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egemnaar
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I am going blue, replacing my useless Narada batteries with Blue Nova. The installer and Blue Nova guaranteed  me

that my Mecer invertor will do. Blue Nova send me the settings for the invertor with Blue Nova batteries.

My only concern is the firmware of the invertor. My invertor is still at 72.40.

Can I, should I, upgrade the invertor direct to 73.00c  (dsp_BF1_73.00c)? 

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17 hours ago, egemnaar said:

Can I, should I, upgrade the invertor direct to 73.00c  (dsp_BF1_73.00c)? 

You can. It's possible that the charge bugs contributed to your old battery failing through chronic undercharging, so it would be good to get the best from your new battery with patched firmware.

The latest firmware went from BF1 (Beta LiFePO₄) to LF1 (release LiFePO4) yesterday.

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Hi  @Coulomb

I have two inverters (I am in the process of commissioning the second one). They both were manufactured May/June 2015 and have the external SCC heatsink and are limited to 60A SCC charging. Currently I have 72.70C LF1 installed. Should I upgrade to your latest software or should I stick with your firmware from Dec 2017?

I would have sent this as a PM but decided forumites would benefit from your reply.

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20 hours ago, Chris Hobson said:

Hi  @Coulomb

Currently I have 72.70C LF1 installed. Should I upgrade to your latest software or should I stick with your firmware from Dec 2017?

You will get minor improvements from 73.00c: a manufacturer glitch where you can't re-edit a setting is fixed, and there will be slight improvements to the accuracy of battery current reporting. But you'll also get the new fan behaviour; see a recent post about this. Perhaps try one inverter on 73.00c, and if you don't like the extra huffing, revert to 72.70c.

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  • 2 months later...
  • 5 months later...
On 2018/07/20 at 8:08 AM, egemnaar said:

I am going blue, replacing my useless Narada batteries with Blue Nova. The installer and Blue Nova guaranteed  me

that my Mecer invertor will do. Blue Nova send me the settings for the invertor with Blue Nova batteries.

Would you mind sharing those settings?

What size battery did you get. How are they performing?

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I hope I'm not repeating what has already been asked and answered

2 of the Blue Nova BN26V-772k mini batteries cost considerably less than one Blue Nova BN26V-154-4k-2017 battery

The 2 smaller ones have a capacity of 2000 watt/hours each and the bigger one has a 4000 watt/hour capacity

If the inverter has a 26V output (the model sticker is attached), is there any reason not to connect two of the smaller batteries in parallel?  I was looking at the YouTube video from Blue Nova, but not sure if this applies to all their lithium batteries

(Its always nice to try and save a bit of money)

Capture.JPG

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8 hours ago, chrisc said:

is there any reason not to connect two of the smaller batteries in parallel?

Not as far as I can see. You will have seen pictures of racks of PylonTech batteries paralleled. It should be much the same in principle.

You'll need to connect them with appropriate cables, using the "diagonal takeoff" technique, but if you're up for crimping a few lugs on cables, that should be straightforward.

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Thanks

I am up to making up cables and have connected all my lead-acid batteries that way. I use 10mm dia cable

Can you explain what the diagonal takeoff method is as opposed to two cables, each to the set of batteries

This what I would have done:

 

 

Untitled.png

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1 hour ago, chrisc said:

 

Untitled.png

Note how much longer the cables are going to that battery on the right. Remember that electricity takes the shortest route. This means your battery on the left does most of the work and also gets most of the charge.

You need to look at the total length of cable, ie add up the length of the positive and negative cables, that is your "round trip" distance. You want that to be equal for both batteries.

So what you want to o in your picture is one of two things. You can keep it the way it is (usually you'd install two busbars, connect the inverter to the busbars, then connect both batteries to the busbars using equal length cabling)... or... the cheaper way is you parallel the batteries normally (equal length cabling for paralleling), and then you connect the positive of the inverter to the battery on the left, and the negative of the inverter to the battery on the right. Everything then balances out.

Busbar method is preferred, because you're supposed to fuse each battery individually.

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Its only a drawing I made with MS Paint.  The cables to each battery are the same length.  The cable has a cross-section of 10mm and is less than 200mm long.  The current carrying capacity of 10mm cable is over 60 amps

What I wanted to know is what the "diagonal take-off" connection technique consists of

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The diagonal technique for two batteries means simply this:

Selection_166.png.717cbbc7d67382d5521fba6f6136ec81.png

By taking the positive and negative side from opposite sides, the total paths are equal. The shorter red cable on the left is balanced by a longer black path from the right, and the same for the other side.

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  • 3 weeks later...

Anyone know if Blue Nova in Somerset West have closed down?  They do not reply to emails, their phone is not answered

Have a friend in Springbok (Northern Cape) who does the occasional solar job.  He paid them over a month ago for batteries and was quoted 2 weeks delay.  Its now 5 weeks and no news

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32 minutes ago, chrisc said:

Anyone know if Blue Nova in Somerset West have closed down?  They do not reply to emails, their phone is not answered

Have a friend in Springbok (Northern Cape) who does the occasional solar job.  He paid them over a month ago for batteries and was quoted 2 weeks delay.  Its now 5 weeks and no news

Have a chat to Dirk Nieuwoudt: [email protected], 021 205 2000.

He is the senior sales executive and has been very good at keeping in touch with me regarding my queries (I have the same inverter as you and have ordered a 26v-154-4k)

I will PM you his cell number

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  • 2 weeks later...

Received the Blue Nova batteries on Tuesday 23rd and they have been in circuit 4 days now.  They are wired in parallel, as per the diagonal method shown above

I'm a little disappointed how they work and the indifferent attitude of Blue Nova to enquiries

a)   There was no RJ45 socket on the batteries, which is specified on the sales literature and in the User Manual
b)   One battery, when new, showed a state of charge as 99%, the other showed 88%
c)   I tested the batteries powering one house circuit and drawing 5.5 amps from each.  In 10 hours, one battery showed a state of charge of 42%, the other showed 6%, yet the voltage had only dropped from 28V to 25.5V
d)  The inverter is configured to switch back to BYPASS (powered by mains instead of PV) when PV power is absent.  Thus it can charge the batteries from the mains.  Nevertheless, one battery will reach 99% but the other will not go above 88%

Blue Nova told me

First - an RJ45 connection must be ordered separately, yet I was not offered the option
Second - since the (Mecer) inverter does not have a CANBUS connection, that would be superflous  (yet the User Manual caters for Canbus and non-Canbus battery connections)
The Mecer inverter can only deal with Flooded batteries thus will never charge the batteries fully.   (there is a choice of Flooded or User for battery type which permits setting of maximum charge, float charge, voltage cut-off point, etc)
There can be a difference of 10% in battery behaviour

Further enquiries were ignored

In the readers opinion, is a battery that discharges more quickly than the other and will not charge fully a faulty unit or not?
 

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Quote

a)   There was no RJ45 socket on the batteries, which is specified on the sales literature and in the User Manual

That is very poor.

Quote

b)   One battery, when new, showed a state of charge as 99%, the other showed 88%

I would disconnect the 99% one temporarily, and see if the 88% other one will charge up to a higher state of charge on its own.

Quote

c)   I tested the batteries powering one house circuit and drawing 5.5 amps from each.  In 10 hours, one battery showed a state of charge of 42%, the other showed 6%, yet the voltage had only dropped from 28V to 25.5V

The small voltage change is not unexpected, because the voltage to SOC graph for LFP cells is so flat. But they are obviously at least quite badly unbalanced (one module to the other).

2 hours ago, chrisc said:

d)  The inverter is configured to switch back to BYPASS (powered by mains instead of PV) when PV power is absent.  Thus it can charge the batteries from the mains.  Nevertheless, one battery will reach 99% but the other will not go above 88%

Again, if you disconnect them and charge them to full separately, they might stay in balance from then on. They might also eventually balance themselves, but it might take days or weeks.

Quote

The Mecer inverter can only deal with Flooded batteries thus will never charge the batteries fully.   (there is a choice of Flooded or User for battery type which permits setting of maximum charge, float charge, voltage cut-off point, etc)

I presume that these are 8S; 28 V from 7S would be 4.0 VPC, and no-one does that to LFP any more. So the proper voltage levels for a 24 V Axpert will not be half of those for a 48 V Axpert; they should be 8/15 ths. So you might have to (at least initially) charge up to 28.4 V, i.e. change the Axpert setting 26 to 28.4 V.

Quote

There can be a difference of 10% in battery behaviour

I doubt it would be as much as that, and in any case it would not affect the maximum SOC that you would see.

Quote

Further enquiries were ignored

That's definitely poor customer relations.

Quote

In the readers opinion, is a battery that discharges more quickly than the other and will not charge fully a faulty unit or not?

It would be, but you have some things to try first before you can be sure that the above is what is really happening.

Edited by Coulomb
Removed excess white space.
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2 hours ago, chrisc said:

a)   There was no RJ45 socket on the batteries, which is specified on the sales literature and in the User Manual

I think it comes down to the BMS used inside the batteries. There are often more than one model, and the cheaper one (often significantly) usually comes without the canbus part. There is no point paying for it if you won't be using it.

2 hours ago, chrisc said:

b)   One battery, when new, showed a state of charge as 99%, the other showed 88%

The BMS takes internal measurements on a cell level, often not on each and every cell, but in a few representative places. The overall SOC is an estimate based across all the measurements. It is perfectly normal for new batteries to be a little out of wack (although I have always heard that BN takes great care in ensuring they assemble a battery from matched cells). Over time, as the battery gets time to balance itself, the discrepancy will go away.

In other words, batteries literally need some time to bed in.

Some batteries, the BYD B-Box-L for example, are quite prone to swithing itself off complaining about high charge current during the first week, and then the symptoms disappear as they balance out.

2 hours ago, chrisc said:

The Mecer inverter can only deal with Flooded batteries thus will never charge the batteries fully.

That might be partially true. One running stock firmware very likely won't work very well with this battery. First there is the float bug, but there is also the matter of the inverter requiring a 4V drop below float voltage to go back into absorb (for Victron inverters it is 5.2V when using lead acid, so this is not an Axpert specific issue... it is a lead-acid vs LFP issue, and stock Axpert firmware only does lead acid). But an inverter running modified firmware should be able to get it up to 100%. If you hold it at the right voltage, around 56.8V, for long enough, it should reach 100% in a few days of cycling.

Edited by plonkster
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My Blue Nova batteries were getting  charged 100% everytime. My firmware is 73.00. I can boil a kettle if my system is on batteries, no problem at all.

I have a different problem...i have no batteries no more. I was hit by lightning 3 weeks ago, that took out my batteries.  How does Blue Nova fix these? You have to ship them to Blue Nova. I don't know what they do if you have a big installation. They now have a facility in Pretoria (Midrand?). My batteries are there and I am still waiting. My batteries were 94% SOC when lightning hit, the batteries are not faulty , the BMS is most likely faulty.  They asked if I had a wired connection to my router as this could taken the BMS out. I have not. The batteries were connected to the raspberry with usb. My raspberry is connected by ethernet cable to the router. My raspberry is still fine and so is my router.

What about my invertor.? Doesn't work without batteries. Was connected to batteries on a test bench and all was fine. We could  not connect the invertor to the panels. If that part works we don't know. The panels are producing the voltage.

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2 hours ago, egemnaar said:

They asked if I had a wired connection to my router ...
The batteries were connected to the raspberry with usb.
My raspberry is connected by Ethernet cable to the router.

🙂 

But I hear you. How can everything else still work and not the batts?

Maybe the rest could take the momentary "spike", the BMS not that robust?

 

2 hours ago, egemnaar said:

You have to ship them to Blue Nova.

How else would one do it? Most suppliers expect you to send it back to them, no?

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On 2019/04/27 at 10:37 AM, plonkster said:

That might be partially true. One running stock firmware very likely won't work very well with this battery. First there is the float bug, but there is also the matter of the inverter requiring a 4V drop below float voltage to go back into absorb (for Victron inverters it is 5.2V when using lead acid, so this is not an Axpert specific issue... it is a lead-acid vs LFP issue, and stock Axpert firmware only does lead acid). But an inverter running modified firmware should be able to get it up to 100%. If you hold it at the right voltage, around 56.8V, for long enough, it should reach 100% in a few days of cycling.

@plonkster this is the issue I am having with my 24v Axpert and Blue Nova battery.

My inverter doesn't take the battery to absorption voltage (28,1v) if the battery voltage doesn't drop below 25v. So at the moment when the inverter charges the battery it does so at float voltage only (27,7v) because the battery voltage doesn't drop below 25v when I discharge it.

The nett result is that the battery's SOC doesn't ever reach 100%.

Unfortunately I can't upgrade the firmware on my inverter to work witj lithium batteryies because its a 24v Axpert and not the 48v unit.

Would I have the same issue with a multiplus ii inverter?

Any idea if Victron is has a 24v version of the MutiPlus ii, or if they are restricting this to 48v unit?

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