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Post by offgridQLD » Thu, 21 Aug 2014, 16:23

I think I found the same inverter on eBay. The Ups I have is about 30kg! as is. (63kg with the internal battery's)

So the inverters (idle on) consumption. Not a real issue when your charging the imiev and draining the battery supply over a short time Considering I would like the inverter to do double duty as a camper van its of some relevance.

Whats the idle consumption like on that inverter. At a guess (going by your 94% efficiency at 3500w) I would say its almost 200w?

Though they are listing its (no load current) as 0.7A (that's under 10W) is that reality?


Kurt
Last edited by offgridQLD on Thu, 21 Aug 2014, 06:24, edited 1 time in total.

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Post by offgridQLD » Thu, 21 Aug 2014, 23:08

Never mind the above questions ACmotor. After some research. I went in another direction.

Settled on this one

PIP-4048MS is a 4000w continuous / 8000w surge, 48V DC input Pure Sine Wave inverter-charger

" · Adjustable AC input voltage 90~280VAC · Supports 50hz or 60hz via LCD program · 4.0KW pure sine wave output with up to 2X surge max 5 seconds · Built-in 3-stage high efficiency battery charger 30A · Total system charging current = AC + SOLAR = MAX 60A · Dual priority operation selectable: AC vs. DC mode · Free monitoring software · Works with 48V battery system only · transformerless, light weight design · RJ45 comm port · Transfer time <10ms · Programmable LCD with menu · 24 hour operation · Intelligent battery charging control · Built-in alarms and protections · Suitable for wall mount · CE, EMC certified"

10kg, might make a good backup unit for the offgrid house if the expensive selectronics unit ever lets me down or needs repairs.

I can do away with the old PV regs on the campervan and just have the one unit (even have it charge the battery's from AC when i have powered site) Not to big and heavy for the Imiev.

So 48v it is Image

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Post by Johny » Thu, 21 Aug 2014, 23:24

How will it handle LiFePO4 Kurt. Three stage appears to be a Lead Acid thing. It doesn't say anything about battery chemistry in the blurb (found it on eBay).

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Post by offgridQLD » Thu, 21 Aug 2014, 23:32

Yes you can program it for any set point via the software on your laptop under the custom setting tab.

as mentioned in the blurb

"**This unit now supports variable charging programming, and LiFePo4 type battery can be supported. This update currently applies only to 4KW model only."

I use 2x very nice Midnite solar 5kw each MPPT regs that I am very happy with (about the best there is at the moment) So wouldn't want to replace them but but the inbuilt MPPT reg is a ok feature (bonus i guess) for the campervan. Perhaps even throw more PV up and take advantage of it.

It's got more features than I was looking for or intending to use so has opened up a can of worms with options now.

I have 1800W of pv on the upper shed roof that is just needs the cable run down to the combiner / box breakers (i was going to make that final conection this weekend but I will hold off) before I pass that on to one of the midnite regs. I will feed it into this new thing and see how the MPPT reg in it performs.

Expect a full review when I get the unit (expected delivery is 27th - 1 so its airmail)

http://www.ebay.com.au/itm/4000W-48V-pu ... 20d8fc97e4

Kurt
Last edited by offgridQLD on Thu, 21 Aug 2014, 13:40, edited 1 time in total.

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Post by acmotor » Fri, 22 Aug 2014, 05:00

They do those maximum solar inverters as a 3 phase linked set too !!

The maximum solar gear is good. I have installed several of their 2.4, 3 and 4 kW units in the past.

iMiEV MY12     105,131km in pure Electric and loving it !

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Post by offgridQLD » Fri, 22 Aug 2014, 12:50

Good to know Acmotor.

It's always a bit of a gamble with the inexpensive import gear. Though I just got a good feeling by the layout and finish of the componentry that it was built with some detail. I couldn't justify spending big $ for what I need it for.

First time using a transformerless inverter. The weight saving was a big draw card but I guess isolation is something I wonder about how safe they are.

Will most likely use 16 calb 100s as the battery bank. Keeping it portable and transferable from the three or so application I have in mind for it will take some thaught.

Kurt

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Post by offgridQLD » Wed, 27 Aug 2014, 04:04

The inverter for the range extender/portable power unit project arrived today from Taiwan. I ordered it Friday afternoon that was fast postage.

First thing I did was take a screwdriver to the cover so I could check out what was under the hood.

BCB - main board looks ok neat-clean overall most of the layout looks ok for what it is. Though the inbuilt MPPT solar charge controller up the top doesn't look to bad its self, noce big heat sink on top. The input was a bit of a "hey why not throw a bonus charge controller in there and make it a one man band" In doing so there are compromises in the layout so the in feed and out feed connections (wire) My view is it's marginal 8mm2 wire on in the in feed and out feed. The former being the longest wire run about 40cm (I guess being MPPT they are counting on you feeding it 80v+ perhaps even 115V or so and the amps will be lower than it's 60A output rating at 48v nom. But the out feed at battery voltage and 60A max I would have liked to have seen thicker wire on that 25cm run. There is not much room for large terminal lugs but perhaps two wires is a work around and the funky extra long standoff to reach the main board is a little suspect Anyhow a shortcoming that I could improve on or at least keep a check on.

That's if I ever use it to its full potential. Although I don't plan to work the charge reg very hard thats if I ever use it at all. As I just got the unit predominantly to use as a inverter, so probably unnecessary.

I would have liked to see a more beefy main DC input stud to attach the battery feed to. The bus-bar strips are fine but the stud is only a little 6.4mm 1.4inch job)have to dig around the parts bin to find a 70mm2 lug with a 6mm hole. Not a big deal 8..more so 10 - 12mm would have been more typical.

I would have liked to see some of the capacitors a little better sported to. Perhaps a bridging collar at the top or at least some hot glue at the base or between the caps.

Though I have to keep telling myself.... this thing cost 10x less than my off grid house inverter...you get what you pay for and it's not using it for critical application. For the price its not to bad value.

I have the configuring/monitoring software installed on my laptop and the cover is back on the inverter. I will test it most likely next weekend with a battery on it and see how it works Charging the Imiev. Perhaps even try a few nasty loads like starting the Air compressor motor just for kicks not expecting great surge capacity from this style of inverter though.

I did make a short utube video will post that when its uploaded a few pics below for now.

Image

Image

Image

Image

Image

One thing that got me thinking was the imiev's EVSE needed the earth pin connected to the natural on the AC out feed as its looking for a ground reference before giving the go ahead to charge. This worked fine on the other inverter I tried . Though its a transformer style inverter. Is that method going to be a issue with a transformer less inverter (without the isolation of a transformer)?

I'm not 100% if this is a true transformer less or just high freq with a small transformer.

Kurt






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Post by antiscab » Wed, 27 Aug 2014, 04:36

cool inverter

I just noticed the hybrid one:
hybrid inverter 3kw

way cheaper than the selectronic one...shame it wouldn't be on the approved inverters list for grid connect
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Post by offgridQLD » Wed, 27 Aug 2014, 13:43

Utube video. A look under the hood.

https://www.youtube.com/watch?v=n5jIKIP ... e=youtu.be

Kurt
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Post by Johny » Wed, 27 Aug 2014, 16:00

antiscab wrote: cool inverter

I just noticed the hybrid one:
<a href="http://www.ebay.com/itm/3000w-Reiner-Si ... 1e8b9f9028" rel="nofollow">hybrid inverter 3kw</a>

way cheaper than the selectronic one...shame it wouldn't be on the approved inverters list for grid connect

It says:
• Certified in Australian standards AS4777/3100
In the Ad.
Is that the correct certification?

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Post by offgridQLD » Wed, 27 Aug 2014, 16:17

I wouldn't even try and to compare them to a Selctronic. The Selectronic units like the SP pro are more or less a no compromise inverter in both spec and features.

My view is the units like the one I just got are fine for less critical use where there shortcomings wont be a big concern and where you can't justify the expense of a better unit. I don't know if I would like count on one running my house 24/7 for years on end.

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Post by antiscab » Thu, 28 Aug 2014, 03:22

Johny wrote:
It says:
• Certified in Australian standards AS4777/3100
In the Ad.
Is that the correct certification?


There's a specific list maintained by the CEC - if the inverter isn't listed you aren't allowed to grid connect

Not an issue if the inverter is UPS only as that would only present as a load, but if it can export no go

that's only if you ask permission, since it meets aust standards I wonder what the case would be if you connected it anyway and later had the house burn down - would the insurance care

I'm not in a position to try it out anyway - the idea of having an array at ~300VDC, loads and input output at 240vac, but having a 48v battery doesn't quite sit right with me. If I could find a hybrid inverter that could deal with a 400v battery, I'd be happy because I could use it for dump charging
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Post by weber » Thu, 28 Aug 2014, 17:38

Good find Kurt. The price is certainly right. Very keen to hear how it stands up to punishment.

It is not transformerless. It is HF transformer isolated. Otherwise there would be dire warnings in the manual about not connecting either side of the battery to ground (and not touching your battery terminals when it's running). There are no such warnings.
http://www.mppsolar.com/manual/PIP-MS%2 ... manual.pdf

[Edit:] And besides, you can see the HF transformer in the photos.

I'd also be keen to know how it went with a grid-feed inverter connected to its output (a so-called "AC coupled PV array"). In particular I'd like to know if the battery can be charged from an AC coupled array via the PIP-4048MS. But I know you don't have the gear to test that.
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Post by offgridQLD » Thu, 28 Aug 2014, 18:29

"I'd also be keen to know how it went with a grid-feed inverter connected to its output (a so-called "AC coupled PV array"). In particular I'd like to know if the battery can be charged from an AC coupled array via the PIP-4048MS. But I know you don't have the gear to test that"

" grid-feed inverter connected to its output"

AC output or AC input?

I wouldn't think it would be designed with true (AC couple PV in mind) like some of the higher priced units from SMA or Selectronic. It has a AC input that is expecting (mains power) or a generator to be feeding it. It can work in bypass mode to just use the grid/gen or fall back to grid under set conditions (user programmable)

Though I would have thought it would need some (smarts) to be able to control a AC grid tied pv inverter connected to its AC input

I know my selectronic PS1 although it has AC input it wasn't designed for true ac coupling. It will sync with my generator and load share or any number of combinations charge battery and so on though you need the next generation SP pro range to do true AC coupling using a AC grid tied inverter (apparently anyhow).


I think the PIP4048 is just a battery powered AC inverter with a built in AC/DC battery charger along with a DC/DC MPPT solar charge controller tacked on top.

It is still a good solution for some one looking for a inexpensive all in one solution. Perhaps for some one who is on the grid and just wants a battery backup system. Or some one who wants to play around with time of use load shifting and run on a small lithium bank during peek electricity times.The free software has some nice features and rules you can set to make this all happen seamlessly.

Two things I want to test on the weekend are the idle consumption on (on) mode and then the efficacy at say 25% 50% 75% and 100% load to see if its even close to the rated 93%.

The 2nd is related to the first but it will be interesting to see how hot things get under continuous load. Charging the Imiev for say 5hrs at 2200w. I want this thing to be able to sit in the back of the Imiev and charge for a few hrs without setting the interior on fire.Image

I do have a small 1500w grid connect PV system with SMA grid tied inverter at my place in Brisbane though I'm probably not the best person to be experimenting with the unit to much. Though if others more qualified to do so want a play with it. I don't mind as long as you don't end up with it showing a smoke signal error code Image


Kurt


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Post by weber » Thu, 28 Aug 2014, 19:29

offgridQLD wrote: "... grid-feed inverter connected to its output"? AC output or AC input?

I wouldn't think it would be designed with true (AC couple PV in mind) like some of the higher priced units from SMA or Selectronic.
I meant what I said, i.e. with the grid-feed inverter's AC output connected to the standalone inverter's AC output, and hence also to the loads. I agree it wouldn't have been designed with that in mind. But you never know your luck in a big city.

Any sufficiently powerful standalone inverter can fool most lower-powered grid-feed inverters into thinking it is the grid. This is a great advantage for those with an existing grid-feed system who want to go off-grid, or want to go to an off-peak-grid-as-backup-only system, as it means they don't have to rewire their PV array for lower voltage and higher current, and they don't need to buy an MPPT charge controller.

But the question is whether, in the absence of the real grid, any of that AC-coupled PV power will flow to the battery when the loads can't use it all. It all depends on the exact topology of the inverter/charger. Typically they would just use the one HF transformer for both inverting and charging and so would have active switching devices on both primary and secondary, so it becomes a fully reversible DC-DC converter. And if the 50 Hz sine wave stage at the AC output is a full bridge with inductor, it will be reversible as well.

In that case, when the loads cannot take all the PV power and the AC voltage rises, the standalone inverter will reduce its PWM duty cycle to try to bring the voltage down, and this will result in power feeding back to the battery.

The trouble may be that the inverter will not know the battery is being charged and will not limit the charge. I have heard that this happens with another low cost Taiwanese inverter/charger, the Power Jack, although this uses a low frequency transformer.
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Post by offgridQLD » Thu, 28 Aug 2014, 20:05

Ok, yes I forgot the grid feed inverters need AC grid voltage to sink with.

thanks for the explanation.

So the high freq transformer is the square thing in the center between the two heat sinks?

If so why is the copper wire braided ?

Given this unit has a MPPT charge controller built into it 2nd best option would be to reconfigure the PV. A lot of people opted for the 1500W systems (as they were the best value cut off point) The built in MPPT controller can handle 3000W.

But like you say it would require a reconfiguration to most likely 2S x (whatever) parallel rather than a run of series panels. Not a big job perhaps just some larger main feed cable and upgraded breakers.

Even two of the PIP units is only $1600 and you can stack them (They sell a parallel board so they work together) 6000w of PV 8kw AC continuous 16kw peek.

One other shortcoming I noticed is there was no temp probe for the in built charge or the MPPT reg (not a real issue with lithium) But if you were charging lead acid its critical (unless your storing your battery's in a temp controlled room at 25c) Some poking around reviled a two terminal connector on the MPPT reg labeled ( temp sensor) Now I just need to find out if the software has support for temp compensation in its charging settings to take advantage of the temp probe.

Again not a issue for me as I will be using lifepo4 but silly they sell it as is. (most people would be charging PB with it).

Kurt
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Post by weber » Thu, 28 Aug 2014, 21:25

offgridQLD wrote:So the high freq transformer is the square thing in the center between the two heat sinks?
Yes.
If so why is the copper wire braided ?
It's called "Litz wire" and is further evidence of high frequencies. You can read about it here: http://en.wikipedia.org/wiki/Litz_wire
Given this unit has a MPPT charge controller built into it 2nd best option would be to reconfigure the PV.
Yes, that does make rewiring more attractive, however it has a very narrow MPPT range (60 V to 115 V, less than 1:2) which appears designed to take only 3S of the 72-cell modules (around 200 W) or 4S of the 54-cell modules (around 250 W). (216 cells in series in both cases).
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Post by offgridQLD » Thu, 28 Aug 2014, 21:52

Thanks for the info on the Litz wire.

Yes it is a narrow band comparing it to my two classic 150's MPPT controllers (that also come in 200v and 250V spec) that run on the offgrid house and I'm sure it's lacking in other specs, features. But again the classic 150's are $1000 each. You get what you pay for But in some applications like what I intend to use it for you might be paying for more than you really need.

The 200w panels I run have a VMP of 36.7v. So 2s would work ok on it. I find sticking closer to to the battery's voltage (around 80v is the sweet spot)I notice with two identical MPPT controllers the one running the same amount input wattage but 3s (due to cable length) runs bit hotter especualy when its lightly loaded , say absorb - float condition.

So its a compromise between efficiency in the controller and efficiency in the cable...copper is expensive so a slightly warmer controller it was.


As long as it charges my Imiev with the stock EVSE at 2200w for a few hrs at a time enough to discharge the 48v-100AH lithium . That will be a great start for the (range extender project).

If the other features turn out to be reliable and useful for something I will take advance of them. The idea behind the portable power unit was for it to be multiple purpose as its a bit of $ to sink into a package that just sits there for the odd longer range trip.

Though one use I could offer once finished is a 5kwh emergency road side charge for AEVA members around Brisbane Image A tad more desecrate/less embarrassing, eco friendly than turning up with a generator in a trailer.

Kurt
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Post by weber » Fri, 29 Aug 2014, 00:30

I think it's great project, Kurt. I will follow it with interest.
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Post by Johny » Fri, 29 Aug 2014, 15:07

weber wrote: I think it's great project, Kurt. I will follow it with interest.
Ditto. We have a 1.5kW system with a feed in of 66c/kwh and I am not allowed to touch it. BUT I have identified another roof space that could handle 1 to 2kw of panels to form a semi-off grid house - so I am really interested in your findings Kurt.

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Post by offgridQLD » Fri, 05 Sep 2014, 17:18

I didn't get any time last weekend to play with the new project as I had family staying from interstate.

So this weekend I should have a little time. I have been gathering a few parts a little at a time.

Yesterday I took a trip out to the local Tycab wholesaler to pick up 5 meters of 70mm2 flex for the main DC input. I will most likely only need 1m or so as I will try and keep all runs as short as I can but the cable always comes in handy.

Some digging around through boxes in the shed I actually found some 70mm2 lugs with 6mm hole. I think I got them cheap a while ago and planed to just drill out the holes to fit what ever stud I was using typical 8-10mm I come across but this time they are just what I need.

Image

I ordered a 15A Ip66 switched socket. The industrial style box mounted with the screw collar. This will be the one and only AC outlet in the package.

I also ordered a reasonably compact 3 gang swich isolator with NT0 fuses as the main DC/ fuse and isolation in the one package and a spare for PV input. I have grown fond of them in my other solar installations. Good value no nonsense package that takes out battery and PV at once and offers some isolation when needed.

Other then the lithium battery and associated hardware. I think it's just some AC protection that is needed. Considering it will be floating (removable unit) I don't know if RCD protection will be viable or of any use so perhaps just a 20A breaker (more like a portable generator).

Frame will be constructed when I have the battery's as it will take some playing around to find the best configuration. All materials I most likely already have.

This weekend I will build a little test battery from 16 X 10Ah headway cells. Just to power up the Inverter and get the software running. I have 2 x 200w panels set aside to play with the on board MPPT reg and see if I can obtain a sensible charge profile for lifepo4.

This way i can play with it on the bench and build some confidence in the units ability, test - measure a few things with ease before the final install with larger battery.

I have also been giving some thought of how to practically use the portable unit 48vx100Ah battery and inverter/mppt CC in my ute with the camping-12-pv package I already have.

I made a small list of my DC loads. The two largest loads are my engle 32lt freezer and Engle 40lt frige. Both consume 48w when running and have a very low start up serge due to the compressor design. Other than the refrigeration the loads are all very small LED lighting (10w), small water pump (30w) dc fan (10W) and a few DC outlets for charging phones,tablets and so on (10-20w). So I am thinking a 200 - 300W DC-DC converter would handle the above loads and solve my 48v-12v issue so I'm more or less fixed on that path.

By reconfiguring my two solar panels that I have already been using when traveling - camping. I can charge the 48v bank through the built in MPPT charge controller in the inverter. Though trying to replenish 5kwh of lithium with just 300w or so of PV is a little under kill.Particualy if I can now bring along a few AC gadjecgts like my express machine to add to the loads(OH joy a real coffee every morning!)


I Have the cars alternator and the original dual battery feed to the rear of the ute so perhaps some kind of booster to up the voltage - lower the amps and give me a voltage I can work with (there are PV regs available that can work from a lower voltage say 14v and boost it to 50 -60v to charge higher voltage battery's though most I have seen are very limited in output 200 - 300w.

I need to think more on the above issue. Perhaps just forgetting the cars alternator assistance, when and if needed all together. Most trips I have made some up to 6 weeks on the road I could have got away with just PV input and not alternator input. Perhaps the odd mains battery charge when I had mains power to make up for bad weather...that's another option as the inverter also has a inbuilt mains AC/DC charger. Though the alternator is still a tempting (nice to have option)

Will update when I have the thing powered up and some more info.

Kurt











Last edited by offgridQLD on Fri, 05 Sep 2014, 07:23, edited 1 time in total.

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Post by weber » Fri, 05 Sep 2014, 18:31

Why 70 mm^2 cable? Aren't we talking about max 4000 W continuous at 48 V and 90% efficiency here? Even if your battery sags to 45 V that's only 100 A. The inverter's surge rating to twice that is only for 5 seconds so that's irrelevant. And your cable run is only a metre or two, so voltage drop in the cable is irrelevant. For 100 A you need at most 35 mm^2.

And for unprotected battery cable, i.e. between cells or between cells and fuse, a rule of thumb is 100 A of short circuit current per square millimetre for 1 second. So 35 mm^2 is good for cells with up to a 3500 A short circuit current. But put a fuse in the middle of the floating pack to minimise unprotected cable.

Incidentally, I never use anything over 50 mm^2 or 0 B&S(AWG) (125 A). After that I use double 25 mm^2 (160 A), double 35 mm^2 (200 A), double 50 mm^2 (250 A). If you need a higher continuous current rating than that, then your voltage is too low.

If you use 70 mm^2 for 160 A instead of doubling up on 25 mm^2 (total 50 mm^2) then you are just wasting your money buying the 20 mm^2 of copper in the middle of the 70 mm^2 cable because, putting it crudely, the heat can't get out from it. And the double smaller cables have tighter bending radii. Although sometimes you have no choice but to use the single large wire because you just can't get two lugs onto a terminal.

Actually, you don't even need single 50 mm^2 for 125 A because double 16 mm^2 will do the job.

Again, this all assumes short runs (0.1 m per volt) so that voltage drop is not significant, and assumes the cable is protected against short circuit or has square millimetres greater than prospective short circuit current divided by 100 A.

And all current ratings I've given above are continuous, and assume the cable has only 75 degC rated insulation and is in a conduit with one or two others, and the conduit is in free air. You can get higher current ratings with higher-temperature insulation or if cables are separated or not in conduit.
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offgridQLD
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Post by offgridQLD » Fri, 05 Sep 2014, 19:19

Yes it's overkill and as you have shown not necessary (ok I just like big orange cables) I understand mathematically its wasteful if your not using the full potential of the cable. Though I guess better than using bell wire to save a few $. I get a good price and probable pay less than most would retail for 35mm2.

Looking at My house bank It has 95mm2 and it's only a short run perhaps 2m on the max run with 250A fusing.(wasn't installed by me) The interconnections between each 2v cell are 70mm2 and about 100mm long. Though they are 1330ah cells.

I had a 50m roll of 50mm2 but I used it all up with long PV / DC runs from shed so Only had a few short lengths laying about (30cm or so )So otherwise I would have just used that.

A few friends want some HD leads made up and they don't have the crimping gear so the left over will be donated to there projects. It's not that big to work with (remember its a simple project with it all run no tight fits situations and easy to access.

The cutouts for the DC inputs in the base of the inverter fit 70mm2 nice though two 25mm not sure.

Anyhow moving on from my big cable fetish Image

Edit: Actually just going over it in my head I'm not sure what I was thinking with the 70mm2 it's way beyond a little overkill..bordering on silly I guess. Lets just hope my mate appreciates his flash HD jumper cables and the 2m I'm using.. Lets just say I have a lot of scope for additional DC loads and then some.

Could I justify it from a protection standpoint the insulation on the 70mm2 is 1.4mm vs 1.3mm thick for 50 and down Image

Kurt

[edited by weber to fix broken smiley]
Last edited by weber on Mon, 17 Jul 2017, 14:33, edited 1 time in total.

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Post by acmotor » Fri, 05 Sep 2014, 22:46

Better to say there it is than where is it when it comes to inverter battery cables.
I find the current peaks when handling start currents of inverter loads show up cabling that, whilst within spec on temperature rise, just allows that extra .1 or .2 V drop during surges that can trip the under voltage shutdown, particularly on 12V inverters.
In this case, single cables or just bulk sqmm is not a waste. That is, surge voltage drop is just sqmm related.
Also, when every bit of power counts, zero temperature rise of the cable is the ideal.
Weber is quite correct re continuous ratings of multiple smaller cables and flexibility though.
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Post by weber » Sat, 06 Sep 2014, 00:18

OK. Well I thought I'd loaded my post up with every caveat under the sun, to avoid nit-picking. Image But yes, I missed one. I was assuming an inverter with a high-frequency transformer, like the one we're discussing, that only has a surge rating 2 times its continuous rating and then only for 5 seconds, not one with a big 50 Hz transformer that might have a 3 to 5 times surge rating. My definition of a "short cable", such that voltage drop (and therefore power loss) are insignificant, would have to reduce in inverse proportion to the surge multiplier.

I assume you noticed, acmotor, that my definition of a "short cable" (for 2x surge) was in terms of metres per volt, which automatically takes care of the "particularly on 12 V inverters" case. i.e. while 4.8 m is "short" for a 48 V inverter, you'd have to go down to 1.2 m to qualify as short for a 12 V inverter (with 2x surge).

So I agree with acmotor, even when he writes: "Also, when every bit of power counts, zero temperature rise of the cable is the ideal."

However I note that it is never the case that "every bit of power counts". There's always an economic tradeoff to be had.
Last edited by weber on Fri, 05 Sep 2014, 15:11, edited 1 time in total.
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