PSU car battery charger

Everyone at some point will experience a dead or near dead car battery but can you charge a car battery from a PSU?

I had a car that hadn’t been turned on or moved in a while. I popped into it and turned they key and nothing! The faintest of lights on the dashboard showed me that the battery was near dead and didn’t have enough juice in the battery to start.

Unfortunately, I didn’t have a car battery charger around the house and I needed to move the car so I had to come up with a plan to get the battery some charge in order for the car to turn on and get it moved. After some thinking, I knew I had an old Power Supply Unit (PSU) that could provide a 12 Volt charge (roughly, Amps can be seen in image below). Low and behold, I had an idea.

I knew if I had this setup correctly, it would take some time for it to charge because usually, car batteries would need a higher voltage than 12V to get a full charge but all I wanted was for the car to turn on and as a result the car would charge the battery again. It is important to note that if a car battery has died or is close to dead it will never perform as it used to and is recommended to get a new one.

The old PSU I had was a Hipro HP-P3507F5P.

Hipro psuHipro HP-P3507F5P

(Obviously do this without the power connected) In order to get the PSU started I had to jump start the PSU. I shorted the 24-pin connector between the green cable and black (Green is usually universal for on switch on 24 pin). I then got a Molex connector and took it off exposing 4 wires. Red, Yellow and 2 blacks. I knew the yellow and black would provide around 12V and the red and black around 5V. I then soldered a 5v car light to red and black. There were no markings on the light but later found out it was polar.

car battery light

Following this, I got the yellow and black cables and wrapped it around the battery terminals. Positive to positive and negative to negative. I knew this might take a few hours to give it enough charge to make the car turn on. I wasn’t expecting a full charge of course. So, I plugged the PSU into the wall and hit the power on switch. The PSU turned on straight away due to the green to black jumper and the 5V car light also turned on. I knew the battery was now really slowly charging.

Charge Car Battery From Power Supply Unit (PSU)

After about 12 hours, I put the battery into the car and low and behold, it started. Sure, it wasn’t fully charged but it got the car running! This is not recommended to do but if you are going to, make sure you look up information about the PSU online and double check voltages with a multi-meter. So from me doing this I was able to charge a car battery from a PSU!


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