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Forum Index : Electronics : A Pilot Project
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Bryan1 Guru  Joined: 22/02/2006 Location: AustraliaPosts: 1972 |
Well went down with my metal detector to try and find this gold necklace but more than likely the lawn mower ate it. So after a few ales the talk got onto what is the power bill where for a moderate house the cost is about $1,000 a quarter. So I have been given the green light for my first on grid house to take it off the grid for most things. Now when I have talked with electricians I generally lose them within a minute when I talk about sizing solar panels to fit a MTTP let alone talk about the inverters that I build. The family I saw tonight is open to get a energy meter installed so they can monitor the house draw. I did tell them a soldering iron will be their friend as the family will have to make the inverter themselves so they understand how it works and if it breaks they will know how to fix it. The big cost in this project is the forklift battery and as 48 volts is considered a high voltage with the current draw being around 3Kw a 24 volt system would work so the wife and young son can learn. Now try and get a lithium battery for 24 volts @600AH for about 5K. Forklift batteries are just right for a off grid setup. Now Kanmantoo is a small town and once I do do a couple of these projects I can will contact my local federal member who is a personal friend too see if I can take this project further Regards Bryan |
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Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 1254 |
Its good to see a new family getting interesting in going off grid, there is a bit of learning involved and an energy edit is a must, to know the power requirements and system to consider building.  from a personal view, I have always used as little energy as possible from the grid when we had it a long time ago, since off grid its so easy to keep adding more and more loads and so the system needed to grow as well.  My last 48v lithium battery was 314Ah and just on $5k with BMS and connectors with a few other things currently for the same 16 cells 624Ah 24v with all the gear is under $5k (local shop) while the energy capacity for these in 24v or 48v is about the same, a much more powerful inverter can be had at 48v. They can go with whatever type of battery they like but it needs to be the right voltage and capacity to start with, especially when using Lead acid batteries. upgrading can get expensive Still, an energy audit will tell how much they will need and find out what is the most power chewing appliance that is used, eg my air compressor starting the other day used 155A from a 48v battery.  Edited 2026-04-29 08:21 by Revlac Cheers Aaron Off The Grid |
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| Solar Mike Guru Joined: 08/02/2015 Location: New ZealandPosts: 1204 |
>> Now try and get a lithium battery for 24 volts @600AH for about 5K. Forklift batteries are just right for a off grid setup. 16 x 314 AH cells from China + BMS would cost approx US$1500 inc shipping, that's 628 AH @24v; heaps more efficient than any fork lift battery..... |
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| tinyt Guru Joined: 12/11/2017 Location: United StatesPosts: 558 |
For house loads(16 max.) power draw monitoring, I used this Fusion Energy Sem Meter . It is less expensive than Emporia Vue. It can be used for pre-project power audit and post-project power monitoring. Just sharing. Edited 2026-04-29 23:01 by tinyt |
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| Bryan1 Guru Joined: 22/02/2006 Location: AustraliaPosts: 1972 |
The other day I saw a post in the local FB group where a guy said he needed a hand as he has a problem with his off grid setup. Now within 20 minutes of the post going up several PV companies and a few sparkies posted their services so I just couldn't resist  I posted some questions about his setup like solar, batteries, charge controllers and everything else to do with off grid power. Well a few hours later a PM came through and the guy came over today where I showed him my setup and we had a look at his on his phone. As he was strapped for time he only stayed for about 2 hours where he mentioned those PV guy's will be here tomorrow so I did say I would love to be a fly on the wall where he said he would be happy if I was there so I can keep these guys on a level.Now his setup is a couple of Selectronic SP inverters and a mate where he can't get it working and change any setting on the the inverter. Now I just looked at the Selectronic site and every inverter manual is there along with install video's so the inverter side is taken care of where the pair of us can work it out. Now for the batteries he has 2 0ff 48 volt banks of AGM batteries and he's saying he has no overnight power. So I have suggested to do a heavy load test with no solar attached so yes my old single and double resistive element cookers will going with me for the load test. For an old school load test on a bank of AGM batteries would be just take a arc welder and earth lead with a few welding rods and see how far the voltage drops Anyway I will be there tomorrow morning for the first of these PV mobs to have a look at his setup and my services will be alot cheaper than a sparkie and do a better job Regards Bryan Edited 2026-05-14 17:33 by Bryan1 |
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| Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 1254 |
Selectronic Are very good at keeping everything for reference later, I got a manual off them a while back.  Have fun Bryan, let us know how it all went. Edited 2026-05-14 19:41 by Revlac Cheers Aaron Off The Grid |
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| Bryan1 Guru Joined: 22/02/2006 Location: AustraliaPosts: 1972 |
Aaron my SA32 Selectronic inverter has been going since '04 and powering my house and hasn't faulted apart from me setting a 22.8 shutdown command. Now on talking with the guy a 1pm visit is on the cards as this first expert calls in. Man it's going to be fun with me stripping him down with true facts of living off the grid and the best part I may getting him to buy a soldering iron as he did show me a aerosharp grid tie now he is half way there on making the Selectronic inverters a past thing as homebrew inverters just work without and bells an whistles. |
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| Bryan1 Guru Joined: 22/02/2006 Location: AustraliaPosts: 1972 |
Talking with this guy last night and he said he has a couple of Pruis electric cars at home and he wants to see if they can be used. So did a bit of research this morning and read a snapon pdf on the pruis battery, they are 2 cells @7.2 volts in series to make a 14.4 volt pack and there are 14 of these to make a 200 volt output. Now these packs are connected by small copper bussbars so re-configuring each pack into 4 packs will give a 48 volts setup. So yes this is going to be an interesting afternoon. Regards Bryan |
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| Bryan1 Guru Joined: 22/02/2006 Location: AustraliaPosts: 1972 |
Morning Guy's, Well it was an interesting day and we did get down to the bottom of the problem, as he had 2 off agm battery packs both connected I suggested to split them and just try that second bank with the SP inverter. Well with only a 25 watt load being the exhaust fan with the laptop connected to the SP the battery voltage went from 57 volts to 30 volts so this did confirm the second bank of agm batteries were toast. Now the original bank of agm's was on 47 volts so we thru the genset on we I found the old Dunlite genny would load up the reset. So I put my DMM in the spare power socket and watched the AC voltage also while watching the battery power display on the laptop, after the Dunlite reset no current was going in then it would ramp up to 3.5Kw and rinse and repeat. I do suspect the run cap could be faulty which is causing this reset problem. Now the AC measurements when the genset reset the voltage was 248 volts and as it ramped up the current the voltage dropped to 213 volts then the current cut out. As he did mention the reason he got that second bank the original bank of agm's are gone so I mentioned to have a look at Ceil batteries and give them a ring on Monday to get a quote for a 48 volt forklift battery. Now with the Pruis battery it was nice and easy to split the bank but with the cells only being 6.5Ah it wasn't really worth the effort Regards Bryan Edited 2026-05-16 10:25 by Bryan1 |
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