Can DC boosters charge 12v battery with 5v input?

Thread Starter

jzeds1491

Joined Feb 5, 2020
19
HI friends
can I use these cheap DC-DC STEP-UP MODULEs to charge a series of li-ion cells making a 12v battery?
I saw some videos that people are using it. it should take at least 5 hrs to fully charge this battery and I have a kind of feeling that this module is going to meltdown.
My main concern is overheating and the reliability of the circuit since this is going to be used in a couple of units.
thanks
ps. only this module is economically usable.
 
Last edited:

ronsimpson

Joined Oct 7, 2019
1,630
Should work. Set the output voltage to the max you want to see on the battery. The supply should current limit a 2A when the battery is below that voltage and then drop back the current as it approaches the voltage set point.

You probably should look for a "li-ion battery charger" board that looks something like that. This one is only good for 3 to 4 volt batteries but there are others.
1626290284865.png
 

Audioguru again

Joined Oct 21, 2019
3,828
A Lithium battery needs to have a charger circuit made for the Lithium battery specs to avoid an explosion and fire.
The You Tube video from India has the tiny power supply set to 13.2V to charge the motorcycle lead-acid battery that is completely different to a Lithium battery.
 

Audioguru again

Joined Oct 21, 2019
3,828
A 3S Lithium battery charger was not linked, it was a "protection circuit" for a huge battery instead. It does not detect and stop charging when the battery is fully charged and damages the battery with overcharging.
 

Audioguru again

Joined Oct 21, 2019
3,828
The "charger" protection board has no details about how you select the charging voltage and charging current (10A will explode your little battery). It does not say that it balance-charges the cells. It does not say it indicates when the charging is completed.
I think it was designed to charge a huge lead-acid battery.
 

Beau Schwabe

Joined Nov 7, 2019
109
We do something similar with an integrated UPS we designed.... The mains voltage supplies 12V to the unit however the unit needs to charge a 12V SLA battery. The overhead voltage for the SLA charging circuit is 15 Volts so we boost the 12V to 15V to provide the overhead to charge the SLA.

I don't know why this would not work for a lower input voltage, but the main thing to consider is whether or not the boost converter can handle the charging current required for the battery. I would not trust the USB 5V to 12V converter for this project,

Remember if you need 2A of charging current at 12V then your 5V needs to supply 4.8A if the conversion was 100% efficient.

(12V x 2A) / 5V = 4.8A

Multiply by 1.25 as a derating factor for 80% conversion efficiency. 1/80% = 1.25

So .... 4.8 A x 1.25 = 6A You;d need at least 6A at 5V input to deliver a charging current of 2A at 12V after the boost converter
 
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