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Axpert 5kva with Panasonic Li-ion


Getskay
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Hi experts,

here want to share with you my current setup using Axpert MV II 5KVA inverter and Li-Ion batary.

Buttery bank build with 6 block each having 14 cells (Li-Ion panasonic from used Ford C-Max enery) with total 84 cells and block voltage of 48 volt.

Solar power connected 10 panel 320W each, every two panel in series, charging battery at 60amp max for 57.0 volt and system discharge it at night untill 46.0 volt then back to utility at 5:00 am on average, with load 500w from house appliance.

I am using this setup to save electric bills, and to act as backup for short term disconnection.

issues: I am still not sure of the settings I am using, also I cant have each block/cell readings with charge/discharge. also I am looking for a way to know how much power per day utilized from Pannel, Battary and utility.

below settings and main page screenshot showing old firmeware version i think, and the parameter set for your review and your advices are most welcome.

 

 

 

WP_ParamPage.png

WP_MainPage all.png

Edited by Getskay
Image updated with secondary CPU version
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  • 2 weeks later...

Hi welcome Getskay. 

On the settings side, the Experts will be online soon.

As for your panels. if this data sheet is the correct one for your inverter, I would run all panels in series to get the most out of low light conditions. 

Mppt will only switch on at 120Volt, how does your system work now right now?

MV2.thumb.PNG.2b159665ac6a586bcfe1ca12025b4820.PNG

 

I will rather let the @Chris Hobson comment on your settings. 

 

 

 

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On ‎2018‎/‎09‎/‎06 at 8:46 PM, Jaco de Jongh said:

I would run all panels in series to get the most out of low light conditions

Thank you friend for the advice.

currently with each two in series I hae my battery full @11:30AM, today it was cloudy so I got the bettery full @2:00PM, I will consider the setup you suggested in winter.

for your question, I don't know how exactly I can calculate total power generated from PV and battery ( I don't have monitoring tools else the inverter itself)

battery with 84 cell, Li-Ion with 28amp each covers my need at night until 7:00am

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This is one of the more difficult questions to answer as one is not quite sure what one is dealing with. You are charging up to 57V and discharging to 46V. If this was LiFePO4 I would say there is a problem but we probably dealing with automotive Lithium Cobalt  chemistry so I just don't know. Having done some research on the web I see the CMax is a Lithium Nickel Manganese Cobolt Oxide (LiNiMnCoO2  - that mouthful is abbreviated to NMC).  So what do I know about this chemistry?  Charging voltage per cell is 4.2V and sometimes a bit higher so 57V seems fine. Charge/discharge should be about 1C . It can go higher but  that will shorten battery life. The minimum voltage is 35V so the 44V cutoff seems good.

Most importantly is the batteries BMS still intact? If not have you replaced it with a suitable alternative. The CMax has cooling system and shuts down warm cells to prevent thermal runaway.

Why do you put some photos up so we can drool at you Lithiums.

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2 hours ago, Chris Hobson said:

Most importantly is the batteries BMS still intact?

Many thanks Chris; for battery cut-off, I left it default 44, are you advice to change Back to grid voltage to be 44 also?

for your question, I don't know what is BMS, but I can attach image for what exactly I have, additionally I installed 48 volt vent FAN on the right side up :

IMG-20180710-WA0020.jpg

Edited by Getskay
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1 hour ago, Getskay said:

I don't know what is BMS......

BMS = Battery Management System. Electronics that manage charging and discharging of Lithium batteries. It ensures that individual cells are neither over charged nor discharged too much. It monitors the temperature of individual cells and prevents thermal runaway.

 

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1 hour ago, Getskay said:

Many thanks Chris; for battery cut-off, I left it default 44, are you advice to change Back to grid voltage to be 44 also?

for your question, I don't know what is BMS, but I can attach image for what exactly I have, additionally I installed 48 volt vent FAN on the right side up :

IMG-20180710-WA0020.jpg

Battery porn ;-)

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2 hours ago, Chris Hobson said:

Ask the engineer

I think he know nothing :D as he told me nothing but to watch the electric company wattmeter :)

What about the charging Amps setting, what is the recommendation, or how can I do the calculation?

On the other hand, can I install 2000W wind generator with controller and connect it as extra solar panel?

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1 hour ago, Getskay said:

I think he know nothing :D as he told me nothing but to watch the electric company wattmeter :)

What about the charging Amps setting, what is the recommendation, or how can I do the calculation?

On the other hand, can I install 2000W wind generator with controller and connect it as extra solar panel?

Then I suspect the term "engineer" is used very loosely :rolleyes:

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Thanks Chris, I searched for that and I believe I don't have BMS, the engineer just put the cells beside and above each other with some bridge connection to link each 14 cells together in series then connect the 6 generated blocks to trunks as parallel (+ & -) and connect that trunks to the inverter.

What problem I should expect?

? how to calculate the charging Amps needed for that battery?

? How much Watt the battery will store if charged full with 56volt?

? Should I change "Back to grid voltage" to be 44?

FYI: my system is the first project the engineer do, he has no experience in this domain before.

 

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1 hour ago, Getskay said:

What problem I should expect?

Without a BMS you can destroy a cell by discharging too low, or cause a fire by charging too high. The cells are not identical and though they add up to 48V (for example), it doesn't mean that each cell is at 48/14 = 3.4V. Some might be at 3.6V while others are only at 3.2V. When you discharge it to 44V,, Some cells might be above 3.5V, others might be below 3V at the same time. Lithium batteries are destroyed if you discharge them too low.

The BMS watches individual cells and disconnects the battery if one goes too low or too high. Additionally it can also balance the cells. This becomes more important as the battery gets older.

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Just now, Getskay said:

WoW, that is bad, How can i fix it now, how to add BMS and what options i could buy to work with 84 cells ?

Well... I'd be more concerned about the high end. At 57V an imbalance is of more concern than at 44V (which is quite far away from the low that Chris mentioned). But better to be safe than sorry in the long term.

There are commercial BMSes on the market, for example BM123, REC, and Orion. None of them are particularly cheap. There are others on this forum who has done their own setups, the so-called "DIY Powerwall". Better ask them... :-)

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  • 3 weeks later...

Hi dears, as per the engineer, no need for BMS as the 84 cells comes in one batch and having same chimical specification and will distribute the voltage across to have all the same voltage.

and he said that he tested that for multiple cycle in his lap with different voltage settings and ampere.

 

as per his feedback, BMS are used only for big number of cells connected to one seriese, for example Ford C-Max connect the 84 cell in series to have over 300 Volt, and charging at extreamly high ampere, thus BMS is neccessary in this case to be sure first cell in series will not be damaged before the last cell in seriese becomes full.

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10 hours ago, Getskay said:

no need for BMS as the 84 cells comes in one batch and having same chimical specification and will distribute the voltage across to have all the same voltage.

I've heard of this way of doing things before. I would however check them carefully every now and then if it was me. Maybe I'm just overly nervous... :-)

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