked i would expect to see it within the range 20-90% and know everything was operating as it should.

If i was setting it up for someone else's battery, then i might take a view on their battery knowledge and if they would be expecting to charge to 100%, and be able to access power down to 0%, in which case they might get confused if it cuts off when still showing 20% and won't charge above 90%, then I'd calibrate the indicator to read 0-100 over the 20-90% range.

[SparWeb]

Charging Margins are becoming better understood and general knowledge is improving among Li battery users, especially where automobiles and portable phones are concerned.  What isn't as widely recognized is that the batteries in cell phones and in EVs and in stationary units for RE are all build differently.  There are a lot of differences in the construction and complexity of the battery management system (BMS) controller the recharge and (in some cases) the discharge.  So watch out, when referring to generic "how-to" documents that don't say what kind of battery they are referring to.  Even the example below misses some variants of the Lithium chemistry.

https://batteryuniversity.com/article/bu-706-summary-of-dos-and-donts

Generic instructions for one will not apply to the other.  What you need are specific instructions that apply to the batteries you actually have.  What we're missing here is that the manufacturer of the Lithium batteries has probably published a user's manual.  Get it and use it.

[dnix71]

I use that chemistry AA cells in microphones. If you over charge too much the cells will heat up and die, but nothing else. From this site https://footprinthero.com/lifepo4-battery-voltage-charts
They are great for low amp stuff. I have tried them for converting nicad drill packs without much success. Just multiply the chart by 4. I would not want to go to 58.4v charging either. The recharge cycles are almost infinite if you never go above 90%.

[Bossrox]

I tried posting a chart but it won't post so I'll just tell you what the chart says 3.350v is 90% & 20% is 3.2v. 3.45v is 99.5%.

[JW]

Ya this will only be temporary, its just a temporary security measure, we've been thru it before.

Yaaaa that one post has some awesome pics, were proud to host them.