ebrsa

I am running the previous patch with no issues.

Question:  How big is your PV array?

- Make sure your settings allow the solar to charge to 40A so it has the time to go all the way to the top...

I'm only suggesting the bulk from Grid as a weekly exercise so you can get the Trojans stired up nicely.

Regards

Mark

Thanks Mark. I have 6 x 260W panels in 2 sets of 3 on the master inverter and 1x260W + 2x250W making another set of 3 on the slave inverter. The set of 3 will result in 750W as far as I know. I have set setting 2 on both inverters to 40A but of course the solar will never reach that. However if I set the grid chargers to 40A once a week or so then I won't have to change setting 2 which will limit charging to 40A. What is not clear from the manual is if charging is cumulative in parallel mode. ie if both inverters have setting 2 set to 40A, will that result in a charging current of 80A. I suppose I can just set that up in grid mode and see what happens.

Yesterday with plenty of sunlight, I set the tail current on the BMV700 to 1.5% which implies a current of  6.75A. The inverters charged at 58.3V from solar until the amps dropped to below 6.75A at which stage the voltage dropped to 54V as it should. However I still had to force it by turning solar and grid supplies off and on again to get the voltage to climb to 58.4. That is what @Coulomb 's patch solves as I read from his explanation.

I am glad to hear that your patched firmware works well. Gives me the confidence to try it too.

Regards, Edward.

Today I could see clearly that the inverter was way short and it went to float with 36Ah to go. I had a good 5 hours straight where the geyser was on and then when the geyser went off at 2pm we almost immediately went to float. Yesterday was cloudy most of the day but when the sun came out at 4:30 pm we still were able to get 1500W. Today at 2 pm about 700W so tomorrow's project is to update the firmware with Coulomb's patched firmware.

This afternoon I managed to lay my hands on a serial cable from a 3kVA Axpert.

Today I reflashed my inverter's firmware from 56.40 to Coulomb's lead acid 72.60. Although I could not get Watchpower to communicate via the serial cable the reflash went smoothly.

Whilst I was busy I reflashed the SCC firmware to 4.10 too.

Tomorrow I will see whether the charging goes according to plan.

 

I look forward to your feedback about the results of Coulomb's firmware upgrade of your inverter. Is your inverter a 5Kva Axpert. If not and the upgrade went well maybe the firmware will work on other models. I thought Coulomb said his firmware was for the 5Kva inverters.

It is good news to hear that both upgrades went well. Gives me confidence to upgrade my 2 x  5Kva inverters. Do you use AICC and if so also a BMV? What are your float voltage and tail current settings? SInce you flashed the lead acid firmware I am very interested as my batteries are Trojan T105 flooded lead acid. 

58 minutes ago, Chris Hobson said:

Today I reflashed my inverter's firmware from 56.40 to Coulomb's lead acid 72.60. Although I could not get Watchpower to communicate via the serial cable the reflash went smoothly.

Whilst I was busy I reflashed the SCC firmware to 4.10 too.

Tomorrow I will see whether the charging goes according to plan.

 

I've also done mine today. Also lead-acid and the MPPT to 4.10.  

We can compare notes

Hi Edward

Yes I have a 5kVA inverter. I use Edmund Pohl's SolarMon but basically the software will interact with the inverter in the same manner as AICC. The software will be unaware of the fact that it is not pucker Voltronic firmware. You query the inverter and then receive a string back that needs to be interpreted. You issue commands and the inverter acknowledges receiving them. If you query the firmware the software will think it is 72.60. Yes I also have a BMV 702 which I rely on quite heavily for battery information.

My bulk and float voltages are 56.4 and 54.4V respectively. At the height of summer I drop bulk to 56.0 V to remain below gassing voltage. My tail current is 2.8% with a charge detection time of 30 min. The values have been settled on over the course of the year. The BMV still goes to 100% a little early but at 2.7% it is way off. Have a look at Dockarl's video.

https://www.youtube.com/watch?v=YXbjJzyIFgg

MY hassle with Axpert and Trojans is that Trojans have a high bulk charging voltage and there is not much headroom in terms of DC bus capacitors as they are rated at 63V. I have noticed that the voltage on Axpert can go 2.2 V above your bulk setting for a short period of time, when you have a variable load like an iron or have a day with broken cloud. Trojans bulk is at 59.2V and you add 2.2V to that and you are very close to the 63V rating of the capacitors. There is an Aussie who has a Youtube channel that was not happy with the Axpert SCC and this may be the reason. I know your system has been up and running for a while. What is the highest voltage seen on your system (H in the BMV's history)?

Hope that answers your questions.

 

 

Do you know if there are any updated firmware for the Axpert MKS plus 3K? 
this is the model with the 60 amp charge controller

this 24 volt model have a max of 29.2 volt during bulk  and if the bank is full and big loads gets switched off ive seen it go up to 29.8 before it drops down to 29.2

5 hours ago, wtjaden said:

Do you know if there are any updated firmware for the Axpert MKS plus 3K? 
this is the model with the 60 amp charge controller

this 24 volt model have a max of 29.2 volt during bulk  and if the bank is full and big loads gets switched off ive seen it go up to 29.8 before it drops down to 29.2

Hi

I have not found firmware for this model. If you do find a firmware upgrade let us know. I have a mate not on the forum looking for 3kVA firmware upgrade.

 

I power a geyser between 9:30 and 2 pm to use excess energy. 

After replacing my firmware with @Coulomb 's patched firmware my Axpert still goes to float early after the geyser is switched off. Something about the hours on end charging at 6-15A  messes with the charging algorithm. It maybe that in fact the batteries are charged but the BMV battery monitor shows 5-12Ah to go. I have the Peukert values on default and it may be that the batteries are in fact charged transitioning from bulk to float with no real absorb.  

Having closely monitored my system it appears that the reason I do not see a long absorb is that the slow charge is charging the battery sufficiently and when there is more power available (due to the geyser going off) the batteries are virtually full charged. So all ends well.

 

Hi Chris,

Thanks a great deal for all your information. I flashed @Coulomb 's firmware for both CPU's on both Axperts on Monday and saw an immediate improvement in the afternoon after I was done. Was not at home yesterday but batteries were at 100% when I got home late afternoon. Today I attempted to upgrade AICC and Machine ID changed so software was no longer registered. Seems like Nomachine had some effect because the ID reverted to what it was before I did a Nomachine upgrade. I decided to uninstall Nomachine and Teamviewer and just use RealVNC viewer which is free. The server is already loaded on Jessie for the RPi. Currently I am waiting for a new activation code for AICC. However today was a mostly cloudy day with some rain and the BMV tell me the batteries are at 87.6% with no grid being used since this morning. Needless to say I am a happy chap so far.

Regarding the bulk charge voltage, the Axpert allows a maximum of 58.4 and it got to that for some time with the patched firmware. It would be useful to know whether AICC uses information like float voltage and tail current from the BMV otherwise there is no point in bothering with that. It would seem that the Axpert does not use BMV data either or there would be no need for @Coulomb 's patches. I am looking forward to see what tomorrow will bring with AICC running again and hopefully a reasonable amount of sunshine which is forecast.

 

Hi Edward

The SOC readings is used by AICC and the accuracy of this is determined by tail current etc. The Axpert in no way is even aware of the BMV. They are from two different stables so were not designed to communicate with each other. Probably my biggest peeve with Voltronic is that they have the means to coulomb count and therefore have a much more accurate SOC reading and yet they do not even try.

On 11/23/2016 at 5:18 PM, ebrsa said:

Machine ID changed

What does the software use for the machine id? Just curious, I discovered something interesting about the Rpi in that regard.

The vrmlogger software I deal with uses the ethernet address of the onboard ethernet device. On the Rpi, this is made up from two parts, the MSB bits indicating that it is a Pi, and the LSB bits basically being the serial number of the board. BUT.... and this is where it gets interesting. The kernel doesn't actually probe the serial number itself, instead it is passed as a boot parameter. The proprietary second-stage loader (start.elf) does this little bit of magic.

What does that mean? Oh... well... with a little effort you can have any serial number you like. Especially if you have u-boot in the mix... which means using the serial number on the Pi really isn't a fool proof way to do licensing :-)

Hi Chris,

Looks like I will have to study the BMV handbook to get some more knowledge. I set the tail current to 2.5% to see what happens as a while ago the charger amps started to slowly drop. Batteries  are at 95.5% at present amps at around 7A and battery voltage at 58.23V. Capacity of the bank is 450AH.  Seems like it has dropped to absorption from bulk. Just jumped to 100% and after a short while voltage came down to 53.93V with amps around zero. This is where I start losing money as watts from panels drops to about the load of 900W and if I turned on my dummy load (a 2Kw heater) panel output goes to 1800W and it is only 14:30 with panel output dropping in about 2 hours. So the only solution is probably more batteries. The 200 liter geyser is already at 58C heated by 16 EV tubes. Then comes winter and I will need more panels to charge a bigger bank followed by summer and same problem arises. I guess better just leave it all alone for a while or run the batteries down to 70% instead of 80% at night.

Hi Ed 

Your experiences mirror my own. I only have a 260 Ah battery bank and fairly early in the morning I noticed I was in late absorb or float and that prompted me to install a electric geyser to heat/preheat our bathwater and so reduce our consumption of gas. As your hot water is already sorted and you live in YF perhaps call on Mike and look at his ant mining project. 

Try and get you BMV setting so that your Axpert and the BMV agree (or nearly so). Tonight my Axpert has gone into float according to the charging LED but the BMV says still 12Ah to go. We are still charging at 9A so I tend to agree with the BMV. Yes float is not 100% SOC but one should be approaching full when one goes to float and full is in my mind still some way off when you charging at 9A. Full in my opinion is when the bank accepts less than 1%.

Hi Chris,

I currently have AICC set to go solar at 5:00 to 18:00 when solar generation is minimal and just before heavy loads are turned on in the kitchen although the stove is gas. It is now 8:30 and already the total load is supplied by solar with batteries at 90.5% and charge current about 4A. Clearly I should drain the batteries to a SOC of 70% max. I am trying to avoid large drain currents from the batteries, hence the time period control and not SOC. It is early days so I am still experimenting. I see your bulk charge time is set to 30 minutes and will increase mine to say 10 mins for a start as at present it is set to 3 mins. Jaco and Manie asked for requests for features for AICC and mine was for a setting of maximum load at which the Axpert would be switched to grid and then back to solar when the load drops below for some time. I believe they are currently busy with programming of a similar feature and will see how it pans out. Then I will be able to run on SOC which for me would be ideal. This forum and Tinkercity are really helping users of solar a great deal. If there are similar forums found on the Internet, we should perhaps start a discussion listing them so we can all benefit from the knowledge out there.

5 hours ago, ebrsa said:

Hi Ed

I see your bulk charge time is set to 30 minutes and will increase mine to say 10 mins for a start as at present it is set to 3 mins.

I think you mean charged current detection time. 

5 hours ago, ebrsa said:

Jaco and Manie asked for requests for features for AICC and mine was for a setting of maximum load at which the Axpert would be switched to grid and then back to solar when the load drops below for some time. 

That will be a very useful feature in the situation where you do have grid available. It is always a toss up between using your batteries and protecting them so that they last. The rapid discharge due to a high load is not very good for batteries so if you can avoid that then it will definitely extend your battery life. 

Yes Chris I did refer to the charge current detection time and made mine 10 minutes. Last night I set solar time from 4:00 to 18:00. This morning at 6:00 the batteries were at 82.7% so obviously I can switch to solar or batteries a bit earlier. What worries me is that current draw jumped from about 20A to 74A when I turned the kettle on for tea. I guess I need to buy a lower power kettle. I have 2 banks of 225AH in parallel but it is still 37A out of each. Does anyone know what the maximum recommended draw from lead acid battries is?

According to a post by Manie on Tinkercity, he and Jaco are busy programming a feature which will allow SOC switching to take place during a settable time period. That will work for me as I will be able to start at say midnight when we are asleep mostly and consumption is low. I aim to set switch to grid at 75% and to solar at 80% with the time period set from midnight to 17:00. So unless it is overcast, I will run on solar for most of the day and optimise on using battery power with limited grid use. However the problem of high current consumption will remain until my requested feature is incorporated in AICC. If it ever is, my system will be truely automated under control of AICC. One lives in hope.

24 minutes ago, ebrsa said:

Does anyone know what the maximum recommended draw from lead acid battries is?

It is on a individual manufacturer/size of battery basis. My AGMs are rated for a max discharge of a unbelievable 2600A. but I would not want to exceed the maximum charging rate of 78A whilst discharging.

4 hours ago, ebrsa said:

I aim to set switch to grid at 75% and to solar at 80% with the time period set from midnight to 17:00.

As you all know, long before there where Axperts and Victron Hub's and panels below R10 per watt, I overcame that problem with relays using a BMV monitor.

SOC is X, go back to Eskom, SOC is Y, use only solar. Times do not matter for the batteries SOC drives it all, as it is the weakest most costly link.

Nothing relied on software, for that can fail, bar the internal BMV software.

Today I am trying to improve that design. An idea I have is to reverse the BMV relay if X watts come in from the panels to switch before the Y SOC is reached.

Just trying to figure how to do it mechanically for although software is the most surest way of doing it, as I said, software can fail and that will be problematic for the batteries.