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Should I be "exercising" my battery regularly?


MdF
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Morning All,

So, installed a solar-inverter-battery system when the last round of loadshedding hit. But as with Murphy's Law, no loadshedding since then.

I have not yet set up the inverter to use battery power at night and then to recharge from solar during the day as I feel I need the battery backup in case the grid goes down (I tend to err on the side of caution mostly).

I ask the question then that should I be "exercising" my battery in order to ensure it performs as it is intended? If that is the case, then I will manually, from time to time, run the system off battery power.

Thanks.

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3 hours ago, MdF said:

Morning All,

So, installed a solar-inverter-battery system when the last round of loadshedding hit. But as with Murphy's Law, no loadshedding since then.

I have not yet set up the inverter to use battery power at night and then to recharge from solar during the day as I feel I need the battery backup in case the grid goes down (I tend to err on the side of caution mostly).

I ask the question then that should I be "exercising" my battery in order to ensure it performs as it is intended? If that is the case, then I will manually, from time to time, run the system off battery power.

Thanks.

 

What batteries do you have?

Different batteries types have different requirements. 

 

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4 hours ago, MdF said:

Morning All,

So, installed a solar-inverter-battery system when the last round of loadshedding hit. But as with Murphy's Law, no loadshedding since then.

I have not yet set up the inverter to use battery power at night and then to recharge from solar during the day as I feel I need the battery backup in case the grid goes down (I tend to err on the side of caution mostly).

I ask the question then that should I be "exercising" my battery in order to ensure it performs as it is intended? If that is the case, then I will manually, from time to time, run the system off battery power.

Thanks.

How much battery do you have? I have 10 kw/h. My system is set to allow discharge down to 4kw/h remaining when there is grid power. This means that when there's an outage I will always have 4kw/h of battery plus whatever solar is available. As regards backups during the night, we run all the big jobs during the day - pool pump, water heating, heavy using appliances etc, and from about 5pm the house is just ticking over - fridges, TVs, phones being charged, some LED lighting. We have a ban on the electric kettle after 4pm. So our load from about 5pm to 7 the next morning seldom gets up to 500w/h, and so that 40% is going to get me a long way over night. I stipulate 7am because that's the time our water heating kicks in. But we have a heatpump rather than a conventional geyser and most days we still are not at 40% by the time I start getting useful solar. 

Now, I have some east facing panels, so my PV gets going early in the morning, but the point is that if you identify your heavy loads and start controlling them, you can use the battery at night without giving up protection against outages, and that will also benefit your pocket.

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2 hours ago, Rclegg said:

 

What batteries do you have?

Different batteries types have different requirements. 

 

Hi All,

The inverter is the Deye 5kw model.

I have the 48v 100Ah(105Ah) 5.1kWh LiFePO4 Lithium Iron Phosphate UPS Battery from Lithium Batteries SA.

And 8 x 400w panels.

 

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15 hours ago, MdF said:

Hi All,

The inverter is the Deye 5kw model.

I have the 48v 100Ah(105Ah) 5.1kWh LiFePO4 Lithium Iron Phosphate UPS Battery from Lithium Batteries SA.

And 8 x 400w panels.

 

I have a similar setup as yours. Same inverter (Sunsynk), same battery and similar PV size. I also had my system installed when there was a bit of loadshedding. 

I discharge the battery to 25% everyday, this way I'm getting a return on investment faster and also not abusing the battery. 

I average about 16kwh each day which is roughly R1000 saved every month.

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20 hours ago, MdF said:

Hi All,

The inverter is the Deye 5kw model.

I have the 48v 100Ah(105Ah) 5.1kWh LiFePO4 Lithium Iron Phosphate UPS Battery from Lithium Batteries SA.

And 8 x 400w panels.

 

Then yes, you should be cycling the batteries every day. LiFePO4's don't like staying 100% all the time. I cycle mine daily to 20%. But check what your battery specs are and look at the DoD spec. 

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Morning All,

Thanks to Phil for his help, much appreciated.

However, I am still trying to get my head around the Time of Use table to understand what happens with the SOC etc. So, below is a stylised setup that I need help with populating please.

The basic concept is as follows:

(1) Midnight to early morning - run the house on battery power. But to what SOC should I deplete the battery to if there may be a chance of loadshedding during the following day (this is why the system was installed in the first place)?

(2) Morning to afternoon - run the house on solar power (which it currently does). When solar power starts in the morning, use excess solar to start charging the battery from previous nights use.

I understand that you can't delete the data in the 6 rows when you tick Time of Use so you need to have settings in all the rows (maybe this is something that should be an option i.e. you can select which rows you want to activate / deactivate).

Thanks in advance.

TimeSettings-01.PNG

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19 hours ago, MdF said:

Morning All,

Thanks to Phil for his help, much appreciated.

However, I am still trying to get my head around the Time of Use table to understand what happens with the SOC etc. So, below is a stylised setup that I need help with populating please.

The basic concept is as follows:

(1) Midnight to early morning - run the house on battery power. But to what SOC should I deplete the battery to if there may be a chance of loadshedding during the following day (this is why the system was installed in the first place)?

(2) Morning to afternoon - run the house on solar power (which it currently does). When solar power starts in the morning, use excess solar to start charging the battery from previous nights use.

I understand that you can't delete the data in the 6 rows when you tick Time of Use so you need to have settings in all the rows (maybe this is something that should be an option i.e. you can select which rows you want to activate / deactivate).

Thanks in advance.

TimeSettings-01.PNG

To answer #1, what is the SoC that the manufacturer recommends? Add 5% to this, and if you want to plan for early morning load shedding, just add that percentage to this, and that's your figure.

Your table looks OK for the rest of the day. Note that exceeding the load on available solar power may allow the inverter to use battery power when SoC is above 80%. If you notice hysterisis, then reduce your charge rate slightly, apparently it helps. I have mine setup in a similar way, and do not mind the odd occasion when battery is used vs grid.

If you have too many entries, then just duplicate one or two of them. 

Edited by YellowTapemeasure
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On 2021/08/29 at 12:13 PM, MdF said:

The basic concept is as follows:

(1) Midnight to early morning - run the house on battery power. But to what SOC should I deplete the battery to if there may be a chance of loadshedding during the following day (this is why the system was installed in the first place)?

(2) Morning to afternoon - run the house on solar power (which it currently does). When solar power starts in the morning, use excess solar to start charging the battery from previous nights use.

Afternoon All,

Thanks once again for the online and offline support.

So, based on my previous post, I have decided to go with the following settings to address points 1 and 2 above.

Would this be OK for what I am trying to achieve?

Thanks

 

TimeSettings_30Aug2021-01.png

TimeSettings_30Aug2021-02.png

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1 hour ago, MdF said:

Afternoon All,

Thanks once again for the online and offline support.

So, based on my previous post, I have decided to go with the following settings to address points 1 and 2 above.

Would this be OK for what I am trying to achieve?

Thanks

 

TimeSettings_30Aug2021-01.png

TimeSettings_30Aug2021-02.png

Looks OK to me, although I would rather have the last entry at 23H59 and the first entry at 00H00. 

What is your baseload draw in the evenings? Mine varies between 200 and 460 W, upper level achieved when the fridge freezer kicks in (about 145W). I would use the same (maybe 80W more) during load shedding.

Edited by YellowTapemeasure
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1 hour ago, MdF said:

Afternoon All,

Thanks once again for the online and offline support.

So, based on my previous post, I have decided to go with the following settings to address points 1 and 2 above.

Would this be OK for what I am trying to achieve?

Thanks

 

TimeSettings_30Aug2021-01.png

TimeSettings_30Aug2021-02.png

The only 'problem' i see here is that the inverter will use the grid between 8am and 3pm as long as the batteries are not fully charged. I prefer supplementing solar with batteries during the day to ensure that i don't pull from the grid during the day.

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Hi Phil,

So looking back at the screenshots you sent me, would it be better to have SOC from 8am to 3pm at 50%?

That way you are covered should solar not be enough for excess to feed the battery, then grid will charge?

MdF

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2 hours ago, MdF said:

Thanks YT,

My base load is about 450 max with fridge at night.

Just saw some info that max number of hours per each row should be kept to 4, or else problems do occur???

Will adjust times accordingly.

MdF

OK, so your baseload it's very similar to mine then. I have 10.5 k storage, 8.4 k usable on my 5K Sunsynk. In the morning I have between 55-65% SoC before batteries start charging, and just today recharged to 100% at 09H30. Plenty left after that for hot water generation, ironing and other stuff. So if there was no load shedding, you may even be able to push yours all night. You almost have the capability to go solo, congratulations!

Not sure about the 4 hour thing, never experienced it on my Sunsynk. It does get a bit confused when your first entry doesn't start at 00H00 though, so it's better to start off closest to 00H00 and make sure that times are chronological (do not overlap or out of order). 

You will need to do a bit of experimenting to see what works for you, with your current generation and storage, and utilisation during the day. And then come the clouds, and the cloudy days.  

This is what currently works for me, rain or shine:

IMG_20210830_202802.thumb.jpg.d374aa6de3d0c77f0e909f9205a4c4e3.jpg

 

   

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13 hours ago, MdF said:

Hi Phil,

So looking back at the screenshots you sent me, would it be better to have SOC from 8am to 3pm at 50%?

That way you are covered should solar not be enough for excess to feed the battery, then grid will charge?

MdF

I have recently changed mine to this since I don't use underfloor heating at night. Battery will drain to 25% at around 5am. I'm not worried about loadshedding during the day because there will be solar to power the essentials.

IMG_20210831_072347__01.jpg

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Right, so then based on the above, this is what the Battery Settings are currently on the system. How should these be adjusted to accommodate the Time Settings?

BatterySettings_31Aug2021-01.png

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2 minutes ago, MdF said:

Right, so then based on the above, this is what the Battery Settings are currently on the system. How should these be adjusted to accommodate the Time Settings?

BatterySettings_31Aug2021-01.png

Looks OK, if battery does get to 35%, then you will get a Low Batt alarm. This may happen at any time between midnight and 08H00, and that's fine if you want it to wake you up, but you may want to set it lower if it's going to disturb your sleep.

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3 minutes ago, YellowTapemeasure said:

Looks OK, if battery does get to 35%, then you will get a Low Batt alarm. This may happen at any time between midnight and 08H00, and that's fine if you want it to wake you up, but you may want to set it lower if it's going to disturb your sleep.

Yip TY, that was my thinking cos the alarm on the Deye is also a "screamer" 😂

Might bring that down from 35% to 30%. Will have to try the system out and see what happens 🥴

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