14 minutes ago, The Terrible Triplett said:

My 2 cents, unless you are DIY'er and want to keep a hand on an inverter, get a Victron kit for example. Plug and Forget. 🙂 

And if you want to follow SA's NRS and SANS regulations, use one that is NRS approved, one that fits your DB board's main breaker i.e. if it is 63amp breaker, don't get a inverter bigger than 3.5kva if you are grid tied.

Because when you do go grid tied, that is where the most savings are ito 1) solar panel generation and 2) can use less batteries.

Thanks for advice 👍

7 hours ago, Liz said:

In your opinion, if we had an original and with our set-up, it would run perfectly and no glitches with pool?

It's impossible to be certain, but yes, I think it's quite likely that you would not be having this problem with a genuine Voltronic Power inverter-charger.

On 2019/05/22 at 12:49 AM, Coulomb said:

It's impossible to be certain, but yes, I think it's quite likely that you would not be having this problem with a genuine Voltronic Power inverter-charger.

Dear Coulomb, thanks to your advice and prompts. The supplier agreed to swop the inverter for a genuine model. So far so good! May bug you for settings some time 😉 Thanks again 🙏

Hi GrahamS

 

I noted you have 6 x 335 Canadian SP. If wired in series this would give a combined voltage of 274.8v yet your inverter is limited to VOC 145 VDC? How did you wire yours to be at 145 VDC?

2 sets of 3 

On 2019/05/22 at 12:49 AM, Coulomb said:

It's impossible to be certain, but yes, I think it's quite likely that you would not be having this problem with a genuine Voltronic Power inverter-charger.

Dear Coulomb. So the new inverter is working well, except we now seem to only get the batteries to 48V which quickly declines again to 47 before it has to go to uti (attached is pic after while day on solar without pool). Even when on uti it only charges for a short period to 48V and then back to batteries. This happens with or without pool. But I also understand the light intensity in SA is currently not high, however, the short charging on uti is baffling. The new inverter also has settings 32-39 extra and I am not sure what optimal is 🤦🏼‍♀️ so have left on default. The panels have been reconnected to 3x3 strings. Any idea what setting is wrong? Thank you 🙏

8 hours ago, Liz said:

 the batteries to 48V which quickly declines again to 47 before it has to go to uti

Your battery is in need of charge. Good thing it's not lead acid.

8 hours ago, Liz said:

(attached is pic

I see no attachment.

8 hours ago, Liz said:

Even when on uti it only charges for a short period to 48V and then back to batteries.

It sounds like setting 13 is set to 48. Change it to something like 53 or FUL. Later you can change it to lower values so you aren't using utility power so much. (I use the equivalent of about 50 V (53 V for 16S is close to 50 V for a 15S battery like yours).

8 hours ago, Liz said:

But I also understand the light intensity in SA is currently not high

The light intensity would be similar to me in Brisbane, Australia. I have no trouble filling my battery on clear days, usually by noon. Though I have 5.5 kWp of panels charging the battery, 3.2 kWp connected to the Axpert.

8 hours ago, Liz said:

The new inverter also has settings 32-39 extra and I am not sure what optimal is 🤦🏼‍♀️ so have left on default.

The settings from 33-39 are all about equalisation; ignore those (leave at defaults) for a lithium battery.

Setting 32 is for an absorb timer. You could set this to 60-90 minutes to try to work around the premature float bug. (With the genuine inverter-charger, you've actually gone backwards as far as charging is concerned. If you have a 64 V model (setting 26 allows you to go past 58.4 V), then you could update to patched firmware version 72.20e. But if not, there is no patched firmware available, and setting a moderate absorb time should get more energy into your battery. Though if you set the float voltage (setting 27) to nearly the same as the absorb voltage (say 53.0 and 53.2 V respectively), then it doesn't matter, as the battery will still be charging even at 53.0 V. In this case, don't bother with the absorb timer, and leave setting 32 at AUt.

4 hours ago, Coulomb said:

Your battery is in need of charge. Good thing it's not lead acid.

I see no attachment.

It sounds like setting 13 is set to 48. Change it to something like 53 or FUL. Later you can change it to lower values so you aren't using utility power so much. (I use the equivalent of about 50 V (53 V for 16S is close to 50 V for a 15S battery like yours).

The light intensity would be similar to me in Brisbane, Australia. I have no trouble filling my battery on clear days, usually by noon. Though I have 5.5 kWp of panels charging the battery, 3.2 kWp connected to the Axpert.

The settings from 33-39 are all about equalisation; ignore those (leave at defaults) for a lithium battery.

Setting 32 is for an absorb timer. You could set this to 60-90 minutes to try to work around the premature float bug. (With the genuine inverter-charger, you've actually gone backwards as far as charging is concerned. If you have a 64 V model (setting 26 allows you to go past 58.4 V), then you could update to patched firmware version 72.20e. But if not, there is no patched firmware available, and setting a moderate absorb time should get more energy into your battery. Though if you set the float voltage (setting 27) to nearly the same as the absorb voltage (say 53.0 and 53.2 V respectively), then it doesn't matter, as the battery will still be charging even at 53.0 V. In this case, don't bother with the absorb timer, and leave setting 32 at AUt.

Thank you, will try that.

Brand New Issue.

Watch Power states that my inverter's Nominal output active power is 4000W, The "sticker" on the side state 5KW????

Supplier says that it has a 4KW Mother board and that a "Power factor Correction card" have been added to get it as close to 5kw as possible.

Can this be true

1 hour ago, GrahamS said:

a "Power factor Correction card" have been added to get it as close to 5kw as possible.

I call bull on that one.

Either the wrong firmware is installed, so you'll be getting 4 kW from 5 kW hardware, or the sticker is wrong and it's not really a 5 kW machine. Power factor correction at this power level would be quite bulky, and besides won't achieve the goal of increasing real power output.

Thanks Coulomb

On 2019/06/05 at 8:11 AM, Liz said:

Thank you, will try that.

Dear Coulomb. So we have added 3 more panels and now have 12. The 4000 W max voltage for panels (on inverter, attached), is that total before or after MPPT changes 130v back to 48v? We have 3x300w panels connected in series total of 12. Are we on 1200w now or 3600w (close to max)?

44 minutes ago, Liz said:

Dear Coulomb. So we have added 3 more panels and now have 12. The 4000 W max voltage for panels (on inverter, attached), is that total before or after MPPT changes 130v back to 48v? We have 3x300w panels connected in series total of 12. Are we on 1200w now or 3600w (close to max)?

either way you swing it 12 x 300 (i am assuming 300 because of the maths) = 3600, i.e you cant just keep adding strings and keep the wattage the same, that wouldn't have any benefit if it didn't add up.

4 strings of 3? isnt the operating range of the mppt 60-115v?

Coulomb is way smarter than me, but imo 3600W is fine as you are under the limit and you will still have losses to account for.

7 hours ago, Dex_ said:

The 4000 W max voltage for panels (on inverter, attached), is that total before or after MPPT changes 130v back to 48v?

4000 Watts is power, not voltage. When you series the 3 panels, you add their voltage (open circuit voltage, Voc, and operating voltage, usually close to Vmpp. Power at 130V or 50 V will be the same, neglecting about 2% loss. So for example 130 V @ 25 A becomes 50 V @ 65 A, both represent 3250 W.

I note that 130 V is where the solar charge controller starts limiting power to protect itself.

12 panels (as 4 strings of 3) is all that inverter should have, although one more string might be OK (but not recommended by the manufacturer).

1 hour ago, Coulomb said:

4000 Watts is power, not voltage. When you series the 3 panels, you add their voltage (open circuit voltage, Voc, and operating voltage, usually close to Vmpp. Power at 130V or 50 V will be the same, neglecting about 2% loss. So for example 130 V @ 25 A becomes 50 V @ 65 A, both represent 3250 W.

I note that 130 V is where the solar charge controller starts limiting power to protect itself.

12 panels (as 4 strings of 3) is all that inverter should have, although one more string might be OK (but not recommended by the manufacturer).

Thank you

2 hours ago, Coulomb said:

4000 Watts is power, not voltage. When you series the 3 panels, you add their voltage (open circuit voltage, Voc, and operating voltage, usually close to Vmpp. Power at 130V or 50 V will be the same, neglecting about 2% loss. So for example 130 V @ 25 A becomes 50 V @ 65 A, both represent 3250 W.

I note that 130 V is where the solar charge controller starts limiting power to protect itself.

12 panels (as 4 strings of 3) is all that inverter should have, although one more string might be OK (but not recommended by the manufacturer).

somehow this quoting got all out of whack

On ‎2019‎/‎05‎/‎20 at 9:44 AM, Coulomb said:

Sure. With the utility charger off, even with the utility powering the loads, something has to power the electronics in the inverter-charger: the processor, lighting the display, relays, other electronics, comes to a non-trivial 35 W or so. So that's why the discharge LED is on, and a small part of the reason for the battery voltage to be falling. But batteries of all kinds will fall in voltage after a charge, till they reach a resting voltage, often around 3.33 V per cell for the LFP chemistry. That's just under 50 V for a 15S battery.

So any voltage above about 51 V is a sort of fluffy region where there isn't real energy behind it. The same happens with lead acid. A typical 12 V battery will float at 13.8V or 13.5 V with very little current, but will fall back to a resting voltage of about 12.8 V, even when fully charged.

All battery voltages are also affected by temperature. There is also a self discharge effect (much worse with lead acid) that gets worse with age.

So the takeaway message is: voltage is not a good indicator of state of charge, especially for LFP at middling SOC.

May I, nevertheless, ask what a reasonable SOC% would be at 49.1V for a 3 month old, 15 cell 2.4kWh 48V LFP battery with float voltage 54.0V, bulk voltage 54.2V and discharge end voltage 40.6V (set on the inverter)? Reading was taken at room temperature 100C to 150C over a period of 90 minutes with no battery charging/discharging taking place and effectively no load.

22 hours ago, nnn said:

May I, nevertheless, ask what a reasonable SOC% would be at 49.1V for a 3 month old, 15 cell 2.4kWh 48V LFP battery with float voltage 54.0V, bulk voltage 54.2V and discharge end voltage 40.6V (set on the inverter)? Reading was taken at room temperature 100C to 150C over a period of 90 minutes with no battery charging/discharging taking place and effectively no load.

I think up front we need to acknowledge that voltage is not a good measure of SOC. Also I am no expert by any means but that discharge end voltage seems very low - mine for example cuts off at 47.5V? From my limited experience i would say that battery is at around 60-70% SOC at 49.1V - but keen to see what people with more experience say.

11 minutes ago, Dex_ said:

... i would say that battery is at around 60-70% SOC at 49.1V ..

If that bank was disconnected for +-24 hours you could get a more accurate SOC checking the volts yes.

If the bank is in operation, well, lets just say it is a WILD thumb suck of what the SOC may be using the volts.

As has been said many times by many members over the years, get a BMV if you want a more accurate SOC based on what was drawn out of and put back into the batt.

Volts are not an option in a working system. Don't even bother to try. 🙂 

Thank you for replying, Dex_.

My clueless calculation resulted in 63%.

Last night the inverter was set on SbU again, and the voltage was 49.1V again at 07:00 this morning. Cloudy day today and the battery is still charging. Boiled the kettle a few times, no switching back to grid. At the moment, 11:30, the voltage is 50.4V, 96% SOC  (according to WatchPower). According to my voltmeter it is 50.6V and 74% SOC according to my calculations.

Thank you for the advice, TTT. I am sad to say I don't know what a BMV is!!!

1 hour ago, nnn said:

I don't know what a BMV is!!!

No problem at all. We are here to help.

Here you go: Victron BMV Battery Monitor

I guess about between R1800-R2200 for a 700. Next one is 712, I guess about R2800 - R3200 

Worth every cent as it helps you to make your lead acid batts last WAY longer and it is a good idea, I now know, for not only lead acid, but also lithium banks.

Invest in one.

Edited August 10, 20196 yr by Guest

On 2019/08/09 at 12:48 PM, nnn said:

reasonable SOC% would be at 49.1V for a 3 month old, 15 cell 2.4kWh 48V LFP battery with float voltage 54.0V, bulk

54V float, so it is most likely a 16-cell jobbie. 49.1/16 ~= 3.1V per cell. In my experience that puts you somewhere below 50% SoC, depending on the kind of load you're pulling. When I'm pulling a C/3 discharge current on my system (about one third of my battery capacity) with the batteries at 50% SoC they sag to 3.2V per cell. So I can't be precise, but 63% seems too high an estiate to me. I'd put them around 40% SOC.

4 hours ago, The Terrible Triplett said:

If that bank was disconnected for +-24 hours you could get a more accurate SOC checking the volts yes.

If the bank is in operation, well, lets just say it is a WILD thumb suck of what the SOC may be using the volts.

As has been said many times by many members over the years, get a BMV if you want a more accurate SOC based on what was drawn out of and put back into the batt.

Volts are not an option in a working system. Don't even bother to try. 🙂 

Do you need a BMV if you have a BMS? can't you just put in a pi with ICC?

38 minutes ago, Dex_ said:

Do you need a BMV if you have a BMS? can't you just put in a pi with ICC?

From a recent discussion here on PF I gathered that not all BMS'es get the SOC right as what a BMV does. The pic I saw was a BMS SOC versus a BMV SOC ... and they where vastly different.

When I get a Lithium bank, and the BMS is not a REC or Orion make, I would most definitely have a BMV on it, using the BMV's SOC to drive things like the Multi's and software like ICC.

Because to get the right SOC, or as close as you can, need need a shunt somewhere. Volts to determine SOC is just not on in my mind, ever.

49 minutes ago, Dex_ said:

Do you need a BMV if you have a BMS? can't you just put in a pi with ICC?

See here: BMV vs BMS SOC