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Another Power Supply question & in/out question

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KnewB

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Hi, I did a search but not 100% sure I found what I need.

Is there anything wrong with charging a 12v 4s or 24v 8s lifepo4 batteries with just a power supply like the one Will has in his top balancing youtube video?

fyi this is not a solar panel set up, its just batteries used to power trolling motors.

Also, if I use a 30v/10a power supply to power a charger, is 30v/10a what I will be able to get out of that charger to the batteries?

tia!
 
KnewB said:
Is there anything wrong with charging a 12v 4s or 24v 8s lifepo4 batteries with just a power supply like the one Will has in his top balancing youtube video?
Click to expand...
Its ok as long as you are aware of the caveats.
First, the psu has to support cc/cv which means constant current, constant voltage.
Second, the different between a cc/cv power supply and a charger is.... charge termination logic.
If you are willing to be the charge termination logic then it will work.
The means disconnecting the charger once the batteries are full.
Exposing the batteries to charge voltage after they are full is unnecessarily stressful to the battery.
 
gotcha makes sense to have a charger then, thank you!

do you happen to know the answer to the second question? so if i have the 30v/10a power supply to the charger, should i be able to get up to 30v/10a into that battery? the charger: Input voltage 10-34V DC, Output voltage 1-34V, Charge current 0.1-20A
 
KnewB said:
gotcha makes sense to have a charger then, thank you!

do you happen to know the answer to the second question? so if i have the 30v/10a power supply to the charger, should i be able to get up to 30v/10a into that battery? the charger: Input voltage 10-34V DC, Output voltage 1-34V, Charge current 0.1-20A
Click to expand...
I'm trying to make sure I understand correctly - Are you saying this charger accepts DC input power and has a variable output? Do you have a link/datasheet on the device?

Benchtop power supplies and electronic loads often times have 3 limits - voltage, amperage, and wattage. An example is our HP 6050A electronic load can do 0-60v and 0-100 amps, but only 600 watts (10 amps at 60 volts, or 20 amps at 30 volts, whatever multiplies to reach 600 watts)
 
HighTechLab said:
I'm trying to make sure I understand correctly - Are you saying this charger accepts DC input power and has a variable output? Do you have a link/datasheet on the device?

Benchtop power supplies and electronic loads often times have 3 limits - voltage, amperage, and wattage. An example is our HP 6050A electronic load can do 0-60v and 0-100 amps, but only 600 watts (10 amps at 60 volts, or 20 amps at 30 volts, whatever multiplies to reach 600 watts)
Click to expand...
1613064628522.png
 
KnewB said:
gotcha makes sense to have a charger then, thank you!

do you happen to know the answer to the second question? so if i have the 30v/10a power supply to the charger, should i be able to get up to 30v/10a into that battery? the charger: Input voltage 10-34V DC, Output voltage 1-34V, Charge current 0.1-20A
Click to expand...

Have to consider specs of charge controller.
Some are PWM, some are MPPT.
MPPT in particular requires higher input voltage, and would not require CC mode of supply.
PWM can charge up to supply voltage, and would require CC mode.

If power supply is CV/CC, then could be used without charge controller. You just have to check occasionally and disconnect after either after has been in CV mode for a while, or after current in CV mode has dropped below some threshold. You could put a mechanical timer on the power cord and it would stop.

Some power supplies do not tolerate being connected to batteries. If output is switched off or power removed, they short out the battery and are killed. In that case, a diode is needed.

If you have a product designed to charge the batteries, then just follow its instructions.
 
KnewB said:
gotcha makes sense to have a charger then, thank you!

do you happen to know the answer to the second question? so if i have the 30v/10a power supply to the charger, should i be able to get up to 30v/10a into that battery? the charger: Input voltage 10-34V DC, Output voltage 1-34V, Charge current 0.1-20A
Click to expand...
A 4s lifepo4 battery has a max charge voltage of 14.6 volts and typically can be charged at up to .5c which means half of its amp hour rating.
For an 8s battery max charge is 29.2 volts with the same amp rating.
For a 16s battery max charge is 58.4 volts with the same amp rating.
Always check the doco for your battery because the charge and discharge ratings may very.
Also sometimes the charge voltages very a bit.
 
So I was researching this charger you linked, and it appears that a reviewer was not able to get the full rated output wattage out of them, despite being rated as such. I would say there is no clear answer as to whether your charger power supply is going to be able to output to its specs.
 
@KnewB are you intending to use this charger on a battery or on cells that are being prepared for assembly into a battery?
 
HighTechLab said:
So I was researching this charger you linked, and it appears that a reviewer was not able to get the full rated output wattage out of them, despite being rated as such. I would say there is no clear answer as to whether your charger power supply is going to be able to output to its specs.
Click to expand...
I only would require roughly 100watts going into the batteries, my 12v batteries are 55ah n 100ah, the 24v is 30ah.
 
You will need a BMS.
For charging, if charging in series not in parallel (4x and 8x faster in series)
For discharging, in the trolling motor application.
 
Hedges said:
You will need a BMS.
For charging, if charging in series not in parallel (4x and 8x faster in series)
For discharging, in the trolling motor application.
Click to expand...
i plan to use a Daly BMS after initial balance
 
HighTechLab said:
So I was researching this charger you linked, and it appears that a reviewer was not able to get the full rated output wattage out of them, despite being rated as such. I would say there is no clear answer as to whether your charger power supply is going to be able to output to its specs.
Click to expand...
what this the correct voltage to charge a 12v (4s)(100ah) lifepo4 pack at?
what this the correct voltage to charge a 24v (8s)(30ah) lifepo4 pack at?
 
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