PIP-4048MS and PIP-5048MS inverters

non-EV Solar, Wind and other renewable power sources
non-EV batteries and other energy storage stuff
Forum rules
Important!
This forum is for discussion of Non-EV matters.
User avatar
Jeff Owen
Groupie
Posts: 156
Joined: Thu, 13 Nov 2008, 15:53
Real Name: Jeff Owen
Location: Brisbane

PIP-4048MS inverter

Post by Jeff Owen » Tue, 02 Dec 2014, 06:54

weber wrote: I conceived of this small-footprint design as "the black monolith" from the movie "2001 a Space Odyssey". But any second now I'm expecting a phone call from Newton who has put vernier calipers to his computer screen, telling me it doesn't appear to have the correct 1:4:9 aspect ratio of that erstwhile device.
Actually, I understand that the dimensions of the monolith are 1.25 x 5 x 11 feet. Yes, the highly evolved aliens with superior intelligence use a measurement system that matches our imperial feet and inches, not the metric system that you so strongly advocate.

I am sure you are already reaching for your copy of the book to check this.

Jeff Owen

User avatar
weber
Site Admin
Posts: 2595
Joined: Fri, 23 Jan 2009, 17:27
Real Name: Dave Keenan
Location: Brisbane
Contact:

PIP-4048MS inverter

Post by weber » Tue, 02 Dec 2014, 21:07

Jeff Owen wrote:Actually, I understand that the dimensions of the monolith are 1.25 x 5 x 11 feet. Yes, the highly evolved aliens with superior intelligence use a measurement system that matches our imperial feet and inches, not the metric system that you so strongly advocate.

I am sure you are already reaching for your copy of the book to check this.

Yes. Let's turn this into the black monolith thread. Image

Sadly I no longer seem to have a copy of the book "2001" although I have "2010", "2061" and "3001". In "2010" page 131 it states that someone "confirmed the famous 1:4:9 ratio to six decimal places". So if the book "2001" also says that TMA-1 is 1.25 x 5 x 11 feet, then clearly those are only approximate measurements. If it had instead claimed it was 1.25 x 5 x 11.25 feet then I would concede that feet and inches are clearly a superior system of measurement used by advanced aliens and I would give up on this SI rubbish immediately. Image

But now lets talk about the monoliths in the movie. The dawn-of-man, moon and death-bed monoliths are clearly the same box made of black-painted plywood. You only need the two images below with their convenient floor grid, and a ruler, to show that while the large face is close to 4:9. The smallest dimension is far less than 1 in relation to them. It is more like 0.65.

Image

Image

If we assume the floor is a 3 foot grid then I get:
8.5 +-0.5 inches (~0.7 feet)
51.5 +-0.5 inches (~4.3 feet)
119.5 +-1.5 inches (~10 feet)

And when you see the hands of the people in ape-suits against the small dimension of the monolith, and scale off a typical adult human hand, 8 to 9 inches is right.

That's approximately a 1:6:14 ratio (nowhere near 1:4:9).

So apparently I'm making a book monolith, not a movie monolith.

But there's another monolith! The "crystal monolith" that Kubrick had made, but decided not to use. It resurfaced some years later as a natty gift for the woman who has everything.
http://www.ianvisits.co.uk/blog/2012/07 ... er-bridge/

The plaque shown in the article claims it is 0.67 x 5.75 x 10.75 feet. But the plaque is clearly unreliable as it also claims the monolith used in the movies was made of "black basalt", which is complete nonsense.
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

User avatar
weber
Site Admin
Posts: 2595
Joined: Fri, 23 Jan 2009, 17:27
Real Name: Dave Keenan
Location: Brisbane
Contact:

PIP-4048MS inverter

Post by weber » Wed, 03 Dec 2014, 04:37

Some progress on the DC side. A possible layout. The 3 Hager 2-pole MCBs are standing in for the Noarks which haven't arrived yet.

Image

Image
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

User avatar
weber
Site Admin
Posts: 2595
Joined: Fri, 23 Jan 2009, 17:27
Real Name: Dave Keenan
Location: Brisbane
Contact:

PIP-4048MS inverter

Post by weber » Thu, 04 Dec 2014, 02:10

I still haven't produced a complete schematic. It's partly because there's a problem I still haven't solved, as described below.

BTW, I measured the coil current of the Pulset MT2/40/12 contactors. It's 300 mA at 12 V (3.6 W).

All the contactor coils, and the IMU that controls them, will be powered from a 48 V to 12 V DC-DC converter. I'm assuming this DC-DC will be connected on the _load_ (i.e. inverter) side of the EV200 battery-isolating contactor (not the battery side).

This has the advantage that if the EV200 is shut off there is no load at all on the battery. So it will not slowly bleed to death due to the quiescent current of the DC-DC if the humans are away for a week or two. This seems an essential requirement.

But it has the disadvantage that there is no power to pull in the EV200 to get things started.

The IMU would only drop out the battery contactor if it found that it couldn't protect the battery by the preferred means, firstly by serial comms to the inverter, secondly by turning off either the load contactor or the charging-source contactors. Battery contactor dropout is the third and final sanction. So it's OK that it should require human intervention to recover from.

I also haven't figured out how to best use the emergency stop switch. This has independent NO and NC contacts (one of each).

Pushing the emergency stop switch could interrupt the power to (or from) the DC-DC so that all contactors drop out.

It would be great if the user could recover from an IMU battery contactor dropout simply by pushing the emergency stop button in and then releasing it. You have to twist it to release it. You probably know the type.

But I can't figure out how to make this happen. Any ideas?
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

T1 Terry
Senior Member
Posts: 923
Joined: Thu, 30 Sep 2010, 20:11
Real Name: Terry Covill
Location: Mannum SA

PIP-4048MS inverter

Post by T1 Terry » Thu, 04 Dec 2014, 03:07

What about 48v from the solar panels somehow connected to the 48/12 converter so the next solar day everything is powered up again yet free to drop out if the system requires a shut down. A diode in the battery supply side to the 48/12 converter so the solar can not bypass the control system and feed directly into the battery.

T1 Terry
Green but want to learn

User avatar
weber
Site Admin
Posts: 2595
Joined: Fri, 23 Jan 2009, 17:27
Real Name: Dave Keenan
Location: Brisbane
Contact:

PIP-4048MS inverter

Post by weber » Thu, 04 Dec 2014, 05:43

Thanks T1 Terry. But I'm still planning a 6P3S array, so nominally 72 V rather than 48.

I have a suggestion from my friend David Chaplin, by email, to add a 12 V battery charged off the DC-DC.

How about, instead of a battery, a capacitor, like this?

Image
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

User avatar
weber
Site Admin
Posts: 2595
Joined: Fri, 23 Jan 2009, 17:27
Real Name: Dave Keenan
Location: Brisbane
Contact:

PIP-4048MS inverter

Post by weber » Fri, 05 Dec 2014, 23:34

I spent a few hours today disassembling and reassembling the monolith with new, correct-length verticals. Here I've taped a black bed sheet to it as a mock-up. The things we do for art. Image

Image
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

T1 Terry
Senior Member
Posts: 923
Joined: Thu, 30 Sep 2010, 20:11
Real Name: Terry Covill
Location: Mannum SA

PIP-4048MS inverter

Post by T1 Terry » Sat, 06 Dec 2014, 00:08

weber wrote: Thanks T1 Terry. But I'm still planning a 6P3S array, so nominally 72 V rather than 48.

I have a suggestion from my friend David Chaplin, by email, to add a 12 V battery charged off the DC-DC.

How about, instead of a battery, a capacitor, like this?

Image

If the battery has discharged to the point the relay drops out, won't the capacitor have discharged as well?

T1 Terry
Green but want to learn

User avatar
weber
Site Admin
Posts: 2595
Joined: Fri, 23 Jan 2009, 17:27
Real Name: Dave Keenan
Location: Brisbane
Contact:

PIP-4048MS inverter

Post by weber » Sat, 06 Dec 2014, 01:24

T1 Terry wrote:If the battery has discharged to the point the relay drops out, won't the capacitor have discharged as well?

Thanks for asking. It sounds like there are (at least) two things I didn't explain very well.

1. The EV200 contactor doesn't have to wait for the battery to get really low before it drops out. The IMU is, in this case, the BMS master, and will actively turn off the contactor when the lowest cell has maybe 10% charge left.

2. It was misleading for me to compare the capacitor to a battery. In this circuit, the normal state of the capacitor is completely discharged. It only charges briefly, in between the e-stop being released and the EV200 contacts closing.

As it charges, the voltage across the DC-DC input drops. The capacitor has to be large enough that the DC-DC supplies power to the IMU which supplies it to the contactor which pulls in before the voltage to the DC-DC input drops below the minimum at which it can work, which is 18 V.

But after email discussions with Coulomb, I'm leaning back towards just connecting the DC-DC input to the battery side of the EV200 and thereby eliminating any need for bootstrapping.

This does mean that the battery can eventually be destroyed by the quiescent current drain of the DC-DC, but I figure it would allow at least 8 days for human intervention. Is that crazy?
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

T1 Terry
Senior Member
Posts: 923
Joined: Thu, 30 Sep 2010, 20:11
Real Name: Terry Covill
Location: Mannum SA

PIP-4048MS inverter

Post by T1 Terry » Sat, 06 Dec 2014, 02:10

Drop the inverter at say 10% SOC but leave the solar connected, bring the inverter back in at say 20% SOC say there is a bit of room between the on/off cycling. We found the easiest way to cut the inverter was a small solid state relay controlling the on/off switch. There still is a small parasitic draw from the inverter this way but far less than the losses through a heavy contactor controlling the main DC feeds.

T1 Terry
Green but want to learn

User avatar
weber
Site Admin
Posts: 2595
Joined: Fri, 23 Jan 2009, 17:27
Real Name: Dave Keenan
Location: Brisbane
Contact:

PIP-4048MS inverter

Post by weber » Sat, 06 Dec 2014, 03:50

T1 Terry wrote:Drop the inverter at say 10% SOC but leave the solar connected, bring the inverter back in at say 20% SOC say there is a bit of room between the on/off cycling. We found the easiest way to cut the inverter was a small solid state relay controlling the on/off switch. There still is a small parasitic draw from the inverter this way but far less than the losses through a heavy contactor controlling the main DC feeds.

Yes, hysteresis is necessary when switching contactors, but I was thinking of it as being more like 1% charge rather than 10%.

I remind you that I wrote, in viewtopic.php?title=pip4048ms-inverter& ... 332#p54604:
"The IMU would only drop out the battery contactor if it found that it couldn't protect the battery by the preferred means, firstly by serial comms to the inverter, secondly by turning off either the load contactor or the charging-source contactors. Battery contactor dropout is the third and final sanction."

And I remind you that the PIP-4048MS is an all-in-one unit with PV and genset charging as well as inverter, so it is not possible to turn off only the inverter part, hence there will be a contactor to disconnect the AC loads.

So, turning off the loads (while leaving the charge-sources) might happen at 20%, and in the unlikely event that this wasn't effective (say the load contactor has welded) then the battery contactor might be dropped out at 10%.

And I note that the EV200 battery contactor has an economiser circuit which means it only uses 1.6 watts after the initial pull-in.
Last edited by weber on Sat, 06 Dec 2014, 15:03, edited 1 time in total.
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

User avatar
weber
Site Admin
Posts: 2595
Joined: Fri, 23 Jan 2009, 17:27
Real Name: Dave Keenan
Location: Brisbane
Contact:

PIP-4048MS inverter

Post by weber » Sun, 07 Dec 2014, 07:39

David Chaplin came over today, and pretty much designed the layout you can see below, for all of the 35 mm² cabling, from the battery, through the DIN-rail double-pole fuse-switch (100 A, 22 x 58 mm fuses), the shunt and the EV200 contactor, to the inverter, and still left room for the DC-DC converter and the IMU in the same Hager 12 way enclosure. Thanks David.

The only way we could fit all that stuff in a 12 way box, given the bending radius limitations of 35 mm² cable, was to move the PV array circuit breakers and Minitactor to the 8 way box you can see above the 12 way.

Image

I note that the monolith has 3 battery shelves, each capable of taking 12 cells. So it can take double the capacity it has now, either as buddy-pairs or as two strings of 16.

Image
Last edited by weber on Sat, 06 Dec 2014, 20:54, edited 1 time in total.
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

T1 Terry
Senior Member
Posts: 923
Joined: Thu, 30 Sep 2010, 20:11
Real Name: Terry Covill
Location: Mannum SA

PIP-4048MS inverter

Post by T1 Terry » Sun, 07 Dec 2014, 11:50

weber wrote:
T1 Terry wrote:Drop the inverter at say 10% SOC but leave the solar connected, bring the inverter back in at say 20% SOC say there is a bit of room between the on/off cycling. We found the easiest way to cut the inverter was a small solid state relay controlling the on/off switch. There still is a small parasitic draw from the inverter this way but far less than the losses through a heavy contactor controlling the main DC feeds.

Yes, hysteresis is necessary when switching contactors, but I was thinking of it as being more like 1% charge rather than 10%.

I remind you that I wrote, in viewtopic.php?title=pip4048ms-inverter& ... 332#p54604:
"The IMU would only drop out the battery contactor if it found that it couldn't protect the battery by the preferred means, firstly by serial comms to the inverter, secondly by turning off either the load contactor or the charging-source contactors. Battery contactor dropout is the third and final sanction."

And I remind you that the PIP-4048MS is an all-in-one unit with PV and genset charging as well as inverter, so it is not possible to turn off only the inverter part, hence there will be a contactor to disconnect the AC loads.

So, turning off the loads (while leaving the charge-sources) might happen at 20%, and in the unlikely event that this wasn't effective (say the load contactor has welded) then the battery contactor might be dropped out at 10%.

And I note that the EV200 battery contactor has an economiser circuit which means it only uses 1.6 watts after the initial pull-in.

Please don't take offence if I question the system, just looking from the outside in to offer ideas that being to close to the build side can be overlooked.
What is the back up plan should either the inverter or IMU should fail? At the moment, if the IMU fails is all control lost? It may fail to safe as part of it's design but does that leaves the house without power? If the inverter fails is the house also without power or a charging system until a replacement inverter is installed?

My thoughts were along the lines of a fail safe to a secondary separate system, like the Victron BMV, and use the relay contacts to switch the inverter itself off by what ever means possible but leaving the charging circuit intact. The idea behind the 20% was enough capacity remaining to run refrigeration and emergency lighting via a separate back up inverter.

As a charging back up system, a simple cell voltage control circuit can act as both a secondary back up charging system and a cell protection system should the IMU fail, a second inverter can act as an emergency power supply for essential loads should there be a system failure.

T1 Terry
Green but want to learn

User avatar
weber
Site Admin
Posts: 2595
Joined: Fri, 23 Jan 2009, 17:27
Real Name: Dave Keenan
Location: Brisbane
Contact:

PIP-4048MS inverter

Post by weber » Sun, 07 Dec 2014, 15:34

T1 Terry wrote:Please don't take offence if I question the system, just looking from the outside in to offer ideas that being to close to the build side can be overlooked.
No offence whatsoever. I welcome your suggestions. I just wanted you to know (a) that the design was already, in effect, dropping the inverter but leaving the solar connected, and (b) why the specific method you suggested, (solid state relay controlling the on/off switch) while good in general, would not work in this case.
What is the back up plan should either the inverter or IMU should fail?
The backup plan is the standard one for off-grid power systems -- an internal combustion generating set. In this case, manual start.
At the moment, if the IMU fails is all control lost?
Yes. If it fails while leaving loads on, the user will eventually be alerted by the beepers on the top of all 16 cells.

Just a reminder to please consider trimming quotes back to the minimum required to identify what you are responding to, to avoid boring or annoying readers. For example, in the previous case, I suspect you could have left my quote out entirely.
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

User avatar
offgridQLD
Senior Member
Posts: 1825
Joined: Tue, 23 Jul 2013, 16:05
Real Name: Kurt
Location: Fleurieu Peninsula, SA

PIP-4048MS inverter

Post by offgridQLD » Tue, 09 Dec 2014, 17:09

"This does mean that the battery can eventually be destroyed by the quiescent current drain of the DC-DC, but I figure it would allow at least 8 days for human intervention. Is that crazy? "

Yes to me its crazy.... 8 days I'm sure a 8 day + absence from ones home isn't something out of the ordinary.

I know you have to draw the line at some point as you can never cover for every possible unforeseen chain of events. Though I think this ones isn't unforeseen. It's more or less a guarantee that if you have a LVD event you have a 8 day expiry date on you expensive cells if your not home.

The component layout looks nice and simple, tidy. How much heat will that dc/dc give off. Is it ok in the closed box?

Like the black sheet cover. Perhaps you can put that to use in the unveiling to the customer Black sheet drops away dramatic sound follow by a few gasps. Then a moment of silence befor the unit springs to lifeImage.

Kurt
Last edited by offgridQLD on Tue, 09 Dec 2014, 08:09, edited 1 time in total.

User avatar
weber
Site Admin
Posts: 2595
Joined: Fri, 23 Jan 2009, 17:27
Real Name: Dave Keenan
Location: Brisbane
Contact:

PIP-4048MS inverter

Post by weber » Sat, 20 Dec 2014, 23:35

offgridQLD wrote:Yes to me its crazy.... 8 days I'm sure a 8 day + absence from ones home isn't something out of the ordinary.

I know you have to draw the line at some point as you can never cover for every possible unforeseen chain of events. Though I think this ones isn't unforeseen. It's more or less a guarantee that if you have a LVD event you have a 8 day expiry date on you expensive cells if your not home.
OK. You and Coulomb have convinced me not to connect the DC-DC on the battery side of the battery contactor, despite the fact that measurement of the quiescent current when the new one arrived, showed that it would actually take more like 30 days for the DC-DC to discharge the last 10% of the battery capacity.

So I'll either be using the previously-posted capacitive bootstrap circuit, or Coulomb's suggestion of a green momentary push-button in addition to the latching red emergency stop button. The green button would simply replace the capacitor in the aforementioned circuit.
The component layout looks nice and simple, tidy. How much heat will that dc/dc give off. Is it ok in the closed box?
Good question. With the cover off, its surface temp is 25 degrees above ambient. This appears to be nearly independent of load, which is consistent with it being nearly all switching losses, due to switching at hundreds of kilohertz to minimise its physical size. The losses are only about 4 watts, so I think it will be OK.

An update on progress. I've had hands-on help from both Coulomb and BladeCar which is much appreciated. Thanks guys.

The monolith is currently powering my house, hoorah, with the mains fed in where the genset would go, and a 1.5 kW PV array.

It's all working fine. But so far it's all manually configured and the contactors manually controlled, not yet operating under BMS control. But Coulomb has translated the PIP CRC code to MSP430 assembler, and an optic fibre input has been added to the PIP, and the BMS has successfully sent a command to change the float voltage.

The float-at-76%-SoC idea seems to be working. With the PIP set for both bulk and float voltage of 53.1 V, yellow LEDs dance across the top of the cells as they bypass at 3.322 V per cell.

When they were around 80% to 95% SoC I could have sworn they were near-perfectly balanced, as they were all at 3.33x V. But it's just that this is an extremely flat plateau in the voltage vs. SoC curve. But when I let the SoC drop below that I saw a much greater spread open up between the cell voltages. Their "rested" or float voltages ranged from 3.30x to 3.32x V. And now the voltages are all together again at 3.28x V under light load, which corresponds to the 3.29 V (rested) lower plateau between about 45% and 65% SoC, as shown in this document:

http://www.cse.anl.gov/us-china-worksho ... %20BMS.pdf

So that little step at around 76% really is there, at least for my blue Sky Energy cells. It remains to be seen for the grey CALBs. Who knows, some new dopant might completely spoil this convenient float point.

I use 3.32 V and 76% SoC, not because it's midway between the two plateaux -- that would be about 3.31 V and 73% -- but because it's the point where the slope is steepest, and because it gives us more usable capacity. But it certainly does require the +- 3 mV accuracy that our BMS gives us.
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

User avatar
offgridQLD
Senior Member
Posts: 1825
Joined: Tue, 23 Jul 2013, 16:05
Real Name: Kurt
Location: Fleurieu Peninsula, SA

PIP-4048MS inverter

Post by offgridQLD » Sun, 21 Dec 2014, 01:17

That's great news that the PIP is powering your house for testing. This should give you some idea of what the AC side of the package is like to live with. I assume some load testing or at least to the extent it will be loaded in the customers home is in order.

Kurt


User avatar
weber
Site Admin
Posts: 2595
Joined: Fri, 23 Jan 2009, 17:27
Real Name: Dave Keenan
Location: Brisbane
Contact:

PIP-4048MS inverter

Post by weber » Sun, 21 Dec 2014, 02:47

What's driving me nuts, and I think is likely to drive the customer nuts, is the fan noise. With only 300 watts being supplied it's unpleasant to be in the same room. When the water pump comes on and the load jumps up to a whopping 600 watts Image the fan instantly roars to even higher speed. The air temperature coming out is indistinguishable from ambient. It doesn't sound much worse when I turn on the 2400 watt kettle.

Can anyone tell me why inverter designers choose to make the fan(s) blow out of the bottom of the case, thereby opposing natural convection and failing to force air to flow fast close to the surface of the heatsink?

I have used Vantec Stealth fans to replace the noisy ones in Latronics inverters in the past, but their air flow (at 27 CFM) is too low compared to the fans in the PIP-4048MS. These are ADDA AD0812XB-A7FGP (80x80x25 mm, 12 V, 6.6 W) which I can't find the airflow specs for, but extrapolating from similar part numbers looks to be about 70 CFM. [Admitting defeat on the non-SI units here]

There's some discussion in another forum here http://www.photovoltaikforum.com/pv-ins ... 04258.html

[Edit: Deleted text "Latronics inverters are the same." They are not. They sensibly blow upward onto the heatsink.]
Last edited by weber on Sun, 21 Dec 2014, 10:49, edited 1 time in total.
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

User avatar
offgridQLD
Senior Member
Posts: 1825
Joined: Tue, 23 Jul 2013, 16:05
Real Name: Kurt
Location: Fleurieu Peninsula, SA

PIP-4048MS inverter

Post by offgridQLD » Sun, 21 Dec 2014, 05:28

So by the sound of it the fan has two speeds fast and very fast. What is the trigger for the 2nd speed temp or load? Sounds more like it's triggered by load.

The inverter is sitting inside a room in your house so that would make it sound worse.I can say with 100% confidence if my selectronic inverter was mounted inside my house even in the garage I would go nuts in one day. Buzzzz..grrrr...hmmmm of the big transformer and although the fan doesn't come on to often it's got a real sound to it like a industrial dust extractor. Lucky It's in it's own cinder block power room separate from the house by about 4 meters and at the end of the house from all the living areas.

If the air flowing from the pip is only ambient temp then it sure sounds like not much heat is being wicked away.Perhaps the fans are shifting to much air unnecessarily?

Kurt
Last edited by offgridQLD on Sun, 21 Dec 2014, 04:59, edited 1 time in total.

User avatar
Johny
Senior Member
Posts: 3729
Joined: Mon, 23 Jun 2008, 16:26
Real Name: John Wright
Location: Melbourne
Contact:

PIP-4048MS inverter

Post by Johny » Sun, 21 Dec 2014, 15:42

I have noticed that any high airflow 80mm fan is noisy. My controller uses two 5.7 W 80x80x25 fans and I hear them easily when stationary.

User avatar
offgridQLD
Senior Member
Posts: 1825
Joined: Tue, 23 Jul 2013, 16:05
Real Name: Kurt
Location: Fleurieu Peninsula, SA

PIP-4048MS inverter

Post by offgridQLD » Sun, 21 Dec 2014, 16:03

A question regarding the current shunt.

For some reason I have it in my mind that shunts should go on the negative cable.(don't ask my why though)

So that's how I have my main 500A shunt wired on my battery and the two other 200A shunts (one for each MPPT controller).

Is there any rule for this or really doesn't it matter?

Kurt


User avatar
weber
Site Admin
Posts: 2595
Joined: Fri, 23 Jan 2009, 17:27
Real Name: Dave Keenan
Location: Brisbane
Contact:

PIP-4048MS inverter

Post by weber » Sun, 21 Dec 2014, 22:15

I was mistaken. Latronics inverters are not the same. They sensibly blow upward and onto the heatsink.

Yes the PIP fans seem to be responding instantly to load, not temperature. And they seem to be running unnecessarily fast at very low inverter/charger power levels.
offgridQLD wrote:For some reason I have it in my mind that shunts should go on the negative cable.(don't ask my why though)
...
Is there any rule for this or really doesn't it matter?

Yes. The rule is, you put it wherever the manufacturer (of the thing that's monitoring the shunt) says. Image

They usually do go in the negative lead, because the device that is monitoring it is typically also measuring the battery voltage, treating the negative terminal as the common reference for both measurements.

In our case, our IMU needs to also measure the PV array voltage, not the battery voltage. It needs to do this so it can protect the PIP's MPPT from array-open-circuit-voltages greater than 145 V, which may occur at dawn on frosty winter mornings with the 3S x 72-cell PV arrangement I'm using. It will do this by leaving off the Minitactor that isolates the array, until the array warms up and its open circuit voltage drops below 145 V.

The MPPT in the PIP has it's positive in common with battery positive and switches the negative. That's typical for non-isolated buck converters.

So to measure both PV array voltage and battery current, the IMU needs to use the positive as the common reference, and therefore the shunt needs to be in the battery positive. We've modified the IMU to measure negative voltage.

[Edit: Corrected the PIP's max array input voltage (open circuit) from "150 V" to "145 V".]
Last edited by weber on Sun, 21 Dec 2014, 18:09, edited 1 time in total.
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

User avatar
weber
Site Admin
Posts: 2595
Joined: Fri, 23 Jan 2009, 17:27
Real Name: Dave Keenan
Location: Brisbane
Contact:

PIP-4048MS inverter

Post by weber » Mon, 22 Dec 2014, 17:03

Johny wrote: I have noticed that any high airflow 80mm fan is noisy. My controller uses two 5.7 W 80x80x25 fans and I hear them easily when stationary.

Yeah. A single 120 mm fan can be a lot quieter than two 80 mm fans pushing the same amount of air. But some fans are optimised for low noise and some are not, at the same diameter and flow rate. The ADDA fans in the PIP clearly are not.

But they are 4-wire (speed controlled by a PWM signal).

I ordered two of these Noctua NF-R8 PWM fans from PC Case Gear in Melbourne,
http://www.noctua.at/main.php?show=prod ... g=en&set=1,
perhaps foolishly, because they can only do 31 CFM, about half the flow rate of the existing ADDA fans. But I plan to make them blow inwards (upwards) in the hope that this will compensate for the lower flow rate. Clearly all this will violate any warranty I might have still had.

I had some more thoughts on possibly why the fans are currently blowing out (downward). When blowing upward, the hot air leaving the top of the heatsinks on the main board will blow onto the electros on the MPPT. So they may be correcting one design-flaw with another. Unfortunately I only thought of this after ordering the new fans. Perhaps I can add a shield for the electros, but that would only protect them from short term peaks in hot air.

But surely, as the fans are now, they will be sucking most of their air, not from the top of the heatsinks downward, but sideways from the openings around the battery busbars at the bottom, right beside the fans. Blowing is directional, sucking is not. I suppose I could block these holes with some foam.

Edit1: See also this post regarding the changes required to the fan plugs: viewtopic.php?title=pip4048ms-inverter& ... 332#p54866

Edit2: I eventually had to restore the original fans because the Noctuas occasionally triggered a "fan locked" warning (code 01) even though they were working perfectly. See this post viewtopic.php?p=62186&t=4332#p62186
Last edited by weber on Tue, 28 Jun 2016, 09:27, edited 1 time in total.
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

User avatar
offgridQLD
Senior Member
Posts: 1825
Joined: Tue, 23 Jul 2013, 16:05
Real Name: Kurt
Location: Fleurieu Peninsula, SA

PIP-4048MS inverter

Post by offgridQLD » Mon, 22 Dec 2014, 23:37

I had the same thought about them not wanting to blow already heated air onto the MPPT charge controller up top.

Edit : Misread your description...hang on no I didn't. Are you sure the fans wont take air from inside the case (the fan is in a baffle/shroud) how can it not take air from the opposite side two what it blows....need to do some googling on that one.

Yes most of the air will come from the air holes on the sides up top and not passing much air over the heat sink on top of the unit. But as mentioned first perhaps that's still better than soaking the mppt charge controllers PCB in hot air.

Kurt
Last edited by offgridQLD on Mon, 22 Dec 2014, 12:57, edited 1 time in total.

User avatar
weber
Site Admin
Posts: 2595
Joined: Fri, 23 Jan 2009, 17:27
Real Name: Dave Keenan
Location: Brisbane
Contact:

PIP-4048MS inverter

Post by weber » Tue, 23 Dec 2014, 01:25

offgridQLD wrote:Are you sure the fans wont take air from inside the case (the fan is in a baffle/shroud) how can it not take air from the opposite side two what it blows....need to do some googling on that one.

I didn't say the fans wouldn't take air from inside the case, i.e. the opposite side from the one they blow to.

When I wrote

"... they will be sucking most of their air, not from the top of the heatsinks downward, but sideways from the openings around the battery busbars at the bottom, right beside the fans. Blowing is directional, sucking is not."

I was only referring to the two heatsinks inside the case, not the MPPT heatsink whose fins project upward outside the top of the case. Its fins will not be cooled by the fans no matter what direction they blow.

Yes, the folded plastic sheet that makes a duct inside the case, enclosing the two heatsinks on three sides, is the only thing that makes any air pass near the heatsinks, given that they're on the suction side of the fans. But there are three holes in the plate the fans are mounted in, that allow the right-hand fan in particular to suck some outside air, and therefore to fail to suck that quantity of air past any heatsink. These holes are inside the duct/shroud/baffle.

Here's a photo, looking up from under the inverter, with purple arrows pointing to the holes I'm talking about. They would not be a problem if the fans blew upward, since blowing is directional.

Image
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

Post Reply