NEED VOLTAGE REGULATOR 14V 40 AMPS

[Ducky_Doug]

After starting my Chevy Duramax Deisel the alternator puts out over 15.5V
and then drops down after a few minutes. This caused my 400W Portawatt
inverter to drop out on high voltage. Is there a simple circuit using
mosfets, 2n3055, etc and using readily available parts to drop the voltage
down to <15V. Regulation isn't neccessary just want to keep the voltage
between the inverters shutdown setpoints.

 

[CBarn24050]

Your alternator should not put out that much, you need a new voltage regulator
or maybe a new battery.

 

[Ducky_Doug]

Thank you for your responses. A #1 welding cable runs from the engine
batteries and feeds the 400 watt inverter in the cab. The buss then
continues on to feed a 2500 watt inverter and 400 amphr deep cycle type
aux. batteries in the back of the service truck. This setup is duplicated
in two of our other sevice trucks and they also suffer from shut down of
the cab inverter which runs a computer and test equipment. The 2.5K
inverter is not a concern. This only happens on our deisel equiped trucks
and GM assures us that this higher first recharge voltage is normal to a
deisel due to its high output alternator. A resistive device is out as it
only acts as a current limiter.

 

[Kim Clay]

On Mon, 20 Dec 2004 01:07:13 -0500, "Ducky_Doug" <dougbraun@telus.net>
wrote:

After starting my Chevy Duramax Deisel the alternator puts out over 15.5V
and then drops down after a few minutes. This caused my 400W Portawatt
inverter to drop out on high voltage. Is there a simple circuit using
mosfets, 2n3055, etc and using readily available parts to drop the voltage
down to <15V. Regulation isn't neccessary just want to keep the voltage
between the inverters shutdown setpoints.

How about a single diode in series with the Pos input of the 400W
inverter (with large heat sink). Diode will drop 0.7V @ 40A= 28W of heat
to get rid of.

Maybe 1/2 of a battery isolator or use both diodes of a 2 battery
isolator & strap both diodes in parallel. You will need good air
circulation to dump the heat.

The inverter may drop out quickly due to low volts if used without the
engine running. The diode will drop a constant 0.7V or so. If the
inverter was set to dropout at 10.5V it would now drop out at ~11.2V.

In your case this may not be a problem.

Just an idea - Kim