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Forum Index : Electronics : Oz-Nano-Warp-verter for 12VDC input?
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| olNick Newbie  Joined: 11/03/2020 Location: GreecePosts: 14 |
Hi all, Been a year since I last posted, where my Victron Inverters sh*t during the lockdown last year. Got an offer from someone that could "definately fix" them. Well, after close to 1 1/2 years later, I managed to get my stuff back, just as I sent it. Lesson learned: There is no Santa... 1st question: I have the transformers from 2 of these 12V 2500VA Phoenix inverters and wonder which, if any of the inverter designs here are ammenable be used w/ 12VDC inputs. If so, I am ready to build. I simply will not be at the mercy of the Vendor/Repair Mafia anymore, I've had it..... 12V system is fine for me, 2500VA is more than enough for my needs. I will make 2 and have a back up. 2nd question: Do these inverters auto switch to charger mode when AC is present? regards, nick |
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| noneyabussiness Guru  Joined: 31/07/2017 Location: AustraliaPosts: 506 |
hi, 1st question, yes the can be adapted for 12v.. as long as everything ( transformer etc . ) set for those voltages it doesn't matter.. no one really bothered with 12v as currents become stupid at any reasonable power level, it's a 166amp at 2kw so cables will HAVE to be super thick and short, that doesn't include inrush currents, doable, just not practical... 2nd , no , they do not " auto charge " with ac present, if you have a grid tie connected to the output you can ac couple it though... I think it works !! |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Agree with Nonya, 12v is really a dead duck at any reasonable power level, its just too inefficient, and the number of mosfets and heatsinks required will be a lot of work and expensive. Seriously, I think 100 amps is about the practical limit for home brewing any inverter. In other words 1Kw at 12v, 2Kw at 24v 4Kw at 48 volts is pretty easy, and has been proven to work really well. It should not be too much of a problem to shuffle your solar panels and batteries around for a higher voltage, and buy a higher voltage solar controller for it. The results of doing so will be vastly better. Cheers, Tony. |
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| Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 378 |
Hi Nick, you could just buy a couple of 8010 based Pure Sinewave Inverter boards, if you make sure that you get 12 volt boards then all you need to add is the transformers , a capacitor and a couple of switches. I have a couple of 24 volt boards that I have used with powerjack transformers, they appear to be working fine, put out a nice sinewave etc. I had 12 volt systems for 40 years before switching to 24 volt in the last year. As long as you don't want to run big things like Air Compressors they work fine. Have a look on ebay or aliexpress for the boards. There are some that you will find that have an inductor on one end, they are conversion boards to convert square wave to sinewave. Don't get them just look for a pure sinwave inverter board that allows you to connect a transformer directly. Pete |
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| olNick Newbie Joined: 11/03/2020 Location: GreecePosts: 14 |
Thank you all for replying, I am aware of the benefits of higher DC inputs. At the present, for various reason$ (ATM, I don't have 2K for a new 24V bank, never mind 48V bank), I am stuck at 12V, and even a 1000-1500W inverter would be ok for me as my loads are minimum, Typically loads are: 100W during the day 150W in the eve, till bedtime, tv, sat internet, lighting 60W overnight (40 of which are the inverter idling) Washing machine, tools, welder etc. are run off the generator, 1-2x per week and batteries charge at the same time, no prob here. Cooking is all propane While we eat fresh every day;-) and left-overs to the chickens, I am looking to add a fridge (beers and cocktails). The new fridges seem to use minimal energy, but do require some surge capacity when starting. My current DC cabling from batteries to buss to inverter are I believe 4/0, so no problem there. I do not know what it means for the internal inverter construction. I am guided by this post by Warpspeed (6th post) surge considerations https://www.thebackshed.com/forum/ViewTopic.php?TID=9756 Some clarification? So specifically: Can I use the 12V Victron trannies as is? I can rewind them if need be, with your help. Do I use 1 of them, 2 of them? What changes/additions are needed to the current Oz boards to do the above (Can I count on help here?) I don't understand this Noneya "2nd , no , they do not " auto charge " with ac present, if you have a grid tie connected to the output you can ac couple it though..." I have a fairly clean AC generator, that I can tie to the output, via a transferswitch? Anyone selling these inverter boards? Lastly, if I ever upgrade to higher voltages, can I still use these PS "Hi Nick, you could just buy a couple of 8010 based Pure Sinewave Inverter boards, if you make sure that you get 12 volt boards then all you need to add is the transformers , a capacitor and a couple of switches." I think Godoh that I would still be in the same boat should something crap out. A couple vendors I checked do not even supply a circuit regards, nick |
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Murphy's friend Guru Joined: 04/10/2019 Location: AustraliaPosts: 580 |
Just a couple of answers; aim for an idling current in the low 20 watts region, read earlier posts on this forum how that is done (transformer winding & choke set your idle power). To charge the batteries from an oz type inverter you need to run it backwards. So you have a solar panel set up for a high enough voltage to power a commercial grid tie inverter. You then feed the AC from that grid tie inverter into the AC output of the oz type inverter, creating your very own mini grid. This will then push charge into the batteries (if there is sufficient solar input). BUT its completely un- regulated, you need to control the AC output from the grid tie inverter somehow. I do that but rather than a lengthy explanation I suggest you spend an evening (or two) reading back posts here, from those who built their own inverter. Most of what you are asking has been discussed many times over already. I have no idea what your transformers look like so you need to supply more info (pictures) if you want an answer if they are suitable or not. |
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Clockmanfr Guru Joined: 23/10/2015 Location: FrancePosts: 427 |
'Murphy's friend' is correct with a OzInverter, infact it was one of the reasons Oztules and myself wanted to AC couple with GTI's. The OzInverter is a H Bridge design and therefore bi directional. Once the GTI is happy with the frequency and the AC voltage the OzInverter is giving out on the mini grid, then the GTI pushes back a few volts over the OzInverter output voltage. When this happens the H Bridge allows the AC to become DC and therefore charge the 48v battery bank. Also the OzInverter gets little use in using the battery bank as the GTI's output power is being used by appliances directly on the OzInverter created Mini Grid. The GTI's need some sort of control to stop them overcharging the 48v battery bank. The OzInverter toroid is wound so the DC back charging reaches about 61V DC. I use 4 off Morningstar Tristar's diversion controllers, (they are not expensive, but really bullet proof) and these monitor the battery state of charge and dump excess voltage from the GTI's, I have 8kW of dump loads, water heating, underfloor heating etc. I have 12KW of GTI's 5off GTI's all below 2.5KW output, and the last two i have left as is from the UK settings and these click in and out depending on the voltage on the OzInverter Mini Grid. Other GTI's i have altered the internal settings so they shut down at a lower voltage. Cable voltage drop is important here as this allows flexibility in the GTI drop out range. I have 5KW of PV on Trackers and this i use with DC chargers to finish the 48v DC battery bank. My 3off 1KW Hugh Piggott Wind turbines are directly wired/clamped to the 48v battery bank. So after 7 years of AC coupling with my system I am very happy with my second hand used cheap GTI's, as they have MPPT and get every last bit of juice. And 12KW of PV with out the need of very expensive DC to DC MPPT charge controllers. If you have a small system then you will need a battery monitor circuit that checks the battery voltage and charge rate and when it is excessive the circuit shuts down the GTI, as you do not want to cook your battery. NOTE, The battery bank must be a suitable large size over 800ah to absorb loads and DC back charging. A 48v Battery bank is really the only safe way to use Ac Coupling. Here's a photo of 2off 1.8KW used SMA old toroid type recently installed on another of my buildings, these feed into the OzInverter created Mini Grid.  Everything is possible, just give me time. 3 HughP's 3.7m Wind T's (14 years). 5kW PV on 3 Trackers, (10 yrs). 21kW PV AC coupled SH GTI's. OzInverter created Grid. 1300ah 48v. |
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| noneyabussiness Guru Joined: 31/07/2017 Location: AustraliaPosts: 506 |
honestly, the loads you are talking about, a cheap 1500 watt high frequency inverter would be plenty ( just make sure your surge currents exceed requirements, aka 3000 watt ish as a guess) ... i know your keen on having a ozinverter / eg8010 job, but it might be unnecessary... most of the lads and ladys on here ( myself included) run our whole houses off solar ... hence 48v recommended... I think it works !! |
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| nickskethisniks Guru Joined: 17/10/2017 Location: BelgiumPosts: 409 |
If the 2 transformers are the same you could put the primaries in series for 24V. The transformers are probably ok because they were build for 12V inverter already. To make sure you could connect the 230V side to 230V main grid ( measure this too) and measure the output voltage. Reading a few topics will give you an idea of the needed ratio, didn't remember. Good luck. |
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| olNick Newbie Joined: 11/03/2020 Location: GreecePosts: 14 |
Tha's quite an impressive setup Clockman. have you yet figured out how to "juice" yourself with all this energy;? nick |
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| olNick Newbie Joined: 11/03/2020 Location: GreecePosts: 14 |
Just wanted to checkin and say I'm reading up on all of this stuff. Will remove my transformers from the case tonite/tmrow and see I find any info on tem. later |
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| Clockmanfr Guru Joined: 23/10/2015 Location: FrancePosts: 427 |
Hi nick, Sadly NO, i just get older every day. However, ...... having all that extra Power does mean that i can run my ECO SALT swimming pool and heat its water to a steady 35c with a air source heat pump with out any difficulty. And one thing about the Eco Pool means that loads of girls and women keep taking their clothes off, and that sure gets my 'Juice' flowing, as it were. LOL Everything is possible, just give me time. 3 HughP's 3.7m Wind T's (14 years). 5kW PV on 3 Trackers, (10 yrs). 21kW PV AC coupled SH GTI's. OzInverter created Grid. 1300ah 48v. |
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