Output voltage adjustment

[lighthunter]

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Mine is a stock PJ 15000W 48V single phase and your instructions are pretty clear.

Adding about 15 evenly-spaced turns of 12AWG magnet wire on both toroids should do the trick.

    [An LF15000 is probably capable of 5000w continuous which translates to 21A continuous per toroid.
You need at least 2 strands of awg12  do 3 if it isnt too much trouble. I should have mentioned that earlier. Awg12 is good for 20A on a straight run but when you curl it in a ball every bit of heat counts and you want to help cool those toroids not heat em up.]


Measuring the output of each before summing them is a great idea just to make sure one is not carrying more load than the other.

. [Absolutely right on! if the two toroids you have were supplying separate load circuits, a mistake in wiring isnt fatal, it just produces wrong voltage but you will be paralleling the windings (unless they kept separate and feed two independent output with instruction not to bridge). When paralleling windings the voltage must be same and the phase must be same. My favorite way to finish this type of connection is to do all wiring except the last secondary winding connection. Then, power up unit and measure the AC volts between that last toroid secondary wire and the point you intend to connect to. If there is a measurable voltage by a small amount .5v or more, the turn numbers are mismatched, if you measure 10 or more volts then the winding output wires are probably reversed. Only if AC voltage is next to 0 can you power off and make final connection.

From your description, it sounds like the split phase version of this unit just puts these two transformers in series [properly phased] with a N reference.  Is this right?

[Yes you are right, although there are powerjack toroids out there that are center tapped for this purpose also. Either way works fine.

One last Q: what is the operating voltage of the two stock internal fans? Are they like a PC's @12V?
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[I couldnt say for sure, Oztules or someone with more experience will hopefully help with that. Both my powerjacks came stock as 24v units and all 4 fans are 24v. I assume that both fans will be same vltage as the design battery voltage. That would make sense but its only a guess.

[lighthunter]

@sunypower, if you ever decide you want 48v instead of 24, the toroids are real easy to split primary windings into two groups and series connect for 48v. The primary is actually overwound once you do that and increases power handling ability. Of course, secondary will still be same. I just bought a new control board of 48v but it wouldnt be hard to clip the two power wires in the ribbon cable and feed the board 24v from a 48v to 24v buck regulator. This solution of course would disable battery volt monitoring so you would need another watchdog for that.

[RickyTerzis]

Hi..i am a new user here. In my setup the PJ is outputing to two separate toroids primaries with series secondaries  producing 240v. The external transformer then is connected across the 240v and feeds back on an isolated.Winding the 110v the pj control needs, to be in balance. This mod does cause the pj control to drive primaries 1 volt higher than original design. In some cases with low battery voltage it could cause a problem.

[lighthunter]

Hi Ricky  welcome!

 

The external transformer then is connected across the 240v and feeds back on an isolated.Winding the 110v the pj control needs, to be in balance. This mod does cause the pj control to drive primaries 1 volt higher than original design. In some cases with low battery voltage it could cause a problem.

At one time I had what appears to be the same connection setup you are describing.
On my setup, the control board was monitoring 110v to be in balance but that was true only because it was originally a 110v/24v 60hz cntrl board. I had added the 240v split phase part.
 
What I didnt realize at the time I wrote some posts in this thread is that the cntrl boards designed for 110/220 normally monitor the 220v not 110 as you describe. I'm curious, was your control board originally a split phase board? Or did you change it into split?
You are absolutely right on about the battery voltage. Thats why i eventually changed the AC volt increase method to a few turns on each toroid secondary and series connected each to AC output without letting cntrl board monitor the boost.

For me low bat volts was never an issue though since i used lithium 24v at that time.

For those that are concerned about keeping AC voltage up to 120 there are two other factors that should be mentioned.


1) wire sizes, if you have a fair distance to transport your AC power you will not regret putting in heavy wire. In USA120/240  split phase service to a residence is often run with 4/0 (107mmsq copper even for distances of 100feet or 35meters. That may be an overkill for an inverter but some guys are reaching incredible power levels and it takes wire to do it without v drop. I choose AWG 6 (13mmsq) and so far it has been solid at 30amps/phase 7kw. My fuses blow after that so its sufficient for me but everyones needs are different.

2.)Unlike most everywhere else, in USA we use much of the power at 120v rather than 240 so efficiency can go down due to vdrop unless we balance the two sides equally. I found that out even with awg 6. All i guess im saying is when you actually watch the numbers during motor starts its more important than a guy thinks.