manfred59 wrote:So , I have done the mod of the 500W M1A-002 PSU like the one which flip_normal has.
Due to my A123 pack 15s6p I replaced the zener with a 56V/1W one and changed the capacitors like Disadvantage did. I also changed R5 (2k7) with 2k2 resistor.
R4 (2K) I did not change.
I have got it to output to 50,2 - 61,3 volts, but after plugging into 230V no battery connected the voltage shows about 5 seconds the max. voltage (56V) and then the voltage decreases quickly to 0V
Perhaps has Disadvantage an idea why this happens.
You are connecting 15 a123 cells in series. a123 cells are charged to 3.65V per cell, so your battery pack should be charged to 15 * 3.65V = 54.75V. IMO 55V is close enough.
I'll assume you know what you are doing, and set the 110V/220V switch to 220V before plugging into your 230V mains. The reason I say this is because I am a bit confused by your saying "I have got it to output to 50,2 - 61,3 volts, but after plugging into 230V..." Did you plug into 110V with the switch at 110V for a first-test that worked correctly outputing 50V to 61V, then decided to try 230V without changing the 110/220 switch when it failed? I would imagine Austria uses 240V mains; I wonder where you got 120V for the first test that worked? Maybe I'm misunderstanding what you wrote.
Anyway, long story short, I really think you need to use a higher-voltage zener diode for ZD1. 55V desired output voltage, set by VR3 and VR1, is very close to the 56V shutdown voltage, set by zener diode ZD1 -- and you are experiencing output shutdown.
Common zener diodes have a 5% tolerance; if we assume your zener is low then 56V * 0.95 = 53.2V which is less than 55V. A 58V or even 60V zener diode would be a better choice, because they provide some range in adjustment. 58V x 0.95 = 55.1V would just barely work, 60V * 0.95 = 57 is a better choice because it give a couple of volts adjustment range.
I'm charging 15 LiMn eMoli cells , which charge to 4.25V, and 15 * 4.25V = 63.75V. I chose a 68V zener for ZD1, 68V * 0.95 = 64.6. My choice is, under worst conditions, close but still above the desired output voltage.
I hope this information helps you get your power supply working. Two months ago I finished the modifications to mine and closed it up. I might go back in though, and change the dropping resistor for the output LED. It seems to glow too bright, and I'm sure it has something to do with increasing the output voltage by 50%.