Orion MBR not charging

[Perry Babin]

It should be charging. What is the DC voltage on all 3 legs of any one of the FETs?

Make a quick check to confirm that they all have approximately the same voltage.

 

[manina]

1 - 0,04
2 - 13,6
3 - 12,5

All are showing the same voltage however 12,5V at the output is not enough to properly charge an AGM battery.

The other MBR I have has 13,3V at the output - much better

 

[Perry Babin]

They are no being driven on.

Post the voltage on all 3 legs of Q8.

 

[manina]

1 - 0
2 - 19,9
3 - 30

 

[Perry Babin]

That transistor is defective.

The use of hyphens as dividers can be confusing, please use a colon or something that cannot be confused as a negative sign in the future.

 

[manina]

ok, I'll change it and see what will be the output.


Thanks so far

 

[manina]

Changed Q8 and now the output is at 13,3V

Issue solved!!!

Perry you are great

 

[Perry Babin]

You may want to check one more thing. With no battery on the output, does the output of both MBRs drop to near 0v?

 

[manina]

No, they do not drop

Actually, they show both the input voltage (13,6V)

 

[Perry Babin]

I don't think that's right.

Is there a resistor that's connected to pin 2, 3 or 15 of IC2 that's not shown on the diagram?

If not, compare the DC voltage on those pins of each MBR.

 

[manina]

No resistors on pin 2,3,15 ad the two MBRs voltages on the pins is now consistent; small variations but nothing significant.

When the MBR is off, there is anyway current on pin 1 of Q5 and this flow to pin2 then R13 and, consequently to the output. Does it make sense? At least from the circuit point of view. I would have expected no voltage at the output when it's off

 

[Perry Babin]

What's the voltage on pin 12 of IC1 with no remote voltage applied?

I'm assuming that the 'power' terminal is the remote terminal with no voltage applied and that you have nothing connected to the output except your voltmeter.

 

[manina]

Pin 12 with the remote disconnected is 0,25V

And, yes, only the meter is connected and "power" is the remote connection (the one that turn the MBR on when V is applied)

 

[Perry Babin]

Do you have a 12v headlamp or some other light load that you can connect across the outputs to see how much current will flow through it?

 

[manina]

Yes; I connected a small lamp to the "In" and the current draw is 0,36A while on the "Out" the draw is 0,30A

The light on the Out is faint compared to when it's connected to the In

Measurements done with the "power" disconnected.

When the power is connected, the draw is identical at 0,36A

 

[Perry Babin]

Connect the lamp to the output terminal and measure the DC voltage across each of the large resistors near the FETs. Does any one read above 0.000v DC?

If you can't read any voltage across the resistors, you may need a larger lamp (like an automotive headlamp).

 

[manina]

Connect the lamp to the output terminal and measure the DC voltage across each of the large resistors near the FETs. Does any one read above 0.000v DC?

If you can't read any voltage across the resistors, you may need a larger lamp (like an automotive headlamp).

I managed to find a 55/60W lamp from my car.

Connected and measured few resistors then one of the FETs (Q11) started to smoke . The resistor connected to the smoking one was at 0,25V while the others I measured were at 0V.

I stopped the test at this point

 

[Perry Babin]

Remove that FET and see if it still produces output while off.

In the future, you should have the FETs clamped to the heatsink whenever you have anything connected to the output terminals that causes current to flow out of the output.

 

[manina]

It was clamped

I'll take it off and see

 

[manina]

Few of the large resistors (on Q19 and Q17) are at 0,03V, few at 0,01 (Q13 ad Q15). Same also on the other side.