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Axpert inverter calibration


Selim ileri
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Hi , I have 2 peace Axpert 5KV inverter . I want to calibrate all these. My battery banks voltage is 52 Volt but one of inverter is 56 Volt other seems 56.7 Volt . I tried to calibrate use AccessPort 137  While calibration .I apply those described in this file  "SOP for bat voltage calibration.pdf"  for calibration but I didn't get (ACK 9. code 

 

]............(ACK9,  code that is meaning inverter accepts the command.................

please  help me ? 

 


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Not an expert here, just reading the documentation.

 

It seems what you have to do is feed the inverter with exactly 56V. Then you send it the BTA0T command over the serial interface and that calibrates the inverter. The inverter responds with some kind of ACK.

 

I was initially unsure if it is BTAOT or BTA0T (AT or zero-T), but the hex to the left of that shows 30, and 0x30 is ascii for zero.

 

Note that you cannot do this using batteries. You have to feed it with exactly 56V, so you're going to need a bench power supply. You then disconnect the batteries, and instead feed the inverter from the bench supply.

 

You might be able to get away with something a bit cheaper. There's some people on BidOrBuy selling cheap Buck/Boost Power Supply units for around R120, but very few of them can manage more than 40V... so I would say, unless you know what you are doing, perhaps get an expert to sort this out for you?

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Juding by the doc there are 3 commands that have to be sent:

 

BAT0 - places unit in battery calibration mode.

BAT1 - Tells the axpert the current (upper) voltage.

BAT2 - Tells the axpert the current (lower) voltage).

 

BAT1 and BAT2 are accompanied by the actual battery voltage in XXX.XX format (i.e. "BAT1056.00"). The mere fact that you tell the axpert what the voltage is tells me you could use any (within the allowable range) voltage, otherwise the axpert would just assume you connected 56V. The same goes for the BAT2 command. That being said, those voltages probably fall within a defined voltage window (e.g. 36...60V [an example]) so you might not be able to use, say 12V and 24V. I could be wrong, though.

 

The clincher is that the command must be followed by the 16-bit CRC of the command, and a <CR> character. That is probably why their example uses 56V and 44V, as those CRC16 values are supplied too. For any other voltage you would have to calculate the correct CRC (i.e. "BAT1036.24" would have a different CRC to "BAT1056.00").

 

I don't know their CRC algorithm, but it is probably the standard CRC16 with a commonly-used polynomial.

 

Anyway, what I'm trying to say is that it could probably be calibrated at any voltage, you might not necessarily need 56V and 44V exactly.

 

When I have time I'll play around with this and see what I can come up with, but I'm sure other people out there already have access to their serial protocol. Maybe someone could be friendly enough to post it here?

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My battery bank has 375 A , 48 Volt (2Volt x 24pcs.=48V) traction battery. this battery need  65V  to fill the full battery . I can not  do this. because Axper inverter work max. 58.5 volt  . also when  inverter voltage is 58.5 volts my battery voltage of 54 volts stays.  and than invertor stop charge.  I tryed  to make calibration to battery voltage and for fixing the inverter voltage. but I can not do this .I need  possible 65 volt to get full ,if not  58.5 volt battery voltage. if inverter ,does not bring  battery voltage of 65 volts or 58.5 the battery will deteriorate in a short time.

The total value of battery is EUR 4000

 

please help me...

 

HOW CAN BE BATTERY VOLTAGE 65 OR 58.5 Volt use this inverters.

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I know some of the Chinese inverters have issues with the voltage at the top end. For example, I know the smaller 24V Axpert has a maximum cut-out of 31V. Now a Trojan bank equalises at 32V... so that is a problem.

 

My guess is that the 65V you mention is for equalisation.

 

There are many Axpert users on this forum, and I believe TTT also uses Trojan batteries (which I believe does absorption at 59.2V) so hopefully he can help.

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Selim hi,

 

I have no experiences on the Axperts at all, sorry. My best suggestion is to chat to the battery supplier to ask them for their advice's.

 

My Trojan's are on 24v, and the Morningstar Tristar controller is adjusted to do it all for me automatically.

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I m from TURKEY . I bought it from here. I send a URL from another country produce but same to my battery bank.

This batteries used forklifts and their life are 1500 cycle. (Lead acid battery / traction for Electric Vehicle (EV) Battery )

 

 

 

http://nhbattery.com/e_productshow/?73-forklift-battery-48v-400ah-tractor-battery-48v-400ah-lead-acid-battery-driving-truck-battery-48v-traction-car-battery-400ah-forklift-truck-battery-73.html

http://www.directindustry.com/prod/exide-technolgies/product-12301-303392.html

 

price

http://www.haselvitrin.com/Inci-Traksiyoner-Forklift-Akusu,LA_8885-2.html#labels=8885-2

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Hi Selim,

 

I have traction batteries, (tubular plate) and yes they do need higher absorb voltage to work properly just like the fork  lift batteries.

 

I have an Axpert 4048 (PIP MS4048) and I have the same issue, so I have a second charge controller (midnight KID) to equalize the pack once a week at 63.2V(the advice from the battery supplier was to charge to 61V daily, but sincse the max is 58.4, he advices that I charge to the maximum and then once a week charge up to 64V) . When I do that I have to take the inverter off-line (I do it manually, turn all breakers off and then only turn on AC line input and inverter and the the AC output brakers ).

 

You should never feed the inverter more than 60V(it will go offline by itself at around 59.8V to 60.4V), I have heard the components are not made to survive much more than 64V, so they will blow. I am sorry I don't have better news but that is how this great piece of machinery works... you will need an external controller. I highly recommend a Midnight KID or one of the Classics with the WhizBang Jr. so you know your exact state of charge and can charge the batteries fully.

 

Regards from Spain

 

 

 

 

 

 

My battery bank has 375 A , 48 Volt (2Volt x 24pcs.=48V) traction battery. this battery need  65V  to fill the full battery . I can not  do this. because Axper inverter work max. 58.5 volt  . also when  inverter voltage is 58.5 volts my battery voltage of 54 volts stays.  and than invertor stop charge.  I tryed  to make calibration to battery voltage and for fixing the inverter voltage. but I can not do this .I need  possible 65 volt to get full ,if not  58.5 volt battery voltage. if inverter ,does not bring  battery voltage of 65 volts or 58.5 the battery will deteriorate in a short time.
The total value of battery is EUR 4000
 
please help me...
 
HOW CAN BE BATTERY VOLTAGE 65 OR 58.5 Volt use this inverters.

 

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Ok Thank a lot ,

I thing that ,maybe we can trick to inverters use calibration. I try to explain this.

 

1- When our battery voltage get 58.5 V .( may be use AC voltage for get this )

 

2- this time we will do calibration for 56v.

(inverter BAT1 - Tells the axpert the current (upper) voltage.)

(inverter feel 56 V but battery voltage is 58.5 v)

 

3- than inverter works and send energy to get for upper voltage for battery. 

 

Perhaps the voltage reaches 60 and 61 V., 

also I must do calibration because our inverter voltage and battery voltage are different. 

 

What is your idea for this?

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I don't think anyone has done calibration here. I don't even own one of these inverters. I will therefore have to guess.

 

My guess is that the inverter uses two voltage points (56V and 44V in this example) to solve a good old linear equation (y = mx + c), that is to determine a factor m and an offset c. What you want is to influence c to be higher, but leave m the same. The reason for all this mathematical reasoning is that determines whether I'm going to offset both the top and bottom voltages or just the one. If it uses this method (which it likely does), you have to offset both voltages. In other words, we're going to feed it with 58V and 46V and tell it that it is 56V and 44V.

 

The process entails two things. 1) Feed the inverter with a known voltage. 2) Tell the inverter what you want it to think that voltage is.

 

To do 1, you need a constant input voltage. For that I would suggest using a bench power supply. If you don't have one, you'll have to beg, borrow or steal one :-)

 

To do 2, you need to communicate with the inverter, and that entails a whole lot of questions.

 

2.1. From this forum, I've learned that some inverters have serial ports, and others have a USB port. Some have managed to get it to work, some not. So the first step would be to connect to the inverter serial port, plug it into a computer, open up a serial emulator (I have no idea what people in Windows land use for this, but that Accessport thing you have there is an example of this kind of software), and see if the inverter will talk back to you. This is the first obstacle to overcome.

 

2.2. Once you can talk to the inverter on the serial port, you have to work out the commands you're going to send to it. For each command you have to work out the CRC too.

 

Then, I'd do something like this.

 

1. Feed the inverter with 58V instead of 56. Turn it on, but don't put a load on it.

2. Put it in calibration mode by sending the command BTA0 (and append the CRC, which according to the example is 0x09, 0x54, or TAB T)

3. Send the voltage with the BTA1056 command, followed by the CRC. You will have to calculate this beforehand. I don't know how to do this. You will have to find out. Someone posted C# code for that on this forum that might help. Or you can assume the ones in the document are accurate.

4. Bring the voltage on the bench power supply down to 46 (instead of 44).

5. Send it the BTA2044 command, followed by the CRC. Calculate this beforehand or use the one in the example.

 

Type the commands in in HEX. That really is the only way to be sure. The 0D you see at the end of every string is an Enter (ascii 13), that sends the command off to the inverter.

 

After the command, the inverter will send an ACK, followed by a CRC.

 

Do this at your own risk :-)

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 (I have no idea what people in Windows land use for this, but that Accessport thing you have there is an example of this kind of software),

 

 

All my devices with serial ports, pick up automatically if I use the devices software, even on Windows 10 64bit!!! Can you BELIEVE that?  ;)

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I also think this may work, but you are still not going to know for sure that the batteries are at 100% charged because the inverter does not do a full charge and you still need an external charge to equalize the bank every month or so.

 

I would suggest getting a second charge controller and using this controller at a higher voltage to finish the charging the batteries, in my opinion a midnight solar should work,  but any charge controller that has an equalize setting should work.

 

Before doing that, I would set the float voltage to 58.2V and see if the battery still takes over much more than 20A when it is on float. If it does still takes much more than 20A it means it is not fully charged.

 

 

 

 

 

 

 

Ok Thank a lot ,
I thing that ,maybe we can trick to inverters use calibration. I try to explain this.
 
1- When our battery voltage get 58.5 V .( may be use AC voltage for get this )
 
2- this time we will do calibration for 56v.
(inverter BAT1 - Tells the axpert the current (upper) voltage.)
(inverter feel 56 V but battery voltage is 58.5 v)
 
3- than inverter works and send energy to get for upper voltage for battery. 
 
Perhaps the voltage reaches 60 and 61 V., 
also I must do calibration because our inverter voltage and battery voltage are different. 
 
What is your idea for this?

 

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  • 4 weeks later...
Quote
BAT1 and BAT2 are accompanied by the actual battery voltage in XXX.XX format (i.e. "BAT1056.00"). The mere fact that you tell the axpert what the voltage is tells me you could use any (within the allowable range) voltage, otherwise the axpert would just assume you connected 56V.

Yes, this appears to be the case. My reading of the firmware indicates that you can use any two voltages in any order (i.e. higher voltage first, or lower voltage first, but a valid BTA1 must come before BTA2). [ Edit: the BTA commands are also sent to the Solar Charge Controller; if it's powered up, it seems to expect the higher voltage first. ] However, they have to be at least 5.0 V apart (both the measurements and the arguments to the BTA1 and BTA2 commands), and the value in the BTA1 and BTA2 commands must not be over 60.0 V, and can't be zero. In addition, the difference between what it measures and what you tell it must not exceed 3.0 V, so you can't "spoof" the battery voltage by more than 3 V (but possibly a little more or less, depending on the natural error). Any violation of these conditions results in the command getting NAK'd instead of ACK'd. It looks to me that the inverter will still be expecting valid BTA1 and BTA2 commands.

Quote
That being said, those voltages probably fall within a defined voltage window (e.g. 36...60V [an example]) so you might not be able to use, say 12V and 24V. I could be wrong, though.

I don't think you can use really low voltages, say < 40.0 V, since it won't run the inverter. You could run it from mains or PV though. There doesn't seem to be a test for a low value, other than for zero, so that might work. However, best accuracy will be had by using realistic voltages.

Quote

The clincher is that the command must be followed by the 16-bit CRC of the command, and a <CR> character. That is probably why their example uses 56V and 44V, as those CRC16 values are supplied too. For any other voltage you would have to calculate the correct CRC (i.e. "BAT1036.24" would have a different CRC to "BAT1056.00").

I don't know their CRC algorithm, but it is probably the standard CRC16 with a commonly-used polynomial.

Yes, it's CCITT, as noted here:

http://forums.aeva.asn.au/forum_posts.asp?TID=4332&PID=57733&title=pip4048ms-inverter#57733

I note that this is when I welcomed Chris Hobson to the Australian Electric Vehicle Association forum, and now this is my first post here.

Thanks for posting about the calibration procedure. I had noticed the BTA commands some time back (along with perhaps fifty test commands) and wondered what they were about.

[ Edit: added comment re 5.0 V difference applying to both measurements and the BTA1/2 arguments. ]

Edited by Coulomb
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I should note that in firmware version 52.30, which happens to be the one I've examined the most, while the BTA0/1/2 commands are all there, and carefully calculate three mysterious values, and their magnitudes are checked (e.g. the main one should be 1024 +- 500), I can't actually find where they are used. It could be that I just haven't found that part of the code, or it might be that they planned to implement this but never finished it, or they had it implemented at one point, and had to comment it out for whatever reason. It may also be that later versions of the firmware have it implemented. I have found very little difference between 52.30 and 72.40.

I'll look at this more closely, but for now, it seems that figuring out how to perform calibration might not be worth too much effort.

Edit August 2018: I have since found what 2 of the three "mysterious" values are for; they are a scale and offset for the battery ADC measurement. So the calibration process seems real.

Edited by Coulomb
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Coulomb, did you disassemble the code in the firmware? It sound like you did :-)

Yes. I was chasing a problem with PV charging LiFePO4 batteries (I don't know if it will happen with lead acid), and got sucked in further and further. It took months to figure out the charging bug, then a week or two to develop and test the patch.

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Hard core man! Getting sucked in sounds like the kind of thing that happens to me too, but the worst problems I have to deal with rarely goes deeper than C code. Occasionally it goes as deep as a kernel driver, thankfully also C, and once it was a compiler bug I had to work around. But so far it's never gone as deep as disassembling proprietary code.

Sent from my GT-I9195 using Tapatalk

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