Statpower

[dave1]

>GMCers
>
>Thought some of you might like to see this. It is taken from STATPOWER
>website. Which is http://www.statpower.com/rv.htm Please understand
>what this means. If you upgraded to a larger alternator you could run your
>roof AC without running the genset. Life is beginning to get exciting.

I requested some additional information from Statpower and here is the
response I received. Thought some of you might be interested.

>Derek Pettingale - RV Distribution Account Manager
>Statpower Technologies
>7725 Lougheed Hwy
>Burnaby, BC V5A 4V8
>Canada
>tel. 604 420 4820 x2127 fax. 604 420 1591
>http:\\www.statpower.com
>
>> -----Original Message-----
>> I am very interested in this solution. Can you
>> tell me more about what kind
>> of "high performance alternator system" is avalable for this
>> application and where I can learn more about it.
>[DP]
>[DP] We tested a Coleman 13,500 Btu roof air on our Prosine 3.0/2.5 and
>1800 units. We ran the inverters off of batteries only (8Ds).
>Obviously, with the support of an alternator pumping DC into the
>batteries the run time for the A/C unit will be extended beyond the
>capacity of the batteries themselves. The amount of extended run time,
>as you are aware, will depend a lot on the quality and capacity of the
>alternator used.
>
>I am somewhat familiar with the alternators available with Prevost bus
>shells. The shells are popular with conversion shops which outfit them
>as RVs. The typical situation is that the Conversion shop orders the
>Prevost shell with 24v/270 amp Alternator option. A typical 13,500 Btu
>roof air needs 17 amps AC while running which is about 2000watts. In
>theory an inverter supplies the 2000 watts off the equivalent of 85 Amps
>DC (24v system). Conversion experts tell me that the Prevost buses need
>about 100 amps for general operation. This leaves 170 Amps available
>for other loads. In theory one can support two roof airs while running
>the engine without consuming battery power. This isn't exact, but it
>explains the general system. There are many other combinations of much
>smaller air conditioners, but the 13,500 roof air is most popular. We
>run a multitude of smaller capacity A/C units made for boats and trucks.
>Other RV manufacturers purchase similar alternator options from their
>enging suppliers, but the Prevost system is the highest capacity I know.
>Blue Bird for example, makes their own in house. The other RV OEM
>systems generally support only one roof air. The alternators are
>options from Catipilar and Detroit Diesel etc.
>
>The only company I am familar with the makes a high quality output
>alternator and is not associated with an engine manufacturer is Balmar.
>However, their focus is on marine applications rather than vehicles.
>
>Contact them at:
>
>http:///www.balmarvst.com or tel. 360 629 3210

You would double the amperage numbers if you used a 12 volt system rather
than the 24 volt system he is referring to here. So that means you would
need to produce 170 amps of current, just to run the A/C!

I looked at the Balmar site and they do have alternators that would be big
enough. Very pricey though. And the cable to carry that much current from
the alternator to the batteries & converter would also be costly.
Interesting concept though. It certainly would be nice to have 110vac for
the A/C while on the road and not have to run the Onan.

Does anyone have information on high current 12v alternators for truck and
bus applications? Maybe a rebuilt Delco from a truck would be more
reasonably priced.

Dave
73 Sequoia

 

[mr.c]

Suggest you use more batteries. Even though golf cart batteries will provide 100
amps, that is only enough for about 20-30 minutes of run time on the air
conditioner. You might want to consider enough batteries, which might defeat the
purpose of the inverter+batteries.
al

> Dave
>
> Glad you picked up on this idea. My new mode is to toss out an idea
> I have for my lady----if nobody bites then I go on with my own thoughts.
> Here is where I am at this time. First: I am going to run 2 golf cart
> batteries
> for starting batteries. Second: I think I want to put inverter up front to
> keep cable runs short. Third: put in a third battery bank under dinette.
> I dont have it all worked out this is where I am at this time. I would
> power the inverter off the engine compartment batteries. I can easily
> get 110 to front AC especially if I move it to the vent hole in the roof.
> I dont see a problem getting 110 back to the fuse box for when I am
> at a campsite. Come out of the engine compartment down the wall
> under the couch and kitchen module and into the fuse box. Then I
> need a 200 amp alternator--check this out.
>
> http://www.mechman.com/alt.htm t=_self]PROPOWER PERFORMANCE ALTERNATORS[/url]
>
> http://www.mechman.com/alt.htm
>
> They even have them in a GMC case. Now this is starting to look
> like fun. OK thats what I am thinking.
>
> Take Care
> Arch 76 GB IL
>
> In a message dated 4/8/99 7:52:32 PM Central Daylight Time, DGMDGM

>
> >
> > Does anyone have information on high current 12v alternators for truck and
> > bus applications? Maybe a rebuilt Delco from a truck would be more
> > reasonably priced.
> >
> > Dave
> > 73 Sequoia
> >
> >

 

[mr.c]

Best I can remember, the starting power on the A/C is very high, and then when
it gets going, it uses less current. The Alternator would have to be quite
heave to put out enough amps to provide some 2000+ watts to the inverter to
run the A/C. Think the alternator would have to have over 167 amps of output
to the input of the inverter to get the wattage you need. I think that might
be on the low side. Might need a bit more. That's just a guess.
Al

> Al not trying to run AC on batteries. Just trying to get system up to
> where I can run AC of the alternator instead of the genset.
>
> Take Care
> Arch 76 GB IL
>
> In a message dated 4/8/99 9:15:19 PM Central Daylight Time, mr.c

>
> >
> > Suggest you use more batteries. Even though golf cart batteries will
> > provide 100
> > amps, that is only enough for about 20-30 minutes of run time on the air
> > conditioner. You might want to consider enough batteries, which might
> > defeat the
> > purpose of the inverter+batteries.
> > al

 

[thomas g. warner]

Golf cart batteries do not function well as starting batteries. they are
not capable of providing large amounts of instant current and still function
as deep cycle batteries.

>Dave
>
>Glad you picked up on this idea. My new mode is to toss out an idea
>I have for my lady----if nobody bites then I go on with my own thoughts.
>Here is where I am at this time. First: I am going to run 2 golf cart
>batteries
>for starting batteries. Second: I think I want to put inverter up front to
>keep cable runs short. Third: put in a third battery bank under dinette.
>I dont have it all worked out this is where I am at this time. I would
>power the inverter off the engine compartment batteries. I can easily
>get 110 to front AC especially if I move it to the vent hole in the roof.
>I dont see a problem getting 110 back to the fuse box for when I am
>at a campsite. Come out of the engine compartment down the wall
>under the couch and kitchen module and into the fuse box. Then I
>need a 200 amp alternator--check this out.
>
> http://www.mechman.com/alt.htm t=_self]PROPOWER PERFORMANCE ALTERNATORS[/url]
>
>http://www.mechman.com/alt.htm
>
>They even have them in a GMC case. Now this is starting to look
>like fun. OK thats what I am thinking.
>
>Take Care
>Arch 76 GB IL
>
>
>
>In a message dated 4/8/99 7:52:32 PM Central Daylight Time, DGMDGM
>writes:
>
>>
>> Does anyone have information on high current 12v alternators for truck and
>> bus applications? Maybe a rebuilt Delco from a truck would be more
>> reasonably priced.
>>
>> Dave
>> 73 Sequoia
>>
>>
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach

 

[bartz paul]

Arch:

Something else you better watch out for by going to such a large alternator
is the wiring connected to your alternator. Chances are its currently not
sized to handle a 200 amp output. Horrible things result!!

Paul Bartz

From: Thomas G. Warner [mailto:warner]
Sent: Friday, April 09, 1999 7:39 AM
Subject: Re: GMC: Statpower

Golf cart batteries do not function well as starting batteries. they are
not capable of providing large amounts of instant current and still function
as deep cycle batteries.

Dave
Glad you picked up on this idea. My new mode is to toss out an idea I have
for my lady----if nobody bites then I go on with my own thoughts.
Here is where I am at this time. First: I am going to run 2 golf cart
batteries for starting batteries. Second: I think I want to put inverter up
front to keep cable runs short. Third: put in a third battery bank under
dinette.
I dont have it all worked out this is where I am at this time. I would power
the inverter off the engine compartment batteries. I can easily get 110 to
front AC especially if I move it to the vent hole in the roof.
I dont see a problem getting 110 back to the fuse box for when I am at a
campsite. Come out of the engine compartment down the wall under the couch
and kitchen module and into the fuse box. Then I need a 200 amp
alternator-check this out.
http://www.mechman.com/alt.htm http://www.mechman.com/alt.htm PROPOWER
PERFORMANCE ALTERNATORS
They even have them in a GMC case. Now this is starting to look like fun. OK
thats what I am thinking.
Arch
In a message dated 4/8/99 7:52:32 PM Central Daylight Time, DGMDGM

Does anyone have information on high current 12v alternators for truck and
bus applications? Maybe a rebuilt Delco from a truck would be more
reasonably priced.
Dave

 

[bright walter]

Arch;
I too would like to do this. The problem I see is this. I upgraded
14 years ago from a weak 65/70amp OEM to a 120amp (huge at the time)
aftermarket like the one you are looking at. The problem is that the
alternator, while rated at 120 amps, gets extremely hot when operated at
anything approaching that output. Once it overheats, it turns off to save
itself. This I'm afraid will be real quick even with a constant 165 amp
load on a 200 amp alternator. You will need to check that it can operate
constantly at this load factor. Also, when engine rpm goes down (below
1,700 rpm or so. This assumes alternator runs 3x engine speed) you will
reach the alternator equivalent of a stall. This will put strain on the
compressor of the air conditioner, etc. that may prove fatal to one or more
components. Belts will also be a problem. At 100% efficiency, it will take
2.8 HP to make 2.1 kw. Assuming 40% efficiency for the alternator, that
works out to about a 7 hp load or 3, 850 ft/lbs. Add 150 ft/lbs tension to
keep it from slipping and you have 4,000 ft/lb on the belt constantly while
in operation, about 7.3 hp. You will need some form of a serpentine/timing
belt. Just some thoughts on the matter. walter bright, 76 GB; Delanco,
NJ.

 

[patrick flowers]

Al,

I believe the golf cart batteries would shoulder the starting load, and
then the alternator would top the batteries back up and handle the
running load. The compressor cycles on and off, so that should help
too. Would just need to be sure that the wiring from the alternator to
the batteries and inverter is large enough(short runs too!).

I wonder tho' if this wouldn't be less efficient than using the dash
air? Converting rotational engery to AC, to DC, back to AC and then
back to rotational. Using the engine compressor cuts out four
conversions and their inefficiencies, but then you have to do a lot of
interior rework to put in the additional evaporator/fan assemblies.

No free lunch,
Patrick

>
> Best I can remember, the starting power on the A/C is very high, and then when
> it gets going, it uses less current. The Alternator would have to be quite
> heave to put out enough amps to provide some 2000+ watts to the inverter to
> run the A/C. Think the alternator would have to have over 167 amps of output
> to the input of the inverter to get the wattage you need. I think that might
> be on the low side. Might need a bit more. That's just a guess.
> Al
>

>
> > Al not trying to run AC on batteries. Just trying to get system up to
> > where I can run AC of the alternator instead of the genset.

- --
Patrick Flowers
Mailtoatrick

The GMC Motorhome Page
http://www.gmcmotorhome.com

 

[bright walter]

- -----Original Message-----
From: Patrick Flowers [mailtoatrick]
Subject: Re: GMC: Statpower

I wonder tho' if this wouldn't be less efficient than using the dash
air? Converting rotational engery to AC, to DC, back to AC and then
back to rotational. Using the engine compressor cuts out four
conversions and their inefficiencies,

No free lunch,
Patrick

I think its worth exploring as a "what if". It makes some sense not to
have A/C under the hood with the condenser & connections all subject to
vibration and leaks. It won't be as efficient, but it might be more
practical (again, its probably choose your poison). You made me think of
two more things. How much power do you have to supply the inverter with to
end up with 2,000 or so watts? Second, I don't think you can count on
batteries to supply more than a minute or even just seconds of power, as the
voltage will drop with discharge. If this causes the inverter to drop
voltage just a few volts it will cause A/C motor efficiency to plummet,
drawing more power, etc. w. bright, 76 GB.

 

[dave1]

>Here is where I am at this time. First: I am going to run 2 golf cart
>batteries for starting batteries.

I am not sure how much starting current you can get from a golf-cart
battery. I would guess you should be OK if you are only using it in the
summer. But you may not get enough current from the batteries when the
weather is cold.

If you can find an alternator that will really support the load of the
inverter and if you NEVER plan on running the A/C with the engine off, then
maybe a good truck battery would be a better choice. It will be better able
to handle the starting surge of the A/C compressor and it will work better
as a starting battery. But if the alternator is not big enough to supply
the A/C at all engine RPM's then a starting battery will have a very short
life.

I guess what we need to know is what is the current required to start the
engine and what is the current rating of the golf-cart batteries you are
planing on using.

>Second: I think I want to put inverter up front to
>keep cable runs short.

That makes sense.

>Third: put in a third battery bank under dinette.

This may not be such a good idea because of the weight. The front
suspension is pretty sensitive to weight. When I added two extra golf cart
batteries I moved all of my house batteries to the rear just so I could get
the weight off of the front suspension.

>need a 200 amp alternator--check this out.

I think you will need a much bigger alternator than 200A. The problem is
these alternators are not designed to run at full load. A 200A alternator
will only produce 200A at high engine RPMS. I also suspect that its life
will be pretty short if its run at 200A for extended periods. What we
really need is something along the lines of a 500A alternator. That way we
can run it in the 200A range and not be pushing its capabilities. But I
don't think such a beast exists. It seems that the weak link is the
alternator.

Another thought would be to change the electrical system over to 24v. That
would cut all the current requirements in half. 24v converters are readily
avalable. 24v alternators still only produce 200-250A but if your load is
only 100A that would be more reasonable. Some problems I see with switching
to 24v would be things like the starter motor on the engine, blower motor
on the heaters, the refrigerator, radios etc. Lots of things to change.

Another potential problem area may be the load on the engine. I think we
are talking about 5-10hp. I don't know what an idling 455 would do with the
additional load. I suspect that it would slow down a lot. That may mean
adding some kind of closed loop idle speed control to keep things turning
at stop lights and such.

I like the idea a lot but I think we really need to find an unusually high
output alternator to make it work reliably.

Dave
73 Sequoia

 

[donald w. miller]

Thomas G. Warner said:

> Golf cart batteries do not function well as starting batteries. they are
> not capable of providing large amounts of instant current and still
function
> as deep cycle batteries.

Tom has good advice here.

I found a pair of new fully charged Sears Golf Cart batteries have too much
internal resistance to power my 2500 watt inverter when it is fully loaded.
They are designed for a 75 amp load not a 200+ amp load which indicates four
Golf Cart batteries will have problems too.

My high power inverters on boat and GMC are considered genset alternatives
so an engine is always running when drawing lots of power from an inverter.

Batteries are great for watching TV or other light loads, but when you fire
up the frying pan and toaster you better think of it as a genset system and
have the engine running.

2500 watts at 12 volts highly stresses all involved components in the
electrical system. It requires there be no weak links in the chain. A
pair of large frame 12 volt alternators has a much better chance for
survival.

12 volts can be made to work but far better to install a 24 volt system or
get really radical and consider 48 volts.

That's my two cents worth of hard learned knowledge.

Don Miller
75 Glennbrook project
Shenandoah Valley of Virginia

 

[john wright]

Donald,
Two 75 reserve amp/220 amp/hr batteries are grossly undersized to power
a 2500W inverter. They only have a 440amp/hr capacity of which only
about 70% is truly usable. The maximum size converter that these
batteries can handle is about 800 to 1000 watts and time would depend on
load. There is a very good book that many GMC Netter have called
"Managing 12 Volts, How to upgrade, operate, and troubleshoot 12 volt
electrical systems" by Harold Barre and can be purchased from
Amazon.com. It is a great book for marine and RV electrical system
design, maintenance and operation ot 12 volt systems. The battery bank
required to successfully operate a 2500W inverter will cause the GMC to
tilt to one side and take a very long time the recharge the batteries.
SOB's with more load capacity can carry the larger batteries systems. If
you compare the cost of a inverter system with batteries vs a
generator/converter charger/battery's I think that the cost is equal or
actually more.

J.R. Wright
GMC Greatlaker
77 Eleganza II
Midland, Mi

>
> Thomas G. Warner said:
>
> > Golf cart batteries do not function well as starting batteries. they are
> > not capable of providing large amounts of instant current and still
> function
> > as deep cycle batteries.
>
> Tom has good advice here.
>
> I found a pair of new fully charged Sears Golf Cart batteries have too much
> internal resistance to power my 2500 watt inverter when it is fully loaded.
> They are designed for a 75 amp load not a 200+ amp load which indicates four
> Golf Cart batteries will have problems too.
>
> My high power inverters on boat and GMC are considered genset alternatives
> so an engine is always running when drawing lots of power from an inverter.
>
> Batteries are great for watching TV or other light loads, but when you fire
> up the frying pan and toaster you better think of it as a genset system and
> have the engine running.
>
> 2500 watts at 12 volts highly stresses all involved components in the
> electrical system. It requires there be no weak links in the chain. A
> pair of large frame 12 volt alternators has a much better chance for
> survival.
>
> 12 volts can be made to work but far better to install a 24 volt system or
> get really radical and consider 48 volts.
>
> That's my two cents worth of hard learned knowledge.
>
> Don Miller
> 75 Glennbrook project
> Shenandoah Valley of Virginia

 

[darren paget]

It is a good idea to check the output of your alternators. I have what is listed,
stamped and verified 100 amp alternator. The great thing is it puts out 135 amps
at 2000 rpm. More than enough to power all I have. Darren

> These PROPOWER alternators are in GM cases not GMC cases. They are not a
> direct replacement for the 27SI 80-100 amp that is on the GMC. They are
> 17SI's. They would have to be adapted. The 200 amp has to be turning at 5000
> RPM to put out the 200 amps. Like Emery said more amps takes more horsepower.
> If anyone wants them I can get 145 amp NEW Delco-style truck alternators for
> about $175.00.
> They are not a direct fit but would not be difficult to adapt.
>
> At least some of the later GMC's had the 145 amp 40SI. That one is a BRUTE.
>
> David

 

[mr.c]

Logic sound right, but the A/Cunit will run those batteries dry in no time, and the
Alternator will be working real hard. Someone at one of the rally's suggested
using a 24v system of Golf carts, and a 24v alternator. Many changes have to be
made, and the inverter gets lots more available (ie the inverter runs with 24v
input). This approach would be more feasible if one wanted to get rid of the gen
and run batteries. But I think the changes would be awsome.
Another alternative, and one I thought about was to put a second exchange unit
where the vacuum heater was and run plumbing to the front. That way, a fan (12v)
could run cold air into the badk of the coach while running the road, or when
parked and the engine running. Any thoughts about the latter.
al

> Al,
>
> I believe the golf cart batteries would shoulder the starting load, and
> then the alternator would top the batteries back up and handle the
> running load. The compressor cycles on and off, so that should help
> too. Would just need to be sure that the wiring from the alternator to
> the batteries and inverter is large enough(short runs too!).
>
> I wonder tho' if this wouldn't be less efficient than using the dash
> air? Converting rotational engery to AC, to DC, back to AC and then
> back to rotational. Using the engine compressor cuts out four
> conversions and their inefficiencies, but then you have to do a lot of
> interior rework to put in the additional evaporator/fan assemblies.
>
> No free lunch,
> Patrick
>

> >
> > Best I can remember, the starting power on the A/C is very high, and then when
> > it gets going, it uses less current. The Alternator would have to be quite
> > heave to put out enough amps to provide some 2000+ watts to the inverter to
> > run the A/C. Think the alternator would have to have over 167 amps of output
> > to the input of the inverter to get the wattage you need. I think that might
> > be on the low side. Might need a bit more. That's just a guess.
> > Al
> >

> >
> > > Al not trying to run AC on batteries. Just trying to get system up to
> > > where I can run AC of the alternator instead of the genset.
>
> --
> Patrick Flowers
> Mailtoatrick
>
> The GMC Motorhome Page
> http://www.gmcmotorhome.com

 

[donald w. miller]

JR,

I think we are saying the same thing but differently.

The two new fully charged golf cart batteries I measured were happy up to
about 75 amps maximum which is about 825 watts maximum at 11 volts.

Perhaps it would have been clearer if I had said "Two Golf Cart batteries
are great for watching TV or other light loads, but when you fire up the
frying pan and toaster you better think of it as a genset system and have
the engine running."

One nice thing about a 2500 watt inverter is it handles all size loads. Our
20" TV works fine without the engine running but this is less than 100
watts.

With two to four golf cart batteries, the 2500 watt inverter does make a
very nice and flexible system provided the owner remembers to crank up the
engine so the alternator helps the batteries during periods of high current
useage.

It is essential to run the engine when inverter loads are heavy. Reasonable
size batteries can't handle these heavy loads without help from a large
alternator.

I have the book you mention, several others from the boating world and a
number of engineering design books for inverters and switching supplies. I
once made my living designing military electronics and avionics.

Don Miller
75 Glennbrook project
Shenandoah Valley of Virginia

> Donald,
> Two 75 reserve amp/220 amp/hr batteries are grossly undersized to power
> a 2500W inverter. They only have a 440amp/hr capacity of which only
> about 70% is truly usable. The maximum size converter that these
> batteries can handle is about 800 to 1000 watts and time would depend on
> load. There is a very good book that many GMC Netter have called
> "Managing 12 Volts, How to upgrade, operate, and troubleshoot 12 volt
> electrical systems" by Harold Barre and can be purchased from
> Amazon.com. It is a great book for marine and RV electrical system
> design, maintenance and operation ot 12 volt systems. The battery bank
> required to successfully operate a 2500W inverter will cause the GMC to
> tilt to one side and take a very long time the recharge the batteries.
> SOB's with more load capacity can carry the larger batteries systems. If
> you compare the cost of a inverter system with batteries vs a
> generator/converter charger/battery's I think that the cost is equal or
> actually more.
>
> J.R. Wright
> GMC Greatlaker
> 77 Eleganza II
> Midland, Mi
>

> >
> > Thomas G. Warner said:
> >
> > > Golf cart batteries do not function well as starting batteries. they
are
> > > not capable of providing large amounts of instant current and still
> > function
> > > as deep cycle batteries.
> >
> > Tom has good advice here.
> >
> > I found a pair of new fully charged Sears Golf Cart batteries have too
much
> > internal resistance to power my 2500 watt inverter when it is fully
loaded.
> > They are designed for a 75 amp load not a 200+ amp load which indicates
four
> > Golf Cart batteries will have problems too.
> >
> > My high power inverters on boat and GMC are considered genset
alternatives
> > so an engine is always running when drawing lots of power from an
inverter.
> >
> > Batteries are great for watching TV or other light loads, but when you
fire
> > up the frying pan and toaster you better think of it as a genset system
and
> > have the engine running.
> >
> > 2500 watts at 12 volts highly stresses all involved components in the
> > electrical system. It requires there be no weak links in the chain. A
> > pair of large frame 12 volt alternators has a much better chance for
> > survival.
> >
> > 12 volts can be made to work but far better to install a 24 volt system
or
> > get really radical and consider 48 volts.
> >
> > That's my two cents worth of hard learned knowledge.
> >
> > Don Miller
> > 75 Glennbrook project
> > Shenandoah Valley of Virginia
>

 

[donald w. miller]

< Don - wouldn't it be better to just start the Onan?

< Emery Stora

Emera, it would have been easier to just start the Onan, but for me that
wouldn't be better.

I have no problem with those who prefer Onans but I reserve the freedom to
try an alternative approach.

Getting rid of my roof AC units and the Onan have been two of my
refurbishment goals.

I don't have much invested in my GMC and it is a test bed for trying
different ideas, some practical and some not so practical.

I enjoy experimenting and designing things. This is a fun thing for me to
do and I get to do some creative thinking which might help keep my mind
functioning a few years longer.

If I get some of these GMC ideas working, great ! if not, it won't be my
first failure and besides, I'm not throwing any of my old parts away.

I look at my Onan and see an aging troublesome extra engine to maintain,
1940 technology, 500 lbs. swinging around back there putting excess weight
and stress on my rear tire side walls, detrimental to good handling, taking
up useful space, making too much noise, burning gas whether the load is
light or heavy, etc.

With newer technology available today, along with some effort and expense,
a 455 engine can fast idle and produce enough power to replace an Onan.

Don Miller
75 Glennbrook project
Shenandoah Valley of Virginia

 

[donald w. miller]

Gene Fisher wrote and Don Miller responds :

> Funny how our experience sets how we think of things.

How right you are Gene. Isn't it amazing how diverse the thinking is among
our group of GMCers?

This diversity of our backgrounds is what makes input from each of us
important for finding good answers to our GMCMH problems.

Any of us can learn something new from most any one else we meet. It only
requires we are willing to be tolerant and keep our minds open and receptive
to new and different ideas.

> I dislike (hate) multi function devices
> like -printer/fax/copyer/modem-
> like - AM/FM/tx/vcr/cd/-
> One rubber roller took down my whole computer system. I don't want a
> single failure to take me out of the game.

I try to avoid multi function stuff especially where it can be life
threatening. Computer failures and most motorhome failures are an
inconvenience rather than life threatening, unless my blood pressure gets
too high.

> If I had my druthers, I would want a 6 KW -50 lb - Propane, silent,
> generator.

Next year maybe. Practical affordable fuel cells are almost certainly in
our near future and I too can hardly wait. Lots of interesting stuff on the
web about this. In the meantime most of us have to play with ancient
technologies while NASA and the big boys play with the good stuff.

> It felt soooo good when my diode isolator ran down all of the batteries
> in the GMC , I punched the ONAN and it started. (even on a low batt.) I
> was back in business , I was hot, I had power, I was charging,I was
> cooking, I was my own person, I was still free. I loved the feeling of
> the raw power of that machine.

Right and you can fill up your Onan at any gas station instead of running
all over town looking for propane

> I am a toy junkey, but when it comes to basic needs, give me raw power
> - Belt fan, big fat tires, Golf cart Batts,Propane ( refer , stove,
> furnace), non-electric toilet with lots of paper.

Different toys for different boys. The important thing is are we each
having fun doing our own thing?

> Keep up the good work, give me some more power

How much power you want ? If you are willing to pay the price, its
available.

Nice hearing from you Gene, I enjoy your web site.

Don Miller
75 Glennbrook Project
Shenandoah Valley of Virginia

 

[mr.c]

Four batteries are better than two, but it does have a bit of problem in that a
bad cell in one would bring all four down. There are ways to isolate the two
sides (two 6 v in series connected to two other 6 vo in series.)
Al

> JR,
>
> I think we are saying the same thing but differently.
>
> The two new fully charged golf cart batteries I measured were happy up to
> about 75 amps maximum which is about 825 watts maximum at 11 volts.
>
> Perhaps it would have been clearer if I had said "Two Golf Cart batteries
> are great for watching TV or other light loads, but when you fire up the
> frying pan and toaster you better think of it as a genset system and have
> the engine running."
>
> One nice thing about a 2500 watt inverter is it handles all size loads. Our
> 20" TV works fine without the engine running but this is less than 100
> watts.
>
> With two to four golf cart batteries, the 2500 watt inverter does make a
> very nice and flexible system provided the owner remembers to crank up the
> engine so the alternator helps the batteries during periods of high current
> useage.
>
> It is essential to run the engine when inverter loads are heavy. Reasonable
> size batteries can't handle these heavy loads without help from a large
> alternator.
>
> I have the book you mention, several others from the boating world and a
> number of engineering design books for inverters and switching supplies. I
> once made my living designing military electronics and avionics.
>
> Don Miller
> 75 Glennbrook project
> Shenandoah Valley of Virginia
>
> > Donald,
> > Two 75 reserve amp/220 amp/hr batteries are grossly undersized to power
> > a 2500W inverter. They only have a 440amp/hr capacity of which only
> > about 70% is truly usable. The maximum size converter that these
> > batteries can handle is about 800 to 1000 watts and time would depend on
> > load. There is a very good book that many GMC Netter have called
> > "Managing 12 Volts, How to upgrade, operate, and troubleshoot 12 volt
> > electrical systems" by Harold Barre and can be purchased from
> > Amazon.com. It is a great book for marine and RV electrical system
> > design, maintenance and operation ot 12 volt systems. The battery bank
> > required to successfully operate a 2500W inverter will cause the GMC to
> > tilt to one side and take a very long time the recharge the batteries.
> > SOB's with more load capacity can carry the larger batteries systems. If
> > you compare the cost of a inverter system with batteries vs a
> > generator/converter charger/battery's I think that the cost is equal or
> > actually more.
> >
> > J.R. Wright
> > GMC Greatlaker
> > 77 Eleganza II
> > Midland, Mi
> >
>

> > >
> > > Thomas G. Warner said:
> > >
> > > > Golf cart batteries do not function well as starting batteries. they
> are
> > > > not capable of providing large amounts of instant current and still
> > > function
> > > > as deep cycle batteries.
> > >
> > > Tom has good advice here.
> > >
> > > I found a pair of new fully charged Sears Golf Cart batteries have too
> much
> > > internal resistance to power my 2500 watt inverter when it is fully
> loaded.
> > > They are designed for a 75 amp load not a 200+ amp load which indicates
> four
> > > Golf Cart batteries will have problems too.
> > >
> > > My high power inverters on boat and GMC are considered genset
> alternatives
> > > so an engine is always running when drawing lots of power from an
> inverter.
> > >
> > > Batteries are great for watching TV or other light loads, but when you
> fire
> > > up the frying pan and toaster you better think of it as a genset system
> and
> > > have the engine running.
> > >
> > > 2500 watts at 12 volts highly stresses all involved components in the
> > > electrical system. It requires there be no weak links in the chain. A
> > > pair of large frame 12 volt alternators has a much better chance for
> > > survival.
> > >
> > > 12 volts can be made to work but far better to install a 24 volt system
> or
> > > get really radical and consider 48 volts.
> > >
> > > That's my two cents worth of hard learned knowledge.
> > >
> > > Don Miller
> > > 75 Glennbrook project
> > > Shenandoah Valley of Virginia
> >

 

[richard waters]

I just received my refurbished Statpower TC40 converter/charger unit,
with a remote display. I also purchased as part of their combo pack a
refurbished Portawattz 1000. I had ordered a PROwatt 800 but they ran out
of them They upgraded me to the Portawattz unit for the same price. I was told
the Portawattz was a newer model and that it has slightly better specs. It runs
continuously at 800 Watts, 1000 watts for 5 minutes and can handle a surge of
2000 watts. The total cost was $590.31 Canadian which is less in US funds.
I won't know the exact amount in US funds until I get my credit card statement.
I went with their standard shipping (UPS Ground) and it took 5 days to reach
me here in Michigan.

Both units looked like brand new (the remote panel was new) and I could not
really see any evidence that they had been used. There is a small price to pay
for getting refurbished, the warranty is only for 45 days. At the rate I'm
going,
the warranty will be over before I get it all installed.

Now the fun begins!

I have a few questions that hopefully the net can answer:

1) Can anyone tell me how far the run is from where the old converter in my
'76 Palm Beach to the house battery compartment? I just got the old buzz box
out and I have no idea where the wires run. I know where they end up, but no
idea how they get there.

2) I'm considering running a single 1/0 or 2/0 AWG cable back to the house
batteries positive side. I would then connect both the TC40 and the inverter to
that
cable in the converter compartment. For the negative side, 1/0 or 2/0 to the
chassis
just like the old ground cable for the converter. Any problem with this plan?

I'm just planning on running the TVs and VCR with the inverter. I don't plan on
using the microwave, coffee maker or toaster while on inverter
power. I guess I could, but I don't think the batteries could take it for long.

Any comments would be appreciated.

Richard Waters '76 PB, Troy, MI

 

[thomas g. warner]

It is going to depend on how your coach is wired. On my 1976 palmbeach the
converter goes through Circuit breaker #2. Only time it has power is when
you are either hooked up to shore power or have the generator on.

>GMCers
>
>Now for my question about Statpower. When I put mine in is there
>a good reason to put in a switch for it. My only thought was that I
>might want to shut it off sometime. I just cant think of when that
>might be. Sure would like to hear from the pros on this one.
>
>Take Care
>Arch
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach

 

[hdavis]

>GMCers
>
>Now for my question about Statpower. When I put mine in is there
>a good reason to put in a switch for it. My only thought was that I
>might want to shut it off sometime. I just cant think of when that
>might be. Sure would like to hear from the pros on this one.
>

Arch,

One reason to put a switch in is to permit you to eliminate the stadby
current draw. Most inverters have a small (relatively that is) draw even
when there is no AC demand. The draw actually can be quite considerable for
high power inverters. You may also want to shut it off electrically when
you condition your batteries.

Just a few thoughts.

Henry
Henry Davis Consulting, Inc / new product consulting
PO Box 1270 / product readiness reviews
Soquel, Ca 95073 / IP reviews
ph: (831) 462-5199 / full service marketing
fax: (831) 462-5198
http://www.henry-davis.com/ http://www.henry-davis.com