Statpower

- -snip-
>IMHO I would not do that. Put the charger in the cabinet--no problem.
>#6 will do just fine. Everything I have seen says to keep the cable run
>to the inverter as short as possible. Some sort of noise ect.

One of the main reasoins to keep the inverter close to the batteries is
that the wires betweent he batteries and inverter will have some voltage
drop. When your inverter draws a large current there will be DC
inefficiencies that are directly proportional to the line drop. Short lines
means less voltage drop. Bigger conductors also mean less drop.

Some inverters may also generate a very high frequency field in the DC
conductors. You may be able to reduce this by installing big capacitors
capable of handling the currents. (I wouldn't do it though)

- -snip-
>
>> 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.
>

IF you only want to run the TV and VCR, you're better off using the DC
appliances from an energy usage standpoint. There's no inverter losses and
no losses converting AC to DC in the TV (although there may well be a DC-DC
converter instead depending on the model).

Of course, the AC versions of most appliances are cheaper.

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
 
Arch,
Thanks for the comments!

I just discovered that hidden compartment between the battery box
and the rear of the coach this evening.

Mine was not quite empty. I found inside a duct from the furnace that still
blows hot air. There is no way for that warm air supply to enter the coach.
On the other side (where the water tank is located) is an unused warm air
register without a duct. The previous owner had a new furnace installed.
I have no idea how the warm air is supposed to jump across from that
enclosed compartment to the water tank side. But that's another story.

Gee six hours ago I was going to run a very heavy cable from the battery to
the inverter. Now I will simply run about a 4 AWG cable the few feet
from the battery compartment to that adjacent empty box. I guess there
would be adequate ventilation in the compartment for the inverter, since
it seems to be open to the frame.

Like you, I'll run the AC back to the converter compartment and also
the inverter's remote panel line back to the area above my stove on the
drawer module. Looks like 6 AWG then from the TC40 to the battery box.
I like the idea of putting the cable in a liquid-tight flexible conduit.

A roll out tray for the batteries would be nice. Right now I have a plywood
platform from the previous owner that seems to be stuck. Have no idea how
to get the batteries out, other then hook up my tractor to them and pull!

> First I want to say I just got mine too. I have not put it in yet but I do
> have a plan. So this is all THEORY. On mine it is 8 feet from the
> cabinet where the charger is to the back of the battery cabinet. I
> am planning to run #6 cable in plastic conduit. Then drill a hole in
> the top of the battery cabinet, install a grommet and drop down to
> the batteries. I will leave a couple of feet of slack because I have
> the roll out battery tray. I have not put it together yet so I dont yet
> know where I will need the wire to be.
> >
> IMHO I would not do that. Put the charger in the cabinet--no problem.
> #6 will do just fine. Everything I have seen says to keep the cable run
> to the inverter as short as possible. Some sort of noise ect. I have also
> read to cable to the neg. battery post and do not rely on chassis ground.
> consider putting the inverter on the back wall of the genset cabinet. I dont
> know if yours is this way but mine was. There was a plywood box built
> between the genset wall and the back cap. When I was tearing things
> apart I took the box apart-----guess what there was nothing in it! I have
> no idea what it was for. You now have room to mount the inverter on
> the genset cabinet. Since the batteries are just on the other side of
> that wall your cable runs will be real short. Even with the roll out battery
> tray I dont think mine will be over 24 inches long. Which gets me down
> to a much smaller cable. Another THEORY I would rather move 110 volts
> at low amperage back to the charger cabinet than 12 volts at high
> amperage that distance.
> >
>
> Thats my comments.
>
> Take Care
> Arch 76 GB IL
> PS if you want to run a wire forward to charge the house battery you
> will need 25 feet. This could also prove to be handy if you were to blow
> the alternator some night. You could fire up the genset and have 40 amps
> to run on. Thats what I think.

So to push 40 amps 25 feet we're going to need something like 1/0 or 1 AWG
wire. Looks to me like the GMC manual shows 1/0 for the upwards of 80
amps the alternator could put out all the way to the back.

I think I would like to put a relay in to switch the power from the inverter
when the generator is running or when on shore power.

Thanks for the good comments Arch!

Richard Waters '76 PB, Troy, MI
 
Thanks Henry,
As the day goes on s my plans keep changing thanks to the internet!
Thanks to Arch I found a place for the inverter that is very close to
the battery box (and where I sleep so I'll make sure to turn it off at night).

The main reason I'm going to use the inverter is because it was cheap.
Much cheaper then getting DC powered versions of my kids video
games (such as Nindeno 64, a decent TV and VCR). I am paying
less then $150 for the 800 watt inverter and installation supplies. Also,
cheaper then running the generator while driving.

Richard Waters '76 PB, Troy, MI

> -snip-
> >IMHO I would not do that. Put the charger in the cabinet--no problem.
> >#6 will do just fine. Everything I have seen says to keep the cable run
> >to the inverter as short as possible. Some sort of noise ect.
>
> One of the main reasoins to keep the inverter close to the batteries is
> that the wires betweent he batteries and inverter will have some voltage
> drop. When your inverter draws a large current there will be DC
> inefficiencies that are directly proportional to the line drop. Short lines
> means less voltage drop. Bigger conductors also mean less drop.
>
> Some inverters may also generate a very high frequency field in the DC
> conductors. You may be able to reduce this by installing big capacitors
> capable of handling the currents. (I wouldn't do it though)
>
> -snip-
> >
> >> 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.
> >
>
> IF you only want to run the TV and VCR, you're better off using the DC
> appliances from an energy usage standpoint. There's no inverter losses and
> no losses converting AC to DC in the TV (although there may well be a DC-DC
> converter instead depending on the model).
>
> Of course, the AC versions of most appliances are cheaper.
>
> Henry
 
Arch,

We wired ours up with a plug just like someone else has already mentioned.
We did it that way mostly because that is the way our original was and it
was the easiest way to do it. It is nice to be able to unplug it or switch
it off if so desired because it can draw quite a few amps from your 120V
service if it is charging at one of its higher rates. If you wanted to run
the roof air off of a marginal 120V service, you might want to or have to
unplug/switch off the Statpower to avoid overloading the service/extension
cord/etc. The same might hold true for electric heaters or other high
power draw devices.

Zak

>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
>
 
An enclosed compartment sure would not be a good place for
a fire. It does however seem to be open to the same area of the
coach as the converter compartment. I will sure make sure there is
ventilation before I go any farther.

Richard Waters '76 PB, Troy, MI
- ----

>
> the battery box (and where I sleep so I'll make sure to turn it off at night).
> >>
>
> Just be aware that an inverter can put out a lot of heat when it is
> operating. Make sure that you have good ventilation in that area so you
> don't start a fire.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
 
Just another question. I wonder how you know when you have enough
ventilation. I hate to install the inverter and then have to keep checking
it all the time to see if the temp is reasonable.
Richard '76 PB

>
> the battery box (and where I sleep so I'll make sure to turn it off at night).
> >>
>
> Just be aware that an inverter can put out a lot of heat when it is
> operating. Make sure that you have good ventilation in that area so you
> don't start a fire.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
 
>Thanks Henry,
>As the day goes on s my plans keep changing thanks to the internet!
>Thanks to Arch I found a place for the inverter that is very close to
>the battery box (and where I sleep so I'll make sure to turn it off at
night).
>
>The main reason I'm going to use the inverter is because it was cheap.
>Much cheaper then getting DC powered versions of my kids video
>games (such as Nindeno 64, a decent TV and VCR). I am paying
>less then $150 for the 800 watt inverter and installation supplies. Also,
>cheaper then running the generator while driving.

Somehow I thought that cost might be one objection! ONe suggestion: before
you install the inverter in your coach permanently, try powering your
appliances of choice from the unit. You may need to fiddle with noise
filters and the like to get them to work the way that you want. Some audio
equipment has pretty poor high frequency rejection on the power supply. The
result is poor sound quality. This latter problem is why some folks go with
true sine wave inverters such as Prosine.

I haven't looked at the output of the specific inverter that you plan to
use. If the output is a square wave, it's likely that cheaper TVs and other
equipment will have some degradation in signal quality. Modified sine wave
output is generally, but not always, better for audio quality.

Good luck,

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
 
>Just another question. I wonder how you know when you have enough
>ventilation. I hate to install the inverter and then have to keep checking
>it all the time to see if the temp is reasonable.

You can tell how much heat will be given off under different operating
conditions. The owners manual should have efficiency numbers at different
operating rates. Use the most pessimistic numbers to establish heat
generation. Provided that there is enough airflow through your cabinet
there will be no problem.

My TrueCharge 40+ has a built-in fan that turns on when the unit is
operating above a certain charge rate. The fan will move enough air through
the (leaky) cabinet to keep the ambient temperature within operating specs.

If you fill the cabinet with electrical ":stuff," you can temporarily
install a recording thermometer that employs two sensors - one for inside
temp and one for outside temp. Radio Shack had a unit for under $20.

To test your specific configuration, I suggest:

1. heat the inside of the coach to the highest temp that you plan on
driving with (90 degrees in summer? 105 degrees in summer?)
2. operate all of the electrical appliances that you plan to operate while
traveling.
3. monitor the cabinet temperature until the temp stops climbing. Wait for
30 minutes to ensure that the temp has leveled off. You now know your
operating conditions.

If the cabinet temp remains under the maximum operating temp for the
electrical equipment you don't need to install any auxilary cooling. If the
temp becomes too high, you will need to insstall one or more fans.

One way to get air moved when it's needed is to go to a computer store and
purchase a CPU cooling fan with built-in temp sensing. make certain that
you buy a fan that oiperates on 12V. Now "all" you need to do is install
the fan in a location where cool air can enter the cabinet and the hot air
can be exhausted. Pushing or pulling the air should not matter.

To wire your new fan, just connect it to the 12V circuit and adjust the
temp sensor to a lower turn on point (if it's adjustable) or bond it to the
heat sink on the inverter.

Or, you could choose to have the fan run whenever power is supplied to the
inverter by wiring across the DC inputs - another reason to switch the DC
input. You could also choose to use a small "pancake" 120v fan like is used
in some PC cases. (this also uses some fo your available AC current and may
cause interference on your TV).

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
 
Henry,
I appreciate the comments.
The Statpower Inverter I purchased was a refurbished unit. The cost to me
as part of one of their refurbished packages (Statpower sold it to me direct)
was less then $150 in US funds! The output is a modified sine wave with
800 watts continuous, 1000 watts for 5 minutes and a surge of 2000 watts.
I think this will be a reasonable size and certainly a good price. But then
what do I know, I am new to all of this. This is just a THEORY as Arch says.

Another reason I decided to go with an inverter is that currently the only
source of
DC power in my coach is the cigar lighter in front. If I want to watch a DC
powered TV in the back of the coach (like by the bed) I would have to run DC
power back there. I know that is easy to do and I may still do it. I already
have AC
power outlets in most places in the coach. So I figured, what the hell. Lets
try
out an inverter. Also how do we run the video games like Ninteno 64 that my
kids insist on playing as a condition of riding in our antique motorhome.

I have a combo TV/VCR that has a buzz when running with my cheap (it cost me
about $150 from the local auto parts super store) 300 watt square wave output
inverter. That inverter works with all of my other TV's etc. just fine except
for
the combo TV/VCR I bought specifically for the GMC. I don't know yet
if the new inverter will work with the TV/VCR combo.

Later I could upgrade to a true sine wave converter like that PROsine. Camping

World is selling the PROsine 1000 for $764.10. It's a slightly larger unit in
size
and should still fit in the same place I intend to install the Portawattz.

I love this forum. I say something here about what I want to do and then I get

all these great comments back. With all of this help I'll get my GMC running
the way I want.

Thanks for the support,
Richard Waters '76 PB, Troy, MI

>
> Somehow I thought that cost might be one objection! ONe suggestion: before
> you install the inverter in your coach permanently, try powering your
> appliances of choice from the unit. You may need to fiddle with noise
> filters and the like to get them to work the way that you want. Some audio
> equipment has pretty poor high frequency rejection on the power supply. The
> result is poor sound quality. This latter problem is why some folks go with
> true sine wave inverters such as Prosine.
>
> I haven't looked at the output of the specific inverter that you plan to
> use. If the output is a square wave, it's likely that cheaper TVs and other
> equipment will have some degradation in signal quality. Modified sine wave
> output is generally, but not always, better for audio quality.
>
> Good luck,
>
> 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
 
Emery,
That makes sense. So the duct is supposed to be that way in the back,
and the problem is the duct was connected to the furnace incorrectly?
Well that could account for part of why my wife is cold back there at
night. She likes it when the thermostat is set to 90 and it feels like a
sauna in the back, but then that's another story.

That would also imply that the closed compartment I found it in is
ventilated. Therefore I could install my 800 watt inverter there
and be somewhat safe. I think that it will be a great location for an
inverter.

I recall someone once said that they had an inverter in the back of
their GMC and had a concern about the electromagnetic radiation
that it put out. I wonder if that was a valid concern?

Richard Waters '76 PB, Troy, MI

>
> Mine was not quite empty. I found inside a duct from the furnace that still
> blows hot air. There is no way for that warm air supply to enter the coach.
> >>
>
> It sounds as if whoever put in the new furnace hooked that duct up wrong. it
> is supposed to pull cold air into the furnace. This draws air from the area
> of the water tank and around the back of the motorhome (behind the rear wall)
> and allows warmer air to flow from the motorhome to those areas.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
 
Henry,
Interesting comments relative to my inverter project. I had not thought
about installing an auxiliary fan and I didn't know you could buy
a "recording thermometer that employs two sensors" from Radio
Shack. Even if I don't need a fan, having that thermometer would be
useful for other projects that I get involved with.
Thanks,
Richard Waters
'76 PB

> >Just another question. I wonder how you know when you have enough
> >ventilation. I hate to install the inverter and then have to keep checking
> >it all the time to see if the temp is reasonable.
>
> One way to get air moved when it's needed is to go to a computer store and
> purchase a CPU cooling fan with built-in temp sensing. make certain that
> you buy a fan that oiperates on 12V. Now "all" you need to do is install
> the fan in a location where cool air can enter the cabinet and the hot air
> can be exhausted. Pushing or pulling the air should not matter.
>
 
>Henry,
>Interesting comments relative to my inverter project. I had not thought
>about installing an auxiliary fan and I didn't know you could buy
>a "recording thermometer that employs two sensors" from Radio
>Shack.

To be clear, the recording is of maximum temp for the cheap unit. Somewhere
I have a unit that keeps a "curve fit" history. I.E. it will tell you the
general trend according tot he equation that thye use but not specific
temperature excursions.

Even if I don't need a fan, having that thermometer would be
>useful for other projects that I get involved with.
>Thanks,
>Richard Waters
>'76 PB
>

>> >Just another question. I wonder how you know when you have enough
>> >ventilation. I hate to install the inverter and then have to keep
checking
>> >it all the time to see if the temp is reasonable.
>>
>> One way to get air moved when it's needed is to go to a computer store and
>> purchase a CPU cooling fan with built-in temp sensing. make certain that
>> you buy a fan that oiperates on 12V. Now "all" you need to do is install
>> the fan in a location where cool air can enter the cabinet and the hot air
>> can be exhausted. Pushing or pulling the air should not matter.
>>
>
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
 
Arch,
Somewhere along the line a new water tank was installed in my GMC.
It must be a different configuration than the original as there is no room at
all now for anything to be connected to the cold air return register on the
water tank side. Then someone must have just cut off the duct and left it in
the compartment by the battery box. They also must have installed it as a
warm air duct by the new furnace. I think I will create a new cold air return
in the compartment for the new inverter by cutting into that plywood cover
and installing a register I'll connect the other end properly to the furnace.
That should help ventilate that area for the inverter I would think.

On the other hand I could do what you did and go with the 4" line to the
bath module to improve the heat there. I would still cut into that plywood
cover to help with the inverter ventilation. So many decisions to make and
so little time.

Richard W.

> Richard
>
> The duct that you found was originally an air return duct. It should have
> ended in the water tank area. The grate next to the water tank was
> for that duct to pull in return air. Since so few RVs have return air
> some repairman must have decided it was a hot air duct. I replaced
> mine with a 4 inch duct that runs almost to the bath module. Then
> the 2 inch on in. I have saved the fan that was behind the stove.
> If the 4 inch duct does not supply enough heat to the bath I am
> going to install the fan next to the water tank and put a switch on
> it. I will bet that with a 4 inch duct and the blower that close I can get
> some heat to the bath. That is what I did.
>
> Take Care
> Arch 76 GB IL
>
> In a message dated 4/19/99 10:01:28 PM Central Daylight Time,

>
> >
> > Mine was not quite empty. I found inside a duct from the furnace that
> still
> > blows hot air. There is no way for that warm air supply to enter the
> coach.
> > On the other side (where the water tank is located) is an unused warm air
> > register without a duct. The previous owner had a new furnace installed.
> > I have no idea how the warm air is supposed to jump across from that
> > enclosed compartment to the water tank side. But that's another story.
> >
 
Precisely why I wanted to SAVE my original OEM tank. It's got the
longitudinal chamfer along the bottom front toward the aisleway. All the new
ones I've looked at are SQUARE top to bottom (like me). :-)
Dick 75 PB in Atlanta

>Arch,
>Somewhere along the line a new water tank was installed in my GMC.
>It must be a different configuration than the original as there is no room at
>all now for anything to be connected to the cold air return register on the
>water tank side. Then someone must have just cut off the duct and left it in
>the compartment by the battery box. They also must have installed it as a
>warm air duct by the new furnace. I think I will create a new cold air return
>in the compartment for the new inverter by cutting into that plywood cover
>and installing a register I'll connect the other end properly to the furnace.
>That should help ventilate that area for the inverter I would think.
>
>On the other hand I could do what you did and go with the 4" line to the
>bath module to improve the heat there. I would still cut into that plywood
>cover to help with the inverter ventilation. So many decisions to make and
>so little time.
>
>Richard W.
>

>
>> Richard
>>
>> The duct that you found was originally an air return duct. It should have
>> ended in the water tank area. The grate next to the water tank was
>> for that duct to pull in return air. Since so few RVs have return air
>> some repairman must have decided it was a hot air duct. I replaced
>> mine with a 4 inch duct that runs almost to the bath module. Then
>> the 2 inch on in. I have saved the fan that was behind the stove.
>> If the 4 inch duct does not supply enough heat to the bath I am
>> going to install the fan next to the water tank and put a switch on
>> it. I will bet that with a 4 inch duct and the blower that close I can get
>> some heat to the bath. That is what I did.
>>
>> Take Care
>> Arch 76 GB IL
>>
>> In a message dated 4/19/99 10:01:28 PM Central Daylight Time,

>>
>> >
>> > Mine was not quite empty. I found inside a duct from the furnace that
>> still
>> > blows hot air. There is no way for that warm air supply to enter the
>> coach.
>> > On the other side (where the water tank is located) is an unused warm air
>> > register without a duct. The previous owner had a new furnace installed.
>> > I have no idea how the warm air is supposed to jump across from that
>> > enclosed compartment to the water tank side. But that's another story.
>> >
>
>
 
You are correct, sir and to steal a line from Martin Short, I knew that.
Uncharacteristically, I misspoke.
Dick 75 PB in Atlanta

>

>
>
 
Dear Emery, Ain't playin' "gotcha" (life's too damn short for games like
that), BUT just went down to the coach and THE FLEX-DUCT TO THE BATHROOM
DOES GO THROUGH THAT AREA along with the H20 line to the bath.
Just wanted to clear it up so other folks running '75s aren't misled.
Regards,
Dick 75 PB in Atlanta

>

>
>
 
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