custom UPS for your Lenovo ThinkCentre M72p using 2x IRF4950 MOSFETs and a 12V 30Ah LiFePO4 battery. The design takes your existing 19V grid power adapter, steps it down to 14.2V via buck converter to safely charge the battery, and uses a boost converter to maintain 19V output to the PC during outages. The MOSFETs provide automatic, seamless switching between grid-charged bus and battery power with minimal loss.

 

There is a very similar post here:
https://forum.allaboutcircuits.com/threads/pc-power-backup-design.210020/
Lithium is not the ideal chemistry for backup power.

 

custom UPS for your Lenovo ThinkCentre M72p using 2x IRF4950 MOSFETs and a 12V 30Ah LiFePO4 battery. The design takes your existing 19V grid power adapter, steps it down to 14.2V via buck converter to safely charge the battery, and uses a boost converter to maintain 19V output to the PC during outages. The MOSFETs provide automatic, seamless switching between grid-charged bus and battery power with minimal loss.

First I agree with IAN as to using a SLA battery.

Next, why don't I just plug mt 19 volt power grid adapter into a UPS?

Finally my Lenovo Think Pad runs fine off its internal battery and if it's low then back to my UPS. My Lenovo grid power adapter requires 100 to 240 VAC and draws 3.5 amps. so 420 watts (st my 120 VAC 60 Hz Power). No problem for any decent UPS.

Ron

 

First I agree with IAN as to using a SLA battery.

Next, why don't I just plug mt 19 volt power grid adapter into a UPS?

Finally my Lenovo Think Pad runs fine off its internal battery and if it's low then back to my UPS. My Lenovo grid power adapter requires 100 to 240 VAC and draws 3.5 amps. so 420 watts (st my 120 VAC 60 Hz Power). No problem for any decent UPS.

Ron

Hi @Ron I want to diy a auto switching circuit board for my pc as I will use the main adapter as charger for the battery

 

Help me build a simple schematic design

 

A "Main adapter" is not the best choice for charging a battery, especially a 12 volt battery. For backup a low power float charger is a better choice.

Help me build a simple schematic design

The functions described do not sound quite like a "simple schematic" to me. Also, not only is a lithium battery not the best choice for backup, but it is a more expensive one as well. AND not quite as forgiving for any charging profile mistakes.

 

I agree with @MisterBill2 that you may need more than a simple schematic; this is hardly a trivial project especially since it is not clear that you have nailed down a simple set of requirements. As with any design project you might be better off taking an indirect approach which involves starting with something simpler and working up to the ultimate goal.

 

What I see is that the TS wants plans to build somthing using the parts they have:two transistors and a battery.
The bad news is that I have no idea as to the actual power requirements for that Lenovo computer, since the TS did not tell us volts or watts.
So what I suggest is an inverter with a transformer output and a 19 volt secondary on the transformer. The inverter can use that lithium battery with a trickle charger direct from the mains, wherever they are in the world. The battery charger can be adjusted to keep the battery charged, so it won't need a good regulator. Just set the charge voltage with a VARIAC or a POWERSTAT variable transformer.