Finished! 2-Channel 12-volt Transient Voltage Protector

Two busses one pos and one neg

MOVs and TVSs connected to bridge the busses

But 2.5 amp rice grain fuses connected in series with each component

I count both the MR2535 avalanche rectifier separate
Because neither requires a rice grain fuse

The TVSs are bi-directional so they can be conntected without any regard to polarity orientation.

Only the MR2535 and the electrolytic capacitor need to be oriented correctly to polarity. The hookup is as simple as it gets.

But a suitable challenge for the one and-a-half-handed assembler :)

Hi Mex,

Thanks for the down to earth (pun intended) explanation.

tvman44 wrote:
A schematic would be more interesting.

It would be super simple. As I understand it, everything is wired in parallel across each "circuit"

A schematic would be more interesting.

So if the 16-17 tightband volts fails the discretes I'll raise it to 17-20 volts. The tighter the better. The 470uf will smeeeuuth out thr ripple from the altermator

He said something about 1.21 jigawatts. :)

Whenever an inductor is saturated then power is cut the field collapses and the 12 volt power oscillates sometines with voltage spikes so high they damage solid state components. In earler MoPar chassis and GM chassis the decaying field would set up ringing between two inductors. Start the generator while the chassis air conditioner clutch was in operation and it would fail the alternator voltage regulator. One GM failed the HEI distributor module AS the generator started.

This isn't Gyro Gearloose grade deduction. For doubters with no heart issues find a Ford with a fender mounted starter solenoid. Grab ahold of the starter motor big stud. OK? Now have another person crank the engine then release the key while you hang on to a piece of bare metal with your other hand.

You have been introduced to a voltage transient event. It can blow a pacemaker or in my case put me in bed for a couple of days.

If an engine is running in a motorhome and the generator is cranked that little starter motor will develop 4 -10 times the reaction that an A/C magnetic clutch does. Not only are positive transients produced but also negative side voltage transients.

That "kick" eats away at solid state components. Little by little or bite by bite every device in the vehicle feels the jolt. Ham radio operators understand this - they have to. Appliances and accessories contain some form of protective device but they are tiny basic and cheap.

I am going to test the durability i.e. longevity of a closest voltage tolerance imaginable suppresor system. On both ignition and battery system.

This exercise was insired last week when I had a brand new factory ND A/C compressor installwd in the toad. It works great but twice now when the unit shuts off it wipes the factory radio settings and clock memory. If.it has eaten the circuit protectionbinbthese devices what's next?

After a year I will autopsy the device's discrete components using resistance and high voltage and see what if anything has failed.

So what does this device protect from? Surges on the twelve volt system?

MANAGEMENT
"Well what did you do today?"

ENGINEER

"Actually very little"

Pink Slip Friday at lunch. SAE electrical engineers busy themselves with a blizzard of data factoids and white papers. Much of that allows proposed vendors a guide as to what is expected of a submission for consideration. There have been far too many elementary design disasters to mislead a seasoned MEE into believing SAE specifications are Holy Writ.

1. If charging voltage temp compensation is likely to impinge upon device selwcted recalculate. In the case of myself 16.0 volts is Arctic operation therefore impossible. I chose 16.0 volt avalanche TVS rated 1500 watts 5/4 then trebled for redundancy.

MOVs have unique properties. Capacity wise they can literally take a bullet (total joules) if the TVS vf exceeds 1.0 volt. 17 volt MOVs are a good choice. Because of lower voltage ratings 17 volt MOVs are rather small. The MR2535 has good inverse voltage response so it acts as a free-wheeling diode plus will shunt avalanche transients of >28vdc.