SLA charger voltage dips under load. Is it safe to increase voltage?

Thread Starter

uraniumhexoflorite

Joined Oct 23, 2016
204
I built a basic SLA charger circuit using a laptop charger and a buck module that has an adjustable maximum voltage and current. I also added a diode so the circuit can just be left attached to the battery when it isn't charging. I detached the battery (diode still attached) to set the maximum voltage and current and set them to 14.5 volts and 0.2 amps respectively. When I attached the charger to the battery and tested it it worked fine until it stopped at 14.2 volts. I left it on for a while to be sure it wasn't actually still charging and the voltage didn't increase any more. I detached it and increased the voltage (without the battery) to 14.8 volts. When I reattached it and tested it again, the battery charged to 14.5 volts and then stopped. Is this ok, or should I set the voltage without the battery to 14.5 volts? I will add a link to the module if I can find it. Thanks in advance for help. I included a basic diagram of the circuit as it is now.
Edit: Here is the buck module
https://www.aliexpress.com/item/32580191958.html?productId=32580191958&productSubject=5A-Lithium-Charger-CV-CC-buck-Step-down-Power-Supply-Module-LED-Driver-New&tmLog=onelink_blank&aff_platform=link-c-tool&cpt=1550466771573&sk=ctuNxGq4&aff_trace_key=c53c7244e33d4df9b1188e93714784f9-1550466771573-09540-ctuNxGq4&terminal_id=c
 

Attachments

Ylli

Joined Nov 13, 2015
891
The voltage drop across the diode increases when there is a load on the output. You should be fine the way you have it set.
 

crutschow

Joined Mar 14, 2008
24,299
Do you have a schematic of the buck converter?
If so you could connect the voltage feedback point to the output of the diode.
That would eliminate the effects of the diode drop.

It should be a Schottky diode to minimize the voltage drop.
 

Thread Starter

uraniumhexoflorite

Joined Oct 23, 2016
204
The diode is a schottky. I probably should have mentioned that. I used the adjustable buck module since I wanted to be able to charge 6 volt batteries with minimal modifications and the module seemed like the simplest way to do that.
 
Top