Nice Remote Mounted Alternator Rectifier

I guess that was a nice set up on your tractor towing the fifth wheel, where it seems the remote rectifier was located in the trailer? That is a great idea. Of course it would take a second rectifier for charging the truck battery. Where you running two alternators? Or two rectifiers for one alternator?

I was thinking about using a dual alternator set up for a retirement truck, to pull a fifth wheel. My idea would be a 24 volt second alternator, hooked up to 4 deep cycle batteries, running a 24 volt pure sine wave inverter, to supply power to the trailer.

However now it is much less expensive to install a large solar panel system in the trailer, rather than upgrade the truck alternator and charging wires.

I was checking the price of a 175 amp alternator, and it was in the $600 range. And it only works a few hours per week, while the solar system will work on average 35 hours a week. And the solar panels on the trailer will keep charging the batteries even while the truck is out on a sightseeing trip. .

Thanks for showing the high output alternator system. Where can someone buy it?

Fred.

Alternators have their own rectifiers built-in to power the chassis just like normal. The stator wires track alternator voltage regulation precisely. And the alternator runs 100F cooler. And lasts a lot longer.

Mount the highest amperage FACTORY OPTION alternator you can get your hands on. It's powerful enough.

It is not necessary to keep the 3 stator wires in order - mix and match.

I hate to digress, but I don't think there would be any discernible advantage of having a remotely-installed rectifier in terms of providing (additional cooling) through the use of enhanced heat sink.

The alternator metal casing and its surrounding environment is more than enough to dissipate the heat along with its built-in fan. If you intend to solely rely on the heat sink fins for a very efficient cooling, you would still have to install a fan to dissipate the heat.

A novel idea, but I don't like to break into the pre DC power source of the 3-phase AC coming out of the stator.

It is not only cumbersome but it can also void any warranty that you may still carry.

Remote rectifiers have been employed by some blue water sailors who are running large Lifepo4 battery banks, which can suck way more juice than lead acid, and for longer.

They have reported only moderate 'disappointing' gains on the amperage delivered, but of course alternator life/reliability should improve since it will run cooler.

I think I'd like to get another 50/120 chrysler alternator and upgrade Diodes and perhaps heatsinking for when my questionable lifetime reman decides to Eff with me.

But with an ammeter measuring total alternator output, and a thermocouple on the casing, I can see mine only really gets hot (180f+) when not moving, hot idling, at max output.

Highway speeds and it ( the casing) rarely exceeds 120F even at large loads. I do not know the temp of the rectifier plate or how different it would be. The cold air intake for alternator I once envisioned will likely never occur.

Should we be looking at running three phase power back to the trailer and rectify right there close to the house battery?

What regulates the voltage after the rectifier? Can this be used on a 24v alternator?

time2roll wrote:
Should we be looking at running three phase power back to the trailer and rectify right there close to the house battery?

I think you would be much better off with a dc to dc 12V battery charger

If it is unrectified, it is likely unregulated and you can get some pretty high voltages !

time2roll wrote:
What regulates the voltage after the rectifier?

Good question, although I know there are after market voltage regulators.

time2roll wrote:
Can this be used on a 24v alternator?

YES ! In fact most alternators will make enough voltage that it can be rectified and regulated to charge a 24V battery, BUT they will not achieve that voltage until higher engine RPM. You could change the pulley size but the bearings would wear faster.

They also make 12VDC to 24VDC battery chargers !

sheesh people !

the regular is in the alternator, it controls the field voltage and current
the voltage on the external diodes, is the same voltage as the internal diodes

the differences are (2)
#1the alternator runs cooler, because the power and heat for the rv batteries are on the external diodes, the load is shared, parted out to the external diodes

#2 and the 14vac doesn't have the voltage drop of the long run DC
the DC is developed at the external diodes from the 14v 3phase ac
same thing as putting the solar controller close to the batteries, not close to the panels, you make the DC near the batteries, not up at the engine

this is still only 14+ volts NOT high voltage

Perhaps this will help explain how it really works.

"Posted By: MEXICOWANDERER on 08/16/12 09:24am

Alternator 102 Scenario (1)
Alternator stator feeding 2 rectifiers. One sense lead for Voltage Regulator.

The OEM sense lead should remain connected to the chassis battery unless the technician knows exactly what he is doing.

Regulator sense lead informs voltage regulator that the setpoint has been reached. Let's call it 14.2 volts for drill. There is ALWAYS a load present on the chassis battery so the alternator never "shuts off" with a full battery.

16.0 Volts AC will be present at the 3 stator taps. The positive rectifier will consume, let's say .9 volts junction drop and the negative also .9 volt junction drop. 16.0 minus 1.8 volts added for the 2 full wave rectification. Result 14.2 volts.

So 14.2 volts must be there or the regulator will kick the rotor field in the pants and scream "WORK HARDER!"

The same 16.0 volts is sent to the remote rectifier. The voltage better not "drop" or there is line loss and it needs to be fixed. Bad wiring.

The remote rectifier declares "Oh look, I see see 16.0 volts, and I too have .9 volt rectifier junction drop meaning I too will have 14.2 at the + and - output terminals.

If the remote rectifier draws down hard and reduces AC stator tap voltage. The alternator output voltage drops and the voltage regulator will scream WORK! WORK!"

If the voltage output mirrors the existing alternator output it would seem to be plug and play. Easy to verify after the money is spent and equipment is installed. Best to know before hand.

Does pulling power direct off the stater bypass the alternator current limitation? Or are maximum amps limited by a maximum field current? I really do not want to burn something up on the first day.

Does it need a monster heat sink if alternator is half the rated capacity?

Depending on where you mount the heat sink
On the engine compartment firewall,
Or
Back in the battery compartment, there may not be any airflow to cool it
So Yes go big
Also you might be pulling 75 percent or more alternator rating thru the external if the house batteries are low and the engine batteries full
The oem diodes are heat sinking to the alternator housing (that's a lot of metal)
The stator winding's still carry all current being produced
You moved the heat from the diodes charging the house batteries, to outside of the alternator, not the amps in the stator windings
Moving heat outside the alternator keeps everything inside there cooler