Re: What is this thing?
- From: Bob Giddings <bobgiddings0@xxxxxxxxx>
- Date: Sat, 28 Mar 2009 23:26:47 -0500
On Sat, 28 Mar 2009 23:55:48 -0400, Neon John <no@xxxxxxxxx>
wrote:
On Sat, 28 Mar 2009 21:35:48 -0500, Bob Giddings
<bobgiddings0@xxxxxxxxx> wrote:
I am considering your idea of using a heavy duty alternator to
improve the efficiency of the charging system.
One clarification. I'm speaking of a separate alternator just for
charging the house batteries. The reason for the separate alternator
is that with a smart three stage regulator, the voltage is high enough
to shorten the lives of any lamps that happen to be on.
Again, this is common marine practice but seemingly rare for RVs.
---------------------------------------------------------------------------------------
"A fourth option would be to have a 100 to 175 amp truck
alternator installed on your main engine and equip it with an
Ample Power smart charge regulator. Idling an EFI'd engine is
actually quite efficient and with that kind of charging capacity,
you'd only be doing it for a short period of time."
--------------------------------------------------------------------------------------
But is that cost effective? Or is it likely to be less
expensive, and more efficient, to just use a small generator to
charge through the converter/charger?
What was the cost when you did it?
Almost nothing. I paid $40 for a used Leese-Neville alternator minus
the regulator but with new bearings and brushes from an auto electric
shop. This one, specifically:
http://www.neon-john.com/RV/Electrical/alternator_large_vs_small.jpg
As you can see, the regulator can be changed out from the outside.
I designed and built the smart regulator. The NextStep from Ample
Power is a commercial equivalent
http://www.amplepower.com/
Heart Interface made an equivalent but less expensive analog smart
regulator called the InCharge. I can't seem to find it on the Xantrex
site so it may not be available. Might be worth an ask.
Finally, an afternoon spent welding up a mounting bracket and the new
fan belt. Probably $20 involved there.
Now let me discuss two other possible options that don't involve a
second alternator but will do smart and fast charge of the batteries.
Both require a heavy duty alternator, one that can sustain full output
continuously. Those are bolt-on affairs. The price varies widely
from maybe $150 to $400 or more. The boom-boom stereo freaks have
driven that market so they're available fairly widely.
The first involves using a solar MPPT controller. A Maximum Power
PoinT controller is designed to take in whatever power is available
and convert it into the voltage necessary to do a smart charge on the
batteries. Basically, it is a very wide input voltage DC/DC
converter. Depending on the specific model, the input voltage can be
below to above the output voltage.
The MPPT goes between the alternator and the house batteries. If you
get a 60 amp controller, for example, it will draw whatever amps at
whatever voltage is necessary to output sufficient voltage to do the
bulk charge at 60 amps.
Here are some of Xantrex's controllers. There are probably better
and/or less costly ones available but this will familiarize you with
the beast.
http://www.xantrex.com/web/id/9/type.asp
You might want to go to http://www.homepower.com and download their
sample issue and look at the advertisers to learn about other brands.
They also have lots of good downloadable info on the site about
off-grid power systems. Everywhere you see a solar panel, gas
generator, micro-hydro or other source of energy mentioned, mentally
substitute "engine alternator".
The other option and the one that I'm actually using now sounds kinda
rube goldbergish but it does about the same thing as the MPPT but at
significantly less cost, depending on what you happen to have on hand.
Here is the architecture.
Alternator--->solenoid contactor-->1500 watt
inverter-->120vac-->Intellipower-->house batteries.
I installed a cheap (one of those Power On Board inverters that I got
on close-out at Sam's Club for $49) 1500 watt inverter connected
directly to the heavy duty alternator. Its only job is to feed the
Intellipower already installed in my rig. The solenoid contactor is
activated when the engine is running so that the inverter doesn't draw
power from the battery. I already have a homemade three way
changeover relay that supplies 120 volts to the house in this order of
priority:
1. Inverter
2. Generator
3. Shore Power.
If I'm on shore power and I crank the generator, the house load
including the Intellipower is transferred to the generator
automatically. If I flip on the inverter with either shore power or
the generator also available, the inverter takes the load.
The reasons for this sequence are as follows.
- if shore power gets grody, under or over voltage or a storm is
blowing up, I want to transfer to generator power by simply cranking
the generator or flipping on the inverter.
- If the generator has been running but I'm finished with it but I
still want to operate some 120 volt loads, I want to flip on the
inverter to pick up the loads and let the generator idle to cool down
for a bit before I turn it off.
Anyway, when I crank the engine and the alternator starts alternating
:-), the inverter receives power when the solenoid relay closes. That
supplies power to the Intellipower which does its smart charge
routine.
I used this same architecture minus the solenoid relay (not allowed to
modify the truck) in my semi to keep the Group 29 AGM charged that I
had tucked under the bunk to run my Engel reefers and my electric
blanket. In both instances, it has worked perfectly for many hundreds
of cycles.
The major advantage of this approach, other than low cost, is that the
Intellipower is ALWAYS babying the house batteries. No chance of over
or under charging the house batteries like there is when the engine
alternator is used. An added bonus is that you have 1500 watts of
power available for other stuff for as long as you want to idle the
engine.
I mounted the inverter under the hood but away from engine heat onto a
bulkhead that Itasca used to hold the front fiberglass clip to the
frame. Only about 3 feet of heavy cable separate it from the
alternator. Ordinary 14 gauge Romex house wiring runs the power back
to the transfer relay.
Since you're going to get an Intellipower anyway, this is probably the
cheapest and most cost-effective application that you can do other
than the ChiCom generator. 1500 watt inverters are available fairly
widely for under $100. Add another $60 for a transfer relay and maybe
$20 for the solenoid relay and a few more dollars for wire and stuff
and you have it.
The 1500 watt POB inverter and the 60 amp Intellipower work extremely
well together. The POB inverter will also run the 80 amp Intellipower.
Can't guarantee any other brand will, though. The POB inverter has a
soft start feature that brings the output voltage up gradually which
in turn avoids the inrush that Intellipowers otherwise have. Without
the soft start, the 80 amp unit might trip the inverter on inrush.
Oh, and the transfer relay is like this:
http://www.neon-john.com/RV/Electrical/Gen_delay/gen_delay.html
And the commercially made version:
http://rvpowerpartsplus.net/index.php?main_page=product_info&cPath=11&products_id=135&zenid=12bd6496b540cfb55fe02838ea8d24b5
Be glad to help you with whichever option you go with.
John
Thanks, John. There's a lot to think about there.
I have just one more question, not about charging.
Was there ever any trouble running the TV or any appliance on AC
supplied by the ETQ 1200? Any problems, say, with supplying
power through a brick to a laptop? Weirdness with a small
Microwave, that sort of thing?
I guess I'm asking how uniform or steady or "clean" the AC output
from that little generator is.
You may have answered this before somewhere, but bear with me.
Bob
.
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