Weber and Coulomb's MX-5

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Post by weber » Sat, 19 Jun 2010, 19:09

7circle wrote: Did you check out the 300W High Voltage Rail Series from AMTEX
Input: 525 - 975VDC    Single: 12 ~ 130V options
http://www.amtex.com.au/power_pdf/power_6a.htm
eg http://www.amtex.com.au/power_pdf/HVI300R.pdf

Yes, we did. TJ pointed us to Amtex about a month ago, and suggested we be sitting down when we hear the prices. The problem with those above is that although the index page claims they start at 12 V, when you look at the data sheets you find they start at 24 V. We could have got some Amtex ones modified but they would have been around $1000 each.

We cannot use a single DC-DC now. Having gone with the 450 V Tritium Wavesculptor 200 drive and hoping to upgrade to a 900 V drive in future, and planning to use two chargers to charge the two half packs separately on occasion, we need to have a DC-DC on each half pack.

It's not the supplies we are worried about with the current sharing. It's the unbalancing of charge on the two half-packs reducing the usable capacity of the pack. Yes they will automatically share perfectly under full load, but not at half-load without very careful voltage adjustment, and some resistance whether internal or external to the supplies. We may not need external diodes. We will check, with a resistor, whether they can sink current as well as source. They were in stock at Mouser so they should be here within a week.

They do have fold-back current limiting, but only if the output voltage in current limit falls below 50% of normal output voltage. This would mean the 12 V battery was stuffed anyway.

If 30 amps is insufficient, as it probably will be, we will add two more of them. The price is right. But we thought we might as well make sure the basic idea works first.
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Post by coulomb » Sat, 19 Jun 2010, 21:12

weber wrote: Yes, we did. TJ pointed us to Amtex about a month ago, ...

Oh, that was those ones.
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Post by coulomb » Sat, 19 Jun 2010, 21:18

After cutting open one of the Elcon 7-pin connectors, I realised that it's possible to open the connector after all. I found this by studying this cutaway image from the datasheet carefully:

Image

Note the thread barely visible in the yellow oval. This is hidden under the front blue ring. The connectors are tight (water tight, I guess), so you may need a pair of pliers on the end of the connector to undo them.

This is the cable to the CAN box (the one I haven't mutilated). You can see that it connects to 4 pins: 2, 3, (ground and power), 6, 7 (TX and RX data).
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Post by coulomb » Mon, 21 Jun 2010, 00:42

I've been trying to suss out the protocol on pins 6 and 7 of the charger, when used with the CAN interface. RS232 is easier for experimentation than CAN bus, at least until our Tritium Drivers Controls box arrives (should be soon).

Pin 7 of the charger seems to send crude RS232 (approx 0.2 to 7 V) from the charger; it seems to expect data on pin 6. Pin 2 is ground.

The protocol is 2400/N/8/1; yes, that's 2400 baud! I was expecting at least 9600, possibly 19200 or even 115200. I suppose there is still plenty time to send 12 bytes (~ 50 ms) every second. This is perhaps why sending more than 2 packets per second confuses the charger; the 2400 baud link is a bottleneck.

The charger sends these 12 bytes every second: 18 FF 50 E5 VVVV IIII SS 00 00 00
where
VVVV is the voltage in tenths of a volt, MSB first, e.g. 03 F0 = 100.8 V
IIII is the current in tenths of an amp, e.g. 00 0A = 1.0 A
SS is the status, as per the lithiumate page, e.g. $10 = communications error (no CAN packet in 10 seconds).

Initially, this comes through as 18 FF 50 E5 00 0A 00 00 10 00 00 00
meaning as far as I can tell "I'm sending 1 packet per second, 8 bytes, some code = $3F destination = all (broadcast), my ID is E5 (charger), present voltage is 1.0 present current is 0.0 status is comms error". Indeed, there does seem to be about 0.67 VDC on the charger output; I'm guessing it's leakage.

I relied very heavily on this Lithiumate page for most of this.

18FF50E5 happens to be the ID mentioned on that page for the status packet from the Elcon charger. The message generated by the Lithiumate BMS is 1806E5F4, which happens to match the number printed on the top of the CAN interface box. So it seems that this is the ID that the Elcon must be expecting.

So presumably what I need to send back is 18 06 E5 F4 10 08 00 0A 00 00 00 00
which I think says "Charger, I'm the BMS, please dial up 410.4 V @ 1.0 A and turn yourself on".

I've written a simple program to send these bytes continuously with a 1 second delay between them. Unfortunately with Windows, you can't run two comms programs on the same port (Linux has no problem with this), so it's not easy to see the results coming back from the charger (at least until I find some example serial port reading code to adapt).

Alas, when I run this, I still get the seven-light code which means "communications interface fault".

So now I'm considering what might be wrong.   Image   I measure about 1M resistance from pin 6 to pin 2, so there seems to be something "listening" (and there isn't an open circuit in the RXD wire). Maybe it wants the RS232 to be clipped at 0V like the charger is sending, but that seems unlikely. I suppose it could be expecting opposite polarity, but that also seems unlikely.

Maybe I need to wait for the status packet to come out before sending back the "BMS" packet. Comments welcome.

[Edit: other code -> broadcast address; E5 = charger]
Last edited by coulomb on Fri, 23 Jul 2010, 05:28, edited 1 time in total.
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Post by mcudogs » Mon, 21 Jun 2010, 01:18

The CAN protocol states the following

Operation Mode
1. BMS send operating information (Message 1) and (Message 10+Message 11+Message 12) to charger at fixed intervals of one second. After receiving the message, the charger will work under the Voltage and Current in Message. If the Message is not received within five seconds, then it will enter into communication error state and the output will be closed.
2. The charger send broadcast message (Message 2) at intervals of one second. The display meter can show the status of the charger according to up-to-date information.

So I think you need to send Messages 10, 11 & 12 as well as 1 which you are already sending.

CAN Bus Protocol

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Post by a4x4kiwi » Mon, 21 Jun 2010, 01:59

Perhaps it is logic level 0-5v (inverted) serial.

edit. can you scope it?
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Post by Squiggles » Mon, 21 Jun 2010, 02:01

If you are using Windows XP or later be aware that windows may if it feels like it interfere with the serial comms whenever it wants.


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Post by coulomb » Mon, 21 Jun 2010, 04:49

mcudogs wrote: So I think you need to send Messages 10, 11 & 12 as well as 1 which you are already sending.

Ah, that sounds right; I was lulled by the Elithium page which only seems to mention the message 1.

It could be tricky trying to figure out the RS232 version of these messages.

Thanks!   Image
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Post by Squiggles » Mon, 21 Jun 2010, 05:04

Very tricky...after all it is CAN not RS232.

CAN has a physical specification and a protocol specification.
RS232 is physical layer only.

By the way somewhere in my archives I have a bunch of code written in Borland C that implements Modbus over RS232. Is it likely to be any use to you?

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Post by coulomb » Mon, 21 Jun 2010, 05:37

coulomb wrote: It could be tricky trying to figure out the RS232 version of these messages.

Actually, it's quite easy figuring this out; it's just a slightly different "desintation" address (E6 instead of E5, really part of the 29-bit extended ID), and different payload data. The other mysterious codes (PF and priority P) always seem to be 6.

I can't see that the charger needs these extra packets, and I suspect it will just ignore the contents. For example, what does the charger care about maximum discharge current? For a while I thought that message 11 might be the way to re-flash the "charger curves", with the battery curve number in byte 7. But now that I read it again, it seems more likely that "battery numbers" simply means the number of cells. Again, what does the charger want with this?

This PDF document seems to confuse "battery" with "cell" and "bit" with "byte".

However, the charger may expect these extra packets to be there, so I may as well try sending them (firstly in the order given, then other orders if that doesn't work) in case it just errors out the moment the information differs from what it's expecting.

I sure hope it doesn't do any error checking on the contents, or the number of possible combinations will be astronomical.
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Post by 7circle » Mon, 21 Jun 2010, 06:32

Ah the fun and games of comm's debugging. Image

Your Post viewtopic.php?p=25792&t=1949#p25792 Shows you have the CAN adaptor.

(EDIT - On the CAN adaptor)

With 12V and 0V on pin 3 to pin 2, what voltage wrt pin 2 is pin 6?

This may help establish the voltage level.
If its over 5V signals are likely to be active low (inverted)
The CAN Box may pull to 12V via opto output.

Also connecting the Computer serial port without OPTO interface could have problems. Elithion suggest connector may be "HOT" (I think you already checke it was linked to EARTH side pin.)

If the Charger is already configured to your battery pack by the supplier, you may only need to send just message 1.

Or you may have to send all 4 messages before time out. Elithion state 10 seconds for time out.

Each message packet has to complete in 1 second. So hand typing it in TERMINAL would be hard. But that time restriction may be only in the CAN domain.

Good luck.

If you make sense of the CANspec pdf and the Elithion circuits and ELCON supplier doc's you guys deserve a NOBLE Prize.

At least you don't have to worry about CRC counts in messages. (I hope)

http://evdl.org/archive/#nabble-td2123349
These guys recently discussed this, but only suggested ZIVIAN
with some mixed opinions.

Added (EDIT - On the CAN adaptor)
Last edited by coulomb on Fri, 28 Jul 2017, 04:47, edited 1 time in total.

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Post by coulomb » Mon, 21 Jun 2010, 06:49

coulomb wrote: I may as well try sending them (firstly in the order given...

Well, that didn't do any good. At least with the packets in the indicated order.
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Post by 7circle » Mon, 21 Jun 2010, 07:13

Just found intersing Simialr Chargers to ElCon

http://www.delta-q.com/products/index.html
Yellow boxes like ElCON mmm

The look like the type of gear to match WAVESCULPTOR, but its only 3.3kW Charger for 200-450Vdc
QMX HF/PFC Battery Charger/12V DC Power Supply Specifications - 3.3kW With CAN, 300W 12DC Aux Output and Water Cooling

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Post by coulomb » Mon, 21 Jun 2010, 07:14

7circle wrote: ... you have the CAN adaptor.
Yes. Though it is unplugged for these experiments.
With 12V and 0V on pin 3 to pin 2,
It's actually over 13 V; somewhere I read it should be 11. They're all good numbers for control logic.
what voltage wrt pin 2 is pin 6?
Pin 6 is the serial input (to the charger); it reads zero volts. I think you meant pin 7; it sits most of the time (mark) close to 0V, slightly positive, and rises to about 7 V for a space.
This may help establish the voltage level.
Yes, that's why I think that it should work straight through to the RS232 USB adapter.
Also connecting the Computer serial port without OPTO interface could have problems. Elithion suggest connector may be "HOT" (I think you already checked it was linked to EARTH side pin.)
This logic is all hot to the negative charger output terminal. I don't actually have a battery connected yet. It's all isolated from frame ground.
If the Charger is already configured to your battery pack by the supplier, you may only need to send just message 1.
Yes, surely only message 1 is needed.
Or you may have to send all 4 messages before time out. Elithion state 10 seconds for time out.
I've also seen 5 seconds for the timeout.
Each message packet has to complete in 1 second. So hand typing it in TERMINAL would be hard.
Very hard, as many of the required bytes have the high bit set, so you need to type ALT-0-2-2-9 for E5, and so on. That's why I wrote a stand alone C program. I use the same [edit: serial sending] code that successfully sends a 2 kB image to the BMUs.
If you make sense of the CANspec pdf and the Elithion circuits and ELCON supplier doc's you guys deserve a NOBLE Prize.
Oh, I'm not that noble, but those documents make reasonable sense to me now. Well, there's obviously something that I don't get yet, since I can't get it to work. [Edit: And certainly I don't deserve a Nobel prize.]
At least you don't have to worry about CRC counts in messages. (I hope)
Yes, there is no sign of a CRC or similar in the bytes from the controller. I assume that means there isn't one needed the other way around.

However, maybe the first byte has to be a special character to say that this is a BMS command; the same RS232 port seems to be used for flash programming the "charge curves". Maybe I need to send a dot or something first, then what I'm sending now; for flash programming all the commands might start with "P" (obviously, many many possibilities exist).

The real way to do this would be to put some sort of "serial sniffer" across the RS232 on a system with a working BMS and CAN interface.

Oh well, we'll just have to wait for a CAN controller and hope we have better luck there.
Last edited by coulomb on Sun, 20 Jun 2010, 21:27, edited 1 time in total.
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Post by coulomb » Mon, 21 Jun 2010, 07:42

7circle wrote: (EDIT - On the CAN adaptor)
With 12V and 0V on pin 3 to pin 2, what voltage wrt pin 2 is pin 6?

Oh, right... yes, that makes much more sense. Great idea! It'll be a while till I can get to it though. Coulomb will sleep now Image
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Post by 7circle » Mon, 21 Jun 2010, 07:52

Note - The voltage measurement on the pins out of the CAN/Serial black box adaptor 7pin connector. So you know what the Charger RX pin is expecting to driven to.
coulomb wrote:... However, maybe the first byte has to be a special character to say that this is a BMS command;
the same RS232 port seems to be used for flash programming the "charge" curves". Maybe I need to send a dot or something first, then what I'm sending now; for flash programming all the commands might start with "P" (obviously, many many possibilities exist).

The real way to do this would be to put some sort of "serial sniffer" across the RS232 on a system with a working BMS and CAN interface.

Oh well, we'll just have to wait for a CAN controller and hope we have better luck there.
Must be tempting to pull both the black box apart and the charger.
I'm suprised this info isn't on the forums yet.

Yes the "sniffer"would be great. How long till you get the CAN Controller?
What are you getting?
USB to CAN of some sort?

The CANbus pdf and the Elthion web page message info appear to line up.
In fact the pdf looks to make more sense.

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Post by 7circle » Mon, 21 Jun 2010, 08:02

Hey found where nancy posted CAN bus spec on endless sphere.
ElCon 1500W charger , New postby nancylooloo@yahoo.cn » Mon Mar 01, 2010 10:56 pm

CAN Bus Communication Spec.pdf

So this may give you more support from supplier rather than back door info.

Image

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Post by weber » Mon, 21 Jun 2010, 12:57

Thanks for all your help guys.

In a document that confuses Bits and Bytes, all Bets are off. Image

Consider this sentence:
"BMS send operating information (Message 1) and (Message 10+Message 11+Message 12) to charger at fixed intervals of one second."

We have an "and" between the parentheses and "+"s inside one parenthesis. The common everyday reading of this would be that the "+"s also mean "and". But why have the parentheses at all if that is the case. Why not write "Message 1+Message 10+Message 11+Message 12". I suggest that either the "+"s should be read as "or", as they are in Boolean algebra, or as seems more likely given the content of the messages, the "and" should be read as "or". So "(Message 1) or (Message 10+Message 11+Message 12)".

However, you've tried sending just Message 1, so if I'm right above, either some data is wrong or the voltages are wrong. Are you sure about that destination address change? Did you try both E5 and E6?
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Post by weber » Mon, 21 Jun 2010, 13:11

If I was designing the charger I expect I'd just use a different message number for flash programming the "charge curves" via RS232. But then I know nothing about CAN bus.

I can't see how the device can tell what "message number" it is receiving. Where is this "message number" in the packet?
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Post by Tritium_James » Mon, 21 Jun 2010, 13:55

Weber, if you have a digital scope that can see a decent length of time and still zoom in for the bit details, why not connect the CAN adapter to the charger, and see what it is sending on the RS232 connection between them? You might not have to have any CAN traffic for it to be sending some kind of heartbeat messages?

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Post by mcudogs » Mon, 21 Jun 2010, 19:03

Or you could use this freeware serial port monitor software.

Serial Port Monitor

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Post by coulomb » Wed, 23 Jun 2010, 04:38

The power supplies arrived today; wow, that's just over 4 days.

Image

Weber pointed out that in the USA, industrial three phase is 480 VAC phase to phase, hence 277 V phase to neutral (480 / √3). So that's just just over 15% higher than our 415/240 system, which is just over the 12.4% extra that we need to handle our half-pack (416/370 = 1.124; most power supplies have a maximum input voltage of about 370 VDC). This apparently is different to the [Edit: American] domestic standard, which is typically 220 VAC centre tapped, though there could be another phase as well, with 208 VAC from neutral to the other phase. Of course, they can have incompatible systems there since every dwelling gets their own transformer. In an industrial setting, 480 V is a bit much for fluoro (or LED!) lighting, so they use the lower phase to neutral voltage, 277 V. Just as we would, I suppose. Another mystery solved.

We attempted to make the two power supplies share a headlight load with clip leads and several multimeters on the kitchen table, but one took 3x the current load of the other. Adjusting the voltages just seemed to make it worse, though we didn't try very hard. I believe that the difference in multimeter shunt resistances, and the substantial resistance of the thin clip leads we used (we paralleled some of the thinner ones) would have led to the imbalance. So with proper wiring, I think they will share well.

We could dim the headlight using the current limit trimpot. The cold start current of the headlight prevented it from coming on again until the limit was increased.

Another delivery arrived today: 16 mm² cable, cable lugs, and a hall effect potbox from EV Works.
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Post by Johny » Wed, 23 Jun 2010, 15:41

According to the hairs on the back of my wrist you should be able to get 16.5 Amps at 13.6 volts (225 Watts) out of them. Without modern air-con and stuff that may well be enough. The Vogue only had a 35 Amp generator in it which supported an inefficient heater fan, twin headlights on high beam, windscreen wipers AND brake lights.
Provided you don't do anything strange (like too many high current contactors) you may get by.
Of course you may also be able to crank the current up slightly above spec. Image

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Post by coulomb » Thu, 24 Jun 2010, 00:17

I'm starting testing of the BMUs in a charging situation with a block of 8 of them. I intend to use a charger designed for 24 V lead acid. Here they are just freshly bolted together:

Image

You can see three wires between the fifth and sixth BMUs. What's that you say? Something unusual at the bottom of the picture?

Image

Ahem. Image I was using a quick and dirty trick to test a string of BMUs like this; you "just" short the opto isolator on the CPU side, and all the error LEDs should come on (it causes a serial "break", so nulls get transmitted along the chain). I've done it scores of times when the BMUs were component side up, but now they are the other way up and it's harder to see where you are poking. Well, you've possibly guessed it, one end of the opto is connected to Cell-, and that pad with the plus sign near it is the positive end of the "FAN" output (which we may never use), and it's connected to Vdd (which is Cell+ via the fuse). I must have connected the two, and the fuse let go.

Alas, we put the fuses under the board, "where it will be safer", says Weber. Well, that's very true, but now to get at the fuse, I need to unbolt all 5 BMUs that are joined together, 10 screws in all, and it turns out that the spare fuses are at the other factory. So it just seemed easier to solder in that fuse for this test. We'll fix the fuse before the cells go into a cage, of course. We can't have a metallic fuse hanging out like that.

The string measures just under 26.4 V, or just under 3.3 V per cell. Not too bad for cells that are likely over 13 months old. (They could have been from the batch of 16 that we bought later from EV Works). The serial numbers suggest a manufacturing date of June 2009, so that's 12 months old.

Edit: "It turns out that there is" -> "I was using"
Edit: string of cells -> string of BMUs
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Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.

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coulomb
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Weber and Coulomb's MX-5

Post by coulomb » Thu, 24 Jun 2010, 00:54

Johny wrote: According to the hairs on the back of my wrist you should be able to get 16.5 Amps at 13.6 volts (225 Watts) out of them.

I wonder about that. My hairs say that you will still be limited to 15 A, or a metric smidge more, meaning you can get more power than nominal (16 V x 15 A = 240 W, coincidentally (?) the power of the rest of the series).

But if we can get 16.5 amps from them, so much the better. I note that the specified voltage range is 14-16, but our units did 13.5 on one and slightly less on the other, and over 16 V at the other end. So maybe the current limits will be similarly generous.
Of course you may also be able to crank the current up slightly above spec.
Well, we won't be doing that by changing internal resistors; these supplies are potted with heat conductive compound; it's part of the IP65 rating I think. So there really are "no user serviceable parts inside"   Image   (unless you want to get really messy   Image Image ).
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.

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