Electronic Circuit Breaker

[Ray64]

Does anyone make an Electronic circuit beaker for our 6 volt cars. If so where to purchase T.I.A. RAY

[nkaminar]

The circuit breaker breaks when the amperage gets to the set level. It does not depend on the voltage. Could be 6 volts, or 12 volts, or 90 volts. Try your local automotive store or search online. Here is one for 40 amps at NAPA: https://www.napaonline.com/en/p/BK_CBF40?gQT=1

[TomInCologne]

Originally Posted by nkaminar

The circuit breaker breaks when the amperage gets to the set level. It does not depend on the voltage. Could be 6 volts, or 12 volts, or 90 volts. Try your local automotive store or search online. Here is one for 40 amps at NAPA: https://www.napaonline.com/en/p/BK_CBF40?gQT=1

But this one is 'automatic re-set' one, so you may not realize that your circuit breaker is tripping often. A wiring fault or other electrical fault may go unnoticed until the fire starts eating your A away...

[Badpuppy]

Sorry to counterdict, but automotive CB's use a heating element and are rated at 12 volts for correct operation. 6V will only provide half the current. A 15 or 20 amp may work, but that's just a guess.

[400A]

Bert's lists one in their current catalog, part #A-11456. It snaps into the fuse block assembly in place of a fuse. I have no experience with this item. Just noticed it in the catalog.

[katy]

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rated at 12 volts for correct operation.

Rated at 12 volts means up to and including 12 volt, not over 12 volts, such as 24 volt or 120 volt (ac).

[nkaminar]

BadPuppy, I normally will not counter respond, but the heating element you refer to in Post # 3 is heated by current not voltage. It is the current squared times the resistance.

Here is what is found on the internet:

"Heating by I squared times resistance" refers to the concept of Joule heating, where the amount of heat generated in a conductor is directly proportional to the square of the current (I²) multiplied by the resistance (R) of the conductor, represented by the formula: H = I²Rt. "

The voltage is important in that too much voltage will break down the insulation. But a 12 volt circuit breaker should work just fine at a lower 6 volts.

[rotorwrench]

It's all about amperage as was mentioned. The only reason they associate them with 12-volts is to indicate a low voltage DC electrical system. 12-volts is the most common automotive voltage in the common era. 1956 was a long time ago as much as I hate to admit it. Short stop circuit breakers use a bi-metallic internal switch that is rated at the max safe amperage of the wire it protects. If a short to ground happens, a 6-volt system will be only slightly slower to trip but we are talking fractions of a second. All it has to do is trip before the wire burns up. If you don't think it will work then it's easy to test. Just short one with power on it to ground and see what happens.

Higher voltage systems can use smaller gauge conductor wire. A 12-volt system can use 18 gauge wire for average light duty circuits. 24-volt systems can used 20 gauge wire. Circuit breakers are sized with slightly higher amp ratings than fuses for the same gauge of wire since it will trip faster at overload. Wire is sized depending on what amperage is needed in the circuit. It can be larger but it can't be smaller. With fuses, they can be a lower rating on the average wire size but it can't use an amp rating that exceeds the rating of the wire or it won't protect the wire. Protection of the wire is the whole point of using circuit protective devices.

[Badpuppy]

No argument, Neil. Power and heat are the same thing, same formula. I'm assuming the operator is a resistive heating element, could be wrong. If so, 6V across it would produce half the current of 12V, thus 1/4 the power (heat). Would require 4x the current to activate the same CB. Would require a variable PS to test this assumption.

[rotorwrench]

Don't forget that a dead short to ground is a lot bigger load than any wire can take for long. I watched a wire in an alternator control circuit burn up when it finally shorted to ground after 32 years in service with a police department. The whole wire burned within 2 seconds since generator and alternator control systems aren't short protected circuits. A person can weld with a 100-amp generator. A battery can store a lot of current too.

[Bob Johnson]

Here is some information:
If you calculate the resistance needed for 30 amps for a 6 and a 12 volt system you get 0.4 ohms for a 12V and 0.2 for 6V. So a dead short across a circuit breaker would require it have those resistance. But that is not how it works. The circuit breaker has a much lower resistance, typicality 0.02 ohms. Thus it will "see" a voltage of 30 X 0.02 = 0.6 volts when it triggers regardless of the overall voltage of the system. The number of watts (power) is what triggers the breaker. In this case it is 18 watts (30A X 0.6V).



Note that when the breaker triggers there is a difference in the "short" resistance for 6V vs 12V. In a 6V system it take a resistance of (6V - 0.6V) / 30 A = 0.18 Ohms for 6V and (12V - 0.6V) / 30 A = 0.38 Ohms for 12V. That would result from a 180 watt load for a 6V system and a 360 watt load for a 12V system. That is where the difference between a 6V and 12V system is seen.




Bob

[nkaminar]

Here is what the ad says:

"Type II - modified reset Type II circuit breakers will remain “tripped” by an internal resistor (in the OFF position) as long as the circuit is powered. Type II breakers can be reset by turning the circuit OFF, or by turning the ignition switch to the OFF position. These devices are sometimes called "non-cycling breakers."

If I read this correctly, if you were to somehow disconnect the circuit, like disconnecting the battery and then connect it again, the circuit breaker would then trip again. It appears that the circuit breaker would not allow the car to burn up.

[TomInCologne]

Originally Posted by nkaminar

Here is what the ad says:

"Type II - modified reset Type II circuit breakers will remain “tripped” by an internal resistor (in the OFF position) as long as the circuit is powered. Type II breakers can be reset by turning the circuit OFF, or by turning the ignition switch to the OFF position. These devices are sometimes called "non-cycling breakers."

If I read this correctly, if you were to somehow disconnect the circuit, like disconnecting the battery and then connect it again, the circuit breaker would then trip again. It appears that the circuit breaker would not allow the car to burn up.

Hmm, not a native speaker here, but i would parse it as 'turning the main switch off and on' will re-set the fuse. I would rather keep the fuse in the 'tripped' position until i manually re-set it.


Ymmv

[katy]

Originally Posted by Ray64

Does anyone make an Electronic circuit beaker for our 6 volt cars. If so where to purchase T.I.A. RAY

Methinks we've gone "off track" here.

https://www.phoenixcontact.com/en-ca...rcuit-breakers

[feufeu]

hi all,
in al my cars i hide this part under the dash board.
https://fr.aliexpress.com/item/10050...Cquery_from%3A

[katy]

Originally Posted by feufeu

hi all,
in al my cars i hide this part under the dash board.
https://fr.aliexpress.com/item/10050...Cquery_from%3A

That link doesn't doesn't work for me.

[feufeu]

https://www.amazon.fr/EBTOOLS-Disjon...0867SH3XX?th=1

hope this will work?

[Badpuppy]

Originally Posted by feufeu

https://www.amazon.fr/EBTOOLS-Disjon...0867SH3XX?th=1

hope this will work?

12 volts, yes. 6 volts uncertain.

[feufeu]

just to avoid burning if there's a short circuit...

[rotorwrench]

The short stop circuit breakers that Ford used in the post war era were a simple bi-metallic switch. Heat is what reacts them. The bi-metallic strip gets hot real quick in a short situation. They had bi-metal switches down to a science pretty early on. King Seeley used this principle for their pressure and quantity indicator systems as early as 1936 when Ford started using them. They are very reliable but can be destroyed in a dead short situation.

Aircraft circuit breakers work on the same principle but they have a toggle mechanism that must be reset to restore current flow. If the short still exists after a trip then the bi-metallic switch won't allow it to reset as soon as it heats back up. A short stop automatically resets after the bi-metallic switch cools back down but will continue to trip as long as the short is still present. Bi-metallic switches are calibrated for the amount of heat they can take before bending. A smaller wire can take less heat so the switch is made to bend at a lower temperature.