₦airaland Forum

NoMoreTrolling:
Hey Niyi, hope you're doing well!

Okay, let's play with the numbers:

8 units of quanta at 12v 200ah vs 2 battleborn 24v 50ah units.

QUANTA:
Usable amphour - 200ah (9.6kwh at 50% DOD)
Cycle life - about 500 cycles at 50% DOD (According to quanta datasheet)
Lifetime amphour = 500 cycles x 200amphours = 100,000 amphour

Battleborn:
Usable amphour - 50ah (2.5kwh at 100% DOD)
Cycle life - 3,000 cycles at 100% DOD (According to Battleborn Datasheet)
Lifetime amphour = 3,000 x 50 = 150,000 amphour


As we can see, theoretically, we should get more usable life out of the 2 small 24v 50ah, than the 8 12v 200ah quanta batteries.


Next, we must consider the possibility of failure:

Quanta (Lead Acid):
Failure occurs if the batteries aren't fully recharged often enough due to sulphation. This is more likely if the batteries are out of balance and charge up to varying voltages, likely leading to one or two batteries not getting to full charge.

Leaving batteries partially discharged over a long period of time can also lead to failure.

Obviously, low cell voltage also adversely effects capacity.

Battleborn (LiFePo4)
Irreparable failure can occur if cell voltage gets too low, which is mitigated with the internal BMS shutting off discharge.

Failure can also occur at high voltages, 4.2v per cell, but again, this is mitigated by the internal BMS shutting off charge

...

So in essence, you can leave your lifepo4 batteries at 50% state of charge and not be worried about capacity loss, while with lead acid, YOU MUST get all those batteries to a 100% state of charge as often as possible, else premature failure would occur.


The advantage of the 8 12v quanta batteries in this case vs the small 24v 50ah BB would be the backup time you would get while the quanta batteries are still in good shape. Running a 500 watt load on those 8 batteries, you would get 20 hours of back up time compared to the 5 hours of backup time you would with the 2 BB batteries. However, over the lifetime, the 2 BB batteries would give you more total hours of backup.



Recharge times:
Quanta Lead Acid:
8 12v batteries charging at the recommended C/10 charge rate, 40 amps, would take 10 hours to charge to full from empty or 5 hours to charge from 50% to 100%. This obviously doesn't account for the time you would need to spend in the absorption phase, which for most inverters is about 2 hours, or a factor of how ever long the bulk phase was. So you could be spending 8 hours to get from 50% to 100%, because that absorption phase is extremely important for lead acid.

BattleBorn:
Those 2 little 24v 50ah units can be recharged at C/2 rates and DO NOT NEED AN ABSORPTION PHASE, which means with 25amps, you'll be done charging in just 2 hours. If you don't mind taking a hit with your cycle life, then you can recharge at 1C during an emergency and have that battery full in just 1 hour. So instead of running your gen for 8 hours waiting for your battery to charge, you'd just need about 1 hour 30 mins of gen time to be back for another cycle.


This was just to show that 2 24v 50ah battleborn units can somewhat match the 8 12v 200ah quanta units. Obviously it would be better to have 4 12v 100ah battleborn units for a 48v system than 2 24v 50ah units.

I am doing more research into building lifpo4 packs from cheap cells since Battleborns are very expensive, but I truly believe lifepo4 is the future of solar, at least as the prices keep crashing downward like solar panels, hopefully.

wirinet:
I am also looking at building Lipo4 battery packs for inverters as they far out perform lead acid. Replacing lead acid batteries every 1 to 2 years is making inverter and solar set up as expensive as running generator, thereby discouraging many people from going solar or acquiring inverter systems.

Your analysis is very good and details but with slight corrections.
The capacity of a lead acid battery is heavily dependent on the rate of discharge. The 200ah specified by the quanta battery is at a rate of discharge of C/20. Most inverter and solar set ups discharges at far less than C/20, most times its between C/5 and C/10. Most people neglect this little detail in calculating battery capacity for lead acid. This is why most people complain they get less capacity than written on the battery pack.

Even though Lipo4 also suffer some loss of capacity with rate of discharge it is very small compared to lead acid.

Another fact with liPo4 is that charging voltage and discharge voltage has a huge impact on cycle life. Nominal voltage for LiPo4 is 3.2v, while maximum voltage is 3.6v. Charging to a maximum of 3.5v can double cycle life. Same thing too for minimum discharge, minimum voltage is 2.5v, discharging to 2.6v can also greatly increase cycle life.

One problem with lead acid which I learnt through experience is power wastage. Lead acid wastes a lot of voltage while charging. This is noticeable with a solar set up. When I measure open voltage with a 100w, 5a solar panel I read 4.2a in direct sunlight, but when I measure current going into my lead acid battery, it is usually around 3.0a. I am losing a whole 1.2a just charging the lead acid battery. When I measure current when charging lithium phosphate, I get more than 4.0a. It seems the internal resistance of lead acid is far higher than that of Lipo4.

The draw back with lithium batteries is that they are unforgiving if you don't handle them well. They are prone to explosions and fire if you overcharge, undercharge or if out of balance. That why proper charger and balancer is crucial.

mikeuz:
Please i just stumbled on this trend.so much technicality and an confused now.

I just need advice, i need an inverter system with solar panel that can help me power my appliances at home, alongside my refrigerator. Can anyone please advise the options available as well as affordability?

sathob:
Well, great people of FTA, I think I should start this on behalf of George_D because of the request made by others who have expressed interest in alternate electricity, especially solar energy. Our FTA independence is not complete if we are to suffer frequent power outages and been dependant on the nation’s electricity grid system always. I have read in this house many times, from members “PHCN don go off, so I will track later when they come back”. No one can run away from power outages in the main electricity grid – not even the west, it happens. Hence, we all should have alternate electricity and using renewable energy is, to me, the best. This means one can enjoy their FTA fully by being totally free and not “dom” (dominated).

Look at some advantages
• Lower or no electricity bills
• Compared to generator users, there is no fuel cost and stress of getting it and no fumes.
• People living in the remote locations where power is unavailable or too expensive to hook-up too can have electricity.
Just to mention but a few.

Without going into detail, one can enjoy electricity by means of using solar energy (energy from the sun), wind mill (using energy from the wind). Don’t forget, where there is frequent electricity supply from the utility company, you can store some energy for back up.

You will need the following to complete a solar project or back up.

1. Solar panels
2. Power Inverter
3. Charge controller
4. Batteries to store energy
5. wires and cables
6. Monitors/meters

The solar panel consists of cells called photo voltaic cells and these, covert the energy received from the sun to electricity in simple terms (this electricity is a direct current
d.c). The panels can last up to 20 years plus. The panels can be fixed, adjustable or of the tracking type. You can decide to go for a complete panel from manufacturers (already made) or build panels by yourself using solar cells- the latter is for the hobbyist. The panels are rated in watts eg 80w solar panel supplying 12v continuous at a given time

The inverter
Power Inverters are available in 3 basic designs, two of which I remember very well now – the one that out sinusoidal waves and those that are modified sign wave type (meaning not pure sine waves and do have limits when it comes to its application) . The power inverter converts your storage battery power into the 240 volts AC that runs your appliances. It is the heart of your solar energy system. Unless you only run 12 volt DC appliances you will need a power inverter to supply your AC. This is just the basics.

The Charge Controller
A Charge Controller is necessary to protect the batteries from over charging and supply them with the proper amount of energy to promote long battery life.

Batteries
Without Storage Batteries to store energy you would only have power when the sun was shining. There is a lot more to batteries than just the ordinary car battery. Yo may need to change batteries over the years.

Wires and Cables
Without the right size of cables, you are likely to experience inefficient transfer of power (greater losses) and overheating.

Meters
This is required to monitor the performance of your solar system.

Firstly, it is very necessary to know what gadgets you will be using (eg.tv, sat. receiver) and how long you will use how long you would have them on the solar power and how much energy your battery can store and which solar panel (rating in power) will supply the required energy.

A lot goes into calculating the cost of setting up a solar system. First one has to consider the period of usable sunlight available at their location to do this calculation. For us here close to the equator, we get about 7 to 8 hours or more of sunlight during dry season, just a rough estimate.

How do I know I need 100w or 80w or 300 watts solar panel for my project?

The power consumption of appliances is given in Watts. To calculate the energy you will use over time, just multiply the power consumption by the hours of use.

Eg. If I have 90W tv set which I want to use for 6hrs, 25W satellite receiver for the same period, and a 50W fan for 3 hours. What will be the energy required from the solar panels for the period?

1. the energy for each appliance is Watts x time (hours) = Wh

So, the watt hours for the tv = 90 x 6 = 540 Wh (watt hours)

Watt hours for sat. receiver = 25 x 6 = 150 Wh

Watt hours for fan will be = 50 x 3 = 150 Wh

2. sum the watt hours for the individual appliances ie. 540 + 150 + 150 = 840 Wh (watt hours)

This means that the solar panel will need to supply 840 watt hours of energy to the battery each day to cover the total power required by these appliances.

3. since there are bound to be losses in the system However, to account for natural losses, we multiply the result by 1.2 (this factor allows for natural system losses, assuming 85% efficiency). Therefore, we will assume the panels will actually need to be able to supply a total of
840 x 1.2 = 1008Wh

4. so, to supply 1008Wh of energy the panel we assume to receive 7 hours of sunlight will be rated at 1008 Wh / 7 h = 144W
So, I will need 144W solar panel to supply energy to my appliances above at the given time.

Regarding point 3, it also means, if I have a solar panel rated at 100W receiving sunlight for 7 hours a day, the total energy supplied considering 85% efficiency will be 100x7x0.85= 595Wh and not 700Wh

5. Your battery should be able to store 1008Wh of energy. Since batteries capacities are rated in Ah (Ampere Hours) you need to multiply Ah by the Volt rating to know the Watt Hour. Power(W) = Voltage (V) x Current (I) ; Watt hour = VxIxHour

Therefore Ah (which is I x h) = Wh / V = 1008 / 12 (the number 12 represents a 12v battery)
= 84 Ah

So it means you will need not less than a 84Ah, 12V battery (deep-cycle batteries, not ordinary car batteries) to do the job.

NB. Another way of calculating battery capacity is explained in this example. Should my battery be rated at 84Ah, 12V the watt hour (energy) will be 84Ah x 12 V = 1008Ah

It implies that the battery can supply a 150watt appliance for 1008/70 = 14hours

Pls don’t just play around with batteries they are dangerous.

pranil:
if you cycle the LiFepo4 between 3.5 and 2.6 ( instead of 3.6 and 2.5) essentailly you are not using the full capacity and hence the cycle life will go up

One much less understood point about lithium batteries is after the end of cycle life the batteries can be still used for less demanding applications ( less current and less reliability) as there is still 80 % capacity left while LEad acid will have to be scrapped or recycles completely;y

kiekie1:
Affordable package !

Saipro:
A bigger UPS!

totalgreen01:
Enjoying my li-ion DIY
will update soon

totalgreen01:
Enjoying my li-ion DIY
will update soon

totalgreen01:
Enjoying my li-ion DIY
will update soon

earthrealm:
omo!!!...guess it took you many days to line up all the batteries.
whats the total bank capacity?

wirinet:
Wow. What's the total capacity of your set up and how many s (series). Hope you are using a good BMS, preferably Batrium.
Proud of you.

Let me tell you some observations and suggestions;
1. Those wires to individual batteries are too thin, you need thicker wires.
2. Arrange your wires in a more orderly manner. It's safer and neater.
3. Look towards using spot welding. Soldering degrades li-ion batteries and sometimes loosens creating weak joints.

babaegun:
Hello Totalgreen01,

Please fill us in on the whole setup and the number of man hours involved. The price of those batteries and the best source to obtain them.

Will like to give it a try.

Cheers.

Saipro:
I really need to know how you got your welding done.
And to the house, I need a DIY-grade spot welder

totalgreen01:
1. I see ur point, but in this se0tup it's not required cause I am passing thru 60A BMS, for 14s each will do a max of 4.2amps which is fine for such tiny cables..... I ran my A/C last night the cable was not even warm

2. will do, just running a test last night thanks for the observation

3. I do have a spot welder, and I have been welding for a while now, only on very small packs... u should NOT do spot welding on such large packs, in fact NEVER spot weld your large packs, for Li-Ion if one cell goes bad(short-circuit ) then like me you will kill all 80cells in the pack, I had to fuse all the cells, but another option is to spot-weld the fuse which is too tedious for an old eye like mine

thanks, I do appreciate your suggestions and observations

earthrealm:
how would you know, if one batt or even a couple of batts go bad??, in your bank, how many need to go back before the effect becomes noticeable

totalgreen01:
Enjoying my li-ion DIY
will update soon

Saipro:
Brand and model of inverter?

JUO:
Fangpusun xtm 4000

GeorgeD1:
whoa! totalgreen! you finally did it bro!
congrats and well done for keeping the dream alive.
cheers!!!

totalgreen01:
My Oga,
thanks

Saipro:
Guess they had a manufacturing contract with Studder. All of sudden, I feel like trying one out. I refuse to accept this temptation.

dgr8truth:
Please test the bms to make sure it will do its work. Especially the overvoltage protection.