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PIP-4048MS inverter

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offgridQLD View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote offgridQLD Quote  Post ReplyReply Direct Link To This Post Posted: 27 October 2014 at 12:57pm
John that sure saved a lot of work. Thanks for that!

Its a bit like (read the manual first) who would have thought the manufacturer would just hand it all out like that.

Kurt
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Johny Quote  Post ReplyReply Direct Link To This Post Posted: 27 October 2014 at 12:59pm
I googled the device name and their website came up. Shame we still don't have the crc.c but I think you've figured that out.


Edited by Johny - 27 October 2014 at 1:10pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote offgridQLD Quote  Post ReplyReply Direct Link To This Post Posted: 27 October 2014 at 2:10pm
"given that this installation has significant shade moving across the array at some parts of the day, I am forced to use three 72-cell panels per string. But then I run into the PIP-4048MS's array open circuit voltage limit of 145 V. The array open-circuit voltage may well exceed this on a frosty midwinter's dawn."

I'm sure you already know all this but just to bring it up.

Is there anyway around the shade at the location. Trim trees, different location, ground mount, creative split string...anything? Shade really is bad in more ways than one. I'm sure you have repaired your share of toasted panels effected by shade. The panels are compromised in there potential output for the life (20+ years) of the install. Now there is a 3rd issue with the need to series up the PV to compensate for it. Even the best charge controllers are less efficient when you start upping the voltage to much beyond the battery voltage the controllers run hotter.

Kurt

Edited by offgridQLD - 27 October 2014 at 5:24pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote T1 Terry Quote  Post ReplyReply Direct Link To This Post Posted: 27 October 2014 at 3:20pm
Originally posted by Johny Johny wrote:

While I'm typing this I'm assuming the next question will be where I got it.
I found the manufacturer and sent them an email this morning when I saw the chatter on the forum. I do this a lot for various things with not much success.
They actually answered.

Dear John

You may be looking for the communication protocol - please see attached.

thanks
Eric

On 2014/10/27 08:55, John XXXXX wrote:

Name John XXXXX
Email john.xxxx@xxxxxxxxx.com
Subject PIP-4048MS
Message Hi. We are adapting this inverter for use in charging Electric Vehicles and using Lithium batteries. Is there as document available that list all the serial commands like the ones that the PC application uses to "talk" to the inverter? We have figures out setting voltages but are wanting to also change absorb timers etc.
Site http://www.mppsolar.com/v3


We have found Eric and their team of engineers to be extremely helpful and only too willing to give out any information that will help you utilise their equipment and therefore sell more of them.

As far as how to work with shade across the panels? We only ever connect enough panels in series to exceed the battery voltage by enough to over come the wiring losses, so 2 panels in series works well. The trick is to parallel all the "A" panels as well as series connecting them to the "B" panels in each series string. The "B" panels are paralleled where they connect at the junction block before the cable run to the controller. This way any part of any panel in the "A" paralleled group can have shade across it but the output from the unshaded panels still feeds into the parallel cabling so any of the "B" unshaded panels can utilise the input from the paralleled 24v nom. supply to produce the required 48v nom. to charge the batteries.

If I didn't explain that very well I'll try to draw it up and see if that makes it easier to follow.

T1 Terry
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Post Options Post Options   Thanks (0) Thanks(0)   Quote weber Quote  Post ReplyReply Direct Link To This Post Posted: 27 October 2014 at 3:41pm
Originally posted by offgridQLD offgridQLD wrote:

Is there anyway around the shade at the location. Trim trees, different location, ground mount, creative split string...anything?

I suggested trimming the trees, and explained the consequences of the shade to the customer, but he made it clear that he just wanted me to quote on a system that would do what they want, without having to trim the trees. Ground mounts have their own problems -- aesthetics, cost of footings and cable trenches, possible damage by cows and horses, and even harder to find a shade-free place for them, being lower down.

What do you mean by "creative split string"?

Quote Shade really is bad in more ways than one. I'm sure you have repaired your share of toasted panels effected by shade. The panels are compromised in there potential output for the life (20+ years) of the install.

No. I haven't. As far as I am aware, the only way that could happen is if:
(a) the bypass diodes are inadequate for the job and fail, or
(b) the reverse breakdown voltage of a shaded cell is inadequate to withstand the voltage produced by the other 23 cells in the string protected by the bypass diode (typically 15 volts).

Quote Even the best charge controllers are less efficient when you start upping the voltage to much beyond the battery voltage so Controllers run hotter.

I don't understand why that should be. For the same power, the MOSFET in the buck converter will have higher voltage but lower average current. The inductor will have the same average current as before. The freewheeling diode (or active-rectifying MOSFET) will have higher average current. It could go either way, depending on the design.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote weber Quote  Post ReplyReply Direct Link To This Post Posted: 27 October 2014 at 3:50pm
No need to draw it T1 Terry. I know what you mean. You have strings of two panels and as well as connecting the ends of the strings together, you have also connected their middles together.

How does that help?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote weber Quote  Post ReplyReply Direct Link To This Post Posted: 27 October 2014 at 4:26pm
Originally posted by Johny Johny wrote:

I googled the device name and their website came up. Shame we still don't have the crc.c but I think you've figured that out.

It would save some time to have the C source-code for the CRC, if you don't mind asking them. Hopefully it will save me generating a 256 word lookup table.

BTW, PlanB, how did you learn what the CRC was?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote offgridQLD Quote  Post ReplyReply Direct Link To This Post Posted: 27 October 2014 at 4:36pm
"What do you mean by "creative split string"?"

I just see a lot of strings of PV lined up in a row or a block for esthetics or because the installer just wanted to take the easy option a lay down one line of racking. A more scattered arrangement might have avoided some patchy shading.

I have months of logs from my two identical charge controllers both have very similar Pv arrays connected to them 4000w on one and 4200w on the other. One is typically at 80ish volts input and the other is at 120 volts. They are mounted in the same location and the one with the 120v runs a lot hotter than the 80V unit. So much so that I contemplated rewiring the PV from 3s - 2s. Feels like there is more heat from the inductor area.

See this post
http://forums.aeva.asn.au/luiquid-cooling-solar-charge-controller_topic4301.html

When I posted about it on a few other forums it seemed like it was well known the choice was loss in the cable (2S) or loss in the controller (higher voltages)(3s+)

You can even see it on the output charts for charge controller the max output is reduced/derated the more you go above Battery voltage.

Kurt

Edited by offgridQLD - 27 October 2014 at 4:53pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote T1 Terry Quote  Post ReplyReply Direct Link To This Post Posted: 27 October 2014 at 5:10pm
Originally posted by weber weber wrote:

No need to draw it T1 Terry. I know what you mean. You have strings of two panels and as well as connecting the ends of the strings together, you have also connected their middles together.

How does that help?

Picture 2 strings of 5 panels, one above the other, the bottom row is Paralleled panel "A" and the top row panel "B"
Shadow cuts across the 2nd panel in the "A" string and the 3rd panel in the "B" string. Normally this would mean the series panels in position 2 and position 3 would have insufficient output to charge the batteries.
If all of string "A" are paralleled the unshaded no.3 panel in string "A" will feed into the unshaded no.2 panel in string "B" effectively reducing the loss to 1 pr of panels instead of 2 pr.
We have found it goes even further than that, the part of a panel that isn't shade effected still puts it's bit in so often the loss is equivalent to half a panel, even though the shade effect was at 2 different points at either end of the string.

Compared to nearly wasting the output from each 3rd panel in series as heat in an MPPT controller when the sun shines on all 3 panels, the 2 panels in series/parallel seems to give a better overall output, it just involves a bit more cabling.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote weber Quote  Post ReplyReply Direct Link To This Post Posted: 27 October 2014 at 5:58pm
Hey guys, the term "string" has a very definite meaning in electrical work. It is not a number of things physically laid out in a row. Nor is it a number of things connected in parallel. It is a number of things connnected in series.

From AS5033 (PV arrays)
Quote 1.4.51 PV string
A circuit of one or more series-connected modules.
[IEC 61836, Ed. 2]

The same goes for cells in a battery. In AS4509 (standalone power systems), although it doesn't have an explicit definition, a "string" of cells is clearly a number of cells in series.

The problem with cross-connections between strings, at any points other than their ends, is that it makes it difficult and expensive to protect the cables and panels against overload or short circuit. You'd have to fuse every panel, not just every string. It isn't even considered as a possibility in the Australian standards.

Here's the last draft of AS5033 (PV arrays) before the current version (the real thing costs $200):
http://solar.poirus.com.au/DR11001.pdf
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Post Options Post Options   Thanks (0) Thanks(0)   Quote offgridQLD Quote  Post ReplyReply Direct Link To This Post Posted: 27 October 2014 at 6:22pm
"
Hey guys, the term "string" has a very definite meaning in electrical work. It is not a number of things physically laid out in a row. Nor is it a number of things connected in parallel. It is a number of things connnected in series."

Yes sorry I do know that, though I was referring to a lot of grid connect systems that I see. Typically just have one (string) of series panels. laid out in a straight row or square block. That if they could be bothered cutting the racking up (wiring all the same) though just spreading the panels around the roof avoiding the shade. More work, less attractive but perhaps worth it if producing power is why you have them on your roof.

Though yes sorry I know it would be confusing (and the wrong word to use) as we are talking about a offgid system it's typically lots of small (2s,3s) strings all paralleled together.

Anyhow Perhaps I should have just said creative PV layout/positioning to avoid shading.


Kurt

Edited by offgridQLD - 27 October 2014 at 6:28pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote weber Quote  Post ReplyReply Direct Link To This Post Posted: 27 October 2014 at 6:55pm
PlanB, I figured out why the 0x0A in the CRC gets changed to a 0x0B. It turns out that either a carriage return (0x0D) or a linefeed (0x0A) is treated as an end-of-packet character. So if either of them turns up in a CRC, it must be changed to something else, presumably just by adding one to it. But I'm only guessing that a 0x0D will be changed to a 0x0E.

I learned this because Coulomb suggested I send a QBOOT command to see if it returned a "1" meaning the DSP chip has bootstrap loading. I calculated the checksum for QBOOT as 0x0A88 but as soon as I typed Ctrl+J to send 0x0A it came back with a "NAK". "Aha!" says I. "PlanB gave me an important clue here."

When I instead typed Ctrl+K (0x0B) then Right-Alt+Ctrl+H (0x88) and carriage return, it came back with "(1" followed by a CRC.

This was using TeraTerm where I edited the TERATERM.INI file to enable the right Alt key to be the "meta" key (functioning as a "set the high bit" key). You have to set the meta key to "raw" mode so it doesn't send them as a two-character-sequence in UTF-8.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote weber Quote  Post ReplyReply Direct Link To This Post Posted: 27 October 2014 at 7:21pm
Originally posted by offgridQLD offgridQLD wrote:

I have months of logs from my two identical charge controllers both have very similar Pv arrays connected ...

Kurt, I never doubted this was the case with your own MPPTs (Midnight Classics). I was only questioning your implication that all makes and models were like that. You wrote "Even the best ...".

Quote When I posted about it on a few other forums it seemed like it was well known the choice was loss in the cable (2S) or loss in the controller (higher voltages)(3s+)

OK. Thanks for that. I certainly haven't found any examples that show the losses going in the other direction, but then most of them don't give such curves, like the Midnight does.

I suppose if they use a passive freewheel diode, its losses would dominate, and they would increase with increasing array voltage. But I imagine that super-efficient MPPTs like the AERL models, would use another MOSFET to freewheel the inductor, and their losses might not be any different at high or low array voltages.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote offgridQLD Quote  Post ReplyReply Direct Link To This Post Posted: 27 October 2014 at 7:56pm
True that was a assumption on my part after seeing references to the issue when a few different brands of well know controllers were talked about.

I will add that I am pedantic about component heat. probably a bit to much so and might be blowing things out of proportion.

How hot is to hot? I don't know even 1% on 4200w is 42w of heat in a aluminum box 2% 84w and so on. Some say if you can still touch the case without going awch then all is well The worst I have seen is about 60C at the fets and around 58C pcb (before being tamed by the 2nd external fan)I just noticed that my other controller never went that high. Part of the feeling that things are hot might be down to the fact the cast aluminum case is actually a big heat sink so its designed to wick heat away from the components inside. Could just be a bad design though (I wont pretend to understand from a technical aspect if it is it is or isn't)

Perhaps the bonus mppt charge controller in the PIP4048 is of a superior design than the classic 150 (if price is anything to go by I don't think so) So I assumed it would be similar or less tolerant to high voltage input than the classic. Perhaps it shares some of the Aerl's design advantages

Kurt

Edited by offgridQLD - 27 October 2014 at 8:00pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote weber Quote  Post ReplyReply Direct Link To This Post Posted: 27 October 2014 at 8:14pm
Found the CRC.c source code on this German solar forum. Had to join to get it, but there was already a weber, so I'm weber2.
http://www.photovoltaikforum.com/pv-inselanlagen-f57/erfahrungen-mit-mpp-solar-taiwan-rules--t99303-s610.html#p1146179
It shows that not only carriage return (0x0D) and linefeed (0x0A) are incremented if they occur in a CRC, but also left parenthesis (0x28) [Edit:] which is the character that precedes all responses.

I tried to upload it to this forum as the file "CRC.c.txt", but this forum won't let you upload anything as dangerous as a .txt file. So here its is, formatted as found, except I removed many blank lines.

INT16U cal_crc_half(INT8U far *pin, INT8U len)
{
     INT16U crc;
     INT8U da;
     INT8U far *ptr;
     INT8U bCRCHign;
    INT8U bCRCLow;
     INT16U crc_ta[16]=
     {
          0x0000,0x1021,0x2042,0x3063,0x4084,0x50a5,0x60c6,0x70e7,
          0x8108,0x9129,0xa14a,0xb16b,0xc18c,0xd1ad,0xe1ce,0xf1ef
     };
     ptr=pin;
     crc=0;
     while(len--!=0)
     {
          da=((INT8U)(crc>>8))>>4;
          crc<<=4;
          crc^=crc_ta[da^(*ptr>>4)];
          da=((INT8U)(crc>>8))>>4;
          crc<<=4;
          crc^=crc_ta[da^(*ptr&0x0f)];
          ptr++;
     }
     bCRCLow = crc;
    bCRCHign= (INT8U)(crc>>8);
     if(bCRCLow==0x28||bCRCLow==0x0d||bCRCLow==0x0a)
    {
         bCRCLow++;
    }
    if(bCRCHign==0x28||bCRCHign==0x0d||bCRCHign==0x0a)
    {
          bCRCHign++;
    }
    crc = ((INT16U)bCRCHign)<<8;
    crc += bCRCLow;
     return(crc);
}


[Edit:] It's an interesting compromise* between the speed of a byte-at-a-time version with a 256 word lookup table and a bit-at-a-time version with no look up table. It's a nybble-at-a-time version with a 16 word lookup table.

*Or it would be an interesting compromise, if our chosen micro-controller had a barrel-shifter. In our case, bit-at-a-time (as suggested by Coulomb on Saturday) would probably be just as fast, with the inner loop unrolled.

Edited by weber - 27 October 2014 at 8:31pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote weber Quote  Post ReplyReply Direct Link To This Post Posted: 27 October 2014 at 8:58pm
Originally posted by offgridQLD offgridQLD wrote:

Perhaps the bonus mppt charge controller in the PIP4048 is of a superior design than the classic 150 (if price is anything to go by I don't think so) So I assumed it would be similar or less tolerant to high voltage input than the classic. Perhaps it shares some of the Aerl's design advantages

Ha ha ha. Yes. I expect you will be able to make toast on it.

But maybe something can be done, like beefing up the freewheel diode. Unfortunately paralleling diodes doesn't work. The hottest one has the lowest voltage drop and so takes the most current.

I wonder what component most limits the maximum input voltage to the MPPT. Probably spikes on the MOSFET. Will have to start digging into that soon.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote offgridQLD Quote  Post ReplyReply Direct Link To This Post Posted: 28 October 2014 at 4:37am
from the Aerl's specs sheet.
"Operating temperature of heat sink at full rated power 35°C temperature rise"

It was about 30C in my power room that day. I was pushing my units hard - 60C max was the recorded temp. So that's only a 30C gain over ambient temps.

Perhaps I am worryied about nothing.

One thought on the PIP4048. If you guys tweak your own unit to make it superior. I wonder if there would be any interest from the manufacturer to implement some changes or if its a huge successes story perhaps becoming a local distributor for a a tweaked version (insert name) Then again it could all go up in flames and be something you want to distance your self from .

Kurt

Edited by offgridQLD - 28 October 2014 at 4:41am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Johny Quote  Post ReplyReply Direct Link To This Post Posted: 28 October 2014 at 11:23am
CRC.c and Readme.txt from Eric.
It looks the same as the code already found.
crc.zip
Edit: Added text view of files (Hah - even the tabbing is flaky in the same places)

Readme.txt
----------
QPI CRC value is: 0xBEAC

QPI: 0x51 0x50 0x49

Return: 0x0D

The QPI command (HEX value) sent to unit is: 515049BEAC0D


CRC.c
-----

INT16U cal_crc_half(INT8U far *pin, INT8U len)
{

     INT16U crc;

     INT8U da;
     INT8U far *ptr;
     INT8U bCRCHign;
    INT8U bCRCLow;

     INT16U crc_ta[16]=
     {
          0x0000,0x1021,0x2042,0x3063,0x4084,0x50a5,0x60c6,0x70e7,

          0x8108,0x9129,0xa14a,0xb16b,0xc18c,0xd1ad,0xe1ce,0xf1ef
     };
     ptr=pin;
     crc=0;
     
     while(len--!=0)
     {
          da=((INT8U)(crc>>8))>>4;

          crc<<=4;

          crc^=crc_ta[da^(*ptr>>4)];

          da=((INT8U)(crc>>8))>>4;

          crc<<=4;

          crc^=crc_ta[da^(*ptr&0x0f)];

          ptr++;
     }
     bCRCLow = crc;

    bCRCHign= (INT8U)(crc>>8);

     if(bCRCLow==0x28||bCRCLow==0x0d||bCRCLow==0x0a)

    {
         bCRCLow++;
    }
    if(bCRCHign==0x28||bCRCHign==0x0d||bCRCHign==0x0a)

    {
          bCRCHign++;
    }
    crc = ((INT16U)bCRCHign)<<8;
    crc += bCRCLow;
     return(crc);
}


Edited by Johny - 28 October 2014 at 11:30am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PlanB Quote  Post ReplyReply Direct Link To This Post Posted: 30 October 2014 at 12:48pm
Just curious guys got a 4048 running here, nothing connected to AC output but inverter switch up (on) so maintaining 240v on the output, fans howling but AC output active power never gets above about 16w so not sure about that 50w figure Dave?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote PlanB Quote  Post ReplyReply Direct Link To This Post Posted: 30 October 2014 at 12:53pm
Glad one of us is smart enough to figure out the CRC hiccup! Nice to know the why of these things.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote weber Quote  Post ReplyReply Direct Link To This Post Posted: 30 October 2014 at 1:34pm
Originally posted by PlanB PlanB wrote:

Just curious guys got a 4048 running here, nothing connected to AC output but inverter switch up (on) so maintaining 240v on the output, fans howling but AC output active power never gets above about 16w so not sure about that 50w figure Dave?

That would be 50 watts DC out of the battery, i.e. about 1 amp. We haven't measured it, except with a clamp meter whose DC current readings are +- 0.5 amp.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Adverse Effects Quote  Post ReplyReply Direct Link To This Post Posted: 30 October 2014 at 1:39pm
pls forgive a dumb question but how dose a shunt measure current
i understand how a clamp one works with magnetic field strength
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Johny Quote  Post ReplyReply Direct Link To This Post Posted: 30 October 2014 at 1:42pm
Originally posted by Adverse Effects Adverse Effects wrote:

pls forgive a dumb question but how dose a shunt measure current
i understand how a clamp one works with magnetic field strength
A shunt is a low-value, temperature stable, calibrated resistor. The meter measures the voltage dropped across it and the scale (usually about 100mV full scale) is marked in Amps.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Adverse Effects Quote  Post ReplyReply Direct Link To This Post Posted: 30 October 2014 at 1:47pm
thank you
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Post Options Post Options   Thanks (0) Thanks(0)   Quote weber Quote  Post ReplyReply Direct Link To This Post Posted: 30 October 2014 at 1:50pm
Originally posted by Adverse Effects Adverse Effects wrote:

pls forgive a dumb question but how dose a shunt measure current
i understand how a clamp one works with magnetic field strength

A shunt is simply a resistor with a very small but very precise resistance and four terminals, two big ones to carry the current and two small ones for reading the voltage dropped across it.

Where ordinary resistors are rated in ohms and watts, shunts are rated in amps and volts, but you can convert between these different ways of specifying, by using Ohms law and the power law.

For example, the shunts used in the MX-5 (and this solar job) are rated at 200 amps 50 millivolts. So that's 50 mV / 200 A = 250 micro-ohms and 50 mV x 200 A = 10 watts.



[Edit:]
Hall effect devices, as used in DC Clamps, have problems of offset and drift due to the earth's magnetic field, other stray DC magnetic fields and residual magnetism in their core. So they are not much use for measuring currents less than an amp. Shunts do not have these problems and so are far more precise. But Hall-effect clamps are inherently isolated, which is good when working with high voltages. However we use an isolated shunt measurement unit in the MX-5 (and this solar job) that is powered via a tiny isolated DC-DC converter and communicates via optic fibre.


Edited by weber - 30 October 2014 at 2:15pm
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).
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