Hi there,

 

I’ve run into some issues with my inverter and/or batteries, and I’m hoping someone can guide me to where the issue lies, and hopefully how to resolve it.

 

It’s a 3000w Axpert King (SOL-I-AX-3K) with 2x 240Ah Omnipower batteries in series, so a 24v system. Photos attached. I’m not using any solar panels. Everything was purchased (inverter and batteries from different suppliers) and installed in April 2019. I have it connected to my lights and a few select items, so the load ranges from 140w -180w, depending on the time of day.

 

A month or so after it was installed, I did a test run by disconnecting it from utility power, and at the time I got to 28 hours before low voltage cut off. A few weeks ago, with the most recent spate of loadshedding, the system shut down somewhere between 1.5 and 2 hours, so I realised something was wrong.

 

I started looking for answers and found some on this forum. I read about the premature float bugs (not sure if my model is affected?) and found some settings to hopefully revive my batteries if they have been constantly under-charged.

 

My current settings are as follows:

Output Source: Utility first

Max charge current: 40A (had it at 50A for 1 week during stage 6 loadshedding)

Battery type: User defined

Operation logic: Eco (I don’t understand this setting, in hindsight should have just left it at the default auto)

Max utility charge current: 40A (had it at 50A for 1 week during stage 6 loadshedding)

Bulk charge voltage: 29.1v

Float charge voltage: 27.4v

Low cut off voltage: 21.0v (23.5v before the settings change 2 weeks ago)

Bulk charge time: 120 min (Auto before the settings change 2 weeks ago)

Equalization: On (Off before the settings change 2 weeks ago)

Equalization voltage: 29.1v

Equalization time: 120 min

Equalization timeout: 180 min

Equalization interval: 1d for a week, then 2d for a week (did this to hopefully revive the batteries if they were at fault, will now set it to 1w or longer)

Firmware – Main CPU (U1): 51.50

Firmware – Secondary CPU (U2): 01.12

Firmware – Secondary BLE (U3): 00.21

Firmware – SCC (U4): 00.00

 

I ran these settings for two weeks, and did another test run this weekend, but again only got out 1.5 hours, so no improvement. The reported voltage relatively quickly drops from the float voltage to about 25.2v and holds around there for around an hour. It then starts dropping at about 0.1v every 1 or 2 seconds until it starts beeping at 22v; 1v from low voltage cut off. Just before the system shuts down, the inverter reported 21.5v and I measured 21.7v with a multimeter at the fuse disconnector terminals (while connected, with load). I then disconnected the batteries and measured the batteries at the fuse disconnector with a multimeter, and that gave me a reading of 25.9v.

 

What is at fault here, the inverter or the batteries? Can it be resolved by myself, either using settings or a firmware update? Everything should still be under warranty, so returning is also an option, if the manufacturers don’t blame me for the failure.

7 hours ago, ascheff said:

A month or so after it was installed, I did a test run by disconnecting it from utility power, and at the time I got to 28 hours before low voltage cut off.

Assuming an average load of 160 W, 28 hours of runtime is about 4500 Wh. Your battery is rated at about 24 x 240 ~= 5750 Wh. So that test was a bit brutal, a nearly 80% discharge. All on its own, that test probably took a few percent of life from the battery.

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A few weeks ago, with the most recent spate of loadshedding, the system shut down somewhere between 1.5 and 2 hours, so I realised something was wrong.

I'm afraid that doesn't sound good for this battery.

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I read about the premature float bugs (not sure if my model is affected?)

ALL Axperts running non-patched firmware have the premature float bugs, sadly. The manufacturer simply refuses to acknowledge it.

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and found some settings to hopefully revive my batteries if they have been constantly under-charged.

Unfortunately, lead acid batteries don't like deep discharges. My guess is that over about a year or so, the under-charging has led to a lower and lower state of charge, which has killed the battery.

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My current settings are as follows:

...

Bulk charge voltage: 29.1v

Float charge voltage: 27.4v

 

Those figures are good for 25°C. Does the battery get hot in summer where you are located? If so, those voltages should be reduced in summer.

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Low cut off voltage: 21.0v (23.5v before the settings change 2 weeks ago)

Both of these are far too low if you routinely use that setting to stop discharging. It's meant to be a last resort thing; you are supposed to use switching to utility to stop discharging the battery way before it gets to this low of a voltage. I suspect you've had a lot of load shedding lately, so the inverter doesn't get the option to switch back to utility. So this setting should be up around 24.8 V (12.4 V per 12 V module) for reasonable battery life. Get the lead acid experts to pick a better number than that; I'm no lead acid expert.

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Bulk charge time: 120 min (Auto before the settings change 2 weeks ago)

This facility, or perhaps the equalisation facility, might be able to be used to work around the premature float bugs.

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Equalization interval: 1d for a week, then 2d for a week (did this to hopefully revive the batteries if they were at fault, will now set it to 1w or longer)

Leaving this at say 2d might be a reasonable way to fight the premature float bug. The problem is that with sealed lead acid, you have to be so careful not to over-charge as well as not to under-charge. So finding the right settings for your climate etc could be challenging.

If it's possible to set the equalisation voltage to less than the bulk/absorb voltage, that would be ideal. Keep the equalisation at 28.7 V (just under the gassing voltage, lower in summer) so that when the battery spends a lot of time in equalisation, it's not gassing off its very limited supply of water.

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Firmware – Main CPU (U1): 51.50

Wow, that's an unusual value for a King, in my very limited experience.

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Firmware – Secondary CPU (U2): 01.12

I suspect that this is the display firmware; I only know 02.00.

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Firmware – SCC (U4): 00.00

This is zero because you have no solar panels.

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I ran these settings for two weeks, and did another test run this weekend, but again only got out 1.5 hours, so no improvement.

Lead acid batteries can recover from some situations, but unfortunately chronic undercharging isn't one of them.

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The reported voltage relatively quickly drops from the float voltage to about 25.2v and holds around there for around an hour.

This is the "working range" of the battery.

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It then starts dropping at about 0.1v every 1 or 2 seconds until it starts beeping at 22v; 1v from low voltage cut off.

That very rapid drop in voltage indicates that the battery is very close to fully discharged. It should never be allowed to get into this range. That's why I suggest setting the low DC cutoff voltage to about 24.8 V, before it's really started this dive.

The beeping at 1.0 V above cutoff voltage (2.0 V for 48 V models) is an undocumented feature of all Axperts (as far as I know).

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Just before the system shuts down, the inverter reported 21.5v and I measured 21.7v with a multimeter at the fuse disconnector terminals (while connected, with load).

That's slightly disappointing accuracy. At least it's stopping the discharge a little early as a result.

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I then disconnected the batteries and measured the batteries at the fuse disconnector with a multimeter, and that gave me a reading of 25.9v.

So with your extremely modest loads (are they still modest, or has it been creeping up?) the battery is springing back by 4.2 V (an average of 1.2 V per 12 V module). That means that the battery has a very high internal resistance, which means it's really in bad shape, as well as very low in charge.

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What is at fault here, the inverter or the batteries?

At least a big chunk of it seems to be inverter / settings related, as noted above. The battery looks decent to me, but get opinions from battery experts. You've paid some school fees with this first battery; many users do. I'd say get another battery (consider a lithium battery with a battery management system built in, if that's within budget), and make changes as noted above. Remember that a 12 V battery module should rarely if ever be seen at actual 12.0 volts.

Thanks for your response, although the news sounds worse than I had hoped.

 

3 hours ago, Coulomb said:

Assuming an average load of 160 W, 28 hours of runtime is about 4500 Wh. Your battery is rated at about 24 x 240 ~= 5750 Wh. So that test was a bit brutal, a nearly 80% discharge. All on its own, that test probably took a few percent of life from the battery.

Is this calculation correct? I have 2x 240Ah batteries, so a total of 480Ah. Should it not be 24 x 480 = 11520Wh, which is nearly a 40% discharge? Or should the Ah of the two batteries not be added together?

 

3 hours ago, Coulomb said:

Those figures are good for 25°C. Does the battery get hot in summer where you are located? If so, those voltages should be reduced in summer.

I'm in Johannesburg and the installation is in my garage. Most summer afternoons temps get to about 33°C. It has probably gone over 25°C since October. What would you recommend? I found the following on the manufacturer website, but have no idea how many "cells" the batteries have to use in the calculation:

1. For standby, 13.6V (at 25°C), -3mV/°C/cell, above 25°C.
2. For deep cycle applications, 14.4V (at 25°C), -5mV/°C/cell, above 25°C.

 

3 hours ago, Coulomb said:

Both of these are far too low if you routinely use that setting to stop discharging. It's meant to be a last resort thing; you are supposed to use switching to utility to stop discharging the battery way before it gets to this low of a voltage. I suspect you've had a lot of load shedding lately, so the inverter doesn't get the option to switch back to utility. So this setting should be up around 24.8 V (12.4 V per 12 V module) for reasonable battery life. Get the lead acid experts to pick a better number than that; I'm no lead acid expert.

I wouldn't say it was routinely; perhaps not more than 5 times, and that was at the slightly higher 23.5V. Loadshedding is usually not more than 4 hours, so when the batteries was still performing "normally", it wouldn't get nearly that low.  One time was at 21V, this weekend. I thought I was actually conserving my batteries by setting it higher than the default 21V, but didn't think it was still way too low. I clearly didn't do my homework on this one. I've changed this to 24.8V, thanks.

 

3 hours ago, Coulomb said:

Leaving this at say 2d might be a reasonable way to fight the premature float bug.

 

3 hours ago, Coulomb said:

Keep the equalisation at 28.7 V

Done and done, thanks

 

3 hours ago, Coulomb said:

Wow, that's an unusual value for a King, in my very limited experience.

Is there anything newer or better available I can upgrade to, that would make any difference to my situation?

 

3 hours ago, Coulomb said:

That's slightly disappointing accuracy. At least it's stopping the discharge a little early as a result.

I have to add, my multimeter is also very cheap, so may not be 100% accurate either. The truth might be somewhere in the middle.

 

4 hours ago, Coulomb said:

So with your extremely modest loads (are they still modest, or has it been creeping up?)

It has been fairly constant within the 140w to 180w range.

 

4 hours ago, Coulomb said:

That means that the battery has a very high internal resistance, which means it's really in bad shape, as well as very low in charge.

This is really bad news. Under a year's use on R11k worth of batteries, with a claimed 12 year design life and 4500 cycles at 20% DOD and even 1000 at 80% DOD. School fees indeed. 🤦‍♂️😭

 

4 hours ago, Coulomb said:

The battery looks decent to me

This contradicts that the batteries are in bad shape, as well as the earlier "killed the batteries" though.

 

4 hours ago, Coulomb said:

I'd say get another battery (consider a lithium battery with a battery management system built in, if that's within budget), and make changes as noted above.

Two batteries, sadly. I could go the warranty route, but it is only a limited manufacturers warranty, i.e. "The manufacturer's defect warranty only covers manufacturing defects and does not cover incorrect use or abuse." I suspect they will see it as the latter, especially since they didn't sell me the inverter.  They also charge money for the testing if it is found that the failure isn't a manufacturing fault - money I may be better off spending on new batteries. The bulk of what the system powers are aquarium pumps, so they are not really for for purpose with the current performance, as it should never switch off.

Not sure if lithium batteries will be in my budget, as the gel batteries were already a stretch, and quick look at prices says it won't. I will however consider all options. I will definitely make all the setting changes though, thank you.

 

4 hours ago, Coulomb said:

Remember that a 12 V battery module should rarely if ever be seen at actual 12.0 volts

I didn't know this. I clearly had just enough information to make myself dangerous. This was my biggest mistake it seems, followed by not using equalization - both settings that are  wrong by default on the Axpert. Lesson learned.

 

Thanks again

 

 

 

Hi AScheff,

I am still learning about Axpert and batteries, but in my my opinion if you act quickly, there is a chance you can rescue the batteries by charging with a good external battery charger. One that can supply a high charging current, which may be able to correct any sulphation on the battery plates. As your batteries are sealed just have to be careful not to overcharge and lose electrolyte through gassing, as the batteries cannot be topped up.

How to charge the batteries:

1. Take them to a battery expert with charging equipment.

2. Buy a good charger

Hawkins are a good local make. These are manual chargers, use with care. They have a sticker 'do not use on sealed batteries'

Ctek make high quality smart chargers, quite pricey,  but quality chargers.

Midas sell a PDS008 charger for less than R1000, highly recommended by the 4x4 community for rescuing abused batteries! I used one of these yesterday and was quite impressed.

Both Ctek and PDS008 are so called smart chargers, they have many phases of charging which do various things to the battery, compared to the manual chargers which just use a brute force charge. Both are good, a charge is a charge!

If you buy a charger, disconnect your batteries, connect the charger and charge each battery overnight, one at a time.

Reconnect the batteries and hold thumbs, hope that the charger has paid for itself.

Let me know what happens, I would be interested in the outcome!

Omnipower are good batteries. Sealed for low maintenance, but probably can be opened to check water level. Of course this will invalidate the warranty.

If you have a good supplier contact, might be worth asking them for advice.

Good luck!

Solo

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PS AGM and gel batteries do not have electrolyte like lead acid batteries. 

Cannot be topped up, so be careful not to overcharge, but it looks like they will accept 40A, so I guess low risk of overcharging with a Ctek or PDS008 charger, I doubt these will supply 40A

Thanks @Solo

10 hours ago, Solo said:

2. Buy a good charger

This sounds like a worthwhile investment to have, even if it doesn't save these batteries it may be useful to keep the next healthy. 

 

10 hours ago, Solo said:

Midas sell a PDS008 charger for less than R1000

I looked at these, they are well priced, but they seem to charge at a maximum of 8 amps, while my batteries require a minimum of 30 amps.

 

10 hours ago, Solo said:

Ctek make high quality smart chargers, quite pricey,  but quality chargers.

On the Ctek I'll have to go for the MXTS40, which charges at 40 Amps, which is my batteries recommended charge current. That is a R17k charger though, so would rather buy new batteries for less. I'll see if I can find another suitable smart charger

 

10 hours ago, Solo said:

PS AGM and gel batteries do not have electrolyte like lead acid batteries. 

Cannot be topped up, so be careful not to overcharge, but it looks like they will accept 40A, so I guess low risk of overcharging with a Ctek or PDS008 charger, I doubt these will supply 40A

These batteries can be charged at 50 amps maximum safely according to the specs.

10 hours ago, Solo said:

1. Take them to a battery expert with charging equipment.

I suspect this will be the route I'll have to go when looking the the cost of smart chargers with a suitable charge current

11 hours ago, ascheff said:

Is this calculation correct? I have 2x 240Ah batteries, so a total of 480Ah.

No, with battery modules in series, you double the voltage, but not the amp·hour capacity. You can never double both no matter how you connect them. Conservation of energy and all that.

So with two nominally 12 V 240 Ah modules in series, you now have a nominally 24 V 240 Ah battery. So you have double the energy (Wh), as you'd expect from doubling the number of modules.

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I'm in Johannesburg and the installation is in my garage. Most summer afternoons temps get to about 33°C. It has probably gone over 25°C since October. What would you recommend? I found the following on the manufacturer website, but have no idea how many "cells" the batteries have to use in the calculation:

1. For standby, 13.6V (at 25°C), -3mV/°C/cell, above 25°C.
2. For deep cycle applications, 14.4V (at 25°C), -5mV/°C/cell, above 25°C.

 

A lead acid cell is nominally 2.0 volts. It's a matter of electrochemistry. So each 12 V module has 6 cells, and your two module battery has 12 cells. They are all in series, so for the purposes of the above calculations, the number of cells is indeed 12. (If you had strings in parallel, then the extra strings would not count.)

So using your figure of 33°C in summer, that's 8°C more than 25°C, so the bulk/absorb voltage per module should change from 14.4 V to 14.4 - (5/1000 x 8 x 6) =  14.16. For your total battery, this would double to 28.8 V → 28.32 V; use 28.3 V.

[ Edit: 14.4 V per 12 V module (2.40 V per cell) happens to be the gassing voltage. So in summer, your battery will start gassing at 28.3 V. So make sure that in summer, the equalisation voltage is no higher than 28.3 V. It can go back to 28.8 V in winter. ]

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I wouldn't say it was routinely; perhaps not more than 5 times...

That's the thing with lead acid; they can only take a handful of really deep (near 100%) discharges.

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Is there anything newer or better available I can upgrade to, that would make any difference to my situation?

I would not recommend attempting to update firmware from such a strange original version number. Plus, there isn't anything that would make a material difference to this situation.

 

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School fees indeed. 🤦‍♂️😭

They sure hurt.

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This contradicts that the batteries are in bad shape, as well as the earlier "killed the batteries" though.

Ah. I meant that the brand looks decent, and another poster has reinforced this.

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Two batteries, sadly.

Ah. I'm using the strict technical terminology; whatever collection of cells and modules you have, that's your battery. We're used to looking at a brick with terminals and 12 V on the side as a battery, and it is, but when you combine these to make a bigger thing, it gets confusing.

So throughout I've been referring to one brick as a battery module; you have two battery modules making up one battery. When I said you need a new battery, that means two new modules if you use the same parts. But you could have replaced it with say 8 Trojan modules, each about 105 Ah and nominally 6 V, connected four in series and two such strings in parallel. All that would still be one battery, but 8 battery modules.

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I could go the warranty route, but it is only a limited manufacturers warranty

I don't see the value in that. It's always a lot of finger pointing.

Edited January 28, 20205 yr by Coulomb

7 minutes ago, Coulomb said:

No, with battery modules in series, you double the voltage, but not the amp·hour capacity. You can never double both no matter how you connect them. Conservation of energy and all that.

Thank you

 

10 minutes ago, Coulomb said:

A lead acid cell is nominally 2.0 volts. It's a matter of electrochemistry. So each 12 V module has 6 cells, and your two module battery has 12 cells. They are all in series, so for the purposes of the above calculations, the number of cells is indeed 12. (If you had strings in parallel, then the extra strings would not count.)

So using your figure of 33°C in summer, that's 8°C more than 25°C, so the bulk/absorb voltage per module should change from 14.4 V to 14.4 - (5/1000 x 8 x 6) =  14.16. For your total battery, this would double to 28.8 V → 28.32 V; use 28.3 V.

[ Edit: 14.4 V per 12 V module (2.40 V per cell) happens to be the gassing voltage. So in summer, your battery will start gassing at 28.3 V. So make sure that in summer, the equalisation voltage is no higher than 28.3 V. It can go back to 28.8 V in winter. ]

Awesome, thanks, I'll make these adjustments. Learning a lot.

 

11 minutes ago, Coulomb said:

I would not recommend attempting to update firmware from such a strange original version number. Plus, there isn't anything that would make a material difference to this situation.

Got it. It sounds like I can work around the shortcomings of the inverter/firmware by optimising the settings anyway, so will stick to that.

 

14 minutes ago, Coulomb said:

So throughout I've been referring to one brick as a battery module; you have two battery modules making up one battery.

Again, learning lots here, thank you.

 

14 minutes ago, Coulomb said:

I don't see the value in that. It's always a lot of finger pointing.

I expect as much after reading the "small print". 

16 hours ago, Coulomb said:

Assuming an average load of 160 W, 28 hours of runtime is about 4500 Wh. Your battery is rated at about 24 x 240 ~= 5750 Wh. So that test was a bit brutal, a nearly 80% discharge. All on its own, that test probably took a few percent of life from the battery.

What is considered a "safe" discharge percentage, if I wanted to calculate how many running hours I could safely expect on my battery (if they were in a new, healthy condition)?

59 minutes ago, Coulomb said:

That's the thing with lead acid; they can only take a handful of really deep (near 100%) discharges.

If you want to get really technical, they can take 1 (ONE!) full discharge. On the next iteration you have 99%, then 98%... after 20 full discharge cycles you have maybe 80% of the original left, and if you continue to discharge the battery until it is dead every time, then after 70 cycles you have half the original capacity left, and so forth. That's simple math if I assume the battery loses 1% on each complete discharge... which is probably not a bad estimate for a UPS-type battery.

In my experience, car batteries are even worse than that. Do that 20 times and that battery is toast...

19 minutes ago, ascheff said:

"safe" discharge percentage

There isn't really such a thing. The application determines what is considered a good value. In your typical UPS setup in a country where there aren't that many outages, a complete discharge is not considered a bad thing. Age will kill the battery long before it dies of hard work.

For a house I've seen people spec their banks anything from 50% DoD to 20%DoD to make them last, but even that seems like an exercise in futility, because generally the DoD vs cycle-life chart is fairly linear, by which I mean that if you discharge it only half as deep it only lasts twice as long. This is true at least for the middle of the "chart". So you can make the batteries last twice as long by only using half their capacity... but in the end your price per kWh stored is going to be very similar.

With all that said, most people will tell you that 50% is a good number.

And they do go faster if you discharge deeper than 80%. As I said, the linear part is only really sort-of in the middle 🙂

 

6 minutes ago, plonkster said:

There isn't really such a thing. The application determines what is considered a good value. In your typical UPS setup in a country where there aren't that many outages, a complete discharge is not considered a bad thing. Age will kill the battery long before it dies of hard work.

For a house I've seen people spec their banks anything from 50% DoD to 20%DoD to make them last, but even that seems like an exercise in futility, because generally the DoD vs cycle-life chart is fairly linear, by which I mean that if you discharge it only half as deep it only lasts twice as long. This is true at least for the middle of the "chart". So you can make the batteries last twice as long by only using half their capacity... but in the end your price per kWh stored is going to be very similar.

With all that said, most people will tell you that 50% is a good number.

And they do go faster if you discharge deeper than 80%. As I said, the linear part is only really sort-of in the middle 🙂

Thanks for that. So it really comes down to what the typical conditions are and how long I want the batteries to last. So taking Coulomb's calculation, for the typical 4 hour loadshedding at my current average load of 160w: 160 x 4 = 640Wh., which is an 11% DOD. This would be "safe".

Less frequently, but not rare would be a cable fault, which takes perhaps 8 hours to fix, which is: 160 x 8 = 1280Wh, which is 22% DOD, which is still okay?

Rare, but not unheard of would be when a transformer explodes, and it may take 24 hours to get back online: 160 x 24 =  3840Wh, which is 66% discharge, and would be bad for the battery. Here ideally I should then switch to my backup generator during the day and/or lower the load to the absolute minimum.

At the "good number" of 50%, I would get 2875Wh to use, which is 18 hours runtime.

 

Am I on the right track with my understanding and calculations?

Just now, ascheff said:

Here ideally I should then switch to my backup generator during the day and/or lower the load to the absolute minimum.

Another option I suppose is adding solar panels, which would mean it would theoretically only draw from battery during night hours, even during very long utility interruptions. Not sure if my complex would "prefer" permanent panels on the roof or a rare generator during the day

49 minutes ago, ascheff said:

an 11% DOD. This would be "safe".

Definitely.

50 minutes ago, ascheff said:

Less frequently, ... 22% DOD, which is still okay?

Yes.

50 minutes ago, ascheff said:

Rare, but not unheard of would be when a transformer explodes, and it may take 24 hours to get back online: 160 x 24 =  3840Wh, which is 66% discharge, and would be bad for the battery.

As you say, it would be best for battery life to stop at 50% discharge. But if you have a business that depends on the electricity flowing, it may well be best to take the slight hit on battery life, rather than lose stock or whatever the costs are of the electricity not flowing. It all depends on your circumstances. And of course, the power may not come back when advertised, so at the end you are continually sweating the choice: do I hang on a bit longer, or quit now?

I've heard it claimed that this ability to take the very rare three times deeper than usual discharge is a feature of lead acid batteries, that for example no lithium chemistry can match. I'm not sure that I agree, but it's something you have that you may as well take advantage of, as long as it really is very rarely.

1 hour ago, ascheff said:

Am I on the right track with my understanding and calculations?

At a low 160W your calculations look about right, but do remember to add the self-consumption of the inverter itself, which for that particular model is around 50W if I recall, so you probably need to work it out at around 200W.

I would not say that a once-in-a-lifetime transformer explosion that results in a 70% DoD is necessarily "bad". As Coulomb just said:

1 minute ago, Coulomb said:

this ability to take the very rare three times deeper than usual discharge is a feature of lead acid batteries, that for example no lithium chemistry can match

 

Thanks guys. While I don't feel any better having to replace the batteries, I do feel better equipped to treat the next ones better.

Good discussion, I am taking notes!

I would definitely try charging the batteries before going to all the cost of replacing them.

I suspect they have been undercharged, the fact that they last 2 hours may be a hopeful sign.. We had 100Ah batteries which lasted 20 mins. They had been severely discharged, several times.

10 minutes ago, Solo said:

Good discussion, I am taking notes!

I would definitely try charging the batteries before going to all the cost of replacing them.

I suspect they have been undercharged, the fact that they last 2 hours may be a hopeful sign.. We had 100Ah batteries which lasted 20 mins. They had been severely discharged, several times.

I'm definitely going to try that first. I'll try to find a place that will do it for me. Perhaps even the guys who supplied them might be able to help. 

It's been a while since I last posted (time flies when you're having lockdown?), so I thought I'd come give this closure on this.

After trying various things at home, like regularly cutting power to the inverter for a few minutes to force charging of the battery when reconnected, I wasn't able get the battery to last any longer than about an hour, or hour and a half. I took them to the supplier, who was able to do a thorough charge, and then run diagnostics. They determined the same as you guys advised, that the battery was probably not charged optimally, but also that the battery was likely damaged by being charged at incorrect voltages during the summer months, due the the Axpert not automatically compensating for temperature. The diagnostics also served as a check on the validity of the warranty, and as expected due to the reasons given, the warranty was invalidated.

They advised that to get the best out of the batteries in their condition, to move them into the house, which is air-conditioned. I did this and ran it this way for a few months. Luckily loadshedding stopped due to the lockdown, so that bought me some time. A long power fault a few weeks back however brought the same issues to the fore.

This prompted me to take the plunge, and I replaced the lead acid battery with a Pylontech UP2500. For now I'm running on charge settings provided by the supplier, but will probably ask for advice on the best settings soon. I will leave that for a separate thread though.

Thanks again for everyone's advice.

Edited June 23, 20204 yr by ascheff
typo

Hey ascheff,

Just wondering how you are coming along with those Pylontech UP2500 batteries?

I also have a 3kVA Mecer (Axpert) and am in a similar position where my 8 lead-acid batteries I bought 3 years ago now need charging every night. They may also have been damaged due to temperature or the fact that I gradually mixed new batteries in with slightly older ones. In any case I am looking at getting at least one UP2500 (I draw at most 40Ah overnight, not sure yet but I may need to buy two and parallel them)

Did you change any of the Axpert's settings and do you have any communication between it and your Pylontech batteries?

Thanks!

Hi All. Just a side note. For situations where the current draw from the battery is much lower than say 0.1C, the low switchover voltage setting of the Axperts is particularly dangerous to rely on routinely, as the battery voltage will remain quite high even if it gets discharged way below 50%. It is a pity that one cannot set the DoD setpoint instead, since from calculations on my system it will do a better job of protecting the batteries against these types of deep slow discharges, even though it is also notoriously inaccurate. The low voltage switchover is not a problem with more significant loads, as the voltage drop is considerably more pronounced even for a full battery and will trigger the switchover conservatively, albeit prematurely. Because of this danger my switchover setting for my 48V system is 49V. AGM Batteries. 

On 2020/08/25 at 6:38 PM, Lindsay said:

Hey ascheff,

Just wondering how you are coming along with those Pylontech UP2500 batteries?

I also have a 3kVA Mecer (Axpert) and am in a similar position where my 8 lead-acid batteries I bought 3 years ago now need charging every night. They may also have been damaged due to temperature or the fact that I gradually mixed new batteries in with slightly older ones. In any case I am looking at getting at least one UP2500 (I draw at most 40Ah overnight, not sure yet but I may need to buy two and parallel them)

Did you change any of the Axpert's settings and do you have any communication between it and your Pylontech batteries?

Thanks!

 

Hi Lindsay,

I'm very sorry, I completely missed your post and only saw it now when I got notification of BosVos' post. It is more than 7 months too late, but I will give feedback anyways, in case it might still help you or someone else.

I really cannot fault the battery; I have now gone through a winter and a summer with it, as well as quite a bit of loadshedding and a few "regular" grid failures. It has now lasted longer than my lead acid batteries did, touch wood.

The guys that supplied the Pylon gave me settings to use, which I've used since installing.
Battery Type: USE
Charge Current: 40A
Bulk Charge: 28V
Float Charge: 27V
Low DC Cut Off: 22V

I have no idea if these settings are optimal considering the Axpert's premature float bug and battery's built in BMS. I should probably start a new thread, as I've been meaning to do since last year, and get some more opinions.

I connected the port labeled Li-Ion on the Axpert to the RS485 port on the Pylon using the supplied RJ45 cable, but I have no idea if that even really does anything. My Axpert doesn't have the PYL option for battery type, and I have not been able to find any firmware update which could enable the function.

My biggest annoyance, which is no fault of the battery, but rather the Axpert, is that I still cannot get true SOC. I was ready to go the ICC route, but after emailing Diversified Solutions to confirm cable support, found out that the cable only works on the  US2000 and US3000, and not the UP2500. I was apparently only the second person ever to enquire about the UP2500, so I guess the one issue with it is popularity, and subsequent lack of 3rd party support.

So I then installed SolPipLog on a Pi, which feeds data to another Pi with Home Assistant. That works great for remotely monitoring everything, except SOC, and I have been unable to get SolPipLog to get data from the Pylon. 

I made my own cable as detailed here, https://powerforum.co.za/topic/2322-youdas-off-grid-lab/page/2/?tab=comments#comment-53641, bought a Sunix USB to RS232 Serial Adapter with Prolific PL2303HxD chip, and although it can communicate with the BatteryView tool in Youda's post on my Windows PC, I can't get it working with the Pi and older SolPipLog with Pylon support built in, or with the latest SolPipLog and PyLog separated. 

So all in all, considering that I use the system for grid backup only (for now) and I also don't draw too much power, I'm happy with the size of my inverter + battery I have now. The big benefit in my case if I had gone for a 48V system instead , would have been for 3rd party support, both for Axpert firmware support as well as ICC software support.

 

Before another year goes by, I have created a new thread for my current system, which I'll use going forward to get my setup optimized.

I have started it off with questions around my current settings.
 

 

Edited April 9, 20214 yr by ascheff

Hi, 

can you do Equalization on the omni power batteries?

 

On 2021/06/10 at 10:50 AM, Barryv said:

Hi, 

can you do Equalization on the omni power batteries?

 

The guy at Sinetech who I discussed my setup with after running into issues said they shouldn't be equalized