Jump to content

General battery and inverter questions


Warren
 Share

Recommended Posts

Hi all

 

Have a few generic questions for all the boffens on this forum. :)

  • My Axpert 5kva software displays the battery capacity in percentage value. Does this value represent the total discarge and drain of the batteries. So in other words I must only use up to the 50 % mark. The floating voltage is 54vdc and the cut off voltage is 42vdc so a difference of 12vdc. Does the 42vdc mean the batteries are completely drained.
     
  • If a 105ah battery with a current draw of 1 amp will take 105 hours to drain completely then how does it work when you have 4 x 105ah in series.
     
  • I know the inverter software wattage used is not accurate and I know that the Efergy monitor is not accurate either but does say in the documentation on the web that it is about 5% to 10 % out. Which one out of the two is more accurate as I see the inverter software fluctuates erratically.
  • Does anybody know how to caclulate the battery capacity in percentage left over in the batteries.

 

 

 

 

 

Link to comment
Share on other sites

Hi Warren

 

  • The Axpert battery cut-off at 42V is madness. Rested and under no load that would be the state of a fully discharged battery - hopeless. The maximum setting is 48V which is roughly a DOD of 50%, also not good enough in my opinion. Battery voltage varies with load, state of charge (SOC) and temperature so it is an impossible task to determine SOC from voltage as load and temperature also have an influence.
  • A 105Ah battery with a current draw of 1 A will take a theoretical 105 h  to drain @ 12V. 4 batteries in series will still take 105 hours to drain with a current draw of 1A. How can this be? What must be remembered is that the voltage is now 48V rather than the previous 12V so 4X more energy is being  supplied still at 1A. Batteries in series result in an increase of voltage but not in Ah. Batteries in parallel the voltage does not change but the Ah is cumulative.
  • The inverter's wattage seems fairly accurate . I don't own a Efergy but I presume it will track the VA reading (apparent power).
  • The only way I know of tracking SOC is an ammeter (using a shunt) with a current logging capability. Then software needs to take into account battery and charging inefficiencies.   
Link to comment
Share on other sites

 

Hi Warren

 

  • The Axpert battery cut-off at 42V is madness. Rested and under no load that would be the state of a fully discharged battery - hopeless. The maximum setting is 48V which is roughly a DOD of 50%, also not good enough in my opinion. Battery voltage varies with load, state of charge (SOC) and temperature so it is an impossible task to determine SOC from voltage as load and temperature also have an influence.
  • A 105Ah battery with a current draw of 1 A will take a theoretical 105 h  to drain @ 12V. 4 batteries in series will still take 105 hours to drain with a current draw of 1A. How can this be? What must be remembered is that the voltage is now 48V rather than the previous 12V so 4X more energy is being  supplied still at 1A. Batteries in series result in an increase of voltage but not in Ah. Batteries in parallel the voltage does not change but the Ah is cumulative.
  • The inverter's wattage seems fairly accurate . I don't own a Efergy but I presume it will track the VA reading (apparent power).
  • The only way I know of tracking SOC is an ammeter (using a shunt) with a current logging capability. Then software needs to take into account battery and charging inefficiencies.   

 

 

So I tried to set the cut off voltage to 48 vdc but it will not let me. It returns a message setting = false. :wacko:

Link to comment
Share on other sites

Hi Warren,

 

What did you make the settings for your battery charge and float voltages?

You would need to get those corrected before you can adjust the cut-off points.

Also, you cannot have a cutoff point higher than say your float voltage.

Link to comment
Share on other sites

Hi Warren,

 

What did you make the settings for your battery charge and float voltages?

You would need to get those corrected before you can adjust the cut-off points.

Also, you cannot have a cutoff point higher than say your float voltage.

 

Hi I am not sure what to set it to. I have 4 time 100ah batteries in series. Each battery has 6 cells. Battery brand Vision 6FM100P-X.

 

I am not sure what to set the following to

 

  • Floating charging voltage : currently set at 54 volts
  • Bulk charging voltage(C.V. voltage) : currently set at 56.4 volts
  • Battery cut off voltage : currently set at 42 volts

Please can someone help me :(

Link to comment
Share on other sites

Hi I am not sure what to set it to. I have 4 time 100ah batteries in series. Each battery has 6 cells. Battery brand Vision 6FM100P-X.

 

I am not sure what to set the following to

 

  • Floating charging voltage : currently set at 54 volts
  • Bulk charging voltage(C.V. voltage) : currently set at 56.4 volts
  • Battery cut off voltage : currently set at 42 volts

Please can someone help me :(

Hi Warren

 

I could not find Vision 6FM 100P-X batteries but I did find Vision 6FM 100D-X. From the cycle service life data on the spec sheet they seem to be UPS batteries. 

 

Charge rate 2.40 - 2.45 V/cell therefore  57.6 - 58.8V @ 25oC.

Float rate  2.3. -2.3 V/cell therefore  52.8 - 55,2 V @ 25oC.

 

Your charge rate is to my mind a bit high above gassing voltage (57.36 V @  25 oC). So I would go with 57.6V.

 

http://www.vision-batt.com/site/product_files/6FM100D-X.pdf

Link to comment
Share on other sites

Hi Warren

 

I could not find Vision 6FM 100P-X batteries but I did find Vision 6FM 100D-X. From the cycle service life data on the spec sheet they seem to be UPS batteries. 

 

Charge rate 2.40 - 2.45 V/cell therefore  57.6 - 58.8V @ 25oC.

Float rate  2.3. -2.3 V/cell therefore  52.8 - 55,2 V @ 25oC.

 

Your charge rate is to my mind a bit high above gassing voltage (57.36 V @  25 oC). So I would go with 57.6V.

 

http://www.vision-batt.com/site/product_files/6FM100D-X.pdf

Hi Chris

This is the PDFs for my battery.

https://www.dropbox.com/s/lxlu762gaoyi1rk/6fm100p-x____vision_100ah_12v.pdf?dl=0

They are very close in specs except for a couple of subtle differences. I'm sure the values you gave me will work too. Thanks for your help. Really appreciate it.

Link to comment
Share on other sites

Remember to adjust you V down 30mV /oC for absorb and 20mV /oC  for float if you are having high summer temps.

 

The P-X service life profile is that of a true deep cycle suitable for solar.

 

Hi Chris

 

Can you explain a bit what you mean as I do not understand fully. :wacko:

Link to comment
Share on other sites

Hi Chris

 

Can you explain a bit what you mean as I do not understand fully. :wacko:

The voltage at which a battery gases (loses electrolytes due to excessive charging) is 14.34 @ 25oC. This voltage drops as temperature increases so one reduces charge rates when battery temp reach 30oC +. Since these are sealed batteries gassing is a no-no. Perhaps my next set of batteries will be vented LA where one has more control over the longevity of the battery.

Link to comment
Share on other sites

The voltage at which a battery gases (loses electrolytes due to excessive charging) is 14.34 @ 25oC. This voltage drops as temperature increases so one reduces charge rates when battery temp reach 30oC +. Since these are sealed batteries gassing is a no-no. Perhaps my next set of batteries will be vented LA where one has more control over the longevity of the battery.

Hi Chris

I was reading through the pdf for my batteries. Apparently even though they are sealed batteries they do have one way pressure valve which allows for venting if they are excessively charged. I have been running them with these settings all day. I am a bit concerned as the LCD charging status on the inverter has been showing its still charging.

If I turn the utilities on to charge it shows charging for a few seconds then shows all 4 bars for battery charged. As soon as I go back to battery power it shows 2 bars. I assume the batteries are charged just not sure.

The status shows my batteries are at 52 % capacity. Is this possible or is there something I should be concerned about. When I used the default battery settings for AGM the batteries it would charge to 100% capacity with no problem in a day. See attached thumbs.

post-785-0-35979400-1444142877_thumb.png

post-785-0-91674000-1444142877_thumb.png

Link to comment
Share on other sites

Hi Warren, 

 

Do not pay any attention to the % charged on Watchpower. It does a woefully wrong calculation based on voltages.

 

It also has much to do with your final battery voltage - if set to 42V (dangerous) the % is more or less right, but if set to 48V (right) it goes totally wonky.

 

Best way to determine state of charge is with something like a battery monitor or by simply making sure your batteries charge at full bulk voltage each day, falls back to float and then stay there for ate least an hour. That is the main indicators - not a % based calc.

 

Just make sure your charge voltages are 100% correct as Chris said. And listen to the batteries like you listen to your wife. If something is wrong they will not last as long as they are supposed to on a daily basis (undercharge and sooner and sooner voltage drop) or they will boil (you can hear it with the naked ear...)

Link to comment
Share on other sites

Hi Chris

I was reading through the pdf for my batteries. Apparently even though they are sealed batteries they do have one way pressure valve which allows for venting if they are excessively charged. I have been running them with these settings all day. I am a bit concerned as the LCD charging status on the inverter has been showing its still charging.

 

 Hi Warren

 

If these one-way valves open it is because gas build up. At a voltage of 2.35 V per cell about half of the energy put into the battery causes the electrolyte to separate into H2 and O2. In a vented battery this escapes to the atmosphere and you top up your electrolyte periodically. In a sealed battery this gas is retained and during discharge the gas re-combines to form water. If however if the gas level become so high that there is a danger of the battery case rupturing this gas is vented off through the one way valves and you have now lost electrolyte you cannot replace.

 

As Edmund mentioned the Axpert readings are dicky. Watch your voltages. Early in the morning (assuming you charging by PV) you are in your first phase of charging and the charge current will be maximum (if there is enough sunlight) set in the Axpert's menu. Mine is set to 20A to remain below C10 (a charging rate based on the Ah of your batteries - read up about charging rates or there is a thread on this forum a while back that explored this). At this charging rate your battery voltage will slowly rise and this is known as the bulk phase. Once your bulk voltage is reached the voltage is maintained and as the battery charges its ability to take charge drops and the current flow drops. The battery's internal resistance does increase slightly but this does not account for the tailing off of the current, this is due to the chemistry. Once the battery is 98-99% full and the battery is accepting very little current the charger will drop the voltage to float which is basically a maintenance charge which is below gassing voltage but above the rested 100% full voltage (12.9 V).

Link to comment
Share on other sites

Thanks Edmund & Chris. This makes me feel a lot better. My batteries seem to be charging okay as they are still working great with the load I have on them. I played around with the settings last night and from what I found is that when you are on utility it displays battery 100 %. I am assuming that means you have 100 % capacity from the utilities and not from the batteries as I saw it bypassed my batteries after charging them for a few seconds. I don't think they thought it out when they wrote the watchpower software

I reverse engineered the watch power software so I can see the code. There is sa lot of code that looks like it is not used eg work in progress. I found a whole bunch of extra protocols commands which are not in the protocol PDFs. I am still going through them to see what the do. I believe as Edmond said the inverter has a temp sensor it could be one of these u known protocols I found

Thanks for the help guys. Much appreciated.

Link to comment
Share on other sites

  • 2 months later...

Hi all, I just want to find out if there is any alternative software to the WatchPower that came with my Axpert 3kVa plus inverter ? I am really concerned about the stats accuracy on the Axpert software. ( 3100 W Renesolar panels , 4 x 180ah FMM batteries ) , Thanks all. Most respectfully, Sir Raven.

Link to comment
Share on other sites

  • 1 year later...

Hi guys. I believe there is a software upgrade on the Axpert 4000w unit that needs to be done. Something about the charging and maintenance of the batteries.

Can somebody help or adviwe me please, I hav 2 4,000w Axperts running with 16 x 170 a/h sealed lead crystal batteries.

Link to comment
Share on other sites

On 5/17/2017 at 2:25 PM, Mark said:
Hi @Deonsr
 
Here is the thread link  - just make sure of your Axpert Model!
Regards
Mark

Hi again...

The best is to search for the thread on this site and also to read the AEVA thread.  they are both very good ito instructions and things to watch out for...

Regards

Mark

 

 

 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...