Connecting Batteries into Solar System

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twscfltx

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Joined
Oct 4, 2016
Posts
40
Hello all,
I'd like help figuring out the re-hooking up existing power systems on a used 2008 NuWa 34LKTG 5er (all components are 8-9 years old). The existing solar components include:

Solar Panels: 4x 150-200W? (TBD)
    - Roof fixed mounted
    - No labels on top or sides.
    - ~2.5x5'
    - 48 V each; all in parallel
    - ~12-16 ga wires

Solar Charger: Outback FlexMax 60
http://www.outbackpower.com/outback-products/make-the-power/flexmax-series-charge-controllers/item/flexmax-6080?category_id=531

Batteries: None as of now
    - previous owner had 2x 12V AGMs (I'm guessing in parallel).
    - I was leaning toward 2x 6V Trojan T-105-REs Flooded in series.
          - http://www.trojanbattery.com/pdf/datasheets/T105RE_TrojanRE_Data_Sheets.pdf
          - We will be full timing, so I'll be able to manage higher maintenance on flooded.
          - We only plan on full timing for a year, so I'm not trying to break the bank on AGM or lithium batteries.
          - Trojan T105 AGM=$300 vs Trojan T105-RE Flooded $150 each (quoted from Houston distributer)
          - I'll have to punch a vent in the storage locker and run 3-4" tube from battery box to vent.

Inverter: Magnum MagnaSine 2800W Pure Sine Inverter Charger MS Series - MS2812

Circuit Layout:
    - Looks like previous owner had solar independent of separate 12V auxilary batteries for slides. I'm fine starting out with this setup to keep it as simple as possible at first. Eventually I may want to figure out how to run the 13,000 BTU AC on generator (Champion 2800 - http://www.costco.com/.product.100302560.html), and the 120V appliances on the inverter. I checked that the generator runs the AC, but I'm not sure it would run the microwave at the same time.
    - I think that the Magnum Charger would charge the solar batteries (T-105-REs) with shore power

I can guess where to start, but I don't want to damage anything playing trial and error. I have a Marine/RV 12V Deepcycle (Advanced Auto) to test the components. There is a RV Service shop (RV Masters in Houston) that says they install and integrate solar systems, but I not sure how much experience they really have.


Questions:
Do I set the settings on the charger and inverter before connecting the batteries?

What order should I connect everything? Do I connect batteries to charger and check that the charger is working, and then to connect the inverter? or connect batteries to inverter and check that the inverter is working, and then connect the charger? or connect everything at once?

Any tips on setting up flooded battery bank to make maintenance easier (hydrometer, adding distilled water, cleaning corrosion, venting, etc)

How do I determine what the amps should be from panels to charger and from charger to batteries?

Thank you,
Tyler

 
I am a small fish compared to some of the other members who are retired engineers and what not..But from what I have read/heard is you hook up your batterys first to your charge controller, then connect your solar panel wires...If you have a meter display from your controller it will/should show you you battery state of charge, your amps coming in and a voltage reading. At least my Renogy Tracer controller gives me that imput.
 
I would recommend that you Google "Jack Mayer". He has a wealth of RV electrical systems information on his web site.
 
Are you saying all the equipment and wiring is in place and you are just going to connect to new batteries?
The order of hookup and testing doesn't matter as long as you connect the solar panel wiring to the controller LAST when dealing with the solar hookup. You must have 12V power to the controller before connecting the panels, otherwise he gets hit with 48 volts. Reverse order when disconnecting.....
Refer to the Outback as a solar controller, and the Magnum as inverter/charger to avoid mixing up the 2.

 
The venting is concerning. I considered flooded in a non-vented compartment and concluded the only way to be certain that explosive gases would be eliminated was through powered venting. Aside from the power used by a fan running 24/7, what if the fan fails? For these reasons I abandoned my extra flooded batteries in non-vented basement project until I go all AGM.

Don't know if simply punching a 3-4" hole is sufficient to ensure air circulation.
 
About the Trojan Batteries.  Save your money and go to Sam's Club or Costco and buy their golf cart batteries for about $80-$100, assuming you go with flooded batteries and not AGM.

Trojan batteries have a good reputation.  They may last longer than the 2-5 years for the golf cart batteries, but you are not planning on needing them that long.  Also keep in mind the long life depends on excellent maintenance, not discharging them more than 25%-30% (that is keeping the batteries 70-75% full at all times.  Run either the Trojan down to 50% or lower will greatly reduce the life of the battery just like it will the golf cart battery. 

About the air conditioner:
(EDIT:  I miss read you posting.  I see you don't want to run the AC off of the inverter, so ignore this part.)
You are not going to run the air conditioner on a pair of Trojan or golf cart batteries.  Running one AC pulls about 125-170amps of 12V DC power while the compressor is running.  You have about 225AH in the pair of batteries.  The AC will use 50% of your capacity in less than 45 minutes of operation. 

There are 2 RV'ers with lithium batteries with 500-600AH of battery and over a 1000 watts of solar.  While in full sun they have run their AC for a few hours.  Keep in mind the solar is putting lots of that power back into the batteries while the AC is on. 
 
twscfltx said:
Hello all,
I'd like help figuring out the re-hooking up existing power systems on a used 2008 NuWa 34LKTG 5er (all components are 8-9 years old). The existing solar components include:

Solar Panels: 4x 150-200W? (TBD)
    - Roof fixed mounted
    - No labels on top or sides.
    - ~2.5x5'
    - 48 V each; all in parallel
    - ~12-16 ga wires
Have you verified the wire size.  It should be 10 ga wire from each panel to the combiner box on the roof and #8 or #6 down to the solar controller depending on the distance.  If no combiner box then you are going to have a pretty large voltage loss running 10ga all the way to the controller
Solar Charger: Outback FlexMax 60
http://www.outbackpower.com/outback-products/make-the-power/flexmax-series-charge-controllers/item/flexmax-6080?category_id=531

Batteries: None as of now
    - previous owner had 2x 12V AGMs (I'm guessing in parallel).
    - I was leaning toward 2x 6V Trojan T-105-REs Flooded in series.
          - http://www.trojanbattery.com/pdf/datasheets/T105RE_TrojanRE_Data_Sheets.pdf
          - We will be full timing, so I'll be able to manage higher maintenance on flooded.
          - We only plan on full timing for a year, so I'm not trying to break the bank on AGM or lithium batteries.
          - Trojan T105 AGM=$300 vs Trojan T105-RE Flooded $150 each (quoted from Houston distributer)
          - I'll have to punch a vent in the storage locker and run 3-4" tube from battery box to vent.

Inverter: Magnum MagnaSine 2800W Pure Sine Inverter Charger MS Series - MS2812

This is a good inverter/charger and should serve you well.

Circuit Layout:
    - Looks like previous owner had solar independent of separate 12V auxilary batteries for slides. I'm fine starting out with this setup to keep it as simple as possible at first. Eventually I may want to figure out how to run the 13,000 BTU AC on generator (Champion 2800 - http://www.costco.com/.product.100302560.html), and the 120V appliances on the inverter. I checked that the generator runs the AC, but I'm not sure it would run the microwave at the same time.
    - I think that the Magnum Charger would charge the solar batteries (T-105-REs) with shore power
Is the generator hard wired into the RV?  If it is not hard wired, just plug your shore power cord into the generator.  If the RV is 50amp you will need a 30amp to 50amp pigtail. 

I would not recommend trying to run the microwave while running the AC.  You can run the thermostat up so the compressor turns off and run the microwave for a few minutes and then lower the thermostat so the compressor comes on.

The Magnum charger will do a good job of charging the batteries

I can guess where to start, but I don't want to damage anything playing trial and error. I have a Marine/RV 12V Deepcycle (Advanced Auto) to test the components. There is a RV Service shop (RV Masters in Houston) that says they install and integrate solar systems, but I not sure how much experience they really have.


Questions:
Do I set the settings on the charger and inverter before connecting the batteries?
I don't think you can operate the solar controller w/o having the battery installed.  My Moringstar controller needs the 12V from the battery to operate.  I would use your 12V battery to check your controller and inverter/charger settings.  Don't leave the inverter charging the little 12V battery.  It is probably set to charge 200AH of battery and your 12V is probably 75-80AH.  You could be overcharging the battery. 

What order should I connect everything? Do I connect batteries to charger and check that the charger is working, and then to connect the inverter? or connect batteries to inverter and check that the inverter is working, and then connect the charger? or connect everything at once?
I'm not sure it matters which you connect first, just do one at a time. I think I would start with the solar controller in late afternoon about 1 hour before the sun sets.  You should see 3-6 amps, maybe more, coming from the panels, depending on how high the sun is up.

Any tips on setting up flooded battery bank to make maintenance easier (hydrometer, adding distilled water, cleaning corrosion, venting, etc)

How do I determine what the amps should be from panels to charger and from charger to batteries?

Thank you,
Tyler
 
I'm not sure of your experience with RV electrical systems but here is a list of links with lots of great info about RV electric systems and solar:

The 12volt Side of Life (Part 1) Batteries
The 12volt Side of Life Part Solar & Inverters
Jack Mayer RV Electrical
Jack Mayer Battery & Charging
RV Dreams Electrical Systems
Deep Cycle Battery Information
Deep Cycle FAQ, Battery Mfg Names List, and
HandyBob's Blog Solar & Elect
 
twscfltx said:
Hello all,
I'd like help figuring out the re-hooking up existing power systems on a used 2008 NuWa 34LKTG 5er (all components are 8-9 years old). The existing solar components include:

Solar Panels: 4x 150-200W? (TBD)
    - Roof fixed mounted
    - No labels on top or sides.
    - ~2.5x5'
    - 48 V each; all in parallel
    - ~12-16 ga wires


Thank you,
Tyler

With ~30 x 60" panels they probably are in a 4x9 grid setup like these 150 watt Kyocera:  https://www.solar-electric.com/kyocera-kd150gx-lfu-150-watt-solar-panel.html  These are:
"Voltage at Max Power (Vmpp) 18.2 Volts"
Open Circuit Voltage (Voc) 22.5 Volts

To have a 48V solar panel I believe you need to have larger panels with a grid of 7x10 or 8x10.  These are also in the 300-350watt and are around 60"x70"

You could have two pair of 2 panels in series for about 36V going to the combiner box. 

Do you have a meter to check the voltage output of the panels.  You can check the voltage output w/o having the solar controller on.  All you need is sunlight. 
 
About venting the battery compartment:

Flooded cell batteries gas off hydrogen gas which rises and is explosive if allowed to collect in an area. 

I would not use an exhaust fan, but install one to push air into the compartment with vent holes to let the air escape. 

A $10-$15 12V computer muffin fan only draws about 0.1A to 0.2A.  However what if the fan stops running, then your venting stops. 

I would like to see multiple 1" to 2"  holes up at the top with an equal number at the bottom.  Maybe 5-8 holes?? 
 
You don't mention a battery monitor.  You really want something like a Trimetric:  https://www.google.com/search?q=trimetric+2030+rv&ie=utf-8&oe=utf-8

The monitor measures the Amp Hours (AH) going out and coming into the batteries.  W/o the monitor you don't know exactly how much capacity is left in your batteries. 

For best battery life you shouldn't use more than 25% of capacity.  However if you only plan you owning the rig for 1 year, using 50% to 60% of capacity would be OK. 

Be sure to get your batteries up to 100% charge at least once a week.  Also if you are using your batteries heavily you should equalize your batteries every month or two.

Lots more detail in the links I gave above.
 
With 750w of solar flat mounted and 675 Ah of AGM battery I can run a small window A/C during peak hours. The solar actually covers the load at that time, the batteries could run it at night but I don't have enough solar to recharge them and run the A/C too.
 
I would assume that the Magnum Inverter is wired to power all, or most all, the 15amp a/c outlets and the microwave.  There would be no reason to install a 2800watt inverter if you didn't want to run the microwave. 

You mention that there is a 12V battery which powers the slideouts.  I would think that battery is the original house battery which powered the 12V controls in the fridge, all the lights, water heater (12V control), furnace, water pump, etc.  This battery was and probably still is connected to the converter and is charged when connected to shore power.  We had a 2005 Hitchhiker and the house battery was in the front compartment on the street (left) side.

If you haven't checked to see how many things are still powered by this battery you will want to, well before you go to use the rig. You don't want to go dry camping or boondocking and find out the fridge, lights, etc are still wired to this battery and it dies and you have to manually bring the slides in.  Can the people you bought the rig from tell you how things are wired? 

 
I bought the NuWa from consignment. The solar batteries are not hooked up to the original 12V system that powers the slides and fridge, so I need to figure out how to charge that dry camping. I'll have my generator, so I could run it a could hours. Does the original 12V battery bank get any charge from the tow vehicle through the 7pin?
 
It can if set up properly but not much. You would be better off turning the truck around and using heavy jumper cables.
 
twscfltx said:
I bought the NuWa from consignment. The solar batteries are not hooked up to the original 12V system that powers the slides and fridge, so I need to figure out how to charge that dry camping. I'll have my generator, so I could run it a could hours. Does the original 12V battery bank get any charge from the tow vehicle through the 7pin?
I would run a 10 or 8 gauge cable from the battery pack to where the original 12V battery is located and just get rid of the original battery.  For ease of running the cable I would go with welding wire, like this from Amazon:  https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=welding+wire+8+gauge  It is a real pain to try to bend the standard #8 or #10 stranded wire you would buy at the local hardware store.  Especially bending in the tight quarters in RV's.

About charging from the truck. Yes, BUT!  There is always a "but" isn't there.  The truck wire for 12V from the alternator to the 7 pin is probably #12 wire, and if I remember correctly the wire in the trailer is #12 as well.  That wire size is so small that the voltage drop at even a small current load of 10 amps charging current it too much voltage drop to put much of a charge into the battery.  You want to be able to charge a deep cycle battery at about 14.6 volts to be able to push the power into the battery.  If the charging voltage at the battery is down around 13V "while charging, not after it has been charged" it takes forever to charge the battery.  Note:  you have to measure the voltage at the battery while under the charging current.  If there is only from 0amp to 2amps going through the wire, all you are measuring is the voltage potential.  Think of a water hose.  If you have a 100' 1/2" water hose and no water is flowing the pressure at the end of the hose is the same as if you had a 1" hose.  But once you open the end of the hose you will get lots and lots more water (same as current) with a 1" hose than you will from a 1/2" hose. 

If you run a #8 or better yet #6 wire from the alternator all the way to the battery then you would get an adequate charge in a few to several hours of driving. 

Here is wire size calculator from BlueSea.com to help determine the proper size wire:  http://circuitwizard.bluesea.com/
 
Our Outback FM-80 is essentially the same controller as your FM-60, it just has a heavier duty cooling system. You can read the panels' amp output right on the controller's LCD display. (Excellent controller, by the way.) Others have given you good advice on hookup and disconnect steps. I'd also recommend installing appropriately rated DC disconnect-switches between the panels and the controller, and the controller and the battery bank - makes maintenance much easier.

I know the previous owner set it up, but in most "typical" RV setups, I don't think there's a good reason to have two independent battery banks. When boondocking, I think you'll find that life is much simpler with one house battery bank that the solar ties into, and which could easily be monitored with a good battery monitor, like the Trimetric RV 2030.

I'm a big fan of our AGMs but they're definitely more expensive than "standard" lead/acid batteries. In my experience, however,  there are other benefits to AGMs. They charge faster than other lead/acid batteries, which reduces generator run-time somewhat. (That's helpful when boondocking.) In any case, the T-105s you mentioned are excellent batteries. You just have to ensure that they're installed upright, the compartment they're in is vented and you check their water levels regularly.

It's just my opinion, but powering an RV's AC unit with batteries and an inverter is just not practical. It may be doable, but it's a strain on the system and leaves you with little power to do much else. Jim has had some luck with a 5000 BTU AC unit, but a 13000 or 15000 BTU unit will be a different story. It's also my opinion that it would be a mistake to plan on regularly charging your RV's batteries with your truck's alternator. Once again, it's doable, but it will put a strain on the truck's electrical system. It would be better (IMO) to buy a portable generator that was designed to do such things.

Kev
 
The point I wanted to make is I have a fairly good sized system/ bank and still can only run a tiny A/C. It works for me because you will find me at 10,000 ft or chasing the mild weather where I need little heat or A/C. On the opposite end I have a 200w My heat that I use in the bathroom for 10-15 minutes at a time and a 135w mat that I use under my chair. Neither do much except make it comfortable just right there.
 
I'm not trying to run the AC on battery. I want to run the ac on geny and the 120V on solar batteries. How would I hook AC directly to generator and still run microwave with solar batteries / inverter. Also my solar batteries are not wire to run 12V systems. Still have the original trailer batteries that charge by shore power to run all 12V, but I'll want solar batteries to run 12V too. Also would like solar charger and/or geny to charge trailer batteries.

How efficient is the inverter? 1.3? Trying to figure out if I can do 225 Amp (*50%) hours or if we need 4xT105s.
 
I want to run the ac on geny and the 120V on solar batteries. .... Also my solar batteries are not wire to run 12V systems.

There is no such thing as a 120V "solar" battery. Solar power is DC (12V or 24V etc depending on the array) and can be used only to charge batteries or run 12V DC items somewhat directly, so I guess you really mean a separate battery bank dedicated to an inverter and charged by solar.

To run any 120V items from 12V you need an INVERTER to do so, as you figured out. An inverter running strictly off a solar panel system would not work very well, too may variables and lack of amps available.  225 amps @12V from batteries produces 2700 watts but not for very long!!  Many microwaves, from your example, will require up to 1000 watts AC over a period of time to cook anything.

A built-in genny does not charge the batteries, it supplies 120V to the converter (and everything else in the trailer) or to another charger that does the job. Most people use 1 or 2 banks of batteries, not separate banks, that are then charged by all three charging systems: solar, when available, generator via the converter when running, or converter when plugged in or can also be charged from the TV (within limits) while running down the road. Solar will charge at all times to help out when sufficient sun is available. (Remember shade, rainy days etc, means no solar help, hence the larger bank requirement.)

It will vary but inverters generally run 85-90% efficient.

Also would like solar charger and/or geny to charge trailer batteries.

One or two 12V battery banks (or more) connected in parallel will accomplish this if connected correctly, with the reminder that the genny does NOT directly charge the batteries, it supplies 120V to the converter to do that unless you are talking of an external generator (like a Honda) that has a separate 12V charging connection that you wish to use but that kind will likely have a very limited charging capacity.
 

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