Hello.

I have a question for the max Amps of a diode.

Assumed I have two 100Ah lead acid car batteries. One is empty. The other is full.

If I connect both negatives and both positives it will give a spark and some decent current will flow from the empty to the full.

If I , instead of bridging the positive legs, connect a 100mA diode between the two batteries, that the diode blocks from the empty to the full. What would happen?

Would the diode blow? Would it still block?

If I would connect it between the two batteries, that the diode blocks from the full to the empty, it would probably blow as too much current (>100mA) will flow.

The question is what the 100mA stand for. For the blocking or the flowing?

Thanks!
VESPUCCI

 

The question is what the 100mA stand for.

It is the maximum, steady-state DC current the diode can carry in the forward direction without being destroyed (with the current being largely determined by the circuit it is connected to).
It's unrelated to how much voltage it can block in the reverse direction.

 

Assumed I have two 100Ah lead acid car batteries. One is empty. The other is full.

If I connect both negatives and both positives it will give a spark and some decent current will flow from the empty to the full.

It is also likely that in this scenario, the "empty" battery is so far gone that it won't accept a large charging current.

If I , instead of bridging the positive legs, connect a 100mA diode between the two batteries, that the diode blocks from the empty to the full. What would happen?

Would the diode blow? Would it still block?

Again, it matters what the condition of the "empty" battery is and what you mean by "diode blocks".

If the diode anode is connected to the good battery, if the "empty" battery is just weak, you would expect the diode to die.

If the cathode is connected to the good battery (to actually "block" the good battery), nothing will happen.

 

Current will flow from the battery with the higher voltage to the battery with lower voltage.
If you want to prevent back flow into the battery, use two diodes, each one rated for the maximum load current.

 

It is the maximum, steady-state DC current the diode can carry in the forward direction without being destroyed (with the current being largely determined by the circuit it is connected to).
It's unrelated to how much voltage it can block in the reverse direction.

Thanks crutschow, this answers my question perfectly.