Hey Matt, from what I read you're way too light on battery & solar with everything you intend running.  Look at everything you have and try to run as much as possible direct from 12v.  I understand using the PC over a laptop, but have a look at the PC's power supply you'll probably find it's 240v AC down to 12v DC, so you might be able to make (or have made) an adapter to run it direct from 12v.  Yeh get a bigger LED Screen although going back to one screen takes some getting used to (ex graphic artist).

You can get 12v chargers & power supplies for any portable device like laptops & phones etc... far better direct on the batteries running 12 volt upto 19-22v than 12v upto 240v AC then back down to 19-22v DC.

Have a look at Bitdeals for their Pure Sine Wave Inverters, I have a 1500w/3000w Peak inverter that we use from time to time and has been great.  Just remember Inverters should be used for emergency only cause they'll drain a battery bank in no time flat!.  In 12 months I probably used my inverter less than 4 times and for no longer than 20 minutes each time.

The wires coming from your solar controller look pretty light to me, and the solar controller..... I've seen a few similar to that used as a boomerang (um... stick! cause when thrown, they didn't come back).  A good controller will have an LED readout showing you some helpful readings with out the need of relying on a multimeter.  Mine records Amps into the batteries over 3 days which is handy cause I've got a fair idea what my daily usage is.  The heart of your solar system is the controller, so best to have a really good one. The trick is getting one that's a true MPPT controller, some say they are but they're not.

Using 240v cable for 12v is not good no matter how you want to sugar coat it, 240 volt cable is designed for Alternating current (AC).  Voltage drop in a DC system can only be overcome by using the correct thickness of DC cable allowing for distance & power and going thicker than the recommended  is better again.  Mixing Batteries.... Sorry I don't agree with your theory, but it's your money... time will tell.

Anyway good luck on your travels.

Steve.

madaboutled wrote:

---

Hey Matt, from what I read you're way too light on battery & solar with everything you intend running.  Look at everything you have and try to run as much as possible direct from 12v.  I understand using the PC over a laptop, but have a look at the PC's power supply you'll probably find it's 240v AC down to 12v DC, so you might be able to make (or have made) an adapter to run it direct from 12v.  Yeh get a bigger LED Screen although going back to one screen takes some getting used to (ex graphic artist).

You can get 12v chargers & power supplies for any portable device like laptops & phones etc... far better direct on the batteries running 12 volt upto 19-22v than 12v upto 240v AC then back down to 19-22v DC.

Have a look at Bitdeals for their Pure Sine Wave Inverters, I have a 1500w/3000w Peak inverter that we use from time to time and has been great.  Just remember Inverters should be used for emergency only cause they'll drain a battery bank in no time flat!.  In 12 months I probably used my inverter less than 4 times and for no longer than 20 minutes each time.

The wires coming from your solar controller look pretty light to me, and the solar controller..... I've seen a few similar to that used as a boomerang (um... stick! cause when thrown, they didn't come back).  A good controller will have an LED readout showing you some helpful readings with out the need of relying on a multimeter.  Mine records Amps into the batteries over 3 days which is handy cause I've got a fair idea what my daily usage is.  The heart of your solar system is the controller, so best to have a really good one. The trick is getting one that's a true MPPT controller, some say they are but they're not.

Using 240v cable for 12v is not good no matter how you want to sugar coat it, 240 volt cable is designed for Alternating current (AC).  Voltage drop in a DC system can only be overcome by using the correct thickness of DC cable allowing for distance & power and going thicker than the recommended  is better again.  Mixing Batteries.... Sorry I don't agree with your theory, but it's your money... time will tell.

Anyway good luck on your travels.

Steve.

 

 

-- Edited by madaboutled on Thursday 11th of February 2016 10:40:27 PM

---

Hey Steve,

  I'll say from the get-go that you obviously didn't read all (or much) of my page - for which I don't blame you a bit. It turned out to be quite a novel...

  Anyways, let's go at it in order of your thoughts

  No, we have nowhere near enough input or storage. I'm thinking we'll need (at best) 5 x what we have now. And yes - the idea is to run everything we can on "12v native". As you mentioned, it's the most efficient way to go. You're also right about the PC P/S stepping everything down to 12v (there's also a 5v rail). PC power supplies are readily available which take 12v input, but I think I might be better off designing and knocking up something to suit my specific needs. I'll need to take a bunch of measurements and some more research to ascertain whether I need to refactor the displays (I'm also looking at physical space, of course).

  Obviously, we're aiming for as close to "native 12v" as possible. I guess you also missed from my writing (haha - or maybe ranting...) that this is the path we're taking

  I'm assuming that the "wires coming from your solar controller" you refer to are the ones coming out of the unit itself. The "controller" is rated for 20a, and those interconnect cables look good for at least 25a. We're not intending to push more than about 15a through it (we're not using it's load / output side), so no issues there.

  You said "The heart of your solar system is the controller, so best to have a really good one" - you're absolutely right if you need to rely on it because you don't know how to manage the system yourself. Unfortunately, it's difficult to be certain that the "controller" you choose is really any good at all. Most are not. And you're again right that a lot of the "controllers" claim to be MPPT when they're absolutely not.

  I meant for my writings to imply that using 240v cabling for longer-length interconnects was absolutely insufficient for 12v systems. I just needed to save some $$$. Thus far, it's all been (almost completely) good. By the way, though, it's got little to do with the difference between AC and DC current profiles - it's more to do with the fact that lower voltages don't travel as well over longer distances via thinner cables. You also said "going thicker than the recommended is better again".  You're wrong on two different levels - you don't need to go thicker than actual spec, and "recommendations" are rarely based on actual facts, but rather on opinion. I feel like I didn't word that very well (thanks a lot, red wine...), but it probably makes enough sense to most...

  Mixing batteries... Haha... I rarely do "theory". I prefer fact. But it's your money... time will tell

Cheers,

 Mattt.

Matt I'll post the power usage figures for you tonight. My thoughts on your computer would be to swap the desktop PC for a similar spec laptop and a second battery to get you through the hours of darkness then charge during the day.

Alan

Hi Jaahn,

  Haha - funny how everyone wants to tell me that the battery setup will kill kittens on a good day, but aren't quite certain enough to actually pull the trigger :p  At the end of the day, let's just say that I wasn't always a software developer

  Of course, you're right about (some of) the wiring and the regulator - they're merely stepping stones. The wiring (240v extensions) will be refactored later for reaching 240v sources when needed (hopefully never, all going to plan). The regulator will wind up being gifted to someone else who's starting their own build in due course. It's cheap, almost nasty crap.

  As said in the blog, I have measured the drops (one doesn't need a "good" MM - just a digital one) - my office continues to supply under 11v which has thus far precluded me from running a 12v laptop adapter which I'm keen to introduce into the system. Problem is (expressed as a real life scenario for clarity) the 5m of cable between the panel and the regulator cost $40. I need about 15m to get to my office. That makes for $120 worth o' 6mm cable, and 6mm isn't good enough for that run. As this office is temporary (would love to think I won't be working here before 2017), I'm not prepared to trivially drop that kinda cash on it yet.

  The "list of 240v items" consists of two things which are non-negotiably (I think I just invented another word :p) 240v - the fridge and the aircon. Of course, a few other items on the list won't be able to be converted in any justifiable way, but they're either sparsely run, low wattage, or both. Oh, and there's the coffee machine but that's somewhat temporary in the scheme of things (the greener we get, the more I think about the pods...).  At any rate, you'd be better off trying to warn the folk who are already successfully running domestic (240v) fridges and aircons on their 12v, off-grid systems. And perhaps the multitudes who run entire 240v households from off-grid and grid-tied systems (although most of those are 48v native, which is admittedly a slightly different ball game). For the record, they work (through their usually 3-5kw inverters) because the inverter is usually installed less than a metre from the storage, and their 220-250v (in AU) output is happy(ish) to travel over longer runs of "thinner" cable to get where it needs to go. That's one of the intrinsic premises of the commercial power grids - thousands of volts over vast runs to localised distribution hubs, then down to 110/240v for local distribution. Seems to work okay

  I would say that my disappointment with our current inverters is because they are cheap crap. Of course, I've run them straight from the battery bank (okay... so some 20mm of (decent) cabling from them...). They simply don't work as advertised (haha - surprise, surprise).

Cheers,

 Mattt.

Hey Nev,

  Firstly, thanks for actually managing to make me jealous :p  I sometimes think I'm not gonna be able to sustain the wait between now and having been out there for 12 weeks. I don't think I've ever wanted anything so badly (although admittedly probably already have just about everything else I've ever really wanted (in realistic terms), so my gauge on this one might not be terribly accurate). I'm working my ass off for a "drive off" date sometime in 2016...

  Yeah, we definitely need a decent monitoring / measuring system. I've thus far held off because I'm starting to develop a plan for building all the "smarts" myself - likely based on an Arduino platform. I wouldn't be the first person to design and build an MPPT regulator from the platform

  Mate, are you *really* tapping your batteries to that depth? I totally understand the sometimes large deficit between needs / wants and resources, but you seriously need to grow your storage bank to the point where you're only skimming, say, around 25% of their rated capacity. Otherwise, you'll potentially go somewhat hungry while shopping (repeatedly) for replacement batteries. And don't forget that, should just one battery in a bank suffer a serious failure and go unnoticed for *any* length of time, it'll murder it's kin. Given your current setup, that's a minimum of $500 per replacement...

  I hear what you (and others) are saying about the workstaion / PC, but I'm afraid that's not negotiable for me. I may very well not even be able to forego the dual display setup (in fact, I'm almost constantly running the laptop as a "third display" of sorts and am kinda thinking about either larger displays or adding a third...

  On the upside, the new Skylake platform is the most energy efficient to date. And I guess I could take the add-on video card out of the equation in favour of the discrete Intel video (which can apparently run three displays, but I'm unsure of the performance), and maybe also the audio card - it was primarily installed for recording muso's, but I rarely do that these days. On the other hand, I'm quite the audiophile and would likely hear the difference in the onboard audio system. Oh - and my RAM usage *never* goes over 30% of the 16gb installed, so maybe it's prudent to pull half of it, although that'll be a bugger as I don't think the board can do dual channel with a single module :-/

  Obviously, I'll need to measure the thing's appetite in due course and formulate a plan based on the results. There are certainly plenty of 12v-input power supplies available, or I could of course just build my own. Internally, there are only three power rails anyways and the largest is 12v...

Cheers,

 Mattt.

G'day,

  Haha - if I had anywhere near even *half* of the answers, I'd not be chained to my desk on this glorious day in one of our many versions of paradise

  But the reason I'm posting is deviously hidden in the third sentence of my first post - "I've just managed to find some time to document what we have so far, and thought I'd give a little back to the community by way of sharing it.".

  Firstly, as I've repeatedly stated, the 240v-rated cable runs currently in use in our build are TEMPORARY. They are not permanent. They are not part of the final design (other than to perhaps source 240v feeds for recharging purposes in the likely case that I don't, after all, have "all the answers"). With that said, I must say it's been interesting to measure and observe the characteristics of said cabling being used "out of spec". But then, I'm a tragic geek :p

  Unfortunately, you didn't specify what a "normal" 240v cable actually is. The stuff I'm (currently, temporarily, non-permanently, not married to, etc) running is very flexible multi-core. I haven't measured how many strands or any dimensional data because I simply don't care. Clearly, it's not up to the task - and yet it's done the job very nicely for us for a few weeks now. And it was dirt cheap. And it was already here, unused.

  You also failed to mention what "auto cable" is, which would have been somewhat important given that there's no such specific thing.

  Any device designed for use in the kind of system we're discussing *needs* to be able to handle up to somewhere around 15v, as that kinda voltage (well, over 14v) is regularly fed to them (notwithstanding voltage drops) while charging. Most such devices can also handle down to 10-11v for similar (although inverse) reasons. In fact, *everything* in my office has been running faultlessly at under 11v (under nominal load), with the sole exception of a ~12v input / 15-24v output laptop inverter I have which demands a minimum of 11v in...

Cheers,

 Mattt.

madaboutled wrote:

---

Hey Matt,

Appoligies for trying to help..... won't happen again!.

Steve.

---

 Hmmm yes gives that sort of feel !

A comment to finish on. "one doesn't need a "good" MM - just a digital one" ?? but cheap multimeters are like " our current inverters because they are cheap crap. .... They simply don't work as advertised (haha - surprise, surprise)".  Just a pointer from me generally!

I wish you luck

Jaahn

Jaahn,

  For brevity, please see my reply to Steve moments ago

  I absolutely see (and fundamentally agree with) your point about the DMM. I guess I'm working on the assumption that even the cheapest of them shouldn't have any real dramas accurately reporting something as simple as <15v to just a couple of decimal places.

  I do miss my trusty Fluke, but the ^*($%$@ who nicked it probably doesn't

Cheers,

 Mattt.

Hey Troopy,

  Thanks mate - I never was a 240v / AC guy...

  Is my thinking that maybe running dual cables (I have other unused 240v extension cables in the garage / workshop) and thus doubling the number of strands (speaking ideally, of course) back to my office would vastly improve the voltage drop situation I'm currently seeing?

Cheers,

 Mattt.

Troopy,

  Very, very cool stuff (copied and pasted into the relevaant e-note) - many thanks

  Will introduce another 240v extension cable when I can find the time (haha - now it's playing on my mind, I bet I find the time sometime today / tonight :p). Hopefully, that'll see me through the next little while until I loosen the requisite orifice and ante up for some appropriate cable. Of course, I'll be able to re-use it in the bus later, so it's not like it's money wasted - just that there are several better things to spend it on presently (like a decent controller / regulator).

Cheers,

 Mattt.

Matt here is the current draw list for the gear in our van but as we run LiFePo4 batteries do the arithmetic using 13V not 12V. This may be of some use in your planning even though you will have your own power use priorities. I suggest you look at the posts by "Plendo" concerning his power set up as he planned to use lots of 240V stuff of his system.

Alan

3way fridge on 12v heating element  RM2350          13  A

Waeco 35Lt fridge /freezer as a freezer                     3.6A

LED replacements for 10Watt QI reading lights         0.19A

original 12v flouro lights                                           0.70A

range hood light                                                       1.7A  (car indicator globe -- rarely used)

range hood fan                                                         0.6A

shower/toilet fan                                                      1.7A

water pump (Shurflo) with one tap open                   4.9A

Sony car radio playing MP3                                      0.8A

TV on standby                                                         0.5A

TV only on                                                               2.0A  Varies a little around this figure

TV playing DVD                                                       3.8A  as above

VAST decoder on standby                                        0.5A  ( omited to measure running)

Diesel heater fan speed 1                                      0.84A

Diesel heater fan speed 2                                        1.1A

Diesel heater fan speed 3                                       1.8A

Diesel heater fan speed 4 (full)                               2.6A

1000W PSW inverter on standby                            0.6A

running twin electric blankets on 1                          3.1A

running twin electric blankets on 2                          4.9A

running twin electric blankets on 3                          9.5A

running ASUS laptop                                        2.5-4.0A  (depends on state of charge of battery)