Is an NTE934 voltage regulator suitable for use in a motorcycle alternator?

Question

Is an NTE934 voltage regulator suitable for use in a motorcycle alternator?

Answer 1

It depends upon what type alternator the bike has.

Most Bikes have Permanent Magnet alternators.

Anytime they spin,,they make current.

You cannot actually turn them Off.

So this type of Alt's  Regulator sends excess current to ground in order to control their voltage.

It Charges ALL the Time,,,,

but Voltage is controlled by bleeding Some to ground.

It's Literally a SHORT to ground.

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A Few bikes have an "electromagnetic" alternator.

Same as most all cars do.

These rely on Battery Voltage to create the Magnetic field in the alternator.

Regulators for these simply Interupt the Battery Voltage TO the alternator,,,,

which actually turns the Alternator OFF.

At the desired Voltage Setting,,,,the semiconductor acts like a SWITCH that opens/closes to deactivate the Alternator's power supply.

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An NTE934 may be suitable for the "Automotive TYPE" of alternator,,,switching it On & Off.

So it WONT work on majority of Bike Alternators,,,which have PermaMag type.

Actually,,,it COULD be rigged to control a Mechanical Relay,,,which would simply cut the Alternator  OUTPUT In/Out of the charging circuit.

Same as if using a manual switch.

But that's VERY inefficient and creates some odd charging characteristics.

.........................................

Most bike Regulators are sorta "Universal" as far as Function.

The Specs & Capacity is what's different.

Adapting the Wiring Connections is the hardest part of adapting "ANY bike-type regulator"

A  Cheap "Heavy Duty Upgrade" is

to get a Used one from a bike salvage place,,

or Ebay,,,,from a bike with a Higher Output Alternator than the bike you're putting it on.

$30~50 will buy almost Any Regulator on Ebay---eventually,,,lol.

But ya can also find them as low as $10~20.

.........................................

It's TUFF to get a price quote on a New Regulator for $75~100 or MORE,,,,,

and Then realize there's only $5~10  RETAIL Price worth of stuff in there which fails.

Seems simple enough to Unsolder a Bad device,,,and replace it with a new $2 one with 3X better Specs.

"On Paper" ,its Just That Simple.

But the Reality of actually DOING that is a lot different.

Most everyone who trys it usually ends up realizing a New,Expensive one is "Worth it",,,

or that a "$50 Used One"  is a Better Bargain than the original $2 Part Swap Plan.

It's POSSIBLE to Repair/Mod  the regulators,,,lots of people Do.

TRY It if You want to,,,I Sure dont wanna Discourage anybody.

You might get Lucky,,heck,,Ya might even be GOOD at it.

But most folks find it to be impractical.

Good Luck

Answer 2

I hate to disagree with TXm42 - he's one of the most knowledgeable people who frequent here. And he's probably got more experience than I have days alive.

However,

My experience has been that motorcycle (road bikes) alternators have been similar to car alternators since the late '70s.

The alternator is a 3 phase unit that uses an electrically excited field instead of permanent magnets. The voltage regulator actually controls the voltage to the brushes, which determines the output of the alternator.

The NTE934 does not work well as a stand alone control in this application, even with a large heat sink. The voltage drop through the device is excessive.

I refused to pay the extreme price asked for the proper part, so I experimented.

I have a CB650 Custom that is currently running a diode trio from a Mitsubishi alternator (from my Dodge truck) and a Ford style voltage regulator. Parts cost for this Super Heavy Duty, won't burn out set up: $9.99 for the regulator. (The truck alternator was junk - bad brushes/holder, but good diodes)