Hi @IreallyLikeHam ,
Thats a great question.
over the past year, I have specialized in making Lifepo4 replacements for UPS.
The one cavet is, you need High discharge LFP, 26650 cells, S4P2.
To discharge 500 watts from that configuration, 12.8v you need Aprox 40Amp discharge from the pack...
Old Post, but still Highly Relevant:
32650 is a more advanced project. Benefits are Better continuous discharge 3C normal, 6C already exists. Also, more reliability. If one cell goes down, the voltage does not fluctuate, the other cells pick up the slack. Because you would have over 10P...
@Will Prowse Thats a great explanation.
So since these cells are probably Second life, Which do you think was the most likely source of ignition, the electrolyte or a design issue, (connections)?
A quick Update:
I Sealed the first box with 5200 fast cure, applied 15 lb of down pressure for 48 hrs. Tight Fit, lid went 65% down.
Worked great.
Pulled the Battery by the Lid Handle!
Hi @Don B. Cilly
Thanks for the head’s up.
Im considering this for my remote land. I wish to make a cabin, to be able to take my wife and kids for over the weekend sleepovers.
For that I need A/C 24/7 while we are there, toilet & shower water and sewage.
I only have small creeks 6-9 months...
Hi @smoothJoey
I dont have the numbers on hand. But I can explain my reasoning.
I checked 3 UPS models for charging and low voltage:
APC 650 12v
APC Pro 1000 24v
Triplite 750va 12v
with 12V models I found they charge at 13.8 -14v and low voltage disconnect >11v
With 24v Models 27.6v and...
Over the 20 UPS I have converted to LFP, I have found the charging voltage and Low voltage disconnect, very conservative and well inside the parameters of LFP.
Mostly APC
Great.
Just to make it clear.
if the chargeverter is connected to a Breaker. when the breaker is turned on, the chargeverter will immediately start charging the battery w/o any other input?
Exactly that is the reason of the question, recently saw a youtube video from a forum member that overvoltaged a 4S JBD BMS and @40v the BMS let the whole voltage through, into the battery. @HighTechLab
That has me concerned..
I´ve Been down that rabbit hole before.
Silicon Wire Is really nice and flexible, not only it resist temperature up to 200celcious, but also insulate its surrounding from that heat. Those are great attributes and highly sought after in some applications. Like Battery Making.
I also tested...
Quoted from:
The Weak Link - The BMS
"We now have a few years of experience with lithium-ion batteries, and what is becoming clear is that while the LiFePO4 cells hold up very well, that is not the case with the Battery Management System (BMS). Overall the number of prematurely failed batteries...
"Float Voltage
"LFP batteries do not need to be floated. Charge controllers have this because lead-acid batteries have such a high rate of self-discharge that it makes sense to keep trickling in more charge to keep them happy. For lithium-ion batteries it is not great if the battery constantly...
The max capacity of your UPS is 810 watts , the max capacity of your lead acid sealed batteries is 500 W each, so it’s more than enough. usually that UPS uses two batteries connected is series for 24 V please check the technical sheet for your UPS to confirm.
correct, ups max draw is...
Hi @mjcother
If the volts are the same for the LFP battery and the UPS, then its compatible.
Then you have to check the charging profile of the ups, to make sure they are in range of LFP.
min 2.5 v
max 3.64 volts
24v would be 8 series.
The other limitation is if the UPS was designed for...