TIDA-00476: Any suggestions why Q2 is blown-up when connecting a 44V panel

Rob Keij

Part Number: TIDA-00476

I want to use this design for 22/44V panels but when I connect a 44V panel Q2 is blown-up.
I did somes test with less powerfull sunlight and it seems to work, but now when rhe sun is more powerfull
Q2 blown-up. With one board also a 7,5A fuse was also blown (fuse in series with + battery).

With a 22V panel I have no problem.

I thought about a 12V zener between the gate and the source, but it seems to me that the Q2 voltage is never reach the voltage limits?

Any suggestions where to look?

Best regards,

Rob Keij

over 4 years ago

0 Desheng, Guo over 4 years ago

TI__Expert 5920 points

Hi, Rob

I looked at this design, the B- is floating. The current loop from panel to battery should be blocked by Q1A.

While if you use non-isolated probe to test the Vgs of Q2, the ground of oscilloscope may short the Q2 to ground.

So I wonder to know, how you did during your test?

It is better to use isolated probe to do the test.

0 Rob Keij over 4 years ago in reply to Desheng, Guo

Intellectual 380 points

Hi Watermelon Noodles,

If I measure I do this isolated, but the issue is not while I'm measuring.

The Solar Charger works perfect with a 22V panel.
But when I connect a 44V panel with the battery connected Q2 is blown.

But it happens only when the sun powerful, so something is wrong when
the 44V panel has to much voltage when the charging is started.

best regards,

Rob

0 Desheng, Guo over 4 years ago in reply to Rob Keij

TI__Expert 5920 points

Hi, Rob

Sorry did not help on this issue.

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TIDA-00476: Any suggestions why Q2 is blown-up when connecting a 44V panel