officialfestus:
7,750 from aliexpress.

Penuelseun:
those buck converters don't last long especially when you are nearing the full current rating, I got a 60a pwm charge controller that can charge a 3s battery for mine then

Trippledots:


Chai...I almost made same mistake some time ago...incase of next time, check konga first, it may be cheaper and faster. This is a 15A shown though

Trippledots:


Chai...I almost made same mistake some time ago...incase of next time, check konga first, it may be cheaper and faster. This is a 15A shown though

Penuelseun:
Yes it will, you can attach a cooling fan to the heat sinks to help with cooling

Penuelseun:
those buck converters don't last long especially when you are nearing the full current rating, I got a 60a pwm charge controller that can charge a 3s battery for mine then

dollarnaira:


Cool but just that few pwm accept editable settings.

officialfestus:
I think this particular product can do it.

officialfestus:
Good morning gurus, After charging my 12.6 volt 3s 40ah, I decided to test with a ups and it beeps low battery and shutdown, the bms cuts voltage also.

What could be the problem?

Cc dollarnaira penuelseun

dollarnaira:

What is the voltage of the battery via bms terminals and direct battery terminals?

dollarnaira:

What is the voltage of the battery via bms terminals and direct battery terminals?

officialfestus:
Good morning gurus, After charging my 12.6 volt 3s 40ah, I decided to test with a ups and it beeps low battery and shutdown, the bms cuts voltage also.

What could be the problem?

Cc dollarnaira penuelseun

officialfestus:
at what charge voltage should I regulate the buck converter to 12.6 or more?

Penuelseun:
That is the issue with li-ion cells in the 3s config, they have a voltage range of 9v to 12.6v which most 12v inverters struggle with, 7s 24v config is the sweet spot for them. Your ups is configured to work with lead acid battery whose voltage range is higher, 11.5v is the cutoff voltage of most ups which in a lead acid battery is around 70% dod
You are better off going for a sachet inverter that can go as low as 10v or boost the voltage to 13v with a boost converter which is not that efficient

officialfestus:
can I use this?

officialfestus:
11.9v

Penuelseun:
That is the issue with li-ion cells in the 3s config, they have a voltage range of 9v to 12.6v which most 12v inverters struggle with, 7s 24v config is the sweet spot for them. Your ups is configured to work with lead acid battery whose voltage range is higher, 11.5v is the cutoff voltage of most ups which in a lead acid battery is around 70% dod
You are better off going for a sachet inverter that can go as low as 10v or boost the voltage to 13v with a boost converter which is not that efficient

ksmart027:

Sorry to ask, is there any inverter that can go below 10v on 12v system?

ksmart027:

Sorry to ask, is there any inverter that can go below 10v on 12v system?

Penuelseun:
That is the issue with li-ion cells in the 3s config, they have a voltage range of 9v to 12.6v which most 12v inverters struggle with, 7s 24v config is the sweet spot for them. Your ups is configured to work with lead acid battery whose voltage range is higher, 11.5v is the cutoff voltage of most ups which in a lead acid battery is around 70% dod
You are better off going for a sachet inverter that can go as low as 10v or boost the voltage to 13v with a boost converter which is not that efficient

Trippledots:


I met someone who savages li-ion cells from laptop battery packs. He said he can build a battery bank for me, #450/cell, BMS 10k/one for 12v battery and he uses soldering iron to assemble.

Do you think I should get the cells and assemble myself?

I don't have much tools for assembling though.

dollarnaira:


What of direct ba3 terminals?

Penuelseun:
it should

officialfestus:
same.

ewizard1:
"In anything Li-ion you assemble, please make sure an active balancer is installed alongside."

dollarnaira:


Why?
Difficult for 12v to derail though it is good.

ewizard1:

"Difficult for 12v to derail"? Only a 1s wouldn't derail.

Better safe than sorry!!!

dollarnaira:


With proper initial balance one is still safe.
What lithium hates is overcharging and depth of discharge. After all no lithium batteries can have exact voltages among themselves. No matter how small there is always a safe difference.

dollarnaira:


With proper initial balance one is still safe.
What lithium hates is overcharging and depth of discharge. After all no lithium batteries can have exact voltages among themselves. No matter how small there is always a safe difference.

officialfestus:
can I connect two different 12v 40ah 3s battery to together in parallel connection?