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Forum Index : Solar : Batteries and Charging

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Davo99
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Joined: 03/06/2019
Location: Australia
Posts: 1578
Posted: 12:09pm 17 Feb 2022
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I have had in mind to set myself up with some batteries for what I believed were Coming power shortages. The announcement today of the closure in 2025 of the countries biggest power station seemed to confirm that but I also learned that 40% of NSW power stations are going to be closed within the next year!That's just scary!
Things just keep getting worse and more insane by the minute in this country.

I have in mind at this stage to go with a 24V system. A big reason for this is I cannot seem to find any economical way to generate 48 V from a engine driven setup.
I have lots of Diesels I can run on free fuel and looking at getting a 24V, 150A alternator that I could couple up to any of several engines I have.  The idea here is even at night, I can run the engine to supply power regardless of battery charge or bring batteries up to charge if need be.

Couple of alternators I have found in 48V which are Modified automotive types are over $3K.
Does anyone have any suggestions for how to charge 48v Other than from solar. IE, with an engine?

One thing I have been wondering about for a few days in playing around is, could I connect 2x 12V alternators to each battery I am currently playing with to charge them WHILE they are connected.  I can't seem to get the mental arithmetic in my head round this one and I'd like to know before I build a twin alternator setup and let the magic smoke out of something. I have plenty of alternators that are good for about a Kilo each which would be good to run the small 2 Kw inverters I have.

With the batteries connected and charging/ inverter running, I can meter across each battery and get a 12V Reading ie, 13.5 rather than 28 etc.
This makes me think that if I hooked one alternator to one battery and another separate alt to the other, then I could indeed charge the 2 batteries this way.
But then there is that link cable between and the awareness that things are never as straightforward as one would like.

If this is possible  ( and I';m looking for the practical rather than purist answer) Then  it would seem that I could use 2x 24V alternators on a 48V battery bank if I run them as 2 Groups of 24 and series them..... I think cause they are 2V batteries and my head has not been well this week.

Think I'm going to start liquidating some assets ( unused equipment ) around the place and put the money into some self more serious sufficiency.

Can anyone recommend an automatic change over switch which could be used in the case of grid power failure or are there any battery inverters that have this Feature?
 
pd--
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Joined: 11/12/2020
Location: Australia
Posts: 122
Posted: 12:35pm 17 Feb 2022
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connect up a 230v alternator to your diesel
have a look at eltec flatpack2 2kw 48v power supplies
hear are sum that are on flebay at the moment
https://www.ebay.com.au/itm/334310254250?hash=item4dd671a6aa:g:ouYAAOSwq1xh9jaX&frcectupt=true

Im offgrid , 48v battery bank and solar panels for primary power and 230v diesel generator for backup

I have a flatpack2 to yous as part of my black start emergency kit

1 get the diesel generator running , house now has power
2 connect up flatpack to battery and 230v
3 charg up battery to the point that i can start up the soler inverter
4 system back to normal
 
Old Seagull Man
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Joined: 21/12/2019
Location: Australia
Posts: 55
Posted: 12:53pm 17 Feb 2022
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I know you have a diesel or two.

What i do up on the farm is use a 13hp 7.5kw Chinese St generator, and feed the 2, 120 volt windings to a couple of big bridge packs.

I end up with about 135v at 35 amps and feed that to an old 180v solar charge controller.

Charges them quite well, but always make me want fish and chips when i do it.

but Im shore there will be many more elegant solutions .
 
Revlac

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Joined: 31/12/2016
Location: Australia
Posts: 977
Posted: 12:53pm 17 Feb 2022
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  Quote  I have had in mind to set myself up with some batteries for what I believed were Coming power shortages. The announcement today of the closure in 2025 of the countries biggest power station seemed to confirm that but I also learned that 40% of NSW power stations are going to be closed within the next year!That's just scary!
Things just keep getting worse and more insane by the minute in this country.

Yeah I saw that tonight, I believe they will be doing power cuts before then.

I think 48v would be your be your best bet because of the higher wattage capacity of an  Elcheapo inverter.

There used to be heaps of old generators around that used to charge the old telephone batteries, still have one connected to an old antique Engine, about 1Kw I think.
There was also the Old Stones Alternators that where used under some (old) railway carriages, The large one I think was capable of 90Amp (will check details later) you might find something travelling around.

Automatic transfer changeover switches, they take a little time to switch, see if there are some that are less than 10ms.


I was writing this up but, Pd--, has a good idea on it.
Cheers Aaron
Off The Grid
 
noneyabussiness
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Joined: 31/07/2017
Location: Australia
Posts: 510
Posted: 06:05pm 17 Feb 2022
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dave, i have several of those 48v flatpacks mentioned earlier... if you want 1 or 2 just give me a heads up and I'll send em to you.. I already set them up to put out 57v etc, they rated at 2kw each and I can confirm that .. they 98% efficient.. Ill pm you with a pic of my setup, they do need some simple mounting...

also, a cheap dc welder works too, not as efficient as the flatpacks but very effective ... you just need to add a turn or 2 to the main transformer and you have a current controlled battery charger... have one of them too...
I think it works !!
 
noneyabussiness
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Joined: 31/07/2017
Location: Australia
Posts: 510
Posted: 10:27pm 17 Feb 2022
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this is the setup I use, got a standard " caravan " input plug from bunnings, and mounted it to wall with a breaker etc... works great...













this is one of the welders I was talking about, just replace the electrode clamps with heavy alligator clips..and add the extra turns on main transformer if needed...

https://www.ebay.com.au/itm/ARC-220Amp-Stick-Welder-DC-Inverter-MMA-Welding-Machine-IGBT-Portable-10A-Plug-/272834881672?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=705-154756-20017-0
I think it works !!
 
Davo99
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Joined: 03/06/2019
Location: Australia
Posts: 1578
Posted: 12:33am 18 Feb 2022
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Thanks for the replies.
The flatpacks sound great. I had also heard of a welder before but forgot all about that. I have one up the back i got a while ago that the feed is Kaput on but is a huge old thing with a big wound transformer. I'll have to fire it up and see what output it does.

This makes going to 48V much more comfortable for me. I knew it was the better option but the difficulty in charging from an engine was off putting.  Only other thing I could think of was a forklift charger but they seem to be mostly 3 phase for obvious reasons.

I have run a 3 Phase motor as an Imag before and connected that to a solar Inverter but never thought of it with an off grid inverter.  I forget more than I know these days.



And just for curiosity, what about the 2 alternators on one battery each while connected in  series?  Still mulling that over in my head and I'd love to know if I was right and it would work or not or I missed something else with that?
 
pd--
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Joined: 11/12/2020
Location: Australia
Posts: 122
Posted: 04:16am 18 Feb 2022
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Isolation could be a bit tricky as neg is usually tied to the case
I think you would probably need to add a filter cap across each alternator to give the regulator a chance at maintaining a stable voltage
 
bob.steel
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Joined: 27/02/2020
Location: Australia
Posts: 188
Posted: 06:44am 18 Feb 2022
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With a MppSolar Hybrid inverter HV2 5048  (54 volts) and now 600 Ah of LiFePo4 (LFP) batteries and 21 Solar Panels on my abode and another 18 Solar panels on my shed roof I have decided to parralel up another Hybrid inverter .

All up sunny days will give me 40 amps of 240 volts A/C without the battery connected even and overnight not needing as much I can run a few Party lights and sound systems for people . On our commune we all share power anyway and have a local offgrid system available too .

Bugger off coal fired sh*t. Bugger off State Government.Bugger off Lead Acid batteries.
Edited 2022-02-18 16:48 by bob.steel
 
Davo99
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Joined: 03/06/2019
Location: Australia
Posts: 1578
Posted: 07:24am 18 Feb 2022
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  bob.steel said  

Bugger off coal fired sh*t. Bugger off State Government.Bugger off Lead Acid batteries.


And most of all....

BUGGER OFF BOB!      
 
Davo99
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Joined: 03/06/2019
Location: Australia
Posts: 1578
Posted: 07:30am 18 Feb 2022
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  pd-- said  Isolation could be a bit tricky as neg is usually tied to the case
I think you would probably need to add a filter cap across each alternator to give the regulator a chance at maintaining a stable voltage


Thanks for the heads up.

Specifically for the Dummy,  where would the cap go? From the neg/ Case to the positive terminal?

I take it a polarised cap would be needed?

The fact they are linked in series but the alts would be connected at each battery terminal wouldn't case an issue other than with the regulator as you mentioned?
 
johnmc
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Joined: 21/01/2011
Location: Australia
Posts: 282
Posted: 10:06am 18 Feb 2022
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Good Day All,

Alternators fitted to vehicles that operate in hazard conditions ie fuel tankers
and also some buses are required to have isolated positive and negative terminals.
Also some alternators can easily have their terminals isolated.

Cheers john
johnmc
 
bob.steel
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Joined: 27/02/2020
Location: Australia
Posts: 188
Posted: 09:20pm 18 Feb 2022
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  Davo99 said  
And most of all....
BUGGER OFF BOB!      


Ha Ha . I refrained from being uncouth and adding you in but little minds can't resist .

Some people have their mouths open all the time .
You will notice you can't get a word in edgeways .
When they get like that they can't hear over their own voice .
If you can't hear you can't learn .
Such be life.
 
bob.steel
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Joined: 27/02/2020
Location: Australia
Posts: 188
Posted: 09:27pm 18 Feb 2022
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  Old Seagull Man said  I know you have a diesel or two.

What i do up on the farm is use a 13hp 7.5kw Chinese St generator, and feed the 2, 120 volt windings to a couple of big bridge packs.

I end up with about 135v at 35 amps and feed that to an old 180v solar charge controller.

Charges them quite well, but always make me want fish and chips when i do it.

but I'm shore there will be many more elegant solutions .


I wondered what you meant by "bridge packs?
The problem with these generators is that they put out say 7.5 Kw of power but do so on 2 lines so you can't join them up to get say 20 amps because the outputs seem to be on different phases .

Your bridge packs appear to overcome that problem.
I would like to do that on mine also because single lines won't run my welder but if I could combine them it would.
 
bob.steel
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Joined: 27/02/2020
Location: Australia
Posts: 188
Posted: 09:47pm 18 Feb 2022
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  noneyabussiness said  dave, i have several of those 48v flatpacks mentioned earlier... if you want 1 or 2 just give me a heads up and I'll send em to you.. I already set them up to put out 57v etc, they rated at 2kw each and I can confirm that .. they 98% efficient.. Ill pm you with a pic of my setup, they do need some simple mounting...

also, a cheap dc welder works too, not as efficient as the flatpacks but very effective ... you just need to add a turn or 2 to the main transformer and you have a current controlled battery charger... have one of them too...


On a generator which has 2 10 Amp 240 volt outputs is there a cheaper way of combining the outputs to get 20 Amps?
 
noneyabussiness
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Joined: 31/07/2017
Location: Australia
Posts: 510
Posted: 12:30am 19 Feb 2022
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  bob.steel said  
  noneyabussiness said  dave, i have several of those 48v flatpacks mentioned earlier... if you want 1 or 2 just give me a heads up and I'll send em to you.. I already set them up to put out 57v etc, they rated at 2kw each and I can confirm that .. they 98% efficient.. Ill pm you with a pic of my setup, they do need some simple mounting...

also, a cheap dc welder works too, not as efficient as the flatpacks but very effective ... you just need to add a turn or 2 to the main transformer and you have a current controlled battery charger... have one of them too...


On a generator which has 2 10 Amp 240 volt outputs is there a cheaper way of combining the outputs to get 20 Amps?


and how is he going to convert it to 48v to actually charge the batteries?? its the point of the thread....
I think it works !!
 
mab1
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Joined: 10/02/2015
Location: United Kingdom
Posts: 198
Posted: 01:30am 19 Feb 2022
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Most 12v alternators I've seen are negative ground so youcwould have to modify 3 if you were to use 4 on a 48v pack.

Most 24v alternators I've seen are isolated from ground so there should be no problem using 2 on a 48v pack - but i haven't been looking in recent years so my knowledge might be out of date.
 
bob.steel
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Joined: 27/02/2020
Location: Australia
Posts: 188
Posted: 02:03am 19 Feb 2022
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Ah I missed any reference to Alternators . I'm intereted in the Generators mentioned though.
 
johnmc
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Joined: 21/01/2011
Location: Australia
Posts: 282
Posted: 02:53am 19 Feb 2022
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By Definition ,

There is no generators they are all  basically  alternators because the conductor
rotates in a magnetic field to produce a alternating current flow.

By convention a generator has has mechanical rectification ie commutator and the output is pulsating dc current.

Where as the alternator output terminals, are a sine wave, the it is, electrically rectified to produce a pulsating  dc current.

Take your pick what defines a generator.

Cheers john
johnmc
 
noneyabussiness
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Joined: 31/07/2017
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Posts: 510
Posted: 06:59am 19 Feb 2022
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http://www.thebackshed.com/forum/ViewTopic_mobile.php?TID=12083&P=2

A thread on the topic on welders as chargers .. if anybody interested..
I think it works !!
 
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