OverTheTopCargoTrailer 7 x 16

[MtnDon]

We have a VFX3524M, 3500 watt Outback inverter/charger. It does not run anywhere near capacity most of the time. But I do use power tools like circ saws, metal chop saws, concrete mixer and even a small 120 VAC welder at times. Those are not long duration runs but over the course of the day it adds up. 1.1 kWh for the concrete mixer, last time I used it.

That is being drawn from 12 GC-2, (210 amp-hour @ 6 volt) wired for a 24 v system. The sun usually makes up the use in a 24 hr period.

I could likely use only 8 of the GC-2, but in winter the 12 makes me more comfortable. My goal is to never use more than 25% of the capacity in one day. Most of the time it is under that. My other goal is to get 10 years out of the batteries. Not sure on that, but so far at 4 1/2 years the plates look as good as they did when new.

[OverTheTopCargoTrailer]

Hi MtnDon

Wow that would be 1260 amp hours at 12 volts or 630 amp hours at 24 volts.
My understanding on batteries is they last long if maintained & recharged properly
70% discharge is ok if 100% recharged daily or in that cycle , it's the guys who go down 80% & only recharge 50- 70%
Who trash their batteries fast. batteries to cold, to hot & low water also kills fast
Frozen batts if discharge are killed fast- its a science

On your Let's just use simple math about 10,000 watts per day @ 25% is only 2.5KW usage
WOW ... Not very much at all for a house. your a frugal kinda guy.
You must also have 3,000 in panels ?

I'm just guessing on my trailer but I would now guess if I wanna run AC 4-5 hours per day , I'm gonna need around
1,500 watts in solar panels & charge controllers. Before I had figured about 2 to one ,
One guy named BoBo on this form estimated 8 x 220 watt panels according to his theory ?
The weak link is the batteries & charge controllers, at first I thought you don't need big batt - BC the AC will
Just use the power from the charge controller - buts that's not really that simple.

Well I better see if I can make a little progress today on the trailer

Jerry

[OverTheTopCargoTrailer]

MtnDon


What do you think of the
Xantrex by Schneider Electric XWMPPT60-150 > 60 Amp 12-60 Volt MPPT


I wanna set it up so it can go to a separate battery 200 amp hours ,
But when needed extra for the AC I can transfer it over to the 400 amp hour battery
For some reason I'm not really happy with the flex Max 80

Jerry

[MtnDon]

Hi MtnDon
70% discharge is ok if 100% recharged daily or in that cycle , it's the guys who go down 80% & only recharge 50- 70%
Who trash their batteries fast. batteries to cold, to hot & low water also kills fast

Jerry

&0% with a full recharge is okay, but better is only a 50% discharge before full recharge and better yet (best?) would be 25% discharge before full recharge.

I am in the 25% discharge daily maximum camp. Many days less than that, maybe 15%.

Cold is not bad unless the cold involves a discharged battery that can freeze. BTW, a fully charged lead acid battery will not freeze until something like -90 F degrees. Yes that is very cold.

Note; the only reason we have 12 GC-2's is the cold weather. Winter in the mtns here can get into the minuses easily; -20 is about as cold as I have personally experienced up there, but weather records say -30 can happen. It is 8800 feet so that helps make it cold quicker. Last night it was 37. Down here at home, 5500 it dropped to 54 by comparison. Only 35 miles further south; cabin north.

You must also have 3,000 in panels ?

We have what many might consider an 'unbalanced' system. The battery capacity was sized to ensure the ability to run 2 to 3 days in winter with clouds. Winter temps greatly reduce the amount of power that can be drawn from lead acid batteries. Summer has us up there nearly full time; late May thru to mid Aug. For summer we could easily do with just 8; maybe even 4? ??? But that would drag down the batteries more and I do not like that. In winter we can not drive the last 3 miles to the cabin; no snow removal. So in winter once the snow is deep enough we snowshoe up the ridge side. A distance of 1.25 miles cross country... old logging roads actually. In winter we might visit twice a month but most likely only once a month for 3 days or so. If it is cloudy we have enough battery to not likely need to run the generator for a few days. I hate generators but do have one.

The cabin only has 624 watts worth of PV panels; 3 x 208 watt. Pole mount faces a little east of due south as if it gets cloudy is will most likely be cloudy after 2 or 3 PM. Mostly it is very sunny. We have better sun hours in winter than many have in summer. FWIW, the 8800 foot altitude is a slight advantage as reduced atmosphere means more sun. Our typical use is low because of LED lamps (used to have CFL, but it is mostly LED now. Small water pump, small microwave use, some TV, DVD, stereo and laptop. Our inverter is larger than normal use would dictate but it does let me run a table saw, compressor, etc when/if I want to. Our low use means the batteries virtually always get fully recharged every day. So looking at it that way we have too many batteries. One day I would like to get more PV and then an electric fridge instead of the propane fridge.

[MtnDon]

MtnDon


What do you think of the
Xantrex by Schneider Electric XWMPPT60-150 > 60 Amp 12-60 Volt MPPT

Jerry

The Xantrex/Schneider XW stuff is very good equipment. I like the Midnight too, when higher panel input voltages are needed

[OverTheTopCargoTrailer]

MtnDon

-20 sounds good, what's your address I'm coming. I Have not seen snow in 35 years ....
I'm beginning to hate global warming & seeing my trees bloom in January.

With 600+ watts in panels at -20 you should get 800 watts ?
Do you have your batteries in a heated space above 50 deg F ?
Batteries like same temp as we do, under 32 they loose 20-30% of their power ?
I also have the feeling my LG 255 are equal to my Keocrya 210 , if that sounds to strange
I was able to pull 680 watts from 840 in panels vs 660 from 1020 in panels
Not sure the time of year however ?? To get exact comparison.

I think I will order Xantrex 60, it has lots of programmable features & can't be worse then the Outback 80
For the AC to work better , it would be best to have all equipment outside of the trailer
That would reduce interior heat load.
But then it's also much hotter & makes even less power
I feel sorta screwed coming or goinging in this case

I got a Ikea foam mattress & spring frame, my trailer is only 76.5" wide
So my standard 12" real mattress won't fit & the sheets can't be changes
And it picked up mold from the thin walls in the metal trailer ....
That won't happen this time around


My feeling that trailers RV's ROT OUT - not always by leaks, but due to interior moisture & condensation
My metal trailer was sweating like Nigra falls in 45 deg weather
That's why I think trailers rot so much, if they are lived in durning winter months
I will also use a dehumidifier if needed durning winter.

Jerry

[MtnDon]

Do you have your batteries in a heated space above 50 deg F ?

The batteries live outdoors. I don't like flooded lead-acid batteries indoors.
The good thing is the cold storage will lengthen their lifespan, given that the water is kept up and nothing else bad happens.



The copper buss bars have been fitted with insulating sleeves to try and minimize the accidents. It is also all locked up to keep curious fingers away.

Batteries like same temp as we do, under 32 they loose 20-30% of their power ?

Standard test conditions is 77 degrees F. I round that to 80 F for convenience.
So at 80 F you have full battery capacity available.
As the temperature falls multiply by the factor to see how many times more capacity is needed to be equal to the STC.
80 F 1.00
70 F 1.04
60 F 1.08
50 F 1.12
40 F 1.18
30 F 1.22
20F 1.28
10F 1.33
0F 1.42
-10F 1.48
-20F 1.55

[MtnDon]

With 600+ watts in panels at -20 you should get 800 watts ?

It is more than the rated number. I don't sweat the numbers as long as the batteries get charged in a day.


A good rule of thumb when looking at a system is that it should always reach float charge when used in an "average" manner. "Average" being different for different folks; also depending on "average" sunshine/weather conditions.


Even with a cloudy day and rain this weekend the noon time was sunny enough that day so we had some Absorb that day (yesterday). No float but it did reach float just before we left today. Gloriously sunny.

[OverTheTopCargoTrailer]

MntDon

In that case I'm king of the float, eventhough I'm using 1.1 to 1.6 kw I'm still getting 5 hours float
So the darn thing says anyway.

I'm waiting for PGE to send me an extra $10 per month bill for my share to support the GRID

I love the argument we want 20% power from solar BUT now we need extra charge to pay for the grid
If you build 500k in new houses & 500k switch to solar = grid change is ZERO !!
Because I know math ...............

But here is the problem, PG&E .... Is guaranteed a 11% return on all Capitol investments AKA the Grid
So if they don't expand the grid by a billion $$$ every year , then loose $110 million every year ROI
So if you switch to solar you really need to pay for EXTRA CAPACITY on the grid

[OverTheTopCargoTrailer]

Ok this morning I ordered the

Xantrex by Schneider Electric XWMPPT60-150 > 60 Amp 12-60 Volt MPPT only another $497

http://www.affordable-solar.com/store/solar-charge-controller/Schneider-Electric-xw-solar-charge-controller

should get here in about a week or less, its already all wired up - just needs to be installed chop chop
I still need 2 sets of Batteries however

Im thinking by around Oct 19-20 weekend, I can take a little test run to the Santa Cruz Beach
and see what the general public thinks of my crazy stuff, will only be 90% done
but so what

[MtnDon]

Jerry,
Sounds like a plan.
Affordable Solar is just a few miles away from home here. I have picked up much of what I've used at their warehouse. Handy. Good prices and service for everyone and no shipping.

[OverTheTopCargoTrailer]

MtnDon

I was just looking, I bought almost $8,000 worth of sh** from them in the last 2 years.
lucky I still have a JOB

everything else included I'll have an easy $10k in solar parts,
now I just gotta live 30 more years to get my money back,
they used to have a better selection of batteries ......
the shipping on those is a killer.

Jerry

[MtnDon]

The other folks I have bought a few things from is the
http://www.thesolarbiz.com/site/index.html

They are not so close to me, BUT they usually come up with good battery deals as they can often ship from different warehouses here & there, or arrange a pickup at a local warehouse.

[OverTheTopCargoTrailer]

im sorta looking for 2 like this with local PU...
maybe latter I can contact them as I get around a bit


http://www.thesolarbiz.com/Trojan-J185P-AC-12V-Battery-205-AH

[MtnDon]

Trojan are great batteries. I am a believer in making series connections rather than parallel, if possible. So if there might be a pair of those 12 volt J185's wired in parallel, search out other choices looking for 6 volt batteries. Two J-185's in parallel = 12 volts with a 20 hour amp-hour total of 450. Two Trojan L16P AC's would be 12 VDC and 420 amp-hours. Close to the J185 capacity. $20 more per battery.

The "if possible" is sometimes influenced by costs.
In the case of our cabin I used three parallel strings because at the time the finances were tight and the GC-2's were much cheaper to buy. Whenever these need replacement I hope to go with something better; less parallel, more series.