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Thread: battery charger
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1st Dec 2021, 09:03 PM #16Most Valued Member
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Ok thanks John we are on the same wavelength now, hopefully i wont need to replace the reg. In an earlier post i mentioned that i might be able to insulate/disconnect the reg from the output power, if i can do this the reg should work independently and i should still get the same charge voltage and maybe the diode trick will then work ????
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2nd Dec 2021, 10:56 AM #17Most Valued Member
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John (shed),
Sounds like a setup I could use here. I've got 6.6kW of solar panels and the damn things disconnect when the power fails! I understand why, but it so frustrating to have no power when there's kilowatts of it available from the roof.
I'll drop in one day for a shufti at your system.Chris
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2nd Dec 2021, 01:44 PM #18Most Valued Member
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2nd Dec 2021, 08:53 PM #19
Hi Chris, Guys,
You need a transfer switch to disconnect the panels from the grid tie inverter and switch them to a charge controller to feed lead acid batteries. I know that John has gone for a 24 volt system, but 12V charge controllers are quite cheap from China, however I don't know if they will take anything more than about 50 volts input. A single domestic panel outputs 56 volts, which my camper one is. I built my own charge controller which was designed to handle 60 volts and outputs over 12 amps @ 14 volts, in full sunlight ! Actually way more than I need, but its nice to be able to run everything even with flat batteries and still be able to charge them.
HTH.Best Regards:
Baron J.
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2nd Dec 2021, 09:21 PM #20Most Valued Member
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It has an extra winding
I learnt 2 new things today, No1 was the word shufti
No2 was when I had a shufti at the guts of this alternator I found an extra winding connected to an extra pair of diodes.
It appears as though this extra winding supplies AC power to the regulator for the rotor windings and the excess power is just fed through the diodes into the charge circuit.
The rotor winding measured 9.4 ohms, at 29 volts that would be only be about 3 amps.
There must be diodes in the reg to supply DC from this to the rotor coil?
Why would they do it that way instead of just pulling DC from the output?
I think that the battery sense circuit is probably connected in the regulator to this AC circuit and I don't think I have the strength or ability to defeat black regulator magic.
I reckon that I will put it back together and forget that I even thought about putting on a stupid gas up the batteries circuit
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2nd Dec 2021, 09:55 PM #21Most Valued Member
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3rd Dec 2021, 06:46 AM #22
Hi John,
Looking at your picture I count seven diodes ! There could be ones that I can't see. Its possible that the regulator gets its reference input from an auxiliary winding by rectifying the AC and using it as a reference.
Normally the windings are a set of three, as in a three phase motor configuration, with six diodes rectifying the AC output from the field coils. One set of diodes providing the positive DC voltage the other providing the negative DC voltage. Depending upon whether the alternator is designed to be positive or negative earth, one set of diodes will be connected to the alternator frame the other will be the output voltage to the battery.
Three Phase Alternator.png
This picture shows the possible wiring configurations of a three phase alternator. Either of the two bottom wiring circuits could be used. "C" is the most common one. The diodes will be connected to the three wires on the right hand side. A secondary winding can be used to provide a reference voltage or even be fed DC to reduce or intensify the generator magnetic field thus altering the output voltage as required.
HTH.Best Regards:
Baron J.
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3rd Dec 2021, 06:59 AM #23
Hi John, Guys,
700 volts ! Ouch.
Normally only five or six panels are in a string putting 280 to 350 volts into the grid tie inverter with two or three strings. 700 V, that effectively means that half of the available power is being lost !
Normally a grid tie inverter would output a nominal 240 volts AC @ 50 Hz.Best Regards:
Baron J.
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3rd Dec 2021, 08:41 AM #24Most Valued Member
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Shed do you invert to 240V to run your cpap or run it on 12V?
I'm dealing with the same issues, trying to decide between running a couple of light loads from a small UPS and adding some storage to that(then I have to get 240V extension leads through walls, which can be frowned upon) or running off batteries through a boast/buck converter, instructions say car battery is fine but not while engine is running, which I take to mean <13V ok >13V not so good.
Isn't that what MPPT is all about? Am I missing something?
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3rd Dec 2021, 09:38 AM #25Most Valued Member
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G/day John, page 69 has the tech details
https://www.google.com/url?q=https:/...2lgNKJMj8UO8uY
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3rd Dec 2021, 09:59 AM #26Most Valued Member
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G/day Stu, in the past i used the 12v forklift battery with a 12/24v resmed converter, it worked fine and i would use a 7 amp ctek charger with it.
It worked well and really the only 2 problem's were if needed the battery in the shed and the continual whining nose that a battery can inadvertantly cause when in a bedroom amongst floral sheets and fluffy pillows.
Mains power was disconnected from selected power points and reconnected into jb's, new power cables run from inverter to those power points.
Well...thats the simple explaination.
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3rd Dec 2021, 10:35 AM #27Most Valued Member
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Not missing anything Stu. The MPPT voltage of my panels is 33V.
John (Baron),
An MPPT inverter will load the panels such that they operate at their optimum voltage (33V for my LG panels). I have a string of 12 panels. 12x33V = 396V. Remember also that 240V RMS is 337V peak.Chris
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3rd Dec 2021, 07:12 PM #28Most Valued Member
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G/day John, i would have to unsolder the windings from the diodes to be able to work out how it is wound but i reckon you are correct regarding the auxiliary coil , it is reassembled now and mounted back on the frame.
Sorry i dd not reply earlier but i needed to get to my poota to do the pics.
A couple of pics showing the 4 pairs of diodes....
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