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RV-Dreams.com Home -> RV-Dreams Community Forum -> RV Maintenance and Technical Tips -> Upgrading 12volt battery to (2) 6volts - wiring issue
Post Info TOPIC: Upgrading 12volt battery to (2) 6volts - wiring issue
RonS


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Upgrading 12volt battery to (2) 6volts - wiring issue
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I'm planning on phasing in solar to my new Venture Sport Trek TT. 

 

1st phase: Change battery from 12 volt to (2) 6 volt T-105 golf cart batteries. Welding on support on front for holding them in position. The wiring to the battery is 8AWG. Not sure if that's satisfactory for now. I know I will have to jump up in size when I get an inverter.

 

2nd phase: Install inverter and controller

 

3rd phase: Add solar panels to the roof

 

Should I jump up the battery cables to begin with or will the 8AWG work with present WFCO Ultra III Converter. 

Thanks for any and all recommendations

 



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LarryW21


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Why do the battery first? I'd get the panels and controller running first with the current battery.

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Winnebago TT 2101DS & 2020 Silverado LTZ Z71. 300 watts WindyNation solar w/MPPT, 2 Trojan T-125s. TALL flag pole. Prefer USFS, COE, BLM, USF&WS, NPS, TVA, state/county camps. 14 year Army vet-11B40 then 11A - old MOS 1542 & 1560.
RonS


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It's about time and money. However I am interested in what you would recommend for PV/inverter/controller. Need to start prepping for a trip out west. Occasional boondocking. (2 days at a time max).


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LarryW21


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I'm a WindyNation guy but other brand controllers, panels etc. are just fine. However, I do believe you should consider changing your thinking regarding "two days at a time max." Either your solar system sustains you completely (except for cloudy/rain days) or I believe its undersized. For me 240 amp hours of battery (two T125s) and 300 watts of solar work fine. Hardly ever use more that 1/3 of the 240. My controller is a 30 amp so I could add another panel but no need since I'm doing everything I want to do and completely recharging daily.

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Winnebago TT 2101DS & 2020 Silverado LTZ Z71. 300 watts WindyNation solar w/MPPT, 2 Trojan T-125s. TALL flag pole. Prefer USFS, COE, BLM, USF&WS, NPS, TVA, state/county camps. 14 year Army vet-11B40 then 11A - old MOS 1542 & 1560.
RonS


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Thanks Larry, I'm agreeing with you about solar. I lived off grid for several years. Had just enough to get by and always, always wanted more panels. When I watched things very closely with the sun co-operating, the batteries would be full by noon. Now I just want to experiment with a few T105's a very quiet gen and a few beers. Have enough power to charge the laptop, use the LED's, pump water and all the other good stuff that uses energy.
My off grid home used very large wires from battery bank to controller, like 04. So when I seen the 8AWG coming from a little 12 volt battery, I knew something had to change, especially if going to an inverter someday soon. Very soon.
Lets say I get a small 1000watt inverter/charger, a MPPT controller and eventually 800 watts of PV. What wire size would I need to run from the (2) T105's and the inverter? Besides the fuse block.


2018 Venture Sport trek Ford F250 New 24volt Aims inverter for sale New Trace C30 Controller for sale Army Vet Love VA & the USA

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Howard


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RonS,

Your converter manufacturer and your inverter/charger manufacturer will tell you what wire sizes to use. Check out the installation manuals or call them directly. There are reasons they suggest the wires they do. Of course, they may suggest going up a gauge depending on the length of the wire run.

I'm guessing the 8AWG will be fine from the battery to the converter, but a 6AWG may be better depending on the length of the run. Keep in mind what the connection terminals can accommodate and verify with the manufacturer.

From the batteries to the inverter, I have seen recommendations of anything from 4AWG to 2/0AWG for a 1000 watt inverter and even up to 4/0AWG for longer runs. So, again, go with the inverter manufacturer recommendations. But consider future upgrades.

You are certainly thinking correctly by paying attention to the proper gauges of wire. Many dealer/manufacturer "pre-wired" systems have inadequate cabling making an installation using their cabling very inefficient. Proper wire sizes for each function and length of the run are extremely important, so work with the manufacturers of each component in your system and when you install the solar panels use the many wire size calculators that are online to figure out what will work best (and use several of the calculators to make sure they all bring you to the same conclusion).

Good luck.

 



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LarryW21


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I used 10 from each of my three panels to the combiner box. Eight to controller and six to the batteries. All within allowable distance. See www.windynation.com/jzv/inf/choosing-right-wire-size

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Winnebago TT 2101DS & 2020 Silverado LTZ Z71. 300 watts WindyNation solar w/MPPT, 2 Trojan T-125s. TALL flag pole. Prefer USFS, COE, BLM, USF&WS, NPS, TVA, state/county camps. 14 year Army vet-11B40 then 11A - old MOS 1542 & 1560.
RonS


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Thanks guys, I'm starting to get the drift. Guess I need to step up the program. You're beating me into submission. LOL

One stupid question. The Windy Nation Wire Chart says: " Example: Let’s take a 450-watt 12V system. At the Vmp of 18V, the maximum current is 450/18 = 25 amps."

They mention a 450 watt system 12V system. Is (the system) size based on the inverter size - the Total PV size - Battery size? Where does this number come from?

So if I purchase a 1500 watt inverter, does that mean I have a 1500 watt system or because I have 240 watts of battery size I would have a 240 watt system. ????






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RonS


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OOPS. Forgot the batteries are in Amps not watts.

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LarryW21


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“The Windy Nation Wire Chart says: " Example: Let’s take a 450-watt 12V system. At the Vmp of 18V, the maximum current is 450/18 = 25 amps."

I believe WN is discussing maximum system capacity with a 450 watt panel system that could produce 25 amps. So you’ll need wire and a controller that can handle the max on those rare days. A 30 amp controller and appropriate wire depending on distance...keeping line losses to 2%.

It’s all based on the max the panels could produce. 

-- Edited by LarryW21 on Thursday 18th of January 2018 08:53:19 AM



-- Edited by LarryW21 on Thursday 18th of January 2018 09:04:08 AM



-- Edited by LarryW21 on Thursday 18th of January 2018 09:06:58 AM

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Winnebago TT 2101DS & 2020 Silverado LTZ Z71. 300 watts WindyNation solar w/MPPT, 2 Trojan T-125s. TALL flag pole. Prefer USFS, COE, BLM, USF&WS, NPS, TVA, state/county camps. 14 year Army vet-11B40 then 11A - old MOS 1542 & 1560.
RonS


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How does this system sound to get me to boon docking heaven:

WN 1500 Watt Pure Sine VertaMax Inverter
(2) Renogy 100 watt panels starter kit
MPPT Rover 40 Amp controller inc. in kit
(2) DEKA 6volt Golf Cart batteries
Bayite PZEM-051 digital meter
(1) 100AMP Shunt
(1) 40AMP in-line fuse
(1) GC-G Battery Box
Wires as required/hardware as required

Am I missing anything? Can I shop for larger panels, trying to stay around 400watts or just add an extra 100watts to the above kit.

Thanks again. You guys are great. Wished u lived next door.




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Ron Sopik
LarryW21


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Do an energy audit to see how many amps you use then times 1.5. You can certainly start with only two panels but do the wiring and combiner box for five, the max that controller can handle. Regarding the batteries, how many amp hours? I like one solar watt on the roof for each battery amp hour...unless you live or mostly camp north of the Mason Dixon line then go 1 1/2 watts per amp hour. Meters are nice but I prefer my WN remote monitor. Cheaper too I believe.

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Winnebago TT 2101DS & 2020 Silverado LTZ Z71. 300 watts WindyNation solar w/MPPT, 2 Trojan T-125s. TALL flag pole. Prefer USFS, COE, BLM, USF&WS, NPS, TVA, state/county camps. 14 year Army vet-11B40 then 11A - old MOS 1542 & 1560.
RonS


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The (2) 6volt batteries 230 watts (each) hooked up in series = 230 watts At 1 solar watt x 230 watts = 230watts worth of PV. Or 2 1/3 panels. Maybe I should look into (2) 120 watt panels?


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Ron Sopik
LarryW21


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Ron, batteries capcity is stated in amp hours. Watts is watts but it takes more amps to produce 40 watts (my TV) at 12 volts than 120..... 0.34 amps at 120 volts but 3.34 at 12 for instance.

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Winnebago TT 2101DS & 2020 Silverado LTZ Z71. 300 watts WindyNation solar w/MPPT, 2 Trojan T-125s. TALL flag pole. Prefer USFS, COE, BLM, USF&WS, NPS, TVA, state/county camps. 14 year Army vet-11B40 then 11A - old MOS 1542 & 1560.
RonS


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Larry, I can't believe my mind keeps getting that mixed up. Yikes! Meant to say 230 amps.

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Ron Sopik
RonS


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Well I ordered some equipment and would like some input. Heres what I ended up getting:

Windy Nation Vertamax Pure Sine 1500Watt Inverter
Tracer 3215RN MPPT 30Amp Controller
(2) Renogy 100-watt Mono Panels and Z Brackets
(2) 6Volt Golf Cart Batteries 230Amps
Bayite DC 6.5 Display Monitor

Decided to KISS (Keep It Simple Stupid). I'll leave my TT converter system separate from solar. Battery and all.
Run a few dedicated outlets inside TT connected to inverter.

My question is if/when the panels can't produce enough to charge the new batteries, what can I use? A battery charger? Since the inverter is not a inverter/charger unit?



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LarryW21


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Many of us carry a small inverter generator for those cloudy days. Mine’s a 2000 watt max Westingtonhouse at 43 pounds. Not used in last 60 days of camping. If I did it again I’d get a 1000 watter...smaller and lighter.

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Winnebago TT 2101DS & 2020 Silverado LTZ Z71. 300 watts WindyNation solar w/MPPT, 2 Trojan T-125s. TALL flag pole. Prefer USFS, COE, BLM, USF&WS, NPS, TVA, state/county camps. 14 year Army vet-11B40 then 11A - old MOS 1542 & 1560.
RonS


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Hi Larry, I do have a small generator. That can run the RV, charge the RV battery, run A/C, etc. But how does/can it charge my Separate solar batteries when the panels aren't producing enough to charge those (2) 6 volts . Do I need a battery charger to bring along just for that?

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Ron Sopik
LarryW21


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Your generator isn’t small if it can run the AC. Pluging the generator into the TT sends power to the converter. Converters charge house batteries. How well depends on the quality of the converter. If your solar batteries are truly ”separate” it won’t. Most of us tie it all together. 



-- Edited by LarryW21 on Saturday 20th of January 2018 01:53:37 PM

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Winnebago TT 2101DS & 2020 Silverado LTZ Z71. 300 watts WindyNation solar w/MPPT, 2 Trojan T-125s. TALL flag pole. Prefer USFS, COE, BLM, USF&WS, NPS, TVA, state/county camps. 14 year Army vet-11B40 then 11A - old MOS 1542 & 1560.
LarryW21


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Surprised Howard hasn’t jumped back in. Always learn something new.

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Winnebago TT 2101DS & 2020 Silverado LTZ Z71. 300 watts WindyNation solar w/MPPT, 2 Trojan T-125s. TALL flag pole. Prefer USFS, COE, BLM, USF&WS, NPS, TVA, state/county camps. 14 year Army vet-11B40 then 11A - old MOS 1542 & 1560.
RonS


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Would love to tie it together, just don't have that skill set. I would love to hear what Howard has to say also.
The small generator is a Champion 3100 watt unit. Looks small in my eyes. And very quiet.

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