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03-18-2016, 02:40 PM
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#221
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Site Team - Lou
Join Date: Oct 2009
Location: South Eastern PA
Posts: 23,269
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Quote:
Originally Posted by ScottBrownstein
Actually, that is not really true. The two 6 volt batteries are in series, you cannot charge or discharge one without the same current flowing from/to the other. When you charge them, the same voltage will be applied (and dropped by each battery.)
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Scott,
How will placing a higher resistance than needed between the cells not effect the overall performance of the stack?
As the batteries discharge, won't the internal resistance load have a real impact on performance? These schematics show a 12 volt battery with an internal resistance under various states of discharge. Picture if you will a similar example but just put that resistor (unnecessary wire resistance) "in the middle" of the battery stack pictured.
I can be taught!
__________________
Lou & Freya the wonder dog
2008 GMC Sierra 3000HD Allison Duramax
2019 Flagstaff 8529FL
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03-18-2016, 04:08 PM
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#222
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Senior Member
Join Date: Jan 2015
Location: Englewood FL
Posts: 2,797
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Quote:
Originally Posted by Herk7769
Scott...
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Sure, any resistance will drop voltage and it really doesn't matter where it is as long as it is in the circuit. Resistance is resistance.
Now, hopefully I didn't make a math mistake here, but the numbers feel right. Let's say that your load (power panel, hydraulic jacks, inverter) is 6 feet from the batteries. If you use #4 cable, that will be 12 feet of #4 at 0.0002530 ohms per foot. (Actually these cables have such low resistance it is quoted in ohms per 1000 feet! At 100 amps, that will drop the voltage (let's say it is 12.7 volts unloaded) 303 millivolts or about 2.39%. Decent drop, but most people calculate less than 3% for critical loads and practically speaking, a hydraulic pump is not a critical load. But no matter! If you add 12 inches of #4 between two 6 volt batteries, rather than using a single 12 volt battery, that cable will simply add its own 25 millivolts of voltage drop at 100 amps...which is an additional .14%, for a total drop of 2.53%. It's really like moving the load another 6 inches away from the batteries.
Now, it you go absolutely crazy and use a #0000 cable between the two batteries rather than the #4, it will add its own 5 millivolts of drop, saving you about 20 millivolts (.04%) when compared to the #4 cable, and .1% in voltage drop. Not a number to go crazy about and remember, 100 amps is not exactly a light load!
These are all for stranded conductors.
Your example diagrams have very significant resistances in them, 1 foot of #0000 cable has a resistance of 0.00005 ohms, while 1 foot of #4 has a resistance of 0.000253 ohms, both of which are really small numbers. Sure #0000 has a resistance of around 20% of #4, but it still is negligible when compared to the rest of the wiring, connectors, switches, solenoids, etc.
Bottom line is that it doesn't matter where the resistance is...as long as it is somewhere in the circuit between the battery and the load (or even between two batteries and the load.
I am still mad af Forest River for putting my converter in the rear power bay and running 22 feet of #6 to the batteries up front. That is 44 feet of #6 and costs me a significant amount of voltage drop with a 70 amp converter. At the very least they could have grounded the converter negative to the chassis and cut the effective amount of #6 to maybe 22 feet since the chassis acts like a pretty big conductor, virtually eliminating half of the run and voltage drop!
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2015 335DS
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03-18-2016, 04:45 PM
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#223
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Site Team - Lou
Join Date: Oct 2009
Location: South Eastern PA
Posts: 23,269
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Yes, chassis = Buss Bar we talked about.
I believe the graphics were from an article on deep cycle lead acid battery internal resistance at various states of charge. I seem to recall the discussion revolved around the internal resistance going up as the capacity to deliver electrons went down (battery discharged). The higher the internal resistance got, the lower the delivered voltage or some such.
Car batteries, which are made different (very thin waffled plates) have much lower internal resistance numbers than deep cycle batteries (thick flat plates). DP (marine) have thicker plates than car batteries and also have grids on the faces and fall in the middle.
Thank you. Like I said; I can be taught.
__________________
Lou & Freya the wonder dog
2008 GMC Sierra 3000HD Allison Duramax
2019 Flagstaff 8529FL
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03-18-2016, 05:32 PM
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#224
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Senior Member
Join Date: Mar 2014
Location: Mountain Foothills of Southern Alberta
Posts: 2,004
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Quote:
Originally Posted by Herk7769
Yes, chassis = Buss Bar we talked about.
I believe the graphics were from an article on deep cycle lead acid battery internal resistance at various states of charge. I seem to recall the discussion revolved around the internal resistance going up as the capacity to deliver electrons went down (battery discharged). The higher the internal resistance got, the lower the delivered voltage or some such.
Thank you. Like I said; I can be taught.
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You are absolutely correct about internal resistance increasing as a lead acid battery is discharging, it is almost linear. This results in it being less efficient (the more it is discharged) when there is a high amperage draw.
__________________
2007 Surveyor SV230 - 200 Watts Solar/MPPT Controller - 220 AH Battery Bank (Two-GC2) - 600 watt PSW Inverter - (2) 2000 watt Inverter Generators - LED Lighting
2009 F150 - 5.4 Litre with Tow Package
Boon Docking 99% of the time.
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03-18-2016, 06:00 PM
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#225
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Site Team - Lou
Join Date: Oct 2009
Location: South Eastern PA
Posts: 23,269
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Here is a terrific article on battery banks.
It also recommends 0 wire "inter-battery" ...
https://www.windynation.com/jzv/inf/...ight-wire-size
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Lou & Freya the wonder dog
2008 GMC Sierra 3000HD Allison Duramax
2019 Flagstaff 8529FL
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03-18-2016, 06:11 PM
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#226
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Senior Member
Join Date: Jan 2015
Location: Englewood FL
Posts: 2,797
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Quote:
Originally Posted by Herk7769
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Well, I agree with it, but that means that every wire on the 12 v load side, including the inverter feed and converter feed should be #0 or whatever. My response was that the wires that go from the batteries to the loads are far more important than the inter battery leads, since they are way, way longer and carry the same current. Replace your longest feed wire with something big and the benefits will be greater than just doing the interbattery leads. If you are going to wire your panel and inverter with #0, by all means do it for all of the battery leads.
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2015 335DS
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03-18-2016, 06:44 PM
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#227
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Senior Member
Join Date: Jan 2016
Location: x
Posts: 12,423
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Too Tall by the time this tread finally wears it's self out you will have had the most researched, analyzed, detailed, taked about, 12 volt to 6 Volt system on a TT know to MAN. You can put a sign on the tung "Approved by Forest River Forum" I will stick with 12V but know where to go if I decide to change.
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Retired Navy
Jake my sidekick (yellow Lab) 10/04 - 05/20
2017 RAM 2500 CC 4X4 Cummins Diesel
2016 Flagstaff 26 FKWS
AF&AM & El Korah Shrine of Idaho
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03-18-2016, 07:09 PM
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#228
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Senior Member
Join Date: Jan 2015
Location: central valley, california
Posts: 498
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I have really not search info for batteries, and have learned a great deal and never probably never really done this much reading unless it was here, great info, and I too have learned from your posts, thanks
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Mark & Annie
2014 COACHMEN PURSUIT 27 KB
Modesto, Central California
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03-18-2016, 07:39 PM
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#229
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Member
Join Date: Feb 2014
Location: Concord,Ca.
Posts: 59
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Quote:
Originally Posted by SeaDog
Too Tall by the time this tread finally wears it's self out you will have had the most researched, analyzed, detailed, taked about, 12 volt to 6 Volt system on a TT know to MAN. You can put a sign on the tung "Approved by Forest River Forum" I will stick with 12V but know where to go if I decide to change.
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As the starter of this thread I will admit that there is a lot of good info here. Not that the average new RV user could understand most of it. My main question was if 2- 6 volt batteries would last longer than 2- 12 volts and if it was worth spending the money for the upgrade. I think I got out of this thread the answer is yes Today I took the plunge and ordered a Duel golf cart battery box like Too Talls. Once it arrives I will probably be purchasing 2 Energizer 6 volt GC2 batteries from Sam's club. Will I still be able to use a regular 12 volt charger? (And how about some simple answers)
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03-18-2016, 07:50 PM
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#230
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Senior Member
Join Date: Sep 2015
Posts: 3,464
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Yes.
2016 Sabre 36QBOK
2015 Ram 3500 CUMMINS
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2017 Dynamax Isata 4
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03-18-2016, 08:06 PM
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#231
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Senior Member
Join Date: Jan 2015
Location: Englewood FL
Posts: 2,797
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Simple questions get simple answers. YES
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2015 335DS
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03-18-2016, 10:08 PM
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#232
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Senior Member
Join Date: Feb 2012
Location: NowthWest
Posts: 126
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This is a great group of folks
__________________
2015 Wildwood 181 BHXL. 2005 1500 Ram Hemi 4x4 W/package
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03-19-2016, 06:18 PM
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#233
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Senior Member
Join Date: Mar 2014
Posts: 939
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Quote:
Originally Posted by SeaDog
Too Tall by the time this tread finally wears it's self out you will have had the most researched, analyzed, detailed, taked about, 12 volt to 6 Volt system on a TT know to MAN. You can put a sign on the tung "Approved by Forest River Forum" I will stick with 12V but know where to go if I decide to change.
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Agree Seadog, I'm going to try that sign and see if I can get a discount on my next FR. I should.
Although it is true I didn't start this thread, I hijacked the h_ll out of it with my stupid questions. I apologize to the OP. I even flamed myself,
Every time somebody recommended something, I ran out and bought it. I was doing fine in my ignorance of battery technology with my little 85 amp/hr battery that was half shot from discharging the h_ll out of it.
This one thread by itself probably cost me over $300 and still going, plus my extremely valuable labor. I got so carried away I even made a friggen movie about it, https://youtu.be/foLGtyt9Rsg
I want to thank all of you for your knowledge sharing and patient in answering the same questions over and over, You are much appreciated. Amazingly interesting and well versed folks.
Now, I've started to wander over to the tire thread so God only knows what that will cost me.
__________________
Rockwood 2104S, 2014 Ram 2500 Diesel.
USMC 68 -70
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03-19-2016, 06:48 PM
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#234
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Senior Member
Join Date: Mar 2014
Location: Mountain Foothills of Southern Alberta
Posts: 2,004
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Quote:
Originally Posted by Too Tall
Now, I've started to wander over to the tire thread so God only knows what that will cost me.
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Don't do it! You will be sorry.
__________________
2007 Surveyor SV230 - 200 Watts Solar/MPPT Controller - 220 AH Battery Bank (Two-GC2) - 600 watt PSW Inverter - (2) 2000 watt Inverter Generators - LED Lighting
2009 F150 - 5.4 Litre with Tow Package
Boon Docking 99% of the time.
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03-20-2016, 12:07 PM
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#235
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Senior Member
Join Date: Mar 2014
Posts: 3,092
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Too Tall
Don't obsess. Do just enough to go camping and have fun. You installed a couple of batteries and have a way to charge them. Does it really matter if the batteries die in 6 years instead of 7?
Same with tires. Air them to sidewall max pressure. Replace them in 5 years and go camping in the meantime.
Fred W
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03-20-2016, 03:00 PM
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#236
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Senior Member
Join Date: Mar 2014
Posts: 939
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Quote:
Originally Posted by pgandw
Too Tall
Don't obsess. Do just enough to go camping and have fun. You installed a couple of batteries and have a way to charge them. Does it really matter if the batteries die in 6 years instead of 7?
Same with tires. Air them to sidewall max pressure. Replace them in 5 years and go camping in the meantime.
Fred W
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Kiss method, I like that. I realize however from talking to you all that I was very lacking in knowledge of all this stuff. Thanks.
__________________
Rockwood 2104S, 2014 Ram 2500 Diesel.
USMC 68 -70
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04-06-2016, 05:06 PM
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#237
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Member
Join Date: Jun 2014
Posts: 64
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Great thread...lots of great info.
Yesterday I went out and bought 4 Interstate 6 volt batteries for our Salem 27RKSS. I'll be connecting them with #4 gauge cables. I'll be hooking up my 180 watts of solar panels to them. I have also bought 6 LED bulb to replace some of the regular bulbs in various high use areas in the trailer.
I also run a TV and satellite receiver off a separate 400W inverter mounted next to electrical panel inside the trailer.This all worked fine last year with my 2 12 volt batteries last year except the batteries were getting very weak at end of season last year.
I am hoping this set up will be sufficient for my use.
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2014 Salem 27RKSS
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04-06-2016, 05:37 PM
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#238
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Senior Member
Join Date: Jan 2015
Location: Englewood FL
Posts: 2,797
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Burgeogull...Sounds like a plan!
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2015 335DS
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04-06-2016, 05:40 PM
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#239
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Senior Member
Join Date: Mar 2015
Location: Florida
Posts: 394
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Quote:
Originally Posted by Burgeogull
Great thread...lots of great info.
Yesterday I went out and bought 4 Interstate 6 volt batteries for our Salem 27RKSS. I'll be connecting them with #4 gauge cables. I'll be hooking up my 180 watts of solar panels to them. I have also bought 6 LED bulb to replace some of the regular bulbs in various high use areas in the trailer.
I also run a TV and satellite receiver of a separate 400W inverter mounted next to electrical panel inside the trailer.This all worked fine last year with my 2 12 volt batteries last year except the batteries were getting very weak at end of season last year.
I am hoping this set up will be sufficient for my use.
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Are they Golf Cart batteries? What is the Amp/Hour rating? If they are indeed Golf Cart batteries and each one has over 100 a/h you'll do very well indeed. Most trailers have a WFCO (Chinese) converter and power center. If this is the case it takes a very long time to charge them. I changed my WFCO and installed a Progressive Dynamics equivalent which works very well.
I also suggest that you bring with you a good battery charger. The rule of thumb is that you should charge your batteries at 10% of your a/h rating. If you have 250 amp hours you should charge them at 25 amps. I used 30 amps as I don't have a 25 amp setting. I'd start my generator, plug in the charger and after about 2-3 hours my batteries would be back to 99%. Now that I have the Progressive Dynamics I no longer have to hook up the charger, just start up the generator and let her run a few hours and I'm all charged up.
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OldBob
I may be old but I'm trying, very trying.
2015 RAM 1500 - EcoDiesel
Rockwood Ultra V 2715VS
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04-06-2016, 05:55 PM
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#240
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Member
Join Date: Jun 2014
Posts: 64
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Quote:
Originally Posted by OldBob
Are they Golf Cart batteries? What is the Amp/Hour rating? If they are indeed Golf Cart batteries and each one has over 100 a/h you'll do very well indeed. Most trailers have a WFCO (Chinese) converter and power center. If this is the case it takes a very long time to charge them. I changed my WFCO and installed a Progressive Dynamics equivalent which works very well.
I also suggest that you bring with you a good battery charger. The rule of thumb is that you should charge your batteries at 10% of your a/h rating. If you have 250 amp hours you should charge them at 25 amps. I used 30 amps as I don't have a 25 amp setting. I'd start my generator, plug in the charger and after about 2-3 hours my batteries would be back to 99%. Now that I have the Progressive Dynamics I no longer have to hook up the charger, just start up the generator and let her run a few hours and I'm all charged up.
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They are golf cart batteries. 235 amp/hr or however that goes. I know nothing about the converter and power center. The dealer told that they should be already charged. I won't be hooking them up until near the end of the month or maybe even May...I'm in Canada and it's too cold and too much snow where I am to even think about camping yet...well...I guess I am thinking about it if I'm already getting ready!! Can't wait!
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2014 Salem 27RKSS
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