Once the pack reaches 3.6 volts i disconnect the charger then let it sit for an hour. Correct?
Then check voltage if voltage is above 3.5v the pack should be balanced. Right?
The ups is rated at 650VA. This is a cheap 27$ ups.
https://prolink2u.com/product/pro701sfc/
Stock battery is a single tiny 7AH Seal Lead Acid.
I jerry rigged a 90AH lifepo4 battery and installed a fan to prevent the UPS from overheating during long charge and discharge.
BMS is 10a discarge and...
Setup:
12v 1000w pure sinewave inverter with AC charging (set to mode#1 - UPS mode)
4s prismatic sinopoly 90ah (2nd hand cells)
30a/15a deligreen bms
4s capacitor type active balancer
NO SOLAR (the thing is powered by grid electricity all the time)
My load is very very small. roughly...
Calculate the battery runtime.
Provide:
battery AH
inverter efficiency
load in watts
Or
Calculate the proper battery capacity to buy.
Provide:
-Runtime
-inverter efficiency
-load in watts
Thanks
Any good advice on Lifepo4 battery charging parameters?
My charger is a cheap china made and i don't trust it connected to the batteries 24/7.
I already bought a charging controller that would cut the power on the charger when the battery reaches a certain voltage.
and also will start charging...
I am planning to add a secondary charger to my UPS with DIY/modded with a used Lifepo4 90AH battery.
The UPS charges very very slow. It would take around ~3days to fully charge the 90AH battery from 30-40DOD.
2nd reason is the UPS charger is so slow my cheapo balancer will not balance the cells...
14.6v - is this kind of high?
most suggest 14.4v
i also seen a suggestion of 14 or 14.1v so as to keep the SOC below 100%
Deligreen BMS. I dont think this has any adjustments.
not sure.
So it would still be better in the long run if i stay with 13.8v?
The batteries would be just on "standby" all the time.
As they would only be needed in case of a blackout.
i have a small bms with 10a discharge and a 5a charge rating.
my charger is rated at 10a charging.
how would the bms handle this?
i have seen videos on youtube on doing discharge with a higher amp than the rating on the bms.
the bms would just cut the power.
but how about charging?
Is there like a simple formula?
Battery capacity (in AH)
Load on the 220v inverter (in watts)
Inverter losses
No charging what so ever.
To calculate the estimated battery standby time (in Hours)
probably.
so i should set the charging voltage to a lower number?
I used a multimeter and the battery now sits at 14.6volts. The charger is keeping the battery at that voltage.
Is this bad?
charging at 3.6v is kind of slow when the voltage reaches around 3.570v.
it take ages to reach 3.6.
is it safe to do 3.65v?
Let the voltage reach 3.63X then just continue charging?
till the amp reading is almost 0?
or should i disconnect once the voltage goes above 3.6v?
so if the float voltage is 13.6v or 13.8v.
theoretically my voltage should drop to below 14volts after couple of days while still connected to the charger?
How to factor in my charging voltage of only 13.6v and my lvd of 11.0v?
Actually i am planning to do a capacity test with bms. I will let the bms hand lvd.
Then capacity test each cell with 2.5v lvd.
Then capacity test with bms but i will set lvd at 11v.
I will post the results here.
BTW my...
Is it safe to squeeze them together inside a tight wooden box?
My issue is also once i squeeze them they will be a pain to remove as they are bloated.
Currently i used multiple zip ties to squeeze them and so far its working except the 2 cells at both ends.
They still budge on the sides.
can you elaborate on this?
does this mean that my charger must be the same voltage as what my ups charges?
My ups charges at 13.6 volts. As the battery would just sit at this voltage and would not go up anymore.
I am not sure the charging amperage of the ups but i imagine it is around ~1.5A (or...