Lithium Batteries [ Group Buy ]

itareanlnotani

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Due to Eskom's unreliability, I think its time for me to go completely offgrid.
I'm going be bringing in Lithium Iron Phosphate Batteries from China to do so.
Pricing will be similar to premium Lead Acid pricing in SA.

I've talked about this a few times in a couple of threads, and a few people have expressed interest in doing a group buy.
Before we start -

There are some caveats if you want to buy and use these batteries.

1) You need a charger that explicitly supports Lithium.
Voltages for Lithium are higher than for Lead Acid, and Lithium charging is a lot different to Lead Acid charging.

Lithium is a lot easier to charge than lead acid, as you just feed in till you reach the required voltage, then stop charging.
There is no peukerts law/curve to worry about, and Lithium is a lot safer to deal with - no hydrogen / explosion issues.


2) You'll need a disconnect relay for low voltage and high voltage to protect the batteries.
Lithium will be damaged if you discharge too low, and will be damaged if you charge too high. Adding extra protection to prevent this is excellent insurance to prevent chargers killing the batteries.


Example disconnect circuit - http://zeva.com.au/index.php?product=101
(also needs relays)

3) Lithium batteries need to be balanced.

I will be ordering battery balancing circuits for the batteries, this will be an extra cost.
Guesstimate roughly 5% of the battery cost, exact pricing to be determined still.

Balancing is essentially making sure that all the batteries in a pack get charged equally. Some batteries will charge faster, some slower. Balancing circuits ensure that all batteries reach the same charge.

Example balancers - http://www.ev-power.com.au/-Thundersky-Battery-Balancing-System-.html


4) I will need to know what voltage you require for charge/discharge.

The CALB Batteries I'm pricing, are 3.2V / 100Ah or 3.2V / 180Ah each.
You'll need to buy enough batteries for your KW required, and inverter charge rate.

48V inverters will require a minimum of 16 batteries.
36V inverters will require a minimum of 12 batteries.
24V inverters will require a minimum of 8 batteries.
12V inverters will require a minimum of 4 batteries.


5) I will need to know what sort of KW size you require.

Lithium Iron Phosphate works best at 20% - 80% usage from the data sheet DoD curves.
This means that you will only have 60% usable capacity if you wish to treat the batteries nicely, and have them last.
You can go higher or lower, but you will reduce cycles. 60%* appears to be the best bang for buck on the lifetime / usage according to my calculations.

This effectively means that you will need to buy 160% of the capacity you actually need.
This compares nicely to Lead Acid where best lifespan is in the 30% range, (and you need 300% of capacity required).

To cut a long explanation short - if you need 10KW of Lithium storage, you will need 16KW of battery*


*You can probably go another 10% extra to 15-85% for 70% usable capacity without too much issue, but I need to test in real life before I can recommend that.


6) I am not offering a plug and play solution (yet).

I am ordering batteries + copper connectors + battery balancers for the pack size you / I require.


- This is not an off the shelf solution.
- You will need to understand how to integrate these with your existing system.
- You will need Items #1, #3, and I strongly recommend #2 above
(I will be sourcing these as part of my install)
- You'll probably need monitoring for voltage, temp etc. eg a Victron BMS or similar product.
- If it works well, I will be looking at bringing in a complete solution (charger / batteries / bms), but this won't be until I have my own system running properly.



7) Shipping will be to Cape Town
You will need to arrange your own collection/ shipping from Cape Town if you are in other parts of the country, and are still interested, despite all my dire warnings above!

Timeframe will be for arrival mid-late August.


I strongly suggest that you read the ENTIRE thread here - https://forums.energymatters.com.au/solar-wind-gear/topic6186.html as it discusses the issues you'll be dealing with. Bonus points if you can guess who I am in the thread there ;)

This is a good overview also - http://www.pbase.com/mainecruising/lifepo4_on_boats


If you have read the above, understand and are still interested, then reply in the thread below with an indication of voltage and wattage required.


FAQ

Why only 100Ah / 180Ah?
Purely due to price. Higher capacity is substantially more at current pricing.

What charger do I need?
Suitable chargers are ones that can change the charge voltage, float values etc to appropriate values.
As a rule of thumb, the more expensive chargers support this, the cheaper ones do not.
eg Victron, Outback..

What batteries are they?
CALB 100Ah or 180Ah in blue plastic shell packaging.

http://en.calb.cn/product/show/?id-627 CALB 100Ah
http://en.calb.cn/product/show/?id-629 CALB 180Ah

Note that the batteries will have a *blue* shell casing.

Whats the expected pricing
Ballpark figures _excluding_ shipping/taxes/duties are about R1000 per 180Ah battery. I guesstimate this to roughly double when landed with costs, so R2000 per 180Ah / 3.2v battery. Final figures will likely be within R1500-R2000 depending on volume.
More units == cheaper overall pricing per unit. This also relies on the rand not taking a huge dive. Guesstimate values are calculated at R2 = RMB1

But thats still expensive!
You need roughly half the total battery capacity for Lithium than you do for Lead Acid, so its comparable per KW usable.

Lead Acid = 30% DoD = 3 x capacity required for usable storage requirements.
Lithum = 60% DoD = 1.6 x capacity required for usable storage requirements.

eg

You need 10KW of usable capacity.
You'd need 16KW of Lithium, or 30KW of Lead Acid..
 
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Gezza

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Damn useless multimedia design degree.

I tried reading all the info, but I'm no engineer.

When you can acquire point 6, I will join in on the fun.
 

The_Traveller

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Great Isheed !

In the event that the Inverter/UPS has a built in charger, how do you bypass this ?
 

itareanlnotani

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Great Isheed !

In the event that the Inverter/UPS has a built in charger, how do you bypass this ?

You'll need to purchase a suitable Inverter/Charger that supports Lithium and replace the existing inverter.
As a general rule, the more expensive ones do. The cheap stuff doesn't.
 

LazyLion

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Nice of you to do this. I wish I knew more about the subject... cos I would love to do this.
 

hj2k_x

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Nice of you to do this. I wish I knew more about the subject... cos I would love to do this.
Indeed. Good work.

When option 6 becomes reality, OP, I think you'll have people queuing up!
 

oober

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I've also considered this and might still do it...but from what I gathered it is still a bit experimental, especially the balancing.

What kW capacity will you be going for? What do you think about lead crystal, if LC works it would actually be easier to maintain and charge since you do not need any balancing. I did not look at costs of LC vs. LFePO4 though.
 

itareanlnotani

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I've also considered this and might still do it...but from what I gathered it is still a bit experimental, especially the balancing.

What kW capacity will you be going for? What do you think about lead crystal, if LC works it would actually be easier to maintain and charge since you do not need any balancing. I did not look at costs of LC vs. LFePO4 though.

Some example math for sizing;

I need roughly 20kWh of capacity;

My inverters are 24V, so I will be buying in multiples of 8 batteries (8 x 3.2 = 25.6V)
8 batteries of 3.2V @ 100A = wired in series to give 25.6V @ 100A / 2560kWh per "pack".
8 of the above packs in parallel to give a total of 800A @ 25.6V / 20480kWh

This will give me:
12.5kWh usable+- @ 60% DoD
14.3kWh usable +- @ 70% DoD

This will give me about 2 days runtime on my own solar install.

If I am in danger of discharging too much after a series of cloudy/ rainy days in winter, I can run a generator to recharge, as this makes far more financial sense than adding more batteries at current pricing.

I have looked at Lead Crystal, but I think LiFePO4 is a better solution.
Benefits of LiFePO4 are that the physical size is about 1/3rd that of Lead Acid.
Actual lifetimes for LiFePO4 should be longer also.
Voltage droop is minimal on LiFePO4, vs Lead Crystal.
Lead Crystal also needs an optimized BMS, so requirements are similar.

Comments made based on data here - https://www.gliderpilotshop.com/lead_crystal
 
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oober

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Some example math for sizing;

I need roughly 20kWh of capacity;

My inverters are 24V, so I will be buying in multiples of 8 batteries (8 x 3.2 = 25.6V)
8 batteries of 3.2V @ 100A = wired in series to give 25.6V @ 100A / 2560kWh per "pack".
8 of the above packs in parallel to give a total of 800A @ 25.6V / 20480kWh

This will give me:
12.5kWh usable+- @ 60% DoD
14.3kWh usable +- @ 70% DoD

This will give me about 2 days runtime on my own solar install.

If I am in danger of discharging too much after a series of cloudy/ rainy days in winter, I can run a generator to recharge, as this makes far more financial sense than adding more batteries at current pricing.

I have looked at Lead Crystal, but I think LiFePO4 is a better solution.
Benefits of LiFePO4 are that the physical size is about 1/3rd that of Lead Acid.
Actual lifetimes for LiFePO4 should be longer also.
Voltage droop is minimal on LiFePO4, vs Lead Crystal.
Lead Crystal also needs an optimized BMS, so requirements are similar.

Comments made based on data here - https://www.gliderpilotshop.com/lead_crystal

8 packs in parallel, any reason why you decided to go this route? Don't they have larger capacity batteries to reduce the amount of strings you will require?

Which brand of LiFePO4 are you planning on bringing in? You mentioned prices will be the same as premium LA, but that doesn't really say much. What will the ballpark price per cell be? Is is there some way for us to go and calculate this ourselves?
 

itareanlnotani

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Good questions :)

8 packs in parallel, any reason why you decided to go this route? Don't they have larger capacity batteries to reduce the amount of strings you will require?

See the newly added FAQ section.
 
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oober

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How much will the CA400 cost? Did you calculate costs for having to buy extra balancers for all those extra strings? You will have 64 batteries?! That seems quite a lot lol.
 

itareanlnotani

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See links in top post for example prices on balancers, they're fairly cheap compared to overall price. Eg In the r100-150 for the evplus inline ones, cheaper for chinese equivalents.
 

AfricanTech

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6) I am not offering a plug and play solution (yet).

I am ordering batteries + copper connectors + battery balancers for the pack size you / I require.


- This is not an off the shelf solution.
- You will need to understand how to integrate these with your existing system.
- You will need Items #1, #3, and I strongly recommend #2 above
(I will be sourcing these as part of my install)
- You'll probably need monitoring for voltage, temp etc. eg a Victron BMS or similar product.
- If it works well, I will be looking at bringing in a complete solution (charger / batteries / bms), but this won't be until I have my own system running properly.

.

Let me know when you have this as a 'plug n play' - including recommending someone who can do the job.

I'm not looking at total off grid - want to run my upstairs (lights in 4 rooms, 4 computers, router, TV, etc) for 4-5 hours and some outside lights, plus alarm and gate motor - want it to be pass-through like a UPS.

No kettle, fridge, stove, geyser, microwave, etc = those are already on gas/solar so not an issue.
 

JohnHay

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I would be interested depending on cost. I'll need to find a way to get the batteries to Pretoria though.

Currently I'm thinking of a smallish system 48V, so 16 X 100Ah.

lsheed I see you did mention Winston cells in another thread. On paper or pdf at least, they seem pretty good with 5000+ cycles at 80% DOD. In the EV forums they seem to do ok. Are their reputation still that much better than the rest?

Well at least your thread got me to register after many years of lurking on MBB. :)

John
 

itareanlnotani

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Will need to check pricing on the Winstons. They do have better cycle times (on paper) than the CALB, but in real world testing they both perform well. I'm hoping for > 10 year lifetimes @ 60-70% DoD cycles. (2000-3000 cycles).

Some talk about both on the energy forums forum here - https://forums.energymatters.com.au/solar-wind-gear/topic6219.html
I think consensus is that Winston exaggerates their cycle lifetimes, but both are good to use especially in a relatively nice light load environment for the batteries with solar energy storage usage.

In other news, it sucks that I get to Shanghai the day that the Solar show ends.
I was planning to go this year and get lots of info on ready to use systems.
I had a friend going, but now he's pulled out.
 
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