Selecting a solar lithium battery

[Isetech]

It seems once again, no apples with apples comparisons, only apples with oranges and pears with grapes.

What are the key factor to consider.

The battery capacity in amp/hr and KWh

Cycle life @ the C rating.

The normal and max charge/discharge current.

The type of cells being used in the battery.

The communication with the inverter.

How many you can connect in parallel.

Working temperature.

The warranty.

Very very important, the support and availability.

[Isetech]

The C rating of the battery, which is better?

Hubble

New Li-ion Prismatic Cells

3000 Cycles @ 100% DOD, Above 6000 cycles @ 50% DOD

New Li-ion Prismatic Cells

Or

Sunsynk

LiFePO4,Lithium Iron Phosphate

6000 Cycles @ 80% DOD / 25°C / 0.5C, 60% EOL

So if you increase the Sunsynk to 1C then it would only offer 300 cycles, it would be the same specs?

I am trying to understand which would be a better buy, they are both the same price, Hubble a little more expensive.

If it were the support, the company I am dealing with for the Sunsynk would be my choice.

It seems they both have the same cells, the communication is better between the Sunsynk inverter and the Sunsynk battery and I hear if I use the Sunsynk battery with the Sunsynk inverter there could be a better warranty period on both products.

DO you have any other suggestions or comments with regards to selecting a battery for the Sunsynk inverter.

Some say the Deye and Sunsynk are the same inverter out the same factory, unfortunately I will only be able to comment on that once I have the inverter and battery setup on my work bench.

[Isetech]

The next question -

3000 Cycles @ 100% DOD, Above 6000 cycles @ 50% DOD

6000 Cycles @ 80% DOD / 25°C / 0.5C, 60% EOL

Lets try get an apples for apples comparison @ 25degreesC :

If both batteries had 3000 cycles @ 100 % DOD, what would be the C rating of the Sunsynk battery?

IF both batteries had 6000 cycles A 80% DOD what would be the C rating of the Hubble battery?

If both batteries had 6000 cycles @ 100% DOD what would the EOL % value be?


What makes the one battery better than the other, taking into consideration that we are going to be installing Sunsynk inverters for our customers.

The shape of the cells, hubble indicates the use of prismatic cells? I would need to find out the shape of the Sunsynk cell, I would think by now they are also using prismatic cells.

The capacity of the individual cells? Could the Hubble battery be using a higher amp/hr cell or more cells to give it a 1C rating and +/- 16 year design life?

Would that indicate that the Sunsynk has a 30 year design life @ 6000 cycles?

The communication between the inverter and the battery and the software for the monitoring?

The make of the cells, Hubble indicate they using BYD ? I somewhere that Sunsynk are using a rebranded BYD battery, I would need to verify this statement.

Just so many questions. I am glad I am at that point where people cant baffle me with all the bullshyte I hear or read. So many experts in this field, trying to find that person who has a little more knowledge than the general ramble, can prove to be a challenge.

[Justloadit]

Very difficult to compare batteries, as each supplier cherry picks the specifications they wish to hand to customers.

The 'C' rating refers to the charge value/capacity for reliable battery life.
Charging Lithium at 1C, will require careful monitoring of cell temperature, and reducing current(C) as the temperature rises.
Un-monitored battery temperature would recommend a below 0.5C

[Isetech]

Been doing more research into batteries today.

I still cannot find what makes one 5 kwh lithium battery better than another brand.

It seems that all batteries are capable of 1C, it just cuts the life span in half.

So if a battery offers 1C capabilities, you will notice it only has a 3000 cycle life span.

So the battery offering 0.5C will have a 6000 cycle life span.

Prismatic cells are not a selling point, like BYD cells used by most reputable brands to build their batteries using prismatic cells.

I am at the point were I believe it boils down to the compatibility of the battery to the inverter. Using a Sunsynk battery with a Sunsynk inverter just makes more sense. I am sure the Sunsynk is rebranded battery spec'd to work with the inverter.

There is a R2000 difference and something else to consider is the delivery cost and courier fees if the battery fails. It starts adding up. Where you source these products could make or break the sale.

[Isetech]

Looking at the spec sheet of the Sunsynk battery, it has a normal charge/discharge rate of 50 amps and a max charge discharge rate of 100 amps. How often would you require your battery to charge or discharge your battery at the max 100 amps? As mentioned then we have the temperature to consider, the quickest way to kill any battery is heat.

Something else to consider, it's gona give you less than 1 hour of backup, so I would say a really badly spec'd system would require a 1C battery.

[Isetech]

How do companies determine the C rating of their batteries.

The capacity of each cell?

The physical size of the cell?

The number of cells in the battery?

The BMS firmware?

Maybe the 1 C battery has cooling fans and the 0.5C battery not?

If the battery is rated at 100 amp/hr battery, using prismatic cells and the same type of cells (BYD).

What am I missing?

[Justloadit]

Batteries usually do not have any fans, so battery assembly probably plays a role in the temperature build up with in the pack during charging/discharging.
Majority of battery packs are made up of the 18650 single cell.
They come in a variety of ampere capacity.
By placing many in parallel, will give the battery ampere capacity in Amps. Then by placing a number of these packs in series, will give you the voltage of the battery pack. The BMS is then wired to each bank of parallel packs to ensure that the pack gets the correct current to match the full pack.
The Tesla battery packs have water ways between the cells, which are kept at a constant temperature with a cooling liquid, and hence the reason they can be quickly charged as the individual cells are cooled down.

[Isetech]

How do you achieve 1C rating, by using more cells in parallel and derating the battery to as lower kwh rating or installing systems like heat sinks or a radiator systems ?

Are prismatic cells made up of 18650 cells?

I heard something interesting on the weekend, if you are selling lithium batteries and using "seconds" would you be required to advertise that your batteries are sold as "used " or could you still sell them as newly built or some other lingo to dodge the fact that your cells are not 1 st generation or off the production line ?

[Justloadit]

How do you achieve 1C rating, by using more cells in parallel and derating the battery to as lower kwh rating or installing systems like heat sinks or a radiator systems ?

the 1C refers to the battery capacity. Adding more cells in parallel basically increases the value in amperes of the battery capacity. Using the terminology of 'C' makes the statement universal to any battery, where you would multiply the 'C' by the battery capacity in Amperes

Are prismatic cells made up of 18650 cells?

Not necessarily.
A prismatic lithium battery, features a cell that has been encased in either aluminum or steel, mainly for the purposes of increased stability.

[Isetech]

I am trying to figue out how one manufacturer sells a battery with a 0.5C and another a 1C, but they are both 5 kwh and both use BYD cells?

From the little knowledge I have acquired about lithium batteries, the only way I can see that you could achieve a higher C rating is if you have a cooling system in place.

The one has increased the warranty to 10 years and the other has reduced the cycles to 3000 but indicates a 15 year life design.

How do you cut through all the bullshit and get the apples to compare apples with apples or 5 kwh with 5 kwh?

Deep cycle batteries had thicker platers and bases, what makes a lithium battery a good battery, what a the key point to identify when selecting a good quality lithium battery?

If I have ever had to deal with an industry that tries to baffle customers with bullshit, this solar industry certainly takes the cake with the cherry on top.

What do we know about lithium batteries, the harder they work the lower the cycle life. Can we agree that if a battery is advertised at 1C with 3000 cycles, then a 0.5 C battery advertised at 0.5C at 6000 cycles, would also be capable of 1C rating if advertised at a max of 100 amps (for a 100 amp hour battery) if we reduce the cycles to 3000 cycles?

[Isetech]

I hear chatter about, lithium batteries being sold which are not off the production line, how could you verify if the cells in your battery pack are off the production line or if they repurposed?

A QR code on the cells maybe, considering a seal would be fitted to all batteries, how would you verify the origin of the cells used in your battery?

This could become a huge problem as older batteries are decommissioned.

[Justloadit]

There are also many poor quality and incorrectly marked cells.
If they sound cheap then there is something wrong!
Keep to the known name brands, they will not compromise their quality for a cheap battery, the investment is just too high.

[Isetech]

Its seems the challenge to get credible information out of battery manufacturers and suppliers is a lot more difficult than I thought.

You get to listen to a lot of "please hold your call is important to us" or "please hold why I redirect your call" or some tune while the technical person you are speaking to has to find a technical person who can relay the information to the technical person who has very basic technical knowledge.

Now I know why we are sitting with really badly designed R150 000.00 solar systems

[Isetech]

Cycle life: determined by the depth

Sunsynk: 6000 Cycles @ 80% DOD

Hubble: 3000 cycles @ 100% DOD and 6000 cycles @50% DOD

Other than the 10 year warranty if used in combination with the inverter, the sunsynk just doesn't seem to stand achance against the Hubble.

Even the price, I can get a Hubble battery R2000 cheaper than the Sunsynk.

The question: will the Hubble battery communicate with the new Sunsynk data logger and software?