12V Car Transient protection.

Thread Starter

Davizuco

Joined Jul 12, 2018
20
Well, surge voltage while connecting my second battery blowed up my wireless shunt circuit.

Now I want to put a protection circuit avoiding new losses using a TVS Diode an a circuit like this:

Transient protection.png
My problem is to choose correct values:
· TVS: P6KE16A ( P6KE15A , P6KE18A ? )​
· Capacitor, 0.1uF , will 200V be enough?​
Any suggestions wil be welcome. (varistors, RL or RC ... )
 
Last edited:

crutschow

Joined Mar 14, 2008
26,998
Typically you want to put a small resistance in series with the fuse to limit the peak transient current (and voltage).
How much current does you circuit normally take?
 

Thread Starter

Davizuco

Joined Jul 12, 2018
20
The circuit takes around 50-100ma.

It's a battery charge/discharge controller that uses Vin to measure battery output voltage.
I think the voltage drop in that resistor could be a problem, How about putting the resistor in series with the diode to protect it?, I know it won't protect the circuit then, but hope diode + capacitor will be enough.
 

Thread Starter

Davizuco

Joined Jul 12, 2018
20
Well, I was taking a look to all articles and videos I could find, (included @ericgibbs 's one, thank you).

Finally I think that using a TVS diode is the best option (newbie's opinion), If I'm not wrong, TVS are faster, and easy to find for this voltages.

Expected Vin in my van is <15V so I will go for an P6KE16A, Vbr= 15.2/16.8, lpp=27A.

I think a 10A fuse protecting the diode will be enough to filter usual van surges without burning it. I will use a second 200ma fuse just for circuit protection.

The circuit will be something like this:

12V Car TVS.png
Finally I prefer to have a precise voltage measurement and won't use an RC filter.
 
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