₦airaland Forum

ojeysky:
I think same can be said for lead acid, you can't get up to a thousand circle at 50% DoD. So I think a fair equivalent will be a 80% DoD of 200Ah lithium and 30% DoD of 400 Ah lead acid. Even at that circle wise a lead acid will have died when a Lifepo4 is just getting to its 80% usable capacity.



Agree but really this is why folks need to have a way of monitoring their lithium cells, it's as simple as that. However lithium cells are usually rated below their capacity, so a 100Ah is actually 105 or 110Ah to give room for 100% discharge at 100Ah without negative impact on the battery.



While I agree with the above, I think it addresses just a scenario in the emergency use cases. Here are a few more:

1. A lithium will have been recharged and used at least twice while a lead acid is still going through her first round of charging. Imagine you have electricity/solar only for a few hours and you have the juice to charge your battery but you are limited to 0.1C (or max 0.2c) on lead acid

2. A lithium handles current surge better in an emergency/normal situation than lead acid. My washing machine does a 2kw surge, this normally trips my former 300Ah lead acid, but the story is different using my current 200Ah Lifepo4

3. We also need to recognize that the occasional below 50% DoD on lead may actually cost 3x or more in overall circle life.

Overall I would still agree that it's a good thing not to get exactly 200Ah lithium just that my reasons and motivation for that is different.

There is a major fallacy in the supposed usability of Lead Acid battery beyond 50% DoD. It is totally dependent on what load you have on the system. And this is where Lithium shines. While drawing up to 80% of its capacity, you still have very high voltage to keep your inverter on. But with Lead acid, the only way you can go that deep is if you are only pulling 2 or 3A depending on your total AH. If you are pulling any significant amount of current, you may not even get to 50% DoD before your voltage sags enough to shut down your inverter.

Because of the way I use my system, I don't think I have ever seen a DoD of 50%. On rare occasions when I had deep discharges, the system will shut down once my water pump comes up in the morning in addition to my fridge and freezer. I sometimes have to temporarily take off the pump to prevent this.

Abigai:
Gurus diagram 1 and 2 which one is more accurate for 24v setup looking at the AH. thanks

The two pictures are the same.

ojeysky:
When charging inverter is higher but when discharging BMV is higher. Yes am using victron cable

Check with a clamp meter to see who is telling the truth and use that to calibrate the BMV. Calibrate your inverter too if that is possible.

ojeysky:
Folks I recently introduced BMV 712 to my setup(great tool by the way), but I noticed there is a 5A difference between what inverter display as charging current and what is actually seen by the BMV. Has anyone experienced this before?

Which one is higher? Are you using a victron cable or a DIY cable?

BetaTechnicians:
The question is a bit tricky, if we have to factor in useable capacity of lifepo4 vs 12V-200AH(Lead-Acid).

If we are to do that, we will be talking of 9 to 12 x12v/200AH batteries depending on intended DOD on both sides.

ojeysky:
Me I don't send request(make seller no think say I dey beg ham), I just wait till the countdown elapse and then I push the dispute in, but 90% of the instances seller extend before the countdown elapse. That said, I have later received refunded item in the past and had to return the funds back to the seller.

How did you refund the sellers? I was in similar situation and I was wondering how to reimburse the sellers?

I have a perfectly working 4-year old 24v outback inverter (VFX-3024E) that I will like to exchange for a 48V variety or another good inverter or sell for cash if I get a reasonable offer. I also have a mate 3 I can sell at a reasonable price.

Dam5reey:
Simply put, in order to use LifePO4, I must change my inverter to one with custom settings, that I can change float, bulk and Low voltage cut off..
That's why I learnt from several YouTube videos, what if you don't have time to babysit, battery monitoring is not an option

YES! You must be able to set charge voltage and current on your inverter/charge controller. You must also able to disable automatic equalization or at least be able to set the voltage.

ceaser:
Fret not.

What he means is "good dangerous" rather than "dangerous dangerous" or "bad dangerous"

He simply means that you get carried away by the sustained voltage over a long time despite load that you won't border to even check out the voltage again. At that point, you may miss when the voltage starts to drop on the meter.

With Lead chemistry, once you put a big load on it, the battery drops by 1volt or less. Then the volt drop with use and time is a linear relationship. However in the case of LFP(compared with Lead for capacity for voltage), if the battery was fully charged to 13.3v (for a 12v LFP battery), you won't really notice the drop in voltage and it can remain at that 13.3v for several hours before you notice any drop. That's the characteristic discharge curve of lithium.

Having said that, the BMS will do justice to ensure you don't overdischarge your battery.

@ Adrusa. I hope to take delivery of an extra 12v 100ah LFP tomorrow. I needed 120ah but 100ah was the last samurai that I was lucky to meet left. Damn, he was even sold out on 24v and 48v.

I actually mean "dangerous dangerous", but not in the way many think. Lead acid and our inverters have been married from factory. Most inverters will cut off from battery around 10V. Your battery's SOC is still substantial at 10V if you have some reasonable load on. So, the arrangement of your inverter cutting off at 10V suits the Lead acid battery very well. When your inverter cuts off your lead acid battery is unlikely to be substantially at risk of destruction. The situation is different with Lithium Battery.

Your Lithium battery's voltage will not drop like that of lead acid. So, when you have used 80/90% of your Lithium battery capacity, your voltage is still well above your inverter cut off voltage. So, before you inverter cuts off at 10V, your lithium battery will be at or precariously close to dangerous levels. However, if you have a good BMS, it will cut off your battery before it gets to this dangerous level. But, some BMS have a reset button which allows you to reset your BMS and still fire your battery a little more. By this time, your battery may actually be on its deathbed.

I therefore opined that you should invest in a battery monitoring system if you are putting money on Lithium. If you have batteries that has BMS that can talk to you, another monitor may be redundant, but if your BMS is deaf and dumb, it is advisable to have a monitoring device to monitor your discharge rate, your voltage and your DoD. Lithium battery is less forgiving of abuse than lead acid batteries. That is the (potential) danger.

ceaser:
Now they are showing their face.

Mr man, you are one of those that did panic buying of lithium battery from that guy. breeze don blow fowl nyansh open

I spoke with him to get info on his offers and 2 days later when I had the chance to forward money to him he told me he's sold out. I just deflate. I was like WTF!

Guys, people are going lithium now o. So wake up.

I didn't do panic buying. You've got to have money to do panic buying . I was actually speaking with some Chinese suppliers on Alibaba before I decided to settle for JEMAG for ease of mind. Didn't even know he sold out because I was planning to buy a little more if I can raise the money. I'm glad I bought, though not easy. Had to take some loans.

saint2ace:
Hello did you get delivery of ur battery as anticipated?

Yes, he is a great guy, he delivered as promised. Putting the thing together to start the life of LFP. One thing to say immediately; the Voltage holds. Your voltage will stay above 50 until the battery is squeezed dried of life. Makes it dangerous to use lithium without monitoring. I also did some capacity test and I got 85Ah out of 100Ah with my voltage still around 52.

I'm on my way to join the Lithium family. Expecting my delivery from JEMAG tomorrow. Thanks to Ojesky for the link.

ojeysky:
No but the guy has a 48v 150AH option, I think that one is 550k

Can you please share his contact?
Thanks.

mctfopt:
That is one of the advantages, the ability to charge at supersonic speed and high current without fear of damage to the batteries. Lithium is just the future.

So, when are we going to see serious local dealers? Buying from China is a logistic nightmare.

NoMoreTrolling:
He doesn't need to double the ah calculation because the OP said he is using Lithium batteries not Lead Acid.

Lithium batteries are a whole different ball game.

That's right to some degree, but even then he still need to add a little more unless he plans 100% DoD which is not recommended even for Lithium.

gtech2sure:
Let me quickly brief you on this. I am not an installer though but a fresh graduate who understand basic Electronics, Electrical and Computer Engineering all together. I had solved solar system problems for few installers who got lost for proper choice of components used and calculations. This calculations pretty work well


I am going to show you simple calculation to know like how many solar panel you need, watt of inverter to use, battery, charge controller and time to get a full charge using calculation.


Mind you, the calculation aren't hard. We only need addition, subtraction, multiplication and division.

Now let's begin
Before i proceed, there are some calculations i will not include in order not to make everything complicate, the calculations are based on energy loss in solar inverter system. With the one i will drop here, you can become an installer overnight with the help of youtube for practical aspect.

This system will be designed in 24v


LOAD: 700 watt

INVETER:
Inverter should be greater 25% than the total Load


Therefore load = 700 watt


700 x (25/100) = 175
700 + 175 = 875 Watt
This is the rating of needed inverter. But go for 24V, 1000 watt inverter or higher


BATTERY:
To know the total battery that could power load of 700 watt for 8 hours, just mutiply total load with time.
ie 700w x 8 = 5600w
This shows you need battery that could generate 5600 watt of power for 8 hours.


Use this formula to convert AH of the battery to watts.


W = V x AH. where w= watts, v= battery voltage and AH = battery amps.


Therefore: 12v x 200ah = 2400watt


Mind you, the system design is 24v
Due to this, you are going to use six 12v, 200ah battery where the three steps battery will be connected in series while loop them together in parallel to give you 24v, 7200 watt.


I know you might be wondering that the watt of battery we got here is more than what we need, just don't worry it's an added advantage. Our 7200watt battery here could power load of 700w for 10 hours.


It's done in this way:
battery watt/load: 7200/700 = 10.2 hours


SOLAR PANEL
To get solar power rating to use and time to get your battery charged depends on choice but i recommend 6 hours charging time because of cost.


It goes this way
Time to charge: battery watt/time (hour)
= 7200/6 = 1200watt
Your battery will get full in 6 hours with solar panel of 1200wat.


Note: You must not put ON any load on the system for you to get full charged within the period of 6 hours. But if you can't abide with this, you have to budget extra 700 watts solar panel to your cost


VOLTAGE CONTROLLER OR REGULATOR:
Power rating of solar used to determines the power of regulator to use.


Note: That Regulator rating are usually in Amps which you would need to convert to watt.


The regulator can be gotten using this formula
A = Solar rating (watt) / Battery voltage
= 1200 watts / 24
= 50 Amp


Therefore, you need 50A, 24V charge controller.


In summary this is all you need
24,V 1000watt inverter
Six 12V, 200AH battery
1200watt solar panel
24V, 50amp charge controller.


Goodluck..

There are some basic assumptions here that will cause serious problem.
1. I didn't see depth of discharge (DoD) here. For lead-acid battery, you don't have all the capacity available, may be about 50% at best. Some may say 80%, but depending on your load and your cut-out voltage, your inverter will cut off well before you can get to 80% of DoD. So, in calculating your AH need, you must double the result from your calculation. If you need 200AH, get 400AH.
2. I also didn't see "efficiency factors" here. In moving from DC to AC in an inverter, some power will be lost. It is usual to give about 10% of your power to this loss. Also, solar panels also have efficiency factor. This must also be taken into consideration. A 1KW array will not give you 1KW in an hour, it will be less. In addition, the sun is not likely to be full blast for full 5 hours in a day. So, some power will also be lost during cloud passes. Finally, batteries don't convert all available energy to storage during charging. Some of the energy are lost as heat. So, in making this kind of calculations, there is a need to make allowances for these imperfections in electronics.

Actually, this is fake news. It is not true.

solasola:
Let's try to educate some folks. Thats the reason we are here. Let's analyze niyi 19kw/19000w panel array. Is it really too much.

19KW of PV? I think it is flexing? Do I think it is too much? I can not say without understanding his use and motivations. But 19KW of PV is huge, it is easy to read waste into it. By the way, how much KWh does he generate per day? I have roughly 7KW for total independence from NEPA except for my AC.

truthbetold22:
Fool, your tv brightness only reduces a little and u save energy... What point are you trying to make exactly because you lost me here.. that you won’t enjoy ur tv on energy saving mode? Na wah o. Shey I don’t use solar in my house?

The whole world is crying save the planet, use less energy, African man says use as much as you can just like with everything else.

Ignorant people..

There are two reasons to go renewable. Conservation and Uninterruption. Some go into it to "safe the planet", others like me go into it to circumvent the failure of public utility and have power 24x7 in my house. For me, conservation is basically a collateral of my limited resources. If I get plenty dough, I will not bother about conservation, but my convenience first. I will therefore like to advise that you watch your language. That someone has made a conscious decision to spend his money in any particular way does not make him a fool. You make good points, but in the most inappropriate language many times. Watch your tongue and express your opinions with greater civility. It costs nothing.

Another case that will be impossible to win. If you will get a refund, you will need to show a receipt and you may need to bring the kidnapper to court to testify that the receipt is genuine and not forged by you.

ojeysky:
Looks like lithium market is going to be interesting this year, ofcourse with expectation for some disappointments as well. There is a 12v 200AH lifepo4 now at 190k its branded Pelton Lithium Ion Battery(google it). Had extensive discussion with seller and his sounds quite interesting. Any one trying this or have tried it already?

Has anyone here had any experience with this seller or his battery? There are others on Jiji, anyone had any experience with them?

ICraft:
purely DIY, I have a very stringent test process, first test for heaters with thermal camera, we then test for capacity( I have 180 liitokala Lii-500 capacity testers that can test 720 batteries per day. 4 batteries each) then we test for self discharge. out of lets say 10,000 cells, only about 4,0000 may pass. we don't solder cells, we spot weld to avoid corrosion. finally we use 4amp fuse wire to link all the cells to the bus bars. we also use active cell balancers lastly, a well caliberated BMS that you can trust. I dont expect any less than 5 years from my batteries. you are right my office is a factory, and its open to the diy community to come in, test and build packs for a litttle fee and go. all tools you need and more available. powered by 42 pcs 320 watts solar panels and 80KWH of 18650cells.

So can you build a pack for me 200AH 48V?

This guy has been laying curses on boko haram for a long time without any consequences for them. Maybe his curses have become diluted, otherwise Boko Haram should have ended by now. Fake prophet.

quest4s:
GURUS PLEASE HELP
Inverter 24v 2.5kva vs 48v 2.5kva which is better or is there no difference

Do 48v if you can afford it. It is less stressful for your system compared to 12v or 24v. It also allows you to use more solar panels on the same charge controller. Your wires will not be as hot and your contacts will not suffer so much burns from arc current. The only disadvantage is the minimum number of batteries required which is 4. You can minimize the cost by going for lower capacity batteries like 100AH.

Barezzi:
I put a timer switch in series with a victron BMV-712 battery monitor relay across the second switch(NO) as permissive to energize the contactor/operate the pump. The timer switch is set to close between 12pm to 1.30pm, while the BMV-712 is set to close at SOC > 85%.

The pump will ONLY switch on between 12pm and 1.30pm as long as the battery SOC is above 85%.
You don't want your pump switching ON anytime it likes, simply because water level is low e.g during the rainy season or poor weather.

I can manually override the timer and BMV by simply activating the NO switch. The float replaces the NC switch.

Good point. My setup at this point is similar. But, I use Home Assistant and Node Red to set up an automation that switches on my pump between 10am and 3pm if my SOC is 86% and my current to battery is higher than 10A. But when I was using NEPA to pump water, I allowed only the float switch to do the control. By the way, the node red and home assistant also run my water heater between 12noon and 4pm if my SOC is 96% and above and my battery current is higher than 20A.

ceaser:
I assume that by contactors, you mean Relay switches, yes?

Well, they work on similar principles but they are not exactly same. Contactors tend to be bigger, more powerful and work with higher power (current and voltage) compared to relays. https://www.springercontrols.com/news/contactors-vs-relays/

durodee:
Oga, can you please draw a schematic outline for us non-technical people?
Gracias !

Below is a schematic I pulled from the internet. The contactor is wired as shown. The two switches, red and green are the two switches that control the contactor. When they are both on, the contactor closes and supply power to the pump. To use it for float switch or as a switch, you keep one of the two switches closed by connecting the terminals together without a switch in-between. Then you connect the float switch (or any other switch) to the second switch. When your tank is full, it pushes up your float switch and makes it horizontal. This will disconnect the contact in the float switch and switch off the contactor. When the float switch drops and becomes vertical, the contacts will be made and switch on your pump. I actually leave the other switch connected so that I can turn off the contactor/pump whenever I wish. If you don't connect the second switch, you will have no control over the pump, only the float switch will do the control.

I use contactors frequently in my setup. I found them a better way to switch high current rather than replacing switches frequently. My normal switches just switch the contactors, not my loads.

adrusa:
Yes. The contactor will do the switching of the pump. The float switch will just switch the contactor. That way the high current needed to drive the pump will go through the contactor while only the very small current needed to switch the contactor will pass through the float switch. That way you will protect the float switch and not need to change it too often. I haven't had to change my float switch for about 5 years now. If the float switch powers the pump directly, it will get burnt and need to be replaced very frequently.

Yes. The contactor will do the switching of the pump. The float switch will just switch the contactor. That way the high current needed to drive the pump will go through the contactor while only the very small current needed to switch the contactor will pass through the float switch. That way you will protect the float switch and not need to change it too often. I haven't had to change my float switch for about 5 years now. If the float switch powers the pump directly, it will get burnt and need to be replaced very frequently.

dejidotun2000:
The float switch is in series with the contactor coil and will energize the contactor.

This saves the float switch from having to make and break the pump(motor current) therefore preserving the float switch contacts.

https://www.aliexpress.com/item/32912304617.html?spm=a2g0o.productlist.0.0.49344a30ONcgu6&algo_pvid=8d3a46c5-aebb-4084-87f3-6c02b6e7cace&algo_expid=8d3a46c5-aebb-4084-87f3-6c02b6e7cace-22&btsid=0a248338-7d48-4f80-8e70-ac37265b130b&ws_ab_test=searchweb0_0,searchweb201602_7,searchweb201603_55

Something like this, but you really don't need to by from Aliexpress as it is available at most local plumbing materials shops for between 1-3K.

earthrealm:
thanks @all for the contributions, the project is about 3months away, so am taking time to get info and material. and its a DIY ops
AHAAA, @adrusa. DIY sweet, abeg gimme the link for the exact float switch you bought. seen some on aliexpress though

Ceaser01:
Earthrealm, I have the following for your automation.

This is an overkill. A simple float switch will do. It will turn on the pump when the tank is empty to your setting and turn it off when it is filled to your desired setting. If you put a contactor in between, the float switch will last you for years. I use a setup like that for more than 5 years now and I never have to bother about my tank. It is set and forget.