Current Regulator

[Bob Bidonde]

I need some advice from the electronic experts on The Barn. >My concern is in regard to running an alternator in a Model "A". When the engine starts, the alternator output is in excess of 20A to rapidly charge the battery which was depleted by running the starter motor. The high current output lasts for less than a minute. >My concern is that any modern electronic devices that are ON during the engine start will be exposed to a current surge that causes damage / failure. >I think that all electronic devices need to be on an isolated circuit protected from the alternator's current surges by a current regulator. >What are your opinions & recommendations?

 

[katy]

Modern cars have "modern electronic devices", and they also have alternators that put out a lot after startup, they don't seem to have a problem w/the higher voltages.

BTW, I'm not an electronic expert

 

[Badpuppy]

The ammeter registers current going into the battery, nothing else. Alternator voltage is regulated, so attached components will draw no more current than they need.

 

[Y-Blockhead]

Does a Modern have surge protectors? They have modern electronic devices. I actually never thought about it. I don't know.

The only modern electronic I have in my Model A is my GPS. The same one I use in my F-150. I don't plug it in until I start the engine(s). I have charged my cell on occassion but again, that is after I have started my engine.

 

[Badpuppy]

Surge protection is mainly for external events such as lightning strokes and static discharges. Most modern automotive electronics have electrostatic discharge protection for each individual unit. Automotive regulators handle the normal load changes encountered within the closed system.

 

[DanK]

The amount of current a device draws is determined by the voltage the alternator maintains and the effective resistance of the device. As long as those two things remain constant the current doesn't change. Right after startup the alternator provides that excess current to the battery but does it at a fixed voltage. The voltage is fixed but the battery internal resistance changes based on it's state of charge. At a fixed voltage the alternator can't force more current into a device than it's internal resistance requires.

 

[butch chase]

Wire your system to the battery. as said above you will receive 12 volts and only draw as many amps as your device demands. your battery is demanding those extra amps for a few seconds.