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PIP-4048MS inverter

Posted: Tue, 23 Dec 2014, 01:59
by T1 Terry
We replaced the fans in our PIP with maglev fans from Jaycar, much quieter. I seem to remember in one of the branches of the menu there was a fan speed setting, one option was constant slow run and a variable speed up/down reliant on the temp of the heat sink, that was the one we selected and it's been that way ever since. The owner is not in the area for a few weeks due to Christmas commitments but I can follow up on the menu setting when he returns if you like.
We do not have the MPPT controller model though, so there could be a major difference in the programme menu between the models

T1 Terry

PIP-4048MS inverter

Posted: Tue, 23 Dec 2014, 02:31
by weber
T1 Terry wrote: We replaced the fans in our PIP with maglev fans from Jaycar, much quieter. I seem to remember in one of the branches of the menu there was a fan speed setting, one option was constant slow run and a variable speed up/down reliant on the temp of the heat sink, that was the one we selected and it's been that way ever since.

Thanks Terry. Good to know someone else is getting away with replacing the fans with a quieter lower-air-flow model.

Did you leave them blowing down out of the case?

I assume you mean these:
But if so, I'm surprised they do variable speed since they are only 3-wire fans. No PWM input.

There's definitely no fan setting mentioned in my PIP-4048MS manual.

My fans speed does not seem to respond to temperature at all. Only to current or power.

PIP-4048MS inverter

Posted: Tue, 23 Dec 2014, 02:32
by offgridQLD
Yes I can see now thanks for the pic (my pip4048 wasn't in front of me befor) Yes that baffle plate should be completely sealing off the two chambers.

      I don't think there is a fan control option on the pip4048 we have. Having the fan thermostatically controlled would be the best option and variable speed that hopefully would keep the fans off at night, slow speed during the day and the odd fast speed during heavy loads and hot weather.

I don't have the software in front of me but isn't the temp reported in the pc software display just to keep tabs on any modifications.

edit: I have three of the same blue Jaycar fans listed above (though a larger diameter version) in my power room exhausting air from different areas of the industrial cabinet that my power electronics are housed. They are quite , smooth quality sounding but (not silent)like some of the pc fans designed for HTPC's yes mine are only 3 wire.


PIP-4048MS inverter

Posted: Tue, 23 Dec 2014, 02:56
by weber
offgridQLD wrote:I don't have the software in front of me but isn't the temp reported in the pc software display just to keep tabs on any modifications.

No temperature is displayed on either the PIP's LCD or by the WatchPower PC software, however the protocol manual kindly supplied by Eric shows that heatsink temperature is returned as the 12th item in response to a QPIGS<crc-16><cr> command.

The present fan speed control algorithm is just ridiculous. When the water pump starts, the fans roar to maximum jet-engine noise just for the half a second of starting surge and then drop back again. It could scare the doodoo out of you if you weren't expecting it.

PIP-4048MS inverter

Posted: Tue, 23 Dec 2014, 02:58
by T1 Terry
They appear to alter the drive voltage but I guess that is still via a PWM circuit. I installed them to blow out the top, I just assumed that was the way it was originally designed but to be honest, it was only an assumption, I didn't really check which way the old ones went, they just died and we replaced them.
I also fitted a second set on the top of the case with a 50 deg thermostat on the top of the heat sink, but that was more because the air was getting trapped inside the cupboard where it was housed so the idea was to push the air out through a roof vent. This unit lives inside a cupboard in a Hino motorhome so noise would be a serious problem. The original roof top rattler Dometic air con threw in the towel and was replaced with an inverter split system unit that is so quite you need to touch it to determine it's actually running. Under full load the fans can now be heard, but it certainly isn't a disturbing noise by any means.

T1 Terry

PIP-4048MS inverter

Posted: Tue, 23 Dec 2014, 03:03
by weber
T1 Terry wrote:I installed them to blow out the top, I just assumed that was the way it was originally designed ...
As you would. That's great to know, Terry.

PIP-4048MS inverter

Posted: Tue, 23 Dec 2014, 03:12
by offgridQLD
That is mad. It's like they are worried it's going to go into instantaneous thermal runaway the second a heavy load applied.

So some way to intercept the fans power feed and control it based on temperature. There is some real smart looking case fan controller units getting around for pc's that don't cost much but what they can do and how they work. I don't know as I haven't had any experience with them but could something like this or similar be of any use ... 1707604678

pdf instructions

something like that could look smart flush mount in a box lid that's already there with some space or new small box.


PIP-4048MS inverter

Posted: Tue, 23 Dec 2014, 03:24
by T1 Terry
When we first fitted it up the fan would start up like that, like it initially powered the fan and then looked to see how fast it should be running, sort of like when you state up a ceiling fan, full power and then set it back to the desired speed. The option with the fan constantly running slow seemed to eliminate the need for a sudden speed ramp up, but there wasn't an option of a fan stopped without that high speed start up. Maybe they had issues in the early days with fan motors burning out and determined it was the result of an under voltage start up.
You could always ask the factory, they are very helpful people, well I've always found them that way.

T1 Terry

PIP-4048MS inverter

Posted: Sun, 28 Dec 2014, 21:36
by coulomb

From a page that Weber linked to back on page 7:

"One has to cut and resolder the proprietary plug - color by color - though."

This was in relation to an Arctic Cooling fan, which happens to use the black red yellow blue wiring scheme, as on the Adda fans on the original PIP. But it seems that there are two, not quite consistent wire colour schemes for fans:


It so happens that the Noctua fans Weber bought use the other wire colour scheme: black yellow green blue. Note that yellow changes meaning! Besides that, the linked-to post above doesn't mention that "color by color" actually results in swapping the middle two pins!

It also happens that to gain access to the fans, you have to remove a clear plastic cover (duct), which requires removing a PCB, and to get access to the screws or the supplied anti-vibration mounts, you have to move the bottom plate of the inverter, which in our case required removing six thick AC wires. Because we didn't imagine that the fan wires would need to be swapped, this had to be done twice Image

However, the final result was miraculous. We had to look at the fan blades to know whether they were actually spinning or not. At normal 200-300 W loads, the fans are silent. With a 2.4 kW load, the fans run a little faster, but still barely audible.

But was the heatsink staying cool? Fortunately, the PIP inverter has the QPIGS command (Device general status parameters inquiry), and one of the many result returned is the inverter heatsink temperature. Even after boiling a kettle, the temperature increased from 32C to only 35C. (Ambient was 24C.) (The CRC for this command is B7 A9, which on TeraTerm can be typed with right-alt-7 right-alt-) (assuming that right-alt has been enabled as the meta-key*).

Hopefully, this information will help someone else not have to pull the inverter apart twice.

[ * Edit: This means editing TERATERM.INI in the Tera Term program folder, changing MetaKey=??? to MetaKey=right, and Meta8Bit=??? to Meta8Bit=raw . Restart Tera Term to take effect. Tera Term is a free terminal emulation program, allowing you to talk to an RS232 serial port. ]

PIP-4048MS inverter

Posted: Sun, 28 Dec 2014, 22:32
by offgridQLD
That's a great outcome. Thanks for sharing the details.

Our pip4048's are slowly becoming special adition versions.


PIP-4048MS inverter

Posted: Tue, 06 Jan 2015, 06:03
by weber
A lot has happened with the Monolith since the installation of the "sanity-savers" in the PIP (the quiet fans blowing upward). Coulomb has been giving me lots of help. But I can't afford to take much time to write about it, as the poor customer is still waiting.

Here's a photo of the two switchboards to the right of the PIP, which are finally complete. They are both DC switchboards. The upper one is at PV array voltage (MPPT-range 60 to 115 V, 6P3S x 72-cell modules x 195 W) and the lower one is at battery voltage (nominally 48 V, 16 x LiFePO4 cells x 180 Ah).


The lower switchboard also contains the BMS master in the upper left. It's a modified version of the current and insulation monitoring unit (IMU) used in the MX-5, which is itself a modified cell monitoring unit (CMU). Its two reed relays, that were used for insulation testing, have been replaced by two large MOSFETs that are used to control two sets of contactors having 12 volt coils.

The two sets are "source" and "load". In fact there is a third set "battery" which doesn't need its own MOSFET since it is diode-ORed from the other two. So it is on whenever either of them are on. Or putting it another way, you have to drop out both sources and loads before the single battery contactor (a Kilovac EV200, middle left of Battery switchboard) will drop out.

Of course the point of all these contactors is to be able to protect the battery under conditions of over-charge and over-discharge.

The source contactor set consists of the genset contactor (Pulset 40 A 2-pole) in the AC switchboard to the left of the PIP (not shown) and the PV array contactor (a Gigavac MiniTactor) on the right of the PV array switchboard (shown).

The load contactor set is entirely in the AC switchboard and consists of a changeover relay feeding 12 V to the coil of one or the other of two Pulset 40 A 2-pole contactors, making a virtual 40 A 2-pole changeover that powers the household AC load from either the inverter or the (manual start) genset (if it's going).

The battery fuses (22x58 mm, 100 A) are on the right, and you can see, alongside the negative battery cable below them (35 mm^2), an optic fibre goes from the right side of the IMU to CMU #1. Alongside the positive battery cable a fibre comes back from CMU #16 to the left side of the IMU. You can't see it in the photo but there are two fibre outputs on the right of the IMU. The other one goes to the PIP in between the two PV array cables (13.3 mm^2, 6 AWG).

The IMU senses the voltage across the current shunt (fine twisted pair) and it senses the open-circuit array voltage, between battery positive (from the left side of the shunt) and PV array negative (from the lower right of the MiniTactor). This is so it can protect the PIP from array open circuit voltages above 145 V which are possible in winter at dawn, before the panels have had a chance to warm up.

The IMU, and through it, the coils of all the contactors, are powered from the DC-DC converter in the middle of the battery switchboard (48 V to 12 V, 30 W). This uses 13 watts continuously to power all the contactors. It only needs its full power briefly while pulling in the EV200 battery contactor.

The circuit board at the bottom left of the battery switchboard was built by Coulomb on Sunday. It contains the 48 V bootstrap circuitry that allows even the DC-DC to be disconnected from the battery in an emergency shutdown, whether triggered by a human via the emergency stop switch, or by the IMU. In order to start up again (which requires a human to release, or push and release, the e-stop switch) the DC-DC needs to be briefly powered directly from the battery, for long enough for it to power the IMU, and through it the battery contactor, thereby latching itself on.

It uses essentially the capacitor/diode bootstrap circuit shown a few messages back, with some rearrangement and the addition of two 1.25 A 100 Vdc fuses to protect the 3-wire cable going (upward) to the e-stop switch.

So from now on, it's all about implementing, in the IMU software, all the required battery protections.

For a week now we've had PI control of the PIP by the IMU, in response to individual cell stresses, while charging from either AC-in or the PV array. That was by far the hardest part of the IMU software. Thanks for all your help with that, Coulomb, both writing and debugging.

Second in difficulty was a bug that cost me a whole day recently. It had apparently been lurking for years in the code written for the MX-5, just waiting for someone to decide they needed to lower the BMS "heartbeat" to 2 Hz. It is currently 15 Hz in the MX-5 and has never been lower than 4 Hz. There is a single timer which is used for both serial comms timing and the cell-status heartbeat, so there is some interaction between the two. I have no time to get to the bottom of why it didn't work with the original start-bit setup-time formula, but adding one to it fixed the problem.

Ah well. That's (software-engineering) life.

[Edit: Improved grammar and punctuation. Added link to battery-contactor bootstrap schematic.]

PIP-4048MS inverter

Posted: Fri, 09 Jan 2015, 23:20
by weber
Here's the AC switchboard that sits to the left of the PIP inside the monolith. It isn't quite finished yet. There are two more items that need to go into it. One is a kilowatt-hour meter. The other will be left as an exercise for the reader, after I explain the problem. Image


The orange circular cables at the bottom are AC to and from the PIP inverter/charger. The two on the top are from the genset and to the main AC switchboard. All are 4 mm^2. The black cable on the bottom right carries +12 V and 0 V and two switched 0 V signals from the IMU, to control source (genset) and load contactors if necessary for battery protection.

From the left: The 25 A MCB protects and isolates the outgoing cable to the main switchboard. The next 3 items are 40 A 2-pole normally open contactors (Pulset MT40s). They switch both active and neutral since they are switching alternative sources of supply. The leftmost switches the genset to the inverter/charger's AC input.

The two rightmost contactors form a pseudo-changeover contactor that chooses whether the loads are powered from the inverter output or the genset. Only one of them is operated at a time thanks to their coils being fed 12 V from the single-pole changeover relay on the far right (a Hager EN145). I did this because I couldn't find a real 40 A changeover contactor with a 12 V dc coil.

That problem I mentioned: When you hit the big red stop button, neither of those contactors gets any 12 V, because the battery is disconnected and so the DC-DC that produces the 12 volts is un-powered, and my pseudo normally-closed contacts from the genset are a very poor pseudo indeed. This means the customer can't run their house off the genset as intended, when the monolith is shut down (whether for maintenance or due to a fault).

I have a solution, but I thought I'd let you think about it for bit before I reveal it. Image Maybe someone will come up with a better one.

BTW, in the above photograph you can also see the black optic-fibre connector at the bottom of the PIP, with its black fibre going off to the right and curving down. It was easy to connect this photo-transistor as the PIP already had an input optocoupler there. We only had to solder our fibre photo-transistor in parallel with that of the opto, and hold it in place with some silicone.

PIP-4048MS inverter

Posted: Sat, 10 Jan 2015, 05:07
by weber
Here's a scruffy looking wiring diagram for the Monolith's AC switchboard, as shown in the photo in my previous post.


I forgot to point out that there's a barrier made of 1 mm clear Polycarbonate (difficult to see in the photo) that separates the 12 Vdc wiring from the 240 Vac wiring.

PIP-4048MS inverter

Posted: Sun, 11 Jan 2015, 00:58
by neilg
"That problem I mentioned: When you hit the big red stop button ..."

Can I suggest a simple solution: A 12v plugpack running directly off the genset output - battery connected or genset running = 12v!


PIP-4048MS inverter

Posted: Sun, 11 Jan 2015, 01:05
by weber
I needed to put that wiring diagram up so my electrician friend had something to keep his mind occupied. Image

He soon made me realise that "INV AC IN" and "INV AC OUT" are rather ambiguous terms. They are intended to refer to the terminals as named on the inverter. So INV (AC IN) rather than (INV AC) IN. The arrows (for direction of power flow) help disambiguate.

He was understandably concerned about the possibility of live exposed pins on the 15 A caravan-style inlet for the genset. But now agrees that the only way that could occur is by contact welding. I did some reading on that and it seems there are only two ways contact welding can occur:

1. when the contacts close between a low impedance source and a capacitive load (or other load with a high inrush current such as a DOL Induction motor, or another source which is out of phase, or a short-circuit), i.e. an extreme current occurring before full contact pressure can be established, and

2. when they open and immediately reclose, while powering an inductive load, i.e. reclosing while arcing.

Regarding case 1: The two sources (genset and inverter) are output current limited to less than the 40 A contact rating.

Regarding case 2: I will ensure, in software, that the contactors cannot change state more often than once every 2 seconds (or maybe 5 seconds).

He also pointed out that it needs a 16 A breaker for the genset inlet, so a more powerful genset cannot be used.

Thanks David.

In regard to the problem I mentioned earlier, where the Normally Closed contacts of my pseudo double-pole changeover contactor are not really normally closed, but annoyingly go open when the battery is disconnected, and thereby prevent the genset from powering the loads:

My dirty deed of a solution is to use one of these AC/DC modules, done dirt cheap at $11.50 for 5 watts.Image And power it from the genset input, to provide an alternative source of 12 volts to the changeover relay contacts, with a diode in the negative leg of each 12 V source ("GND" on the wiring diagram, not to be confused with Earth).

PIP-4048MS inverter

Posted: Sun, 11 Jan 2015, 01:11
by weber
neilg wrote:Can I suggest a simple solution: A 12v plugpack running directly off the genset output - battery connected or genset running = 12v!

I'm glad someone posted a solution before I posted mine. Image

And yes, that's essentially what I'll do. Thanks Neil.

PIP-4048MS inverter

Posted: Sun, 11 Jan 2015, 02:34
by coulomb
Or, of course, use an actual changeover contactor [ edit: actually, this is a relay ], like this one:


From Ali Express.

Of course, I'll be the first one to admit that finding something on Ali Express or similar is not the same as being able to actually buy just one.

Plus, of course, it's most convenient to have a DIN rail mountable contactor that looks as though it might last.

It might have been wise (in hindsight) to design what is now the 12 V section to be 24 V. Industrial gear tends to be much more available at 24 V.

PIP-4048MS inverter

Posted: Wed, 14 Jan 2015, 21:34
by weber
Well found Coulomb. And yes, I think the next monolith will have 24 V contactor coil drive. The only annoyance is, the MOSFET drivers will still need a 12 V supply.

PIP-4048MS inverter

Posted: Wed, 14 Jan 2015, 21:54
by coulomb
weber wrote: The only annoyance is, the MOSFET drivers will still need a 12 V supply.

I use TC4431 drivers on a project at work. 24 V drivers, max 30 V.

These are the DIP equivalent, inverting: ... dp/1852208

PIP-4048MS inverter

Posted: Sat, 17 Jan 2015, 03:21
by weber
Thanks for the info on 24 V MOSFET drivers, Coulomb.

It was nice to have visits today, at different times, from my friends Trevor Berrill and Greg Breslin (Bladecar). Both interested in the Black Monolith, and both helpful. Thanks guys.

The 5 watt AC/DC module finally arrived (the orange rectangular thing on the lower right in the photo below). So I installed it, and the energy meter, and the breaker for the genset inlet, as you can see below.



Now that the AC switchboard is complete, I have labelled it. Note the gaps beside the contactors for cooling.

PIP-4048MS inverter

Posted: Sat, 17 Jan 2015, 04:36
by offgridQLD
Looking good,
             It would have to be very close to installation now on location?


PIP-4048MS inverter

Posted: Sat, 17 Jan 2015, 20:06
by weber
offgridQLD wrote: Looking good,
             It would have to be very close to installation now on location?

Yes. It's booked for Thursday, and I am very grateful that my friend and former co-teacher (of grid-PV design and installation), David Chaplin, has agreed to be the attending electrician.

But it's a bit of a worry that I'm still making changes to the battery management software at this late stage. I'm currently running the battery down, with both coulomb counting (whole battery) and estimated OCV (individual cells) to see how well the estimated OCV detects the 20% SoC point under varying load conditions. OCV = Open Circuit Voltage.

PIP-4048MS inverter

Posted: Sat, 17 Jan 2015, 22:03
by weber
I've noticed that very few people know the difference between a relay and a contactor. (We're talking electromechanical here, not solid state). If you google it, you'll find forums with all sorts of nonsense being confidently asserted in response to the question, "What is the difference between a relay and a contactor?". Wikipedia doesn't even get it right.

They will go on about how it has to do with the power rating, or the voltage rating, or the presence of arc suppression or blowouts, or whether it is used for power switching versus control, or whether it is used with a motor, or relays go click while contactors go clunk, or "contactor" is just a trade name for a type of relay. While some of these statements may be rescued from complete falsehood by beginning them with the word "Typically", none of them actually tell you what the difference really is. In some forums, there may be one guy giving the right answer, but he will be drowned in the shower of bullsh*t.

It's dead simple.
In a relay, the moving contacts are hinged.
In a contactor, the moving contacts are floating.
That's it.

Not hinged like a door hinge, but flexibly attached at one end so they only make or break at the other end.

Not floating as in mid-air -- they are still mechanically connected to a piece of iron that is moved by the magnetic field of the coil -- but electrically floating -- not permanently connected to any terminal. Because they are floating, they make or break at both ends at once.
Normally open contacts

---/  o---  relay

---o  o---  contactor

Changeover contacts

---/  o---  relay

---o  o---
---o  o---  contactor

Here's a link to the only page I found that gets it right. It has some good diagrams showing how the two types work. ... contactors

PIP-4048MS inverter

Posted: Sat, 17 Jan 2015, 22:34
by T1 Terry
Thankyou Weber, I'll commit that one into the memory banks, and maybe cut and paste it some where as that is likely to be more reliable form these days Image I knew there had to be a fundamental difference as technical people speak of them as two different terms within the one sentence.
Learning every day till I die.... not quite sure what happens with all that knowledge after that :lol:

T1 Terry

PIP-4048MS inverter

Posted: Tue, 20 Jan 2015, 23:04
by weber
T1 Terry wrote: Thankyou Weber, ...
Thanks T1 Terry, for all your contributions to this thread. And thanks Johny, for those papers with much more precise and readable charts of open circuit voltage vs SoC for LiFePO4.
T1 Terry wrote: Learning every day till I die.... not quite sure what happens with all that knowledge after that :lol:

Well, with good enough backups, whatever knowledge you post here may outlive you. Image

And I'm in need of that knowledge right now. I admit I haven't been very interested in your methods before now, because I was planning to do something better, wasn't I Image, controlling the PIP-4048MS on an individual cell basis, with Coulomb's and my BMS software. So why am I now eating a big serve of humble pie?

Because the system is booked in to be installed on Thursday, and although last night I went to bed happy (mind you that was at 3:30 am) because the PI-control was working well and had been tuned to perfection (while charging from the grid), this morning I got up and tried it charging from the PV array and it failed utterly.

The "thinking" of the MPPT device in the PIP seems to go something like this:
Oh, you want me to do something.
OK I see the battery voltage is less than the set absorb voltage.
I'll connect the PV array to myself. Relay clicks on.
I'll slowly reduce the operating voltage of the array until I get enough power to put enough current into the battery to bring it up to the voltage you want.
What's that you say? You have a new absorb voltage for me.
Never mind that it's the same as the previous voltage. I'd better drop what I'm doing and start over. Relay clicks off.

So because it gets a new voltage setting every 2 seconds, it spends all its time just getting started and never puts any current into the cells. Or only puts it in for about 2 seconds. It seems to ignore the voltage commands until it starts actually putting a little current into the battery, otherwise the relay would be clicking every 2 seconds.

When I disconnect the optic fibre to the PIP and manually set the ideal voltage for the present state of balancing it works beautifully. By watching the array voltage with a multimeter I can see it operating between max power voltage and open circuit voltage. When I have no AC loads I see it working near the OC voltage. When I put loads on, I see it working near the MP voltage.

So the only problem is this stupid business where it thinks it has to disconnect the array and start over every time its absorb or float voltage is updated (even if it doesn't actually change in value).

I have just 24 hours to get this thing completely working, with the customer's cells, and loaded in the back of the Prius with all the needed tools. David Chaplin (electrician) is arriving at my place 8am day after tomorrow. Therefore it would be madness to start trying to implement some new control scheme.

So it's time to forget about PI control and it's either find a Plan B, or find a warm bath and a razor blade.

And since a couple of people say they like having me around, it had better be Plan B (no, not you Kris). So I think I'm ready to place enormous and ridiculous faith in the inherent balanceability of LiFePO4 cells (after an initial manual balance).

So Plan B is:

Set the CMUs for a 95% SoC charge. Forget this 75% nonsense for now. I'll have the IMU send fixed bulk/absorb and float voltages to the PIP on startup and not do any PI control. Just turn the contactor off at stress 12 and back on at stress 7 to save an individual cell if necessary. And hope it never gets to stress 15 which will drop out the battery contactor and require a human to cycle the stop button to get it going again. I'll set the bypass voltage to just below the average cell voltage of the PIP's setting and hope it gets enough balancing to keep them all balanced.

Then I'll build Monolith #2 and work on more refined software at a more leisurely pace.

What I need from you, T1 Terry, are the magic numbers you suggest for the fixed bulk and float voltage setting for the PIP, and the bypass and alarm (contactor dropout) voltage settings for the CMUs. The CMUs can only bypass 0.8 A. It's a 16 cell system, nominally 48 volts with a maximum charge current from the array of 60 amps. The cells are new 180 Ah grey CALBs.