Hi Community, it's a very busy start to 2023 for a whole host of reasons but I had some very rare spare time & I thought to describe a very important aspect of battery purchasing & just general understanding. 

What is C rating of a lithium battery? 

It's the ability for the battery to deliver the goods 🤣

Let me explain: If a battery is 1C it means it can deliver it's entire kWh rating all at once instantaneously without limits. 

If a battery is 0.5C means it can only deliver half of its rated kWh rating at once. 

The battery manufacturers keep this info very hidden & we get the usual way they try to confuse you by description. So 5kWh = 100ah so meaning 100amps for an hour.

However, let's use Pylontech & FelicitySolar as examples of 0.5C. They don't say on the label 0.5C. They will say maximum discharge 100a, Maximum continuous discharge 50a. It can discharge 100a for a few seconds then it's BMS will stop discharging because it cant do that continuously. 

Why its so important? 

So here is where it gets interesting. You want to buy an inverter it's the 12kW Sunsynk inverter & you plan on 2 X Felicity solar 8kWh batteries. Because your think 🤔 16kWh of energy paired with 12kW inverter power good pairing ???

Absolutely not!!! Same as a Pylontech user could tell you. These are 0.5C or half C rated. Take the 16kWh ÷2 = 8kW available continuous power availability. So your 12kW Sunsynk will draw too much from this battery combo. Yes you can limit that inverter output on the inverter. However, so many ppl think there is zero imitation. 

Read the fine print on the data sheet & be aware of its meaning. 

To help ppl make a good choice I have attached the Felicity Solar battery data sheet below as well as the FreedomWon battery. The FreedomWon is just not apples for apples in comparison. 

Please feel free to add or comment but we need to bust myths & get good outcomes. We spending our hard earned cash on this equipment. Know what you buying & what it can & cannot do. 

Edited January 23, 20233 yr by Steve87

Has anyone drawn up a list of the most popular batteries, with their relevant C ratings?
May be a useful quick reference for some. Thanks for the info above, very helpful.

Something I have been wondering though. Given a rating of all 1C...
Is it better to have one 8KWh battery, or 2 x 4/4.8KWh batteries when you are considering an installation?

14 minutes ago, Chaos said:

Has anyone drawn up a list of the most popular batteries, with their relevant C ratings?
May be a useful quick reference for some. Thanks for the info above, very helpful.

Something I have been wondering though. Given a rating of all 1C...
Is it better to have one 8KWh battery, or 2 x 4/4.8KWh batteries when you are considering an installation?

There was a spreadsheet on MyBB that had this info, will try and dig it up. 

All depends on horses for courses. I still like a good quality 1C battery. 

What's further to this discussion is why the C rating is such? It's based on the cells & the BMS & for different reasons.

Will elaborate further in a bit. 

I am thinking of purchasing Freedom Won 5/4 home. Discharge current 3C (300amps max) (240amps cont.) Charge current 1C (100amps) very impressive for 5kwh. 10 Year warranty stated wonder if their will be fine print🤔 for the load shedding cycles currently. 

That can't be right?
https://www.freedomwon.co.za/lite-home-5-4/

11 hours ago, TaliaB said:

I am thinking of purchasing Freedom Won 5/4 home. Discharge current 3C (300amps max) (240amps cont.) Charge current 1C (100amps) very impressive for 5kwh. 10 Year warranty stated wonder if their will be fine print🤔 for the load shedding cycles currently. 

That cant be correct. Please see link that Chaos shared.

I got the above data sheet from the Freedom Won site maybe a misprint thought it was odd that the 5/4 has the same discharge rating as the 10/8 thanks Chaos for pointing that out then i will rather go for the 10/8 as i am running a 8kw Deye and 12 x 455 solar panels

9 minutes ago, TaliaB said:

I got the above data sheet from the Freedom Won site maybe a misprint thought it was odd that the 5/4 has the same discharge rating as the 10/8 thanks Chaos for pointing that out then i will rather go for the 10/8 as i am running a 8kw Deye and 12 x 455 solar panels

The 5/4 is certainly a 1C battery, even if you halve the discharge current given on that sheet. A 100ah battery that you can charge at 100A and continually discharge at 120A. The latter is not recommended for a full load shed, but it is helpful to be able to burst up to that limit.

Another thing to check with any battery is that your inverter can do the job. I have a 10/8, but limits on my inverter mean that I can never charge it or discharge it at it's maximum rating. This doesn't hurt me in practice, but it does limit my bragging power a bit.

Edited January 26, 20233 yr by Bobster.

Deye 8kw kan do 190a charge 190a discharge that should be ok for the 10/8 what do you think?