How to Repair a 12V battery charger?

[plaed]

Here I measured the resistances as follows:
- live (black lead of the multimeter on the +) with caliber on 200 ohms I note 170,
- in reverse (red lead of the multimeter on the +) with caliber 2 kohms I note 1,788.

I get the same results on the 2 top diodes (not verified on the bottom ones).

I can then try to measure voltages with a multimeter, but I won't have an oscilloscope at my disposal!

Thanks in advance for any future suggestions!

[plaed]

Where is the 1,6 amp fuse, (mains side).
And the welds, contacts, cables, have they been checked one by one?

I skipped those questions; the 1,6 fuse seems intact to the eye, as well as the welds and cables (the device having never been opened or even jostled), but I did not do any tests.

[izentrop]

Here I measured the resistances as follows:
- live (black lead of the multimeter on the +) with caliber on 200 ohms I note 170,
- in reverse (red lead of the multimeter on the +) with caliber 2 kohms I note 1,788.

I get the same results on the 2 top diodes (not verified on the bottom ones).

I can then try to measure voltages with a multimeter, but I won't have an oscilloscope at my disposal!

Thanks in advance for any future suggestions!

Ok, if the output selector was indeed on 6v, no need to measure the bottom stage.
The reverse resistance seems correct, but the forward seems too high, the current may have difficulty flowing.

The charger can be connected to 230 V without risk. It remains to measure the 12 V output, which should be greater than 14 V off-load.

Carry out a test on a battery, see if the current manages to rise to more than 3 A in a discharged battery... If this is not the case, the replacement of the diodes will be essential.
In any case, replacing them will guarantee better performance.

[plaed]

The charger can be connected to 230 V without risk. It remains to measure the 12 V output, which should be greater than 14 V off-load.

Carry out a test on a battery, see if the current manages to rise to more than 3 A in a discharged battery... If this is not the case, the replacement of the diodes will be essential.
In any case, replacing them will guarantee better performance.

Understood I will make an attempt; it is therefore simply necessary to measure on the clamps intended to be fixed to the terminals of the battery?

[Obamot]

Yes, it can do that too. It's even better than putting a battery “in the circuit”.

[izentrop]

; it is therefore simply necessary to measure on the clamps intended to be fixed to the terminals of the battery?

Yes at first and being careful that the clamps do not touch each other, but that, I suppose you knew.

[plaed]

; it is therefore simply necessary to measure on the clamps intended to be fixed to the terminals of the battery?

Yes at first and being careful that the clamps do not touch each other, but that, I suppose you knew.

Hi,

Here I have finally measured the output voltage on the clamps, and I get the following values ​​for the 4 positions of the charge intensity selector:
- position 1: 10.80
- position 2: 11.35
- position 3: 12.30
- position 4: 13.18

I have a battery on hand that needs to be partially discharged and can therefore attempt a measurement while charging.

In this case, what should be done: charge then measure the intensity of the current at the terminals of the battery, looking for a value close to 3 A?

[Obamot]

And on the 6V it gives what...?

[izentrop]

; it is therefore simply necessary to measure on the clamps intended to be fixed to the terminals of the battery?

Yes at first and being careful that the clamps do not touch each other, but that, I suppose you knew.

Hi,
Here I have finally measured the output voltage on the clamps, and I get the following values ​​for the 4 positions of the charge intensity selector:
- position 1: 10.80
- position 2: 11.35
- position 3: 12.30
- position 4: 13.18

I have a battery on hand that needs to be partially discharged and can therefore attempt a measurement while charging.

In this case, what should be done: charge then measure the intensity of the current at the terminals of the battery, looking for a value close to 3 A?

You can connect the battery without worries.
What you are measuring is the average rectified voltage. The battery will charge at the peak voltage which will be 13.18/ 0,9 = 14.6 V in position 4, the maximum voltage where charging must be stopped for a car battery https://fr.wikiversity.org/wiki/Redress ... phas%C3%A9.

The charging current may not rise very high due to the forward resistance of the diodes being too high. In this case, the load may drag on and the replacement of the diodes will be a necessity.

[plaed]

And on the 6V it gives what...?

Here are the measurements on the 6V position;
- pos. 1:5.54
- pos. 2:5.83
- pos. 3:6.23
- pos. 4:6.61