Reply
 
Thread Tools Display Modes
Old 01-17-2012, 09:58 PM   #1
Junior Member
 
Join Date: Jul 2010
Posts: 6
Location of Converter in 8281SS or similar units (and other inverter install ?s)??

Hey all.

I installed a solar system last year and four deep cycle 6V batteries, and am planning on adding a good quality 1500W pure-sine inverter this year. I'm looking at a few ways to wire it... everything from just running an extension cord with power bar into the unit, to adding a couple dedicated plug-ins internally, to switching some breakers. I'm also wondering about the possibility of directly connecting the shore cable into the inverter, and wondered if others have done that. I know I need to switch off the converter to keep it from the circle charging situation, and keep the refrigerator on gas (the water heater is gas only). Is there any other issues with directly connecting the shore power cable to the inverter? I won't be using it a lot... probably no more than an hour or two a day, and I'll be turning it off when not in use, so I'm not too worried about long term trickles, but would like to be aware of what might be out there.

Second question, does anyone know where the Converter is located on the 8281SS (2010 bunk model), or on similar Rockwoods? In all my exploring through the coach I haven't stumbled upon it yet, and if I need to switch it out of the system I'd like to figure out how to do that... and knowing where it is would be the first step.

Thanks in advance for any help.
__________________

__________________
hdarby is offline   Reply With Quote
Old 01-18-2012, 12:26 AM   #2
Junior Member
 
Join Date: Jan 2012
Posts: 2
Converter location

I have a 8281ss .2008. Converter is located below fridg.
__________________

__________________
bdrake is offline   Reply With Quote
Old 01-18-2012, 12:45 AM   #3
Junior Member
 
Join Date: Jul 2010
Posts: 6
Perfect, thanks Bdrake. I appreciate it.
__________________
hdarby is offline   Reply With Quote
Old 01-18-2012, 07:44 AM   #4
Site Team - Lou
 
Herk7769's Avatar
 
Join Date: Oct 2009
Location: South Eastern PA
Posts: 21,154
Howard,

<quote>
"I'm also wondering about the possibility of directly connecting the shore cable into the inverter, and wondered if others have done that. I know I need to switch off the converter to keep it from the circle charging situation, and keep the refrigerator on gas (the water heater is gas only).

Is there any other issues with directly connecting the shore power cable to the inverter? I won't be using it a lot... probably no more than an hour or two a day, and I'll be turning it off when not in use, so I'm not too worried about long term trickles, but would like to be aware of what might be out there." <unquote>

It took a while, but I figured out what you are trying to do.
Short answer is "Not recommended."

Long answer is more complicated. The inverter must be connected directly to the battery with very short high amperage cables. due to the large amount of current to be pulled from your battery.

Example:

Given: (guess work to use as an example)

AH capacity of EACH 6 volt battery = 200 AH
Two cells of 2 6 volt batteries (12 volts) TOTAL AH Capacity = 400AH
Size of Inverter max power available = 1500 Watts
At max draw, AC amps being used 1500 / 120 volts = 12.5 amps

BATTERY amps needed to supply 1500 watts at the converter ignoring current usage IN the inverter 1500 watts / 12 volts = 125 amps

Pulling 125 amps at once from your 400 AH stack will reduce AH capacity by approximately 30% (see attached charts)

AH actually available from a fully charged stack - 280 AH

Hours of run time till all 4 batteries are deader than Grant - 280 / 125 = 2.24 hours.

In order to avoid replacing your entire battery bank every year or so, you should try to never discharge those batteries more than 50% (EVER).
Assuming no help from the solar unit, your battery bank will last about an hour before you will need to recharge it.

Now, your solar charging system (and being VERY careful about what is plugged in or turned on) will extend the life of your battery bank somewhat by replacing "on the fly" some of those amps.

Second part of long answer.

Trying to plug in your shore power cord into your inverter to power your entire rig will cause problems as you suspect with the "converter" part of your power center trying to use battery power to charge your battery.
This is very easy to get around by moving the converter's power source from the circuit breaker it is currently on (assuming it is not dedicated) to one you can switch off when you want to power your complete rig from your battery bank.
Attached Thumbnails
Click image for larger version

Name:	battery Life as a function of charge discharge cycles.jpg
Views:	48
Size:	28.2 KB
ID:	9976   Click image for larger version

Name:	battery voltage and capacity Curve vs Discharge Rate.jpg
Views:	51
Size:	44.9 KB
ID:	9977   Click image for larger version

Name:	battery voltage and capacity Curve.jpg
Views:	43
Size:	46.5 KB
ID:	9978  
__________________

Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW
Herk7769 is offline   Reply With Quote
Old 01-18-2012, 09:49 PM   #5
Junior Member
 
Join Date: Jul 2010
Posts: 6
Thanks for the math, Lou. I knew using the full 1500W would use up my available stored power quickly, but didn't know the numbers, so that helps.

I had originally been looking for a smaller inverter because my main usage would be for TV for an hour or two a day at the most, and charging my laptop and cell phones, but when the dealer friend I contacted had some good quality 1500W units he bought a few months ago from the manufacturer on sale, and was willing to sell to me at a price not much above the smaller units, I figured I'd go with the 1500W so I had the ability to power the microwave and blender when I wanted. Those items will only be used for a few minutes at a time (we only plan to warm things in the microwave, not cook a full meal), so I'm assuming that given the heavier draw in those short periods, and the main usage being closer to around 300W, I'll be okay, and the inverter will will only draw what it needs. If that's not correct please let me know if my thinking is wrong.

As mentioned, those calculations are handy. My plan was to add more batteries and solar panels if I started to use the inverter more (I bought a solar controller with extra capacity, and used large wiring that could take extra load if I grew the system), so this will help me figure out the best point to ramp up.
__________________
Howard Darby
Silverado 2500, Rockwood 8281SS 5th Wheel, Sea Doo 150 Speedster Supercharged
hdarby is offline   Reply With Quote
Old 01-18-2012, 11:20 PM   #6
Site Team - Lou
 
Herk7769's Avatar
 
Join Date: Oct 2009
Location: South Eastern PA
Posts: 21,154
Howard,

The peak watts on start up of a (say) 1000 watt microwave unit may go as high as 1500 watts when initially powering the magnetron. That may trip your inverter off line and you will need to reset it (remove power completely) to get it back again. Check the watts and the peak watts on the manufacturer's plate. Also it has been reported that some microwaves require pure sine inverters and modified sine inverters fail to fire the magnetron.

Trial and error here. Let us know how you fare.
__________________

Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW
Herk7769 is offline   Reply With Quote
Old 01-18-2012, 11:27 PM   #7
Junior Member
 
Join Date: Jul 2010
Posts: 6
Yep, I've looked into the microwave stats, and it has 1350 peak, and the pure-sine inverter I'm buying has 2000W initial load capability, so I'm assuming I should be good.

Thanks.
__________________
Howard Darby
Silverado 2500, Rockwood 8281SS 5th Wheel, Sea Doo 150 Speedster Supercharged
hdarby is offline   Reply With Quote
Old 01-19-2012, 12:26 AM   #8
Junior Member
 
Join Date: Jan 2012
Posts: 2
Try again. Think shore power should go to breakers else there won't be any safety. Got our rock wood a month ago.
Have fun. Bill drake, San Antonio TX
__________________
bdrake is offline   Reply With Quote
Old 01-19-2012, 07:51 AM   #9
Site Team - Lou
 
Herk7769's Avatar
 
Join Date: Oct 2009
Location: South Eastern PA
Posts: 21,154
Quote:
Originally Posted by bdrake View Post
Try again. Think shore power should go to breakers else there won't be any safety. Got our rock wood a month ago.
Have fun. Bill drake, San Antonio TX
I think you misunderstood his idea (or maybe I did).

As long as he has an appropriately sized fuse (150 - 200 amps) in the line between the battery and the inverter; plugging the shore power cord into the inverter to power his AC in the camper should not cause any safety issues. The main breaker in the power panel should still protect all the assets in the camper as normal. The fuse will protect the inverter and battery.

My only concern here is that he install a 50 amp DC rated switch in the charging line from the converter to the battery. This will isolate the battery from the charger.

I initially thought it could be done by removing AC power from the converter using the ac feed to the converter; but on reflection I think that MIGHT also isolate the DC circuits that are in the power center.

Just installing a switch at the battery red terminal between the converter and the battery should solve that issue.
__________________

Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW
Herk7769 is offline   Reply With Quote
Old 01-19-2012, 08:34 AM   #10
Junior Member
 
Join Date: Jul 2010
Posts: 6
Lou, bdrake's reply, and the "Try again" comment, was because I had IM'd him with a question, and he had tried to reply by IM, but there were issues with the reply getting back to me so he posted it here.

Since he had the same model unit as I do I had asked if he had noticed if the shore power cable had anything in the circuit prior to reaching the breaker panel and converter under the fridge. I assumed not, but thought he may have investigated it and could confirm. My thought was that I could run the power from the inverter to that location, then use some sort of A/B switch to flip between the shore and inverter power feeding the breaker panel (along with a switch for the converter).

I'm picking up a 200 amp fuse and holder when I get the inverter, so that should cover that protection there.

As for the converter, I was going to look at the wiring and see if there was a separate breaker for it. If so, I assumed that would work as the shut-off. If not, I hadn't decided where the switch would go in the circuit, but will look into what else is on the converter circuit.

Thanks.
__________________

__________________
Howard Darby
Silverado 2500, Rockwood 8281SS 5th Wheel, Sea Doo 150 Speedster Supercharged
hdarby is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



» Virginia Campgrounds

Reviews provided by




ForestRiverForums.com is not in any way associated with Forest River, Inc. or its associated RV manufacturing divisions.


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 10:48 AM.