From: John De Armond
Subject: The Power Quest Continues
Date: Sat, 15 Jan 2000 03:28:41 EST
A few weeks ago I posted about my quest to equip my Itasca Class C
motorhome with enough engine alternator and inverter to run all
normal 120 volt loads except the air conditioner without having to
run the generator. Specifically, the microwave and coffee maker.
My desire is to be able to achieve continuous operation with the
engine running while not dipping into the house batteries. I intend
to have two alternators on the engine - one for the engine and
cranking battery and a totally separate system for the house
batteries and the inverter. A standard cross-connect relay will
remain installed so that the systems can be cross-coupled if one
My last post had to do with making the decision between 12 volt and
24 volt systems. I wanted the 24 volt version but alas, there
simply isn't enough room for a 24 volt alternator in the engine
bay. Indeed, space is going to be the single biggest problem.
To run a 1500+ watt inverter, I need about 200 amps of generating
capacity. A quick search of the net pops up products from places
like Ample Power but at very steep prices, sometimes approaching
$1000. Too rich for my blood. Besides, the engineer in me said "do
it yourself". Another potential source was the vendors of high
output alternators sold to the kids who like to make their cars go
BOOM BOOM with big stereos. Alas, an examination of several of
these alternators revealed that they are little more than slightly
reworked regular alternators. In other words, low duty cycle and/or
short life at the higher output. It appears that they spent more
time on the chrome plating than they did on re-engineering the
I talked to a local ambulance company owner and inquired as to who
equipped their ambulances with high capacity alternators. He
pointed me to Red Hot Battery Service here in Cleveland. Dudley,
the owner, builds the special, high capacity alternators. He uses
the large frame semi truck alternators and rebuilds them to make
200+ amps as a 1 wire unit (self-exciting). The price was great
too, at $265.
Brought a bad unit home to check for clearances. Damn! Itasca
built the body of the MH so tightly around the engine that I would
have to cut away and rebuild part of the bracketry that supports the
body on the frame. Doable, but very time consuming. Back to Red
Hot. We decided to take a look at late model large car and SUV
alternators. The alternators have grown with the increasing power
demand in late model cars. Our eyes settled on a Delco alternator
for a late model Cadillac. This alternator is rated for 145 amps.
Dudley told me that he was sure that when converted for one wire
operation, it should be capable of near 200 amps. The best part is
the price for a new (not rebuilt) unit is going to be under $150.
Normally this alternator comes with a serpentine belt pulley.
Dudley knows how to convert it to a V-belt drive which I must have.
The nice thing about this alternator is that if one isn't enough, it
is small enough that another can be mounted alongside it.
OK, so the alternator is on order and will be here middle of the
week. I have a bad core unit to use to begin fabricating the
mounting brackets. I'll keep the list informed on how this goes.
Assuming everything works OK, I'll post part numbers and Dudley's
phone number. It looks like I can get the power generation side of
this system done for under $200.
I'll initially use the internal diode bridge in the alternator but I
intend to fit the alternator with larger external diodes later.
I've had great success in doing this in the past. This gets the
diode heat away from the alternator, the engine heat away from the
diodes and lets me use rugged high voltage stud rectifiers instead
of the crappy little chip rectifiers the OEMs use. More on that
The specialty deep discharge battery charging voltage regulators
such as the ones made by Ample Power (http://www.amplepower.com/)
and Cruising Equipment (http://www.cruisingequip.com/ - note: these
pricks charge for tech support!) are computer-controlled and will
very rapidly recharge large house batteries. They implement the 3
stage charging cycle and monitor battery temperature to prevent
overcharging. They are also quite expensive. They are primarily
aimed at the offshore marine market where it is desirable to
recharge the house battery with only a short engine run time each
day. I'm going to initially use a simple internal regulator. The
regulator that Dudley uses can be strapped to one of several
voltages to match the application. Then I'm going to study the
build-or-buy decision on the smart regulator. I kinda have the
urge to do another embedded microprocessor project so I have a hunch
I'll be building my regulator, particularly since I want to do some
things that neither of these commercial ones do.
I'm going to order the Statpower ProSine pure sine wave inverter,
probably the 1800 watt unit. I've had very good luck with this
brand in the past and I just can't justify the price difference
between the Statpower and the Heart and other high priced units,
especially since I won't need high power shore power battery
charging. I'm going the sine wave route because I'm tired of trying
to suppers the hash that pseudo-sine inverters generate. Really
screws up AM and ham radio. The pure sine inverter is a bit less
efficient but since my main use is to run it from the alternator,
that doesn't matter much.
I'll keep the group apprised of what is happening. This is going to
be fun! And it gives me the excuse I needed to order a new MIG
welder (the Miller 250X kicks butt!) yesterday. :-) I'll probably
end up with a writeup and some pictures on the web site when I'm
From: John De Armond
Subject: Re: The Power Quest Continues
Date: Mon, 17 Jan 2000 20:01:43 EST
Dick Lucas wrote:
> Neon John wrote in message <38803011.49AE74BE@bellsouth.net>...
> >the price for a new (not rebuilt) unit is going to be under $150.
> >Normally this alternator comes with a serpentine belt pulley.
> >Dudley knows how to convert it to a V-belt drive which I must have.
> Be careful with your conversion from serpentine to v-belt. My '83
> southwind, with a 65amp alternator regularly went through the v-belts. I
> have seen a number of posts about the same problem with that setup (454
> Chevy) and came to the conclusion that a single v-belt simply couldn't
> handle that much power reliably. 65 amps is around 1.25 HP, a 200 amp
> alternator would require about 4HP, which is a lot for a single v-belt.
> Also on that belt was the water pump and the air pump, but they don't
> consume much power. Sometime around 87 or so, the 454 switched to a
> serpentine belt. I suspect that it was just because of the belt problems.
> To reliably transmit that much power may require a dual v-belt setup.
> I got pretty good at changing the belt on the side of the road, and always
> carried at least 2 spares for the alternator belt.
yeah, me too. My 68 Fury's appetite for belts runs about 2 a
summer. :-( One of the little things one learns to put up with to
enjoy old cars, at least until the engine transplant :-) I've been
eyeing a serpentine belt conversion for my MH. I'm not sure if I
want to do that much work or not. I think I can mount the new
alternator so I can get a dual belt drive on it. If not, wellll,
then I'm pretty good at changing belts.
From: John De Armond
Subject: Re: Inverter battery capacity adequate?
Date: Tue, 21 Mar 2000 18:19:52 EST
Randy Howe wrote:
> Cool idea John. How did you mount the second alternator? Do you have a main switch on
> it so that there is no electrical load and consequently no mechanical load on it when
> not in use?
Welded up a bracket to mount where the old, long abandoned AIR pump
was. Extended the waterpump belt to fit.
I went one-wire because the alternator shop guy recommended it.
I'd probably not do that next time so I could turn the alternator
off whenever I needed to by switching only the excitation. Now I
have the second alternator hooked directly to the house batteries.
I still have the cross-over relay so that I can parallel the
batteries if either alternator fails. I'll probably put another
relay or manual disconnect in the second alternator lead at some
time in the future. The nature of the one-wire regulator is that it
does not excite the alternator until 12 volts is applied to the
output terminal so switching it off is as easy as disconnecting the
To tell the truth, if I had it to do over again on my particular
rig, I'd just put the Cadillac alternator in place of the stock 80
amp unit and be done with it. It was a LOT of work to fit the
thing in this tight engine compartment. The chassis load is pretty
low unless the headlights are on so I would have lost only a little
capacity by running the chassis on this alternator too.
Tip for fitting a different length belt to a modified drive system
without a lot of guessing. Get a belt longer than what will be
needed. Cut the belt. Pull it around the pulleys. Overlap the
ends. Mark one end where it overlaps the other. Take this belt to
the auto parts store and ask them to measure the belt on their belt
measuring tool while holding the marks in alignment. This technique
saves a LOT of headaches in getting just the right length belt, as
you don't have to worry about groove depth compensation and such.