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Hi I need some help setting up a BMV 702 , It will need to be a step by step guide for dummies?

I have 5 x axpert 5kva inverters in parallel , 1 x string of 24 x 2 volt rolls lead acid batteries

set up is off grid.

I also have a raspberry pi that I'm trying to integrate?

any settings / advice would be greatly appreciated.

 

cheers

 

george

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Hozid George 

25 Kva  Setup , I think this is the biggest Axpert setup yet. 

The victron site has quite a nice installation guide that you can use. Cant get much simpler than that

I also found this video to be quite good :

 

Regarding on if you are willing to spend time or money - ICC will be your quick bet or there are quite a few option on Gidhub available for the BMV alone there is even a Victron solution as an Image. 

 

I assume that you have your hardware setup done , ie fuses , bracers etr. Just be sure to sync the BMV after setup. 

 

Ps. Would you mind  giving us the full speck on your system? 

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6 hours ago, PaulF007 said:

there is even a Victron solution as an Image

Indeed, we ported Venus (the name of the firmware that runs on the Victron monitoring hardware, otherwise known as the Color-Control GX or CCGX for short) to the Raspberry Pi and we're giving it away for free. But it cannot monitor your Axpert and it never will, as a matter of principle. We would much rather sell you a decent inverter than do that :-)

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20 hours ago, George Major said:

I also have a raspberry pi that I'm trying to integrate?

Head over to ICC webpage where you can download software for your RasPI to monitor and control your 5x parallel Axperts;

http://iccsoftware.co.za/

ICC will also take the info from your BMV which greatly improves the allround operation of the system. I use the ICC-Win version so others would need to assist you with further setup advice.

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Thank you all for the advice so far.

I am moving forward ,

I have followed the setup as per video on the bmv702 as from paulF007,

I have the pi working and the icc software running.

But i do not think my batteries are charging up properly ?  I measured them this morning with a hydrometer - picture attached.

I ran on generator through last night and voltage was reading 56.5 as per viltron BMV702 pictures attached. 

10 minutes off generator batteries reading 50,1 volt ?  load was 1500 watts max.

If i read the instructions that came with the rolls battery they suggest bulk charge at 60 v ?  the axpert allows 58,4 v ?

I have attached some pictures of settings and set up.

Would be most grateful for any more suggestions ?

cheers

 

george

IMG_0320.jpg

IMG_0321.jpg

IMG_0322.jpg

IMG_0323.jpg

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2 hours ago, George Major said:

But i do not think my batteries are charging up properly ?  I measured them this morning with a hydrometer - picture attached.

Hi George 

Nice battery bank.

What size are the batteries? (Looks like about 1000Ah somewhere thereabouts).

What size is your PV array(s)?

You say you ran on the generator last night and the voltage was 56.5V. Was that this morning?

What charging rate are you using from grid/generator?

The 50.1V under the 1500W load was that early this morning before the sun was up?

Whether you managed to charge you batteries depends a lot on how far down you draw them overnight. The Axpert's inability to charge as high as 60V is a problem as your bank charges slower and there may not be enough daylight to spend a couple of hours in float. 

@plonkster likened charging with an Axpert that cannot hit 60V to driving down the freeway in one of those old 1600 cc Izuzu bakkies. You will get to your destination (get your batteries fully charged) but it might take a bit of time and with a solar installation you don't have all day.  

Axpert have produced a model that can charge to 60V. I cannot find the model now. I must admit the plethora of Axpert models makes my head spin.

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19 minutes ago, Chris Hobson said:

those old 1600 cc Izuzu bakkies

I used a Land Rover Defender as an example if I recall... but close enough :-) Though there are plenty of vehicles that fit the bill. Mahindra makes a really good contender, they have a knock-off jeep thing that has a top speed of maybe 120km/h... down a mineshaft.

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7 hours ago, Chris Hobson said:

Hi George 

Nice battery bank.

What size are the batteries? (Looks like about 1000Ah somewhere thereabouts).

What size is your PV array(s)?

You say you ran on the generator last night and the voltage was 56.5V. Was that this morning?

What charging rate are you using from grid/generator?

The 50.1V under the 1500W load was that early this morning before the sun was up?

Whether you managed to charge you batteries depends a lot on how far down you draw them overnight. The Axpert's inability to charge as high as 60V is a problem as your bank charges slower and there may not be enough daylight to spend a couple of hours in float. 

@plonkster likened charging with an Axpert that cannot hit 60V to driving down the freeway in one of those old 1600 cc Izuzu bakkies. You will get to your destination (get your batteries fully charged) but it might take a bit of time and with a solar installation you don't have all day.  

Axpert have produced a model that can charge to 60V. I cannot find the model now. I must admit the plethora of Axpert models makes my head spin.

Thanks Chris ,

batteries are 1288 ah @20c

yes 56,5 v was the battery voltage whilst the generator was still running this am.

almost immediately after turning generator off the voltage dropped to 50,1v

 

each Axpert is linked to 3 Strings of 3 panels of 255 watts each  so 45 panels in total

Set to charge at 10 amps per  axpert off generator

what should I use as bulk and float voltage ?

 

cheers

george

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Posted (edited)

Very nice bank... we are all very envious...

I would set bulk to the highest setting 58.4 and float to 54.4 and then each axpert to charge @ 20A (- I think highest @25A) so 120A to 125A max (both AC and PV).  I think we all agree hat 10% charge rate of max capacity, so 128.8A for your bank.

That bank needs serious amps to get it to a full charge!  Obviously check water levels regularly, I would expect to see a nice bubbling of the electrolyte ;)  Check the cable spec... can it handle 120A (they look ok...)

@Chris Hobson what do you think!

Regards

Mark

Edited by Mark

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Posted (edited)
31 minutes ago, Mark said:

That bank needs serious amps to get it to a full charge!

Agreed. It's a 1200Ah bank, you want to be above C10 or at least 120 amps! When you're generator is running you don't want to waste time, it's expensive to run it and you want to charge as quickly as possible (but not too quick, because then your efficiency takes a dive and you start boiling electrolyte). Some batteries allow you to charge at a C5 rate (around 20% of their capacity) at a bit more boil-off, that would be 200 amps even. The general rule of thumb is that for cyclical solar use, you want to charge around 12-15% of Ah capacity, and when a generator is running at 15% or as much as the manufacturer allows (eg some forklift battery makers allow higher... time is money for those guys). So you could probably set those chargers to as much as 30A or 35A each and still be good. Of course you also need a 10kva or larger alternator and a nice large engine too, possibly even larger.

Edited by plonkster

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Hi George,

You will get a number of different opinions here, so you may well finish reading the thread being more confused than when you started:huh:

2 hours ago, Mark said:

I would set bulk to the highest setting 58.4 and float to 54.4

I agree with Mark that your bulk voltage (AxMenu 26) should be set to the Max which is 58.4V, however I don't agree with float voltage settings (AxMenu 27) of 54.4V, and here is why;

Your batteries have the following manufacturers recommendations (at 25'):

  • Bulk AND Absorb = 2.5x24 = 60V,
  • Float = 2.25x24 = 54V,
  • Equalize =  2.6x24 = 62.4V

Firstly you can forget about equalizing, you will never get there. The Bulk/Absorb/Float is what we need to think about.

Bulk is the period where you system will raise the bank voltage over time from wherever it landed up overnight to the Bulk setting in Menu26 (58.4V), at this time your bank voltage will continue to charge at Float setting in Menu 27 (54V). This arrangement completely skips the Absorb period recommended by your manufacturer, which is an amount of time where your bank should be held at the Bulk voltage (this is when real work is done by your charger!).

Your manual gives an Absorb time calculation as follows;

  • T=0.42 x C/I
  • T = Absorb time
  • C = 20hr rated capacity (or 1288)
  • I = Charging current (recommended 10% - 20% of C20) - I suggest 200 Amps
  • T = 0.42 x 1288 x 200 = 2.7hr (call it 3 hours at 200amps or 40amps/Ax)

Given that Bulk charge will take a few hours in the morning, you can comfortably use the rest of the solar day at absorb voltage, and forget about float charging which is more important for standby batteries than cycling batteries.

So to summarize - set BOTH Menu 26 and 27 to 58.4V, and then accept the result - which will be acceptable:D

 

 

 

Rolls_Battery_Manual_Flooded.pdf

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Also note the following;

  • Panel capacity = 9 x 255 x x5 = 11.5kW (at 100%)
  • Absorb req = 200A x 58.4V = 11.7kW

So the panels will seldom (if ever) provide the full 200amps suggested with 40amps per inverter set in AxMenu [02] and [11]. When solar charging the system will send [panel power - load power] to the batteries, so final power provided to the batteries is very load dependent.

It sounds like you may be Off-Grid from your comment regarding charging with a generator, if so your gennie will need to be a beast (like 15kVA would be good) - also make sure Menu [01] is set to Uti, (off grid only, for grid assist use SBU).

Good luck, hope it works out well for you.

 

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Thanks Pilotfish now i know how to calculate the Bulk charging time for setting 32 on inverter . This setting works to the min  the inverter reaches bulk charge voltage . Does not go away even if high loads is applied during bulk/absorb charge . Thanks again

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35 minutes ago, Chris Louw said:

how to calculate the Bulk charging time for setting 32 on inverter

My Axpert MKS5k doesn't have a Menu 32 sadly as I am still using stock firmware - maybe time to upgrade firmware using Coulomb/Weber patch<_<

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This Meccer branded inverter produced March 2018 firmware 74 20 is realy a beter inverter . Battery charging is much beter . The 7 days using it the early morning battery voltage is up by  0.2 volt . The rasing of input watts when applying loads is very smooth . No matter what happens bulk does not fall away . Greetings all

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2 minutes ago, Chris Louw said:

This Meccer branded inverter produced March 2018 firmware 74 20 is realy a beter inverter

I wonder if my U1-72-40 can be upgraded and if they will provide the firmware?

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Inverter supplied by mustek , but we have to work through a dealer . I bought from Inverter Warehouse , the salesman Gary Bowes (011 058 1069 ) told me that they have guys that do firm ware . Remember I ask you about the 3000 watt heating element .Used a universal heater element and made a 3 ohm resitor and power consumption  2000 watt . Tumble dryer and wife happy .

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8 hours ago, pilotfish said:

Also note the following;

  • Panel capacity = 9 x 255 x x5 = 11.5kW (at 100%)
  • Absorb req = 200A x 58.4V = 11.7kW

So the panels will seldom (if ever) provide the full 200amps suggested with 40amps per inverter set in AxMenu [02] and [11]. When solar charging the system will send [panel power - load power] to the batteries, so final power provided to the batteries is very load dependent.

It sounds like you may be Off-Grid from your comment regarding charging with a generator, if so your gennie will need to be a beast (like 15kVA would be good) - also make sure Menu [01] is set to Uti, (off grid only, for grid assist use SBU).

Good luck, hope it works out well for you.

 

Thanks Pilotfish

That makes sense , I will try the settings and let you know how I go.  Generator is 18KVA.

Cheers

 

George

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20 hours ago, George Major said:

Thanks Chris ,

batteries are 1288 ah @20c

yes 56,5 v was the battery voltage whilst the generator was still running this am.

almost immediately after turning generator off the voltage dropped to 50,1v

 

each Axpert is linked to 3 Strings of 3 panels of 255 watts each  so 45 panels in total

Set to charge at 10 amps per  axpert off generator

what should I use as bulk and float voltage ?

 

cheers

george

Hi George

Sorry my day job interfered with me replying and you have received comprehensive replies.

As mentioned already you are probably under-gunned in the PV department. I did some slightly different calculations to pilotfish and came to the same answer. I do not know what your overnight draw is but let for arguments sake say you on a heavy load night draw down your batteries to 50% SOC (1288Ah  * 48 V =  31kWh. You have 11kW of panels and to recharge 31kWh probably need 35-36kWh  which is a stretch in winter anyway but I assume you have some sizable loads (5 Axperts -  couple of pumps and a DIY electric chair on loan from @plonkster).

Crank up your AC charging to 100-120A. The Axpert charging does not have to be even some can be on 30A and some on 20A to give you a total of 120A. One of the problems with lead acid batteries is if the current is not high enough all you do is elevate battery voltage and very little energy is stored. So those cloudy overcast days can really mess with your charging especially on a big bank like yours. I find that the  morning mist here in the Karoo is a solar killer. Whereas I have had ¼ of my normal solar production while it is raining I have had less than 100W due to mist and the light intensity appears much the same.

@pilotfish's suggestion of holding the batteries in absorb is a good one especially in light of the fact that the Axpert  cannot hit 60V.  Any loss of electrolyte can easily be replaced.

Setting Program 1 to UTI is great and confirm that program 16 is set to SNU.

 

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55 minutes ago, Chris Hobson said:

Hi George

Sorry my day job interfered with me replying and you have received comprehensive replies.

As mentioned already you are probably under-gunned in the PV department. I did some slightly different calculations to pilotfish and came to the same answer. I do not know what your overnight draw is but let for arguments sake say you on a heavy load night draw down your batteries to 50% SOC (1288Ah  * 48 V =  31kWh. You have 11kW of panels and to recharge 31kWh probably need 35-36kWh  which is a stretch in winter anyway but I assume you have some sizable loads (5 Axperts -  couple of pumps and a DIY electric chair on loan from @plonkster).

Crank up your AC charging to 100-120A. The Axpert charging does not have to be even some can be on 30A and some on 20A to give you a total of 120A. One of the problems with lead acid batteries is if the current is not high enough all you do is elevate battery voltage and very little energy is stored. So those cloudy overcast days can really mess with your charging especially on a big bank like yours. I find that the  morning mist here in the Karoo is a solar killer. Whereas I have had ¼ of my normal solar production while it is raining I have had less than 100W due to mist and the light intensity appears much the same.

@pilotfish's suggestion of holding the batteries in absorb is a good one especially in light of the fact that the Axpert  cannot hit 60V.  Any loss of electrolyte can easily be replaced.

Setting Program 1 to UTI is great and confirm that program 16 is set to SNU.

 

Thanks Chris 

should i and can I add more panels ?

 

cheers

george

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Yes and Yes.

If you have the space then add 3 more panels to each inverter so that you are running 4 strings of 3 (or 3s4p). That will put you at 3060W per Axpert which is great.

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@George Major I have 2 Axpert MKS 5Kva in parallel with 450AH Trojan T105 flooded lead-acid batteries. Float voltage is 54V, bulk/absorb voltage 59.3V and equalization 64.8V. So I have a similar problem to you as the Axpert's maximum charge voltage is limited to 58.4V. However I contacted Trojan in the USA and they advised that the Axpert maximum charge voltage will be suitable but bulk charging and equalization will just take longer. I have flashed both my inverters with the latest beta Aussie firmware by @Coulomb / @weber  and that allows for setting the bulk charging time under parameter 32. It is also worthwhile to download their manual. The link is to be found under Axpert Firmware on the forum. Based on the manual for your Rolls batteries, for which @pilotfish posted a link above, I would need to bulk/absorb charge for some 200 minutes at a current of 60A. The manual seems to me to be a real treasure for all flooded lead acid battery owners as there surely cannot be that much difference between various brands.

The correct settings for my BMV700, connected to a Raspberry Pi running ICC-Pi with the MQTT app on a Windows10 PC in my office remains a problem. The batteries are not bulk/absorb charged for long enough when parameter 32 on the Axperts is set to Auto so I suppose the better method is to set parameter 32 to the calculated time according to the Rolls user manual, which I have just done. Also I was advised by the original partner of @Manie to set the battery to utility (parameter 12) at a low value or it would interfere with the workings of ICC-Pi so mine is set to 44V. Parameter 13 on the Axperts is set to 48V for the same reason, parameter 26 (absorb voltage) to 58.4V and parameter 27 (float voltage) to 54V. My reasoning differs from that of @pilotfish on this particular setting as I would expect the batteries to be fully charged after being at 58.4V for 200 minutes. If the SG of cells do not indicate a full charge, one could increase the time setting of parameter 32. However since you are off grid, your needs may be different, particularly for how long your genset runs.

 

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