Page 34 of 97

PIP-4048MS inverter

Posted: Wed, 03 Feb 2016, 21:18
by evric
Northland wrote: I came across this today, 95% cheaper than those other battery computers
J34 Free Shipping Capacity Tester Indicator Coulometer 35-80V 50A Lithium/Lead-Acid Battery Meter

http://s.aliexpress.com/7zmaEzQB


That looks interesting - especially when it is for between 35-80V and the photos show it reading a 12V battery!

PIP-4048MS inverter

Posted: Wed, 03 Feb 2016, 21:59
by coulomb
evric wrote:... especially when it is for between 35-80V and the photos show it reading a 12V battery!

They probably make a 12 V and a 24 V version, and use the same photo for each. The Chinese are notorious for not caring about details like that.

For example, the wiring diagram shows B- connected to RS-, when the whole idea is not to get any stray current through RS- or RS+. Obviously B- should go to battery minus.

It's a shame that the shunt is only rated for 50 A continuous (2500 W), and 100 A peak (5000 W). But that could suit smaller installations. The terminals seem too flimsy for connecting to say 8 mm^2 cable.

It's an unusual shunt that looks like a bridge rectifier. I suppose it makes sense - they use the same packaging that they use for high current semiconductors, and you can bolt it to a heatsink near the high current wires.

[ Edit: I love the word "coulometer". I've never heard it before, but it fits perfectly. Sounds a bit like "kilometer" though. ]

PIP-4048MS inverter

Posted: Wed, 03 Feb 2016, 22:11
by offgridQLD
Perhaps if you could find out the MV rating of the little shunt you could replace it with a larger shunt of the same MV rating?

Perhaps a 200A shunt or so with nice big terminal bolts each end and a mounting plate.

Though as mentioned the little one included might be ok for little loads (as I think even there listed rating are optimistic while maintaining accuracy as it gets hot, based on the pic anyhow)

Kurt

PIP-4048MS inverter

Posted: Wed, 03 Feb 2016, 23:50
by Northland
50A either in or out of the batteries for me would be extremely rare. The most I've seen is 30 since the hw mod.

I've ordered one and will have a play with bigger shunts

I asked about the display vs the working range, she repeated the working range as a response. But some of the feedbacks say it worked well on their car

PIP-4048MS inverter

Posted: Thu, 04 Feb 2016, 00:25
by coulomb
offgridQLD wrote: Perhaps if you could find out the MV rating of the little shunt you could replace it with a larger shunt of the same MV rating?
That might work. But more current will produce more voltage across the same-resistance shunt (and it has to stay the same resistance, or the SOC won't be right), and it will likely run into ADC voltage limitations on the microprocessor.

For example, say the micro can read voltages from 0.0 to just under 3.0 V (as digital 0x000 to 0x3FF say, for a 10 bit sample). You don't want three volts across your shunt (!), so there would be an op-amp in there to amplify the 100 mV or 150 V at 100 A to say for example 2.8 V. So there is a little head room there (but the head room might in fact be zero), so you can measure to 3.0/2.8 times 100 A, which is 107 A. Any higher currents would put more than 3.0 V at the analog input of the processor (or the op-amp might clip), so you'd still read 0x3FF, the same as you'd get at 107 A.

So you'd be guaranteed of 5000 W continuous with an appropriately larger shunt, but peaks over that might not get recorded properly. If they effectively clip at 107 A (continuing the above example), then 140 A (7000 W) for 10 seconds might get treated like 107 A for 10 seconds. That's an error of 330 As (amp.seconds) or 0.09 Ah. That might not be too serious for many applications; a single PIP-4048 inverter is already at 125% of rated capacity at 100 A / 5000 W, and is only rated for a 5 second overload.

In the above, I've been assuming that the battery voltage is 50.0 V, and I've been ignoring inverter losses. So the power limits are approximate.

[ Edit: changed example to 7000 W. ]

PIP-4048MS inverter

Posted: Thu, 04 Feb 2016, 00:37
by weber
I was about to suggest you guys start a new thread to discuss this battery monitor because it is clearly unsuitable for use with a PIP. But yes, provided you have a 50 amp battery fuse, it might be OK.

However I don't understand why you would buy a 4 kW inverter and then limit it to 2.5 kW. And I don't see how you are supposed to connect that shunt to cable that needs to be at least 8 mm^2 (or 8 AWG), as coulomb said.

BTW, the term "coulometer" already refers to an electrolytic cell which measures electric charge by measuring the mass of a substance deposited at an electrode (typically silver, copper or hydrogen).

PIP-4048MS inverter

Posted: Thu, 04 Feb 2016, 00:58
by Northland
Unsuitable?
You have made several errors in your snarky response.
1. Using a 50A shunt does not limit the inverter to 2.5kw. It limits output to 2.5kw AT NIGHT ONLY. Output can still be 5kw during the day. You forget that pv or battery or both can be inverted.
2. You are dismissing the possibility of using a bigger shunt before anyone has even tried, likely solving the 50A limit and wiring size issues. Even if inaccurate over 50A or 100A as the case may be, this would not limit the inverter to 2.5kw

PIP-4048MS inverter

Posted: Thu, 04 Feb 2016, 01:56
by offgridQLD
Northland, I'm 100% sure Webers response wasn't intended to be Snarky. I think he was just pointing out It isn't the ideal meter for the PIP4048 and in standard form is not rated to more than 50A continuous.

I suggested it could perhaps be used more safely at least with a larger external shunt with the appropriate rating. Though Coulomb pointed out the issues you might have with accuracy of the sensing/ metering side over the rated max.

Though when installing a inverter or any electrical appliance you need to spec everything to the maximum continuous rating of the appliance. It's no good saying . "oh I only intend to run a desk lamp from it" As you cant say that's how it will be used for it's life.

Sure we all experiment with things and some times temporary installations for experimental reasons is ok. Though I can see how others reading the thread could go out and purchase that 50A shunt meter thinking it's ideal for the pip and cook the thing or burn the house down. Running a EV charger or heavy load for hrs through it.

Kurt

PIP-4048MS inverter

Posted: Thu, 04 Feb 2016, 03:02
by weber
Northland wrote: Unsuitable?
You have made several errors in your snarky response.
1. Using a 50A shunt does not limit the inverter to 2.5kw. It limits output to 2.5kw AT NIGHT ONLY. Output can still be 5kw during the day. You forget that pv or battery or both can be inverted.
2. You are dismissing the possibility of using a bigger shunt before anyone has even tried, likely solving the 50A limit and wiring size issues. Even if inaccurate over 50A or 100A as the case may be, this would not limit the inverter to 2.5kw

Hi Northland. I'm sorry you found my response snarky.

I know you're an ex sparky, but I wanted to make sure everyone else realised they would need a 50 A (or less) fuse to prevent a possible fire if they used the 50 A shunt and whatever skinny wire it is possible to attach to its terminals, presumably by soldering.

You're right that I forgot about direct inversion of PV power. But whatever applies at night also applies to some degree when a cloud goes over. And fuses aren't cheap, so it doesn't sound very convenient to have to check the skies and the existing loads every time you want to turn something on.

And you're right that I'm dismissing using a bigger shunt before anyone has tried it. But that's because I have an uncanny ability to predict the future of such things, using the dark arts known as physics and maths. Image

Coulomb has pointed out the problems with one possibility -- keeping the same shunt resistance, or millivolts per amp, but with a higher power rating.

The other option, the one that offGridQLD suggested -- keeping the same maximum millivolts but using a 200 amp shunt -- has the problem that the amp, amp-hour and watts readings would only be a quarter of what they really are. But yes, the SoC figures could still be correct if you tell it the battery capacity is one quarter of what it really is.

PIP-4048MS inverter

Posted: Thu, 04 Feb 2016, 03:17
by offgridQLD
Yes good point Weber. I forgot the devises have been using have a range shunt options but setting do need to be changed in the meters to tell it what external shunt your using.

Kurt

PIP-4048MS inverter

Posted: Thu, 04 Feb 2016, 13:06
by Northland
Lots of assumptions flying around.

1. A shunt cannot safety exceed it's rated current.
Looking at the wiki page for "shunt", it states that shunts are derated by 66%. Therefore a 50A rated shunt has been tested to carry 150A (we can theorize looking at the photo of this one but let's actually test it shall we? We have already established that the voltage as per the photo is not correct, maybe the shunt isn't either. In the absence of contrary evidence let's rely on the manufacturers rating of 100A surge. The same as the inverters surge rating, ie one does not adversely affect the other). This particular shunt looks like it can accept a heatsink, so the given rating could be factoring that in.

2. More than 50A through the shunt could cause a fire.
The same wiki page shows the properties of Manganin, and the math proves that there is insufficient resistance to create the necessary power loss to give off the amount of heat required to "start a fire".

3. A 50A fuse will save the day
A fuse is defined as a "course protection device" allowing 1.5x the rated current for 4hrs, and may allow up to 4x it's rated current before actually blowing. Any thinking that a fuse will instantly blow once 51A is reached is incorrect. A circuit breaker however is defined as a "close protection device" operating at 1.25x for 4hrs (ie much better than a fuse). Now since you should already have a DC breaker fitted, why would you replace it with an inferior form of protection? Again a 50A won't trip with a 100A surge I would expect. Is there a legal basis for this "requirement?"

4. All measurements will be wrong over 50A
The item description does not state this. It states that it can work up to 100A surge. Again, actually testing it will be required before drawing this conclusion.

5. You can't fit a 16mm cable to it.
I will prove you can, though I admit it will require some physical restraint

I already have a 50A shunt in my circuit so will try that first.

Considering the low cost and simplicity of a shunt, why the hell isn't there one on the pip already?   

PIP-4048MS inverter

Posted: Thu, 04 Feb 2016, 17:32
by weber
Northland,

I have not made any of the assumptions you list except for number 3 -- a 50 A HRC fuse will save the day. That was wrong. I now realise a 40 A fuse is necessary, but agree it may not be sufficient. It will be sufficient if the cable in its actual thermal environment is rated for at least 50 A continuous, and if this shunt (which is clearly designed to be soldered to a printed circuit board and mounted on a heatsink) really is capable of 50 amps continuous, and the same overloads-vs-time as the cable. By all means, do the experiment. Yes, it may well require a heatsink to achieve even a 50 A continuous rating.

I am well aware of time-current curves for cables, shunts, fuses and circuit breakers. I have been designing such systems for 15 years now, and have taught this stuff to electricians. The thing is, it's OK for a 40 A fuse to take 4 hours to blow at a 1.5 times overload because a 50 A cable can take that too. I agree that whether that particular shunt can take it, remains to be seen.

There is a very good reason why we use HRC fuses and not circuit breakers in some applications, particularly battery cables, despite their slower tripping on overloads. You're an ex sparky. Surely you can tell us why.

And you should be well aware that the legal basis is that the New Zealand Electricity Act requires compliance with AS/NZS 3000:2007 Wiring Rules, as does every state electricity act in Australia.

See sections 2.5.3 and 2.5.4 of AS/NZS 3000:2007. If your copy is older, I expect you will still find sections on Protection against overload current and Protection against short-circuit current which will not have changed much.

What makes you think there isn't a shunt in the PIP already? It has to measure battery current somehow, and I can't see a hall effect device on the battery side. It may consist of a length of PCB track and imay not be very accurate, as suggested by the 1 amp resolution on the display. The question is more: Why don't they use it for amp-hour counting and SoC determination?

PIP-4048MS inverter

Posted: Thu, 04 Feb 2016, 18:04
by offgridQLD
On the topic of AH counting and battery SOC using the PIP.

What are your plans for future PIP based systems in this area. As I think simple and reasonably accurate SOC monitoring is a nice feature for the end user. That is missing on the PIP (the build in SOC monitoring is very misleading and not worth looking at)

To date I'm finding a shunt based system that can just coulomb count with the ability to automatically (reset) to 100% each time the end of absorb - float transition is triggered doesn't have much time to drift between float triggers typicality it's just a 24hr or so cycle.

Though it has the shot fall that as the battery ages it still assumes it's the same predetermined capacity. I think this isn't to bad a compromise as a new baseline can be reset some time down the track after a full cycle test. (to be honest I think a lot of the Chinese lithium cells are under rated from the factory so it might take a few years even to decline to there rated capacity when treated gentle.

I use a system that's based around my Solar charge controllers with a few accessory's that let it track a few shunts and come up with a graphical display of what is going in and out of the battery.

Though with the Pip have you given any thought to future systems SOC readings for the end user to use. The average person who didn't care much about the technical side of there system would adapt well to a simple 0 - 100% number graphically displayed as they are accustomed to that with mobile phones or laptops.

I know when people visit our offgrid house and ask how full are the batterys. If I mention 300ah out of 400ah available for some reason there eyes start gloss over. Though mentioning 75% full seems to register well.

Kurt




PIP-4048MS inverter

Posted: Thu, 04 Feb 2016, 18:45
by weber
Almost missed this:
Northland wrote:In the absence of contrary evidence let's rely on the manufacturers rating of 100A surge. The same as the inverters surge rating, ie one does not adversely affect the other).
The inverter's maximum surge current is far more than 100 A. 100 A is more like its maximum continuous battery current. Its maximum surge battery current is at least 200 A.

In the PIP-4048MS manual, page 5 (pdf page 7)
http://www.mppsolar.com/manual/PIP-MS%2 ... manual.pdf
we see that the manufacturer recommends a 120 amp fuse and cables rated accordingly (1 x 38 mm^2 or 2 x 28 mm^2). I have used 35 mm^2 cable with 100 A fuses.

[Edit: Correction: Not 2 x 28 mm^2, but 2 x 14 mm^2, as pointed out by Coulomb, here]

PIP-4048MS inverter

Posted: Thu, 04 Feb 2016, 18:55
by coulomb
weber wrote: BTW, the term "coulometer" already refers to an electrolytic cell which measures electric charge by measuring the mass of a substance deposited at an electrode (typically silver, copper or hydrogen).

Well, a coulometer measures charge. Wikipedia mentions that these were also called voltameters. I don't see why the term coulometer has to be restricted to the first kind to be implemented (the electrolytic cell kind). Somehow Faraday and the others must have overlooked microcontrollers for this application Image

PIP-4048MS inverter

Posted: Thu, 04 Feb 2016, 19:01
by Northland
weber wrote:And you should be well aware that the legal basis is that the New Zealand Electricity Act requires compliance with AS/NZS 3000:2007 Wiring Rules, as does every state electricity act in Australia.

See sections 2.5.3 and 2.5.4 of AS/NZS 3000:2007. If your copy is older, I expect you will still find sections on Protection against overload current and Protection against short-circuit current which will not have changed much.


You are referring to regulations specifying voltage over 50v AC or 120v DC. These exist due to high short circuit fault currents possible when a main board is near a transformer. The short circuit current may exceed the braking current rating of the circuit breaker.
But this is completely irrelevant when discussing overload protection on a battery series with internal resistance (those resistances added I might add).

Before throwing the rule book at someone, best to read it.
The following clause says you are wrong (2000 version)

Image

I will restate my question : is there any legal basis for this requirement? I can find no regulations that would apply to a 48v battery

Edit: why are we creating a short circuit scenario for a shunt? How is it possible for it to short circuit when only the positive conductors are present? Should it overload, it will either heat up by 5 degrees (reality) or "fail spectacularly" creating an open circuit.

PIP-4048MS inverter

Posted: Thu, 04 Feb 2016, 20:01
by weber
I've got bad news for you. AS/NZS 3000 now specifically covers ELV as well as LV.

And there's no point quoting an obsolete version of the standard. It has no legal standing whatsoever. That clause has had several conditions added to it and is now numbered 2.5.4.4.

Even in its old form it doesn't amount to the complete omission of short-circuit protection, only an alternative position for it.

So what does the battery manufacturer say the maximum short circuit current of your batteries is? And what is the maximum DC breaking current of your circuit breaker?

Yes, internal resistances of batteries add in series, but so do their voltages, so the short circuit current stays the same and the arc gets harder to extinguish.

The shunt would carry the full fault current in a scenario involving a short at the inverter's battery terminals -- e.g. a tool slips while working in that space.

Yes, the shunt will fail spectacularly, but it won't create an open circuit. It will create an arc. That's why HRC fuses are filled with sand and why shunts are not legal short-circuit protection devices.

PIP-4048MS inverter

Posted: Thu, 04 Feb 2016, 20:44
by weber
Hi Kurt,

Our plans for SoC monitoring in future PIP-based systems are much the same as they were for Black Monolith #1, which you can find by using the index in the first post in this thread, and which operate exactly as you suggest, except that we have an analog meter as the 0 to 100% "fuel gauge". But in future we hope to use a Beagle-Bone-Black to serve a web page via wi-fi with an SoC meter.

A 0 to 100% load meter (based on instantaneous power) is also well understood by non-technical people.

PIP-4048MS inverter

Posted: Fri, 05 Feb 2016, 01:26
by coulomb
Beware of Chinese made copies of the Taiwanese designed and Chinese made Voltronic / MPP Solar inverters:

http://www.mppsolar.com/v3/company-anno ... -must-ups/

From that page: "We are also in contact with Business Trade Bureau in China about this violation though there are no positive feedback due to the low respect for intellectual property rights in China."

I've seen these on Ebay, and thought initially from their red colour that they must be Giant Power models. But they don't look quite right.

Image

[ Edit: It seems that they are also branded other than Must; the way to tell them apart from the real thing is that the knock-offs have the LEDs (AC/INV, Chg, Fault) at the left of the LCD, whereas the real Voltronic manufactured models have LEDs under the LCD, just above the buttons.

The sky blue stripe at the bottom may also indicate the fake, and it's easier to spot at a glance, but it would be all to easy to not include the stripe, or for an unethical distributor to paint over it. ]

PIP-4048MS inverter

Posted: Fri, 05 Feb 2016, 02:00
by coulomb
Monkeytom wrote: I was wondering if I could use the Gen start function to switch the second inverter on and not waist the second standby power till it was needed
As far as I know, the generator start / dry contact connections are relay outputs. I can't see how they could remotely start the inverter. Yet the remote panel seems to use this port for the "remote switch" input for the remote panel. If you don't have a dry contact "port", you don't use the second connection, and you don't get remote start capability.

[ Edit: this is sorted out in a later post. ]

It's totally unclear how the "remote switch" cable is supposed to connect to the remote panel. The cable in Ebay photos seems to show two bare wires at the inverter end. So presumably this connects to command and ... Normally Open?

Does anyone with a remote panel get remote start capability, and if so, how did you wire it up to the dry contact terminal block?

Remote panel installation manual: http://mppsolar.com/manual/PIP-HS_MS%20 ... 140609.pdf

PIP-4048MS inverter

Posted: Fri, 05 Feb 2016, 02:23
by T1 Terry
offgridQLD wrote: On the topic of AH counting and battery SOC using the PIP.

What are your plans for future PIP based systems in this area. As I think simple and reasonably accurate SOC monitoring is a nice feature for the end user. That is missing on the PIP (the build in SOC monitoring is very misleading and not worth looking at)

To date I'm finding a shunt based system that can just coulomb count with the ability to automatically (reset) to 100% each time the end of absorb - float transition is triggered doesn't have much time to drift between float triggers typicality it's just a 24hr or so cycle.

Though it has the shot fall that as the battery ages it still assumes it's the same predetermined capacity. I think this isn't to bad a compromise as a new baseline can be reset some time down the track after a full cycle test. (to be honest I think a lot of the Chinese lithium cells are under rated from the factory so it might take a few years even to decline to there rated capacity when treated gentle.

I use a system that's based around my Solar charge controllers with a few accessory's that let it track a few shunts and come up with a graphical display of what is going in and out of the battery.

Though with the Pip have you given any thought to future systems SOC readings for the end user to use. The average person who didn't care much about the technical side of there system would adapt well to a simple 0 - 100% number graphically displayed as they are accustomed to that with mobile phones or laptops.

I know when people visit our offgrid house and ask how full are the batterys. If I mention 300ah out of 400ah available for some reason there eyes start gloss over. Though mentioning 75% full seems to register well.

Kurt



For the cost, the Victron 700 or 702 BMV is well worth the added investment. The shunt is continuous rated at 500amps, the base model handles from 12v to 95v and the HV model from 0v to 385v, that should just about cover any monitoring requirements.

T1 Terry

PIP-4048MS inverter

Posted: Fri, 05 Feb 2016, 02:39
by weber
T1 Terry wrote:For the cost, the Victron 700 or 702 BMV is well worth the added investment. The shunt is continuous rated at 500amps, the base model handles from 12v to 95v and the HV model from 0v to 385v, that should just about cover any monitoring requirements.

Yes, those Victron BMVs are great. I've used them on several off-grid solar jobs back in my lead-acid days. No failures, and the customers seem to like them.

PIP-4048MS inverter

Posted: Fri, 05 Feb 2016, 03:32
by coulomb
weber wrote: In the PIP-4048MS manual, page 5 (pdf page 7)
http://www.mppsolar.com/manual/PIP-MS%2 ... manual.pdf
we see that the manufacturer recommends a 120 amp fuse and cables rated accordingly (1 x 38 mm^2 or 2 x 28 mm^2).
Actually, it says 1 x 2 AWG (= 34 mm^2 per Wikipedia), or 2 x 6 AWG (= 2 x 13.3 = 27 mm^2). They offer 38 mm^2 and 28 mm^2 as approximate equivalents; it's obviously not meant to be 2 x 28 mm^2.

I note that the paper manual that came with my PIP (paper manual version 1.4; web PDF as above is manual version 1.7) says 1 x 4 AWG or 2 x 8 AWG, and offers 22 and 14 mm^2 as rough equivalents (Wikipedia page would say 21 mm^2 or 17 mm^2).

So there are quite a lot of options to choose from Image

PIP-4048MS inverter

Posted: Fri, 05 Feb 2016, 04:08
by coulomb
coulomb wrote: Remote panel installation manual: http://mppsolar.com/manual/PIP-HS_MS%20 ... 140609.pdf

Giant Power have an updated manual: http://www.giantpower.com.au/assets/fil ... manual.pdf . It clearly shows the "switch in" cable connecting to C and NO of the dry contacts.

I wondered if the changes to JP1 and JP2 mentioned in the manual change the function of the "dry contact" terminal block. So I removed my serial board and buzzed it out. Sure enough, the JP1 and JP2 headers connect the dry contact terminals NC and NO to either the relay's NC and NO contacts (in the position marked DRY) or to CN5, which connects to the local inverter start switch. The C terminal always connects to the C contact of the relay.

[ Edit2: had C and NC swapped Image ]

So the "dry contact" can either be a generator start output, or a remote on/off input. [ Edit: but not at the same time; it's either/or. ]

C = Common, NO = Normally Open, NC = Normally closed.

PIP-4048MS inverter

Posted: Fri, 05 Feb 2016, 04:35
by weber
coulomb wrote:Actually, it says 1 x 2 AWG (= 34 mm^2 per Wikipedia), or 2 x 6 AWG (= 2 x 13.3 = 27 mm^2). They offer 38 mm^2 and 28 mm^2 as approximate equivalents; it's obviously not meant to be 2 x 28 mm^2.
Ah yes. Thanks. Silly of me. And yes, their supposed equivalents are a bit off. In IEC cable sizes the same-or-higher equivalents would be 1 x 35 mm^2 or 2 x 16 mm^2.
I note that the paper manual that came with my PIP (paper manual version 1.4; web PDF as above is manual version 1.7) says 1 x 4 AWG or 2 x 8 AWG, and offers 22 and 14 mm^2 as rough equivalents (Wikipedia page would say 21 mm^2 or 17 mm^2).

So there are quite a lot of options to choose from Image

I'd say they saw their error and corrected it in the later (i.e. online) manual.