Off Grid RV System

BB.

Re: Off Grid RV System

Correct... As ILFE says--The clamp measures the "total current" passing through the hole in the middle.

If you clamp both the outgoing and return wire run, the total current adds up to zero amps.

-Bill

Blackcherry04

Re: Off Grid RV System

You need to make a short break out adapter with the 3 wires exposed with a Male Plug on one end and a Female receptacle on the other, makes it easy to use. You Just plug what you checking into it and plug it into the wall. If your going to do this long makes life easy.

Similar to this this one has a 30 amp plug and you'd want a 15 amp.

Attachment not found.

Chris

Re: Off Grid RV System

Thanx for the tip, that's a great idea......I was thinking of striping back the insulation on one of my extension cords.....but I'd much rather make one of those.

Chris

Re: Off Grid RV System

Hi Guys,

So...I'm 99% sure on my battery selection now, 4X US2200's in series parallel (being a trailer I'm stuck with a 12volt set up). Now after seeing a link posted on another thread (HandyBob) man that's a looooong read LOL but very informative.

He talks alot about the importance of absorb voltages......so I went to the US battery site and found that they recommend "2.583 volts per cell" = 15.498 volts.

Does this seem a little high? I know trojan wants 14.8. is this what you guys have your controllers set to with these batteries?

The guy who I have bought alot of gear threw in the past only sells the EP Solar Tracer's that are not adjustable and there set to 14.6 which he says will do the job just fine (sounds a little fishy to me) so just had to ask about this.

Now, I do plan on ordering a "Kid" controller so I will have the ability set voltages and just wanted to be sure that this is the right way to set it up.

Thanx, Chris

westbranch

Re: Off Grid RV System

I don't know where you found that info , I located this sheet, showing 2.45 (14.7V) for up to 3 hrs.
http://www.usbattery.com/usb_images/usb_2200_data_sheet_2013e.pdf

they show an EQ at 2.55V / cell

BB.

Re: Off Grid RV System

Some battery chemistry/designs do "like" higher voltages and even charging current.

With solar, you have a small window of time (around 6-10 hours) to fully recharge a battery bank. And you have the choice of a lower charging voltage and never really fully charging the bank--Or hitting a battery with relatively high voltage (and current) to get it full. Neither is ideal--But it is sort of the life with off grid solar... And an RV were your panels many not be tilted towards the sun, and a relatively small battery bank (weight/space limits)--And you are probably cycling deeper than the average off grid home.

Another issue with over ~15 volts charging--Many DC appliances and AC inverters will may fault or even fail with that high of charging voltage. You have to look for inverters that will take 15.5 to 16+ volts to ensure that they will operate while you are charging.

Add cold climates where very cold battery banks also need higher charging voltages--AC inverter high voltage cutoffs issues are pretty common in many colder regions.

-Bill

Chris

Re: Off Grid RV System

westbranch wrote: »

I don't know where you found that info , I located this sheet, showing 2.45 (14.7V) for up to 3 hrs.
http://www.usbattery.com/usb_images/usb_2200_data_sheet_2013e.pdf

they show an EQ at 2.55V / cell

Thanx for the info.....I was looking for that info for the specific battery but the only thing I could find was under their FAQ and they said the quoted voltages
http://www.usbattery.com/usb_faqs.html

So, 14.7 it is then

Chris

Re: Off Grid RV System

BB. wrote: »

And an RV were your panels many not be tilted towards the sun, and a relatively small battery bank (weight/space limits)--And you are probably cycling deeper than the average off grid home.

Another issue with over ~15 volts charging--Many DC appliances and AC inverters will may fault or even fail with that high of charging voltage. You have to look for inverters that will take 15.5 to 16+ volts to ensure that they will operate while you are charging.

Add cold climates where very cold battery banks also need higher charging voltages--AC inverter high voltage cutoffs issues are pretty common in many colder regions.

-Bill

I do have the advantage of having my rig permanently parked at our spot at the lake, so I do have my panels mounted on a tilting stand. As for the batteries I have the space at the front of the trailer for what ever size and or weight I need for the batteries :cool:

As for the high voltage cut off on the inverter that's a good point, I never even considered this......time to go dig out the instruction book. Thanx

westbranch

Re: Off Grid RV System

So the Tracer only hits 14.6v for Bulk, is it the same for Absorb? If os you could do a longer Absorb phase, not the best but would help, however with PV that can be a challenge, getting enough time per phase.

Chris

Re: Off Grid RV System

Chris wrote: »

Now, I do plan on ordering a "Kid" controller so I will have the ability set voltages and just wanted to be sure that this is the right way to set it up.

Thanx, Chris

I was just asking about the Tracer as it was a controller that I was considering, so from what I've read about the Kid this should be a non-issue. After reading HandyBob's blog I think I may have made a mistake with the placement of my current CC. I have it mounted under the fridge (aprox 15ft from the battery bank) I do how ever have (I believe) #6 wire run to the batts (but will have to inspect the next time I'm out to be sure) I have it hooked to the out put side of the lines off the converter. So from what I gather this is to long of a run to avoid voltage drop? should I be going threw a pile of work to re-wire and position it closer?

Thanx again guys, your info has been invaluable to building my understanding to make my system run properly

westbranch

Re: Off Grid RV System

well the best location is the one as close to the battery bank as possible, what ever that means to you. You will want to use the voltage drop calculator in this string, near the beginning I believe http://forum.solar-electric.com/showthread.php?29-voltage-drop-calculator

reason is that your CC to battery voltage will be ~14v during charging as the CC will have dropped it from ~28 -34V (panels in series) or 17V if in parallel, hence more V drop per foot. closer = smaller wire = lower cost bit ti is always good to go for the largest wire you can afford, up to the max the CC can take (#4ga for Classics) so if you upgrade in future , no changes needed there.
You want the CC to have plenty ventilation too, so don't put it in a cubby hole.

vtmaps

Re: Off Grid RV System

Chris wrote: »

He talks alot about the importance of absorb voltages......so I went to the US battery site and found that they recommend "2.583 volts per cell" = 15.498 volts.

Does this seem a little high? I know trojan wants 14.8. is this what you guys have your controllers set to with these batteries?

US Battery and many other manufacturers use the term "absorb" differently than we do in the RE world. Notice that US Battery has a bulk voltage AND an absorb voltage. That means they can not be using the same charging profile that your charge controller uses.

Good explanation by 'stephendv' here: http://forum.solar-electric.com/showthread.php?p=110231#post110231

--vtMaps

Rybren

Re: Off Grid RV System

Chris,

I have a set of US Batteries, here are the charging parameters that they recommended (via email) for my 24V bank:

"Since you are off-grid, I would suggest a bulk and absorption charge setting of 2.40 volts per cell (28.8 volts for a 24 volt system).
If the specific gravity does not come up to full charge regularly, you can move it up to 2.45 - 2.50 vpc (29.4 - 30.0 volts).
Float charge voltage would be 26 volts and equalization charge voltage would be 30 - 31 volts."

Hope you had a good Christmas

Jerry

Chris

Re: Off Grid RV System

Thanx Jerry,

If that's what the manufacturer told you then that's what I will set it to....well except divided by 2 LOL being an RV I have to stick with 12 volts. How far do you have your CC from your batteries? and what gauge of wire did you use between the two?

Rybren

Re: Off Grid RV System

Chris,

I have a Classic and epanel. There's a 18"-ish run of 6 AWG from the CC to the panel and about 36" of 1/0 from the panel to the batteries.

Chris

Re: Off Grid RV System

Ok, so this might be a dumb question......but what is an E-panel and what is it's purpose? I looked them up....and I gather it's something like a breaker panel in a house?

BB.

Re: Off Grid RV System

An E-Panel is a pre-wired panel+components, can be designed for a specific brand/model of charge controller/inverter setup.

If this is the first time you have ever done a complex off grid power system and you need to get the system up and running quickly--An E-Panel can save a bunch of time.

If you have time/experience/want to make DIY project--You certainly can do your own.

-Bill

vtmaps

Re: Off Grid RV System

BB. wrote: »

An E-Panel is a pre-wired panel+components, can be designed for a specific brand/model of charge controller/inverter setup.

To amplify: The ePanels are made by Midnite Solar. They come prewired or as kits. You can buy them as a package with the inverter and charge controller of your choice.

Actually, you have less choice now... it appears that the only complete package systems they sell now are the Magnum systems. I asked on their forum why they stopped selling the Outback systems, but got no response.

--vtMaps

Rybren

Re: Off Grid RV System

Chris,

BB and vtMaps covered most of the basics of the epanel. It comes with a main breaker for the inverter input, and you can add DC breakers for your PV panels and CC. In addition, you can also add AC breakers for the inverter output. They also come with a shunt for a battery monitor and/or WhizBangJr.

Mine is setup with a 125A inverter breaker, a DC PV and DC CC breaker, and three AC breakers to control the 110V distribution to the cabins. Each cabin has its own AC panel.

Santa brought me a WhizBangJr - Did you know that he shops at NAWS? - I can't wait for spring to hook it up.

vtmaps

Re: Off Grid RV System

Rybren wrote: »

It comes with a main breaker for the inverter input, and you can add DC breakers for your PV panels and CC. In addition, you can also add AC breakers for the inverter output. They also come with a shunt for a battery monitor and/or WhizBangJr.

The stretch versions of the ePanel also come with lightning arresters. The ePanel also comes with a manual bypass switch that is external to the inverter. This allows the generator to bypass the inverter so that the inverter can be removed for repair. (normally the inverter has its own automatic built-in bypass switch and switches the generator output as needed).

--vtMaps

Chris

Re: Off Grid RV System

Ok I think I get it now,

So basically, it's a breaker panel set up for solar, pre-wired for several different circuits to combine everything into one box?

Chris

Re: Off Grid RV System

Rybren wrote: »

Santa brought me a WhizBangJr - Did you know that he shops at NAWS? - I can't wait for spring to hook it up.

Lucky guy....I bet your pumped to get out and play with it. I got told that Santa doesn't know how to make Charge controllers and batteries were way to heavy for his sleigh LOL
How long till the road is melted off enough to get into the cabin?

vtmaps

Re: Off Grid RV System

Chris wrote: »

So basically, it's a breaker panel set up for solar, pre-wired for several different circuits to combine everything into one box?

Not necessarily pre-wired... you can buy the kit and follow their instructions (and videos) to assemble it. The ePanels are fairly shallow and the doors are modified to hold the inverter. (takes up less wall space) Since the inverter is on the door, all the breakers are on the left and right sides of the ePanel.

Many installers favor the ePanel over the all-in-one offerings from the inverter manufacturers... easier to work in and more customizable.

--vtMaps

Rybren

Re: Off Grid RV System

Chris wrote: »

How long till the road is melted off enough to get into the cabin?

At the rate that we're getting snow this year, I'd say very late April. I'll probably snow shoe or x-country ski into the camp at some point this winter, but I won't try to install the whizBang until the spring.

ILFE

Re: Off Grid RV System

Okay. I'll bite. What is a Whizbang?

westbranch

Re: Off Grid RV System

here it is:

http://www.midnitesolar.com/productPhoto.php?product_ID=519&productCatName=Charge%20Controllers%20-%20Classics&productCat_ID=21&sortOrder=9&act=pc

ILFE

Re: Off Grid RV System

And there I thought it was like a "sky hook" or a "cable stretcher".

God, how I miss the days of running new guys around the shop looking for such things.

Rybren

Re: Off Grid RV System

My favourite from my old flying days was the bucket of prop wash.

Chris

Re: Off Grid RV System

I took a trip out to the lake yesterday to check on things and see how the system was running. Was quite happy with what I found considering how my system is set up right now.

I was getting about 10 amps to the batteries when I put a load on it (they were fully charged, well as good as my old dieing cells will charge) how ever I found that I was loosing a 1/4 volt in my wiring between the CC and the Batts

When I get my new controller I'm going to be trying to do some re-wiring to fix this......
right now I have the out put of the CC connected to the out put of the converter (useing 10 awg), from that point it has 6 awg running aprox 15ft to the batteries. Now I assumed that both + and - were run all the way but I discovered the the - is just connected to the frame after it goes threw the floor........
is this going to cause voltage drop?
I'm already going to be switching out the 10 awg between the CC an converter for 6 should I be running the - all the way to the batts at this time?

westbranch

Re: Off Grid RV System

Chris, as said earlier about 12 V, the crux of your drop is the low (12V) voltage system you are using over longer distances (15'). The closer you can get the CC to the bank the better.

So as you suggest, going to larger wire should improve your losses. At 12 V , the bigger the better, within reason.
Use this calculator to see what various wire sizes will do for you...
http://forum.solar-electric.com/showthread.php?29-voltage-drop-calculator