I made a common mistake, identical to an earlier post "Using a 12 V 3 A bilge pump on a 12 V 8.5 A LED power supply".
The pump was 3.8 amp so I purchased a 5amp led transformer, which just worked, but failed under load ie (under water). So I understand the problem of initial toque surge load requiring a higher amp transformer (I Think).
The pump works fine on a car battery, but I need a permanent "plug & play" solution. I connected my battery charger to the pump, & it also worked fine. The transformer needs to be on full time so as to automatically empty the sump when water enters.
These are my questions;
1) Why does my 20 year old 4amp 12volt Battery charger (see image) work fine as a power supply for the 3.8amp 12v pump?
2) & can I use the battery charger as a permanent power supply for the pump, ie could it overheat & cause a fire?, as they are not normally left on permanently.
3) As I don't want to waste money buying another unsuitable transformer. Will a " 40amp DC12V Driver AC 230V Power Supply Transformer for LED Strip Light" see image be a suitable power supply for the 3A 12v pump?
It can get expensive buying a standard transformer, but led transformers & battery chargers etc are mass produced, so they are much cheaper options.
thanks for any input.