Modification to a Switching Power Supply Transformer 4.0 @ 40 amp to charge 5 volt battery bank for iPad

[sam_sam_sam]

This is the switching power supply that is used in this project

https://www.ebay.com/itm/164440680270?var=464055952700

Here is the BMS protection board

https://www.ebay.com/itm/38688703079...Bk9SR47sydbRYw

This is the first time that I have seen a switching power supply that has a 40 amp output for 3.3 volt output bypassing the USB controller charging circuit but use a single battery cell BMS protection board for charging only because when you have a very high amp hour battery pack it takes forever to charge it when at 50% percent of charge

This switching power supply will also be recapped if needed before being put into service

[Donny2derby]

How in the name of god do you end up with a 40amp output from a SMPS with no load on it??🤣🥹😅

[sam_sam_sam]

How in the name of god do you end up with a 40amp output from a SMPS with no load on it??🤣🥹😅

I was referring to is maximum current with a corresponding load I going to use a different charging BMS to do fast charging then hook it up to the USB charger to maintain it and charge it up the rest of the way

But the maximum BMS current rating I could find is 24 amps which would do for me I might have to split the the battery pack in two sections instead of one but even this is not a disaster because the majority of battery bank charger have a maximum of 10 amp hours anyway and then when you exceed that the battery gauge is inaccurate because it can only count up maybe 12 amp hours any way

See I have these battery packs that are originally made for hospital computer backup and it is set up for 24 volts but I going to make my own circuit board to hold the battery cells in place but put them all in parallel so it would only have 4.2 volts

The only thing that I have not decided on is what battery cells to use because I do not need battery cells that have more than 4 to 6 amp load capacity but have a long run time on low current applications like running an iPad for many hours away from the wall outlet

[sam_sam_sam]

Well I had time to recap this switching power supply doing a burn in test the only capacitors that I did not replace was the 3300 @ 16 volts I only had 6.3 volt ones I have some that are 16 volt ones but they slightly too tall and the cover would not fit properly if used them I just need to order the right ones so the cover will fit properly

I also did not replace the main filtering capacitors because I did not have this value either

[sam_sam_sam]

I have these battery packs that are originally made for hospital computer backup and it is set up for 24 volts but I going to make my own circuit board to hold the battery cells in place but put them all in parallel so it would only have 4.2 volts

The only thing that I have not decided on is what battery cells to use because I do not need battery cells that have more than 4 to 6 amp load capacity but have a long run time on low current applications like running an iPad for many hours away from the wall outlet

I going to see if I can cut the circuit board tomorrow to fit the enclosure so I can start testing some battery cells for this battery pack because I have the battery bank boards from some battery banks that the battery cells that went so I going to put them to good use

[sam_sam_sam]

I am rethinking the idea of using this switching power supply for this modification I found a small 12 volt @ 3 amp switching power supply and I found my 5 volt @ 60 amp switching power that is a Mean-well switching power which is a better power supply than the one that is in it and the one that I was going to use

I just got to wire in the supply line to the small 12 volt switching power supply

There was an issue with the switching power supply yesterday when I was testing it at 5 amps and higher that the display was getting a little bit brighter when the 5 volt rail was loaded more than the 12 volt supply rail this would be an issue over long period of time this is the reason why this was not used and a boost converter was used because of this issue which I now understand why it was done this way

I want to put another cooling fan on the controller board that controls the display back light and the function buttons because I noticed that after running for a while the board was getting a little warm the load cooling fan only comes on when the charge/discharge functions are used but I will probably use a small 24 volt cooling fan with the 12 volt power supply rail which would make the fan run at a slower speed

One note the temperature controlled cooling fan with the temperature sensor mounted on top of heat sink works really well with it loaded at 4.2 amp the temperature of the heat sink was very cool to the touch just what I was looking for

The switching power supply that I was going to use for this project is going to be used in another project where the loading of the two power supply rails are not going to be an issue too deal with because they will not be in an application that requires it to be turned on and off repeatedly